4508 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

PART VII
Appendix A
Guidelines for Maintenance of Electrical Equipment
A.1 In case of electrical appliances, manufacturer’s instructions for the usage and
maintenance of the equipment should be strictly followed.

A.2 The detailed/working drawings of all the components of electrical installations

should always be available with the maintenance unit. Following records should
be available.
(a) Manufacturer’s name.
(b) Nameplate of the equipment and its salient features such as capacity, rating
etc.
(c) Manufacturer's recommendations regarding availability/usage of spare
parts.
(d) Manufacturer's recommendations for periodical maintenance and post fault
maintenance.
(e) Details of the maintenance operations performed in the past.
A.3 Care should be taken while selecting replacement parts. The spare parts should be
correct and suitable, preferably as recommended by the manufacturer of the
installation. During the placement of order for the supply of spare parts, nameplate
particulars and serial number should be quoted.
A.4 The space where the equipment is kept should be clean and properly ventilated.
Equipment should not be disturbed needlessly. Before cleaning, the equipment
should be made dead. For internal cleaning a section cleaner should be used.
A.5 Covers and doors should not be left open unnecessarily during maintenance.
Afterwards they should be promptly and correctly closed and locked.
A.6 Before removing the covers and connections, all covers and cable terminations
should be marked to ensure correct replacements. Disturbed connections and
temporary connections should be marked to facilitate re-connection. Temporary
connections and markings should be removed before the installation is put to use.
A.7 Those connections which have not been disturbed should also be checked for
soundness and overheating.
A.8 All insulations should be regularly checked. Solid insulations should be checked
for cracks and other defects. Fibrous and organic insulations should be checked
for sign of blistering, delamination and mechanical damage. For insulating oils the
interval between tests should be carried out as per the recommendations of the
manufacturer and keeping the adverse environmental conditions in mind.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4509

A.9 It should be ensured that the earthing connections are sound and all contact screws
are tight.

A.10 During the examination of interlocks it is necessary to take precautions to prevent

danger to plant or persons in the event of malfunction or inadvertent operation. A
person responsible for checking and maintaining any interlock system should have
thorough knowledge of the extent, nature and function of the interlock.

A.11 If the equipment is ventilated then it should be ensured that the airflow is smooth
and not restricted. If filters are provided, they should be cleaned or replaced as
necessary.

A.12 The standby system for tripping and closing supplies should always be kept in
good order. Indicators and alarms should be maintained in time with the
manufacturer's instructions.

A.13 Tools, spares and instruments should be stored near to the installation. These
should be regularly checked against an inventory.

A.14 Before the start of maintenance of the circuit switches it should be ensured that all
incoming and outgoing main auxiliary circuits are dead and remain so during the
maintenance. Overheating of the circuit switches is the root cause for faults.
Overheating may be caused by inadequate ventilation, overloading, loose
connection, insufficient contact force and malalignment.

A.15 Some circuit breakers are not intended to be maintained, such as miniature circuit
breakers (MCBs). Such items should not be dismantled for maintenance. These
should be renewed periodically.

A.16 For the maintenance of fuses periodical inspection should be done for correct
rating, security, overheating and correct location/orientation. Element of
renewable fuses should be renewed when the deterioration is apparent. The
availability and correct replacement of fuse links should be ensured.

A.17 If a fuse link of certain rating has failed and is replaced, then all fuse-links of
same rating apparently subjected to the fault should be destroyed and replaced by
new fuse links.

A.18 In order to be reasonably sure that circuit breaker is capable of operation when
required, these should be tripped and reclosed at regular intervals. Tripping should
be proved manually and where possible electrically via the protective relay
contacts. The leakage of oil, sign of corrosion, and any unusual smell which may
indicate over-heating should be detected through inspections.
4510 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

A.19 Timing devices are mostly designed for specialist maintenance. These should not
be dismantled for maintenance or overhaul purposes unless specifically
recommended by the manufacturers'. Actual timing periods should be verified
with set values and application requirements.

A.20 In case of cable boxes and terminations, security of mounting and earthing should
be examined. Exposed tails should be inspected for good conditions of insulation
and freedom from moisture.

A.21 Battery cells should be inspected for shedding of active material, sedimentation
and buckling of plates. Level of electrolyte should be regularly checked and the level
should be corrected with distilled water.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4511
PART VIII
Chapter 1
Electrical and Electronic Engineering Services for Buildings
1.1 Introduction

1.1.1 Scope

The provisions of the Code presented in this Chapter, cover the Electrical and Electronic
Engineering Services for Buildings to ensure that the related installation work becomes
perfect and safe for the persons residing in and around the building. The term safe means
safe for the persons and safe for the properties.

Provisions of the Specifications are to set minimum standards for Electrical and
Electronic Engineering Installations in various Occupancy categories of buildings, as
described in Part 3 of this Code, including annexes and premises. All the systems and
equipment intended for the supply of normal power and standby power to all these places
are covered by the provisions of this Code.

The provisions of the Code for various Electrical and Electronic Engineering systems
and/or installations for the buildings include, but not limited to:
(a) Lighting and illumination.
(b) Fans, cooling and heating.
(c) Normal and standby power supply.
(d) Supply system and feeder for lifts/escalator/moving walk, including protection.
(e) Cable television distribution.
(f) Electronic access control.
(g) Burglar alarm/CCTV monitoring/security.
(h) Electrical cables/conductors and equipment.

(i) Switches, sockets, other accessories.

(j) Cables and conductors in a building that connect to the supply of electricity.

(k) Electrical protection system.

(l) Earthing system of an electrical installation.

(m) Lightning protection of a building and its electrical installation.

(n) Fire alarm.

(o) Multi-media communications, data communications and telecommunications.

4512 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Electrical wiring/cabling form a major part in the above mentioned installation works.
Electrical wiring/cabling must be reasonably safe to persons and property. Installations,
alteration, or extension of Electrical wiring/cabling systems conforming to the provisions
of this Code shall be deemed to be reasonably safe to persons and property.

The provisions of the Code in this Chapter do not cover Installations in ship, water craft,
railway rolling stock, aircraft, or automotive vehicles and recreational vehicles,

1.1.2 Designing an Electrical and Electronic Engineering Installations in

Buildings and Related Structures

The provisions of the Code presented in this Section are not meant to provide adequate
information to design Electrical and Electronic Engineering Installations and Systems in
Buildings and related structures. These should not be taken to be adequate or complete
for the efficient design work of installations.

Such design work, the required features, detailed technical specifications, schedule of
items etc., should be obtained through the services of an engineer adequately qualified in
this area. Applications of energy efficient appliances should be kept in mind while
preparing electrical design of a building or related installations.

1.1.3 Terminology and Definitions

This Section provides an alphabetical list of the terms used in and applicable to this
Chapter of the Code. In case of any conflict or contradiction between a definition given in
this Section and that in Part 1, the meaning provided in this Section shall govern for
interpretation of the provisions of this Chapter.

ACCESSORY A device associated with current using equipment or with the

wiring of an installation; for example, a switch, a plug, a socket
outlet, a lamp holder, or a ceiling rose.

ALIVE See LIVE.

APPARATUS Apparatus means Energy Efficient Apparatus. Electrical

apparatus including all machines, appliances and fittings in
which conductors are used or of which they form a part.

APPLIANCE Appliance means Energy Efficient Appliance. An item of electric

current using equipment other than a luminaries or an
independent motor.

BDB Branch-Distribution Board located in the same floor of a building

and connected to one of the SDBs in the same floor.
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BRANCH A branch circuit supplying energy to one or more outlets to

CIRCUIT, which appliances are to be connected; such branch circuits do not
APPLIANCE have any permanently connected lighting fixtures except those
that are integral parts of the appliances themselves.

BRANCH A branch circuit that supplies a number of outlets for lighting

CIRCUIT, and/or appliance.
GENERAL
PURPOSE

BRANCH A branch circuit that supplies only one utilization equipment.

CIRCUIT,
INDIVIDUAL

BUNCHED Cables are said to be bunched when two or more are either
contained within a single conduit, duct, ducting, or trunking or, if
not enclosed, are not separated from each other.

CABLE PVC insulated copper cables having copper cross section of 1

mm2 and above. A length of single insulated conductor (solid or
stranded), or two or more such conductors, each provided with its
own insulation. The insulated conductor or conductors may or
may not be provided with an overall mechanical protective
covering.

CELING ROSE A ceiling rose is used for terminating the point wiring for a Light
or a Fan in the ceiling. It has brass terminals in which incoming
cables are terminated using brass screws on the terminals and the
outgoing flexible cables get connection through the screw
connections.

CIRCUIT An assembly of electrical equipment supplied from the same

origin and protected against overcurrent by the same protective
device.

SUB CIRCUIT, An outgoing circuit connected to one way of a distribution board

FINAL CIRCUIT or a fuse board and intended to supply electrical energy, to one or
more points, to current using appliances without the intervention
of a further distribution fuse board other than a one-way board. It
includes all branches and extensions derived from that particular
way in the distribution board or fuse board.
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CIRCUIT A device designed to open and close a circuit by non-automatic

BREAKER means and to open the circuit automatically on a predetermined
overcurrent, without injury to itself when properly applied within
its rating.

CIRCUIT A device used to break a circuit during over current or short

BREAKER circuit condition. An LV Circuit Breaker is used in a low voltage
distribution system and an HV Circuit Breaker is used in a high
voltage distribution system.

CORD, A flexible cable having large number of strands of conductors of

FLEXIBLE small cross-sectional area with a soft PVC insulation. Two
CABLE flexible cords twisted together may be termed as twin flexible
cord. However, some flexible cords are made following the style
of a twin core PVC insulated copper cables but much soft and
flexible.
CUTOUT Any appliance for automatically interrupting the transmission of
energy through a conductor when the current rises above some
predetermined value. A cutout contains a part for holding either
fuse wire (rectangular cross section type) or a part for holding
tubular fuse (cylindrical body rectangular cross section type).
(see FUSE)

DB Distribution Board. This may be the box where the main

incoming cable enters and terminates from the main service feed
connection. The SDBs get feed from a DB.

DEMAND The ratio of the maximum demand of a system, or part of a

FACTOR system, to the total connected load of the system or the part of
the system under consideration.

DUCT A closed passageway formed underground or in a structure and

intended to receive one or more cables which may be drawn in.

EARTH The conductive mass of the earth, whose electric potential at any
point is conventionally taken as zero.

EARTH A metal plate, pipe or other conductor electrically connected to

ELECTRODE the general mass of the earth.

EARTH LEAD The final conductor by which the connection to the earth
WIRE electrode is made.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4515

EARTH The conductor, including any clamp, connecting to the earthing

CONTINUITY lead or to each other, those parts of an installation which are
CONDUCTOR required to be earthed. It may be in whole or in part the metal
(ECC) conduit or the metal sheath or armour of the cables, or the special
continuity conductor of a cable or flexible cord incorporating
such a conductor. ECCs of appropriate size must run from an
MDB to its DBs, from a DB to its corresponding SDBs, from an
SDB to the Switch Boards under this SDB, from an SDB to the
BDBs if there are any, from a BDB to the Switch Boards under
this BDB, from an SDB or a BDB to the Sockets under this SDB
or BDB.
EDB Emergency Distribution Board. This may be the box where the
main incoming cable from the Emergency or Standby Generator
Panel enters and. The ESDBs get feed from a EDB.
EFDB Emergency Floor Distribution Board located in each of the floors
of a multistoried building. The EDBs get feed from EFDB.

ENGINEER-IN- An engineer responsible for implementation/execution of the

CHARGE work of a building or a project. Such an engineer is expected to
have significant knowledge in Electrical Engineering, Electrical
Construction, Measurement, Codes and Practices of such work
and availability of different materials needed for the
construction.

FDB Floor Distribution Board located in each of the floors of a

multistoried building. The DBs get feed from FDB.

FUSE A device that, by the fusion of one or more of its specially

designed and proportioned components, opens the circuit in
which it is inserted when the current through it exceeds a given
value for a sufficient time. Fuse is generally made of fusible
wires of appropriate ratings which is either mounted inside glass
tubes or porcelain tubes or on a two terminal cutout.
FUSE SWITCH A composite unit, comprising a switch with the fuse contained in,
or mounted on, the moving member of the switch.
LIGHTING A device for supporting or containing a lamp or lamps (for
FITTING example, fluorescent or incandescent) together with any holder,
shade, or reflector; for example, a bracket, a pendant with ceiling
rose, or a portable unit.
4516 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

INSULATION Suitable non-conducting material, enclosing, surrounding or

supporting a conductor. Usually PVC, polymer, specially treated
rubber.

LIVE Electrically charged so as to have a potential different from that

of earth. Also known as ALIVE.

LUMINAIRE A complete light fitting consisting of lamp, holder, starting gears,

reflectors, housing and mounting accessories.

LT / LV and HT/ LT or LV in this document indicates 230 Volt single phase and
HV 400 volt 3 phase. HT or HV in this document indicates 11 kV
Line to line 3 phase system.

MDB Main Distribution Board. This is the distribution box where the
main incoming cable enters and terminates from the main service
feed connection of a large building. The FDBs get feed from
MDB.
OVER-CURRENT A current exceeding the rated current. For conductors, the rated
value is the nominal current carrying capacity.

PANEL BOARD A single panel or a group of panel units designed for assembly in
the form of a single panel including buses, automatic overcurrent
devices, and with or without switches for the control of light,
heat, or power circuits, designed to be placed in a cabinet or
cutout box placed in or against a wall or partition and accessible
only from the front.

PLUG A device carrying metallic contacts in the form of pins intended

for engagement with corresponding socket contacts and arranged
for attachment to a flexible cord or cable. A plug may contain
tubular fuse inside it although some plugs do not contain fuse.

POINT (in wiring) A termination of the fixed wiring intended for the connection of
current using equipment e.g., a Light, a fan, an exhaust fan.

SDB Sub- Distribution Board located in the same floor of a building

and connected to the DB. The BDBs get feed from SDB.

SERVICE The conductors and equipment required for delivering energy

from the electric supply system to the wiring system of the
premises served.
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SWITCH A manually operated device for closing and opening or for

changing the connection of a circuit. A 5A SPST switch is used
for the control of a Light or Fan point. A 5A SPDT switch is also
used for the control of a Light or Fan point.

SWITCHBOARD An assemblage of switchgear with or without instruments; the

term, however, does not apply to a group of local switches on a
final sub-circuit where each switch has its own insulating base.

SWITCHGEAR Main switches cutouts or fuses, conductors and other apparatus

in connection therewith, used for the purpose of controlling or
protecting electrical circuits or machines or other current using
appliances.

1.1.4 Voltage Ratings

The provisions of the Code specified in this Chapter covers installations utilizing nominal
voltage not exceeding 415 V AC between conductors or 240 V AC to earth. The nominal
voltage in Bangladesh is 230 volts AC single phase and 400 volts AC 3 phase.

1.2 Lighting and Illumination

1.2.1 Determination of Illumination Levels for Different Application (Principle of

Lighting )
The essential features of an efficient lighting system are:
(a) Visual comfort through adequate illumination of the working surface,
(b) Prevention of glare,
(c) Avoidance of shadows, and
(d) Ease of maintenance.
The design of a lighting system shall involve:
(a) careful planning of the brightness and colour pattern within both the working
areas and the surroundings so that attention is drawn naturally to the important
areas, so that details can be seen quickly and accurately, and so that the
appearance inside the room is free from any sense monotony,

(b) use of directional lighting to assist perception of task detail,

(c) controlling direct and reflected glare from light sources to eliminate visual
discomfort,
4518 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(d) minimizing flicker from certain types of lamps and paying attention to the
colour rendering properties of the light,
(e) the correlation of lighting throughout the building to prevent excessive
differences between adjacent areas, so as to reduce the risk of accidents, and
(f) the installation of emergency lighting systems, wherever necessary.
The general impressions associated with different illuminance and colour appearances of
light are shown in Table 8.1.1. The various colour rendering groups with examples of use
are presented in Table 8.1.2.
Table 8.1.1: General Impressions Associated with Different Illuminance and Colour
Appearances

Illuminance (lux) Associated Impression (Colour Appearance)

Warm Intermediate Cool
≤ 500 Pleasant Neutral Cool
500 – 1000 Pleasant to Neutral to Pleasant Cool to Neutral
Stimulating
1000 – 2000 Stimulating Pleasant Neutral
2000 – 3000 Stimulating to Pleasant to Neutral to Pleasant
Unnatural Stimulating
≥ 3000 Unnatural Stimulating Pleasant

Table 8.1.2: Lamp Colour Rendering Groups

Colour Range of Colour Examples of Use

rendering Index Ra Appearance
Group
Cool Textile industries, paint and printing
industries
1 Ra ≥ 85 Intermediate Shops, hospitals

Warm Homes, hotels, restaurants

70 ≤ Ra < Intermediate Offices, schools, department store, fine

2
85 industrial work
40 ≤ Ra < Interiors where colour rendering is of
3
70 comparatively minor importance
Note: Certain applications, e.g. colour matching, may be extremely critical with regard
to the colour rendering properties of the lamps used. Here, the minimum colour
rendering index used shall be 90.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4519

1.2.2 Planning the Brightness Pattern

The brightness pattern seen within an interior is composed of three parts.

(a) Brightness of the task itself.

(b) Brightness of the immediate background of the task and

(c) Brightness of the general surroundings of walls, ceiling, floor, equipment,

furnishing etc.

1.2.2.1 The illumination of all work areas within a building shall be a minimum of 150
lux.

1.2.2.2 Where work takes place over the whole utilizable area of a room, the general
illumination over that area shall be reasonably uniform and the diversity ratio of
minimum to maximum illumination shall not be less than 0.7. This diversity ratio does
not however take into account of the effects of any local lighting provided for specific
tasks.

1.2.2.3 When the brightness appropriate to an occupation has been determined, the
brightness of the other parts of the room shall be planned to give proper emphasis to
visual comfort and interest. The recommended brightness ratios are shown in Table 8.1.3.

Table 8.1.3: Brightness Ratios between Task, Adjacent Sources and Surroundings

For high task brightness (above 100

cd/m2)
Maximum ratio between task brightness and 3 to 1
the adjacent sources like table tops

Maximum ratio between task brightness and

illumination of the remote areas of the room 10 to 1
not being used as work areas

For low and medium task brightness The task must be brighter than both the
(below 100 cd/m2) background and the surroundings; the
lower the task brightness, the less
critical is the relationship.

1.2.3 Lighting Calculations

1.2.3.1 In order to determine the necessary number of lamps and luminaires for a
specified illumination level or the average illuminance obtained from a particular lighting
design, the Lumen Method of calculation shall be employed.
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1.2.3.2 Unless the reflection factors are known to the lighting designer, the triplet
0.7/0.5/0.3 for the reflectance of ceiling, walls and working plane respectively shall be
used for offices and the triplet 0.7/0.5/0.1 for other premises. Typical reflection factors of
smooth coloured surfaces are given in Table 8.1.4.

Table 8.1.4: Reflection Factors of Smooth Coloured Surfaces

Colour Reflection Factor Colour Reflection Factor

Flat white 0.75 – 0.85 Light green 0.40 – 0.50
Ivory 0.70 – 0.75 Grey 0.30 – 0.50
Buff 0.60 – 0.70 Blue 0.25 – 0.35
Yellow 0.55 – 0.65 Red 0.15 – 0.20
Light tan 0.45 – 0.55 Dark brown 0.10 – 0.15

1.2.4 Recommended Illumination Values

The recommended values of illumination required for buildings of different occupancies,
based on activity, are given in Tables 8.1.5 to 8.1.14. The initial illuminance should be
higher than the recommended value as the illuminance drops below this value by the end
of the cleaning and replacing period. A gradual transition (rather than a sudden change)
of brightness from one portion to another within the field of vision is recommended to
avoid or minimize glare discomfort.
1.2.5 Artificial Lighting to Supplement Daylight
Supplementary lighting shall be used when illumination from daylight falls below 150
lux on the working plane. For supplementary artificial lighting when daylight availability
becomes insufficient, cool daylight fluorescent tubes with semi-direct luminaires are
recommended. To ensure a good distribution of illumination, the mounting height should
be between 1.5 and 2.0 m above the work plane with a separation of 2.0 to 3.0 m between
the luminaires.
1.2.6 Selection of Appropriate Light Fittings
1.2.6.1 Light fitting
An electric lamp and its fitting accessories, reflector, diffuser, mounting brackets,
suspenders etc., shall be regarded as one unit. During design, an appropriate type of light
fitting shall be selected to match the requirement of desired distribution of light. While
selecting light fittings having focus or aiming arrangements which enable the light
distribution to be varied by adjustment of the lamp position, care should be taken to select
the appropriate type of fitting with appropriate beam to serve the aimed lighting
applications.
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1.2.6.2 Classification of light fittings

Light fittings may be classified into five categories according to the proportion of the
total light output in the lower hemisphere. These are:
 Direct fittings, giving 90-100 percent light downwards
 Semi-direct fittings, giving 60-90 percent downwards
 General diffusing fittings, giving 40-60 percent light downwards
 Semi-indirect fittings, giving 10-40 percent light downwards
 Indirect fittings, giving 0-10 percent light downwards
(a) Direct fittings: Direct fittings shall be used in situations where efficiency of
illumination is the major criterion, while contract of the light source with the
surroundings, shadows, and direct/reflected glare may be considered to be of
relatively minor importance.
(b) Semi-direct fittings: Semi-direct fittings shall be used in areas where it felt
that the reduction of contrast resulting from the small indirect component of light
directed towards the ceiling shall be sufficient for the purpose.
(c) General diffusing fittings: General diffusing fittings shall be used where, in
addition to a substantial indirect component of light aiding materially to the
diffused character of the general illumination, an upward component providing a
brighter background against which to view the luminance, especially for interiors
with light-colored ceiling and walls, is desirable.
Table 8.1.5: Recommended Values of Illumination for Residential Buildings
Illuminance Illuminanc
Area or Activity Area or Activity
(lux) e (lux)

Dwelling Houses Hotels

Bedrooms Entrance halls 150
General 70 Reception and accounts 300
Bed-head, Dressing table 250 Dining rooms (tables) 150
Kitchens 200 Lounges 150
Dining rooms (tables) 150 Bedrooms
Bathrooms General 100
General 100 Dressing tables, bed heads, etc. 250
Shaving, make-up 300 Writing rooms (tables) 300
Stairs 100 Corridors 70
Lounges 100 Stairs 100
Garages & Porches 100 Laundries 200
4522 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Illuminance Illuminanc
Area or Activity Area or Activity
(lux) e (lux)

Basement Car Park 100 Kitchens

Porches, Entrances 70 Food stores 100
Sewing and darning 600 Working areas 250
Reading (casual ) 150 Goods and passenger lifts 70
Home work and sustained reading 300 Cloak-rooms and toilets 100
Bathrooms 100
Above mirror in bathrooms 300

Table 8.1.6: Recommended Values of Illumination for Educational Buildings

Area or Activity Illuminance (lux) Area or Activity Illuminance (lux)

School and College Assembly halls Offices 300

General 150 Staff rooms and common rooms 150
When used for 300 Corridors 100
examinations
Stairs 100
Platforms 300
Gymnasium 100
Class and Lecture Rooms
General 150
Desks 300
Matches 300
Black boards 300
Library see Table 8.1.8
Embroidery and sewing rooms 500
Living quarters see Table 8.1.5
Laboratories 350
Art rooms 400

Table 8.1.7: Recommended Values of Illumination for Health Care Buildings

Area or Activity Illuminance (lux) Area or Activity Illuminance (lux)

Hospitals and Clinics Hospitals and Clinics (contd.)

Reception and waiting rooms 150
Outpatient department 150 Doctor's examination rooms 150
Wards Radiology departments 100
General 150 Casualty 150
Beds 150 Stairs and corridors 100
Operating theatres Dispensaries 250
General 300
Tables (with adjustable
operation lamp lighting)
Minor 2000
Major 5000
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Table 8.1.8: Recommended Values of Illumination for Assembly Buildings

Area or Activity Illuminance (lux) Area or Activity Illuminance (lux)

Cinemas Theatres

Foyers 150 Foyers 150

Auditorium 100 Auditorium 70

Corridors 100 Corridors 90

Stairs 150 Stairs 150

Libraries Indoor Sports Centre

Shelves (stacks) 150 Halls 200

Reading rooms (newspapers and Swimming pools 250

magazines) 200
Lawn or table tennis,
Reading tables 300 badminton, volley ball

Book repair and binding 300 Tournament 300

Cataloguing, sorting and stock rooms 150 Club 200

Museums and Art Galleries Recreational 150

Museums Shooting ranges

General 200
On target 300
Displays special lighting
Firing point 200
Art galleries
Range 100
General 250
Football 500
Paintings 250

Restaurant

Dining rooms 150

Cash desks 300

Self-carrying counters 300

Kitchens 200

Cloak-rooms and toilets 100

4524 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Table 8.1.9: Recommended Values of Illumination for Business and Commercial

Buildings

Illuminance
Area or Activity Area or Activity Illuminance (lux)
(lux)
Airport Building Doctor's Surgeries
Reception areas (desks) 300 Waiting rooms and consulting 150
rooms
Baggage, customs and immigration 300
halls Corridors 70
Circulation areas, lounges 200 Stairs 100
Banks Eyesight testing (acuity) wall
charts and near vision types 450
Counter, typing and accounting 300
book areas
Public areas, lobby 150 Jewellery and Watch-Making
Offices 200 Fine processes
700
Book Binding Minute processes
3000
Pasting, punching and stitching 200 Gem cutting, polishing and
setting 1500
Binding and folding and
miscellaneous machines 300
Finishing, blocking and inlaying Laundries and Dry-Cleaning
Works
Dental Surgeries
Receiving, sorting, washing,
Waiting rooms 300 drying, ironing (calendaring) 200
Surgeries 150 and dispatch

General 300 Dry-cleaning and bulk machine

work 200
Chairs special lighting
Fine hand ironing, pressing,
Laboratories 300 inspection, mending and 300
spotting

Offices Offices (contd.)

Entrance lobby and reception areas 150 Stairs 100
Conference rooms and executive 300 Lift landings 150
offices
Telephone exchanges
General offices 300
Manual exchange rooms (on 200
Business machine operation 450 desk)
Drawing office Main distribution frame room 150
General 300 Shops and Stores
Boards and tracing 450 General areas 150 to 300
Corridors and lift cars 70 Stock rooms 200
Display windows 500
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4525

Table 8.1.10: Recommended Values of Illumination for Industrial Buildings and

Processes
Area or Activity Illuminance
(lux)

Aircraft Factories and Maintenance Hangars

Stock parts productions 450
Drilling, riveting, screw fastening, sheet aluminium layout 300
and template work, wing sections, cowing, welding, sub-
assembly, final assembly and inspection
Maintenance and repair (hangars) 300
Assembly Shops
Rough work, for example frame assembly and assembly of 150
heavy machinery
Medium work, for example machined parts, engine assembly 300
Fine work, for example radio and telephone equipment, 700
typewriter and office machinery assembly
Very fine work, for example assembly of very small 1500
precision mechanisms and instruments
Automobile Manufacturing
Frame assembly 200
Chassis assembly line 300
Final assembly and inspection line 600

Table 8.1.10: Recommended Values of Illumination for Industrial Buildings and

Processes (contd.)

Area or Activity Illuminance

(lux)

Body Manufacturing
Parts 200
Assembly 300
Finishing and inspection 700
4526 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Table 8.1.10: Recommended Values of Illumination for Industrial Buildings and

Processes (contd.)

Area or Activity Illuminance

(lux)

Automobile Service Garages

Repairs 250

Active traffic areas 100

Storage 25

Bakeries

General working area 150

Decorating and icing 250

Breweries and Distilleries

General working areas 150

Brew house, bottling and canning plants 200

Bottle inspection special lighting

Carpet Factories

Winding and beaming 200

Designing, Jacquard card cutting, setting pattern, tufting,

topping, cutting, hemming and fringing 300

Weaving, mending and inspection 450

Chemical Works

Hand furnaces, boiling tanks, stationary driers, stationary and 150

gravity crystallizers

Mechanical furnaces, evaporators, filtration, mechanical 200

crystallizers, bleaching

Tanks for cooking, extractors, percolators 200

 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4527

Table 8.1.10: Recommended Values of Illumination for Industrial Buildings and

Processes (contd.)

Area or Activity Illuminance

(lux)

Chocolate and Confectionery Factories

Mixing, blending and boiling 150
Chocolate husking, winnowing, fat extraction, crushing and 200
refining, feeding, bean cleaning, sorting, milling and cream
making
Hand decorating, inspection, wrapping and packing 300

Clay Products and Cements

Grinding, filter presses, kiln rooms moulding, pressing, 150
cleaning and trimming
150
Enameling
Colour and glazing - rough work 400
Colour and glazing - fine work 750
Clothing Factories
Matching-up 450

Cutting, sewing
Light 300
Medium 450
Dark 700

Inspection
Light 450
Medium 1000
Dark 1500

Hand Tailoring
Light 450
Medium 1000
Dark 1500
Pressing 300
4528 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Table 8.1.10: Recommended Values of Illumination for Industrial Buildings and

Processes (contd.)

Area or Activity Illuminance

(lux)
Dairies
General working areas 200
Filling and bottle inspection 450
Cooling equipment 150
Laboratories 450
Pasteurizers 150
Separators 150
Electrical Industries
Impregnating 250
Winding and insulating 500
Assembly works
Fine 500
Very fine 750
Testing 500
Electricity Generating Stations (Indoor Locations)
Turbine halls 150
Auxiliary equipment, battery rooms, blowers, auxiliary
generators, switchgear and transformer chambers 150
Boiler house (including operating floors) platforms, coal
conveyors, pulverizers, feeders, precipitators, soot and 100 to 150
slag
Boiler house and turbine house 150
Basements 100
Conveyor house, conveyor gantries and junction towers 80 to 100
Emergency lighting - all areas 30
Control rooms
Vertical control panels 200 to 300
Control desks 300
Rear of control panels 150
Switch houses 150
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4529

Table 8.1.10: Recommended Values of Illumination for Industrial Buildings and

Processes (contd.)

Area or Activity Illuminance

(lux)
Electricity Generating Stations (Outdoor Locations)
Switchyard 70
Conveyors 70
Fuel oil delivery headers 70
Oil storage tanks 70
Cat-walks 70
Platforms, boiler and turbine decks 70
Transformer and outdoor switchgear 100
Emergency lighting - all areas 50
Flour Mills
Rolling 150
Sifting 150
Packing 150
Purifying 150
Product control 300
Cleaning screens, man lifts, aisleways and walkways, bin 100
checking
Forge Shops and Foundries
Forge shop 150
Annealing (furnaces) 150
Cleaning 100
Core making (fine) 300
Core making (medium) 150
Grinding and chipping 200
Inspection (fine) 1000
Inspection (medium) 300
Moulding (medium) 300
Moulding (large) 150
Pouring 150
Sorting 200
Cupola 100
Shake out 150
4530 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Table 8.1.10: Recommended Values of Illumination for Industrial Buildings and

Processes (contd.)

Area or Activity Illuminance

(lux)
Garages
Parking areas (interior) 70
Washing and polishing, greasing, general servicing and pits 200
Gas Works
Retort houses, oil gas plants, purifiers, coke screening and
coke handling plants (indoor) 70
Governor, meter, compressor, booster and exhauster houses 100
Open type plants
Cat-walks 20
Platforms 50
Glass Works
Furnace rooms, bending, annealing lehrs 100
Mixing rooms, forming (blowing, drawing, pressing and rolling) 150
Cutting to size, grinding, polishing and toughening 200
Finishing (bevelling, decorating, etching and silvering) 300
Brilliant cutting
General 200
Fine 500
Inspection, etching and decorating 500
Glove Making
Pressing, knitting, sorting and cutting 300
Sewing
Light 300
Medium 450
Dark 700
Inspection
Light 450
Medium 1000
Dark 1500
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4531

Table 8.1.10: Recommended Values of Illumination for Industrial Buildings and

Processes (contd.)

Area or Activity Illuminance

(lux)
Hosiery and Knitwear
Circular and flat knitting machines, universal winders, cutting 300
out, folding and pressing
Lock-stitch and overlocking machines
Light 300
Medium 450
Dark 700
Mending 1500
Examining and hand finishing, light, medium and dark 700
Linking or running on 450
Iron and Steel Works
Manufacturing by open hearth
Stock yard 20
Charging floor 100
Slag pits 100
Control platforms 100
Mould yard 25
Hot top 100
Hot top storage 100
Stripping yard 100
Scrap stockyard 20
Mixer building 100
Calcining building 50

Rolling mills
Blooming, slabbing, hot strip, hot sheet 100
Cold strip, plate 150
Pipe, rod, tube, wire drawing 200
Merchant and sheared plate 100
4532 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Table 8.1.10: Recommended Values of Illumination for Industrial Buildings and

Processes (contd.)

Area or Activity Illuminance

(lux)

Tin plate mills

Tinning and galvanizing 200
Cold strip rolling 200
Motor room, machine room 150
Sheet metal works
Miscellaneous machines, ordinary bench work 200

Pressing, folding, stamping, shearing, punching and 200

medium bench work
Tin plate and galvanized sheet inspection 500
Structural Steel Fabrication
Fabrication and general work 150
Marking and cutting 300
Plating shops
Vat, baths, buffing and polishing 200
Final buffing and polishing 500

Leather Manufacturing
Cleaning, tanning and stretching, vats 150
Cutting, fleshing and stuffing 200
Finishing and scarfing 200

Machine Shops
Rough bench and machine work 150
Medium bench and machine work, ordinary automatic
machines, rough grinding medium buffing and polishing 300
Fine bench and machine work , fine automatic machines,
medium grinding, fine buffing and polishing 700
Extra fine bench and machine work, grinding fine work 1000
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4533

Table 8.1.10: Recommended Values of Illumination for Industrial Buildings and

Processes (contd.)

Area or Activity Illuminance

(lux)

Paint Works
General, automatic processes 200
Special batch mixing 450
Colour matching 700
Paper Manufacturing
Beaters, grinding, calendaring 150
Finishing, cutting, trimming, paper making machines 200
Hand counting, wet end of paper machine 350
Paper machine reel, paper inspection and laboratories 500
Rewinder 500
Paper box manufacturing 200

Pharmaceuticals and Fine Chemical Works

Raw material storage 200
Grinding, granulating, mixing and drying, tableting, 300
sterilizing, preparation of solutions, filling, labelling,
capping, wrapping and cartoning
Control laboratories and testing 300
Fine chemical processing 200
Fine chemical finishing 300

Printing Industries
Photo-engraving
Block-making, etching and staging 200
Finishing, routing and proofing 300
Masking and tint laying 300
Colour Printing
Inspection area 700
4534 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Table 8.1.10: Recommended Values of Illumination for Industrial Buildings and

Processes (contd.)

Area or Activity Illuminance

(lux)

Type foundries
Matrix making, dressing type 250
Front assembly and sorting 200
Hand casting 300
Machine casting 200
Printing plants
Machine composition and imposing stones 200
Presses 300
Composition room 450
Proof reading 300
Colour inspection and appraisal 1000
Electrotyping
Block-making, electroplating, washing and baking 200
Moulding, finishing and routing 300

Rubber Tyre and Tube Manufacturing

Stock preparation
Plasticating, milling 100
Calendering 150
Fabric preparation
Stock cutting, bead building 250
Tube tubing machines 250
Tread tubing machines 250
Tyre building
Solid tyre 150
Pneumatic tyre 250
Curing department
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4535

Table 8.1.10: Recommended Values of Illumination for Industrial Buildings and

Processes (contd.)

Area or Activity Illuminance

(lux)

Tubing curing, casing curing 350

Final Inspection
Tube, casing 1000
Wrapping 200

Shoe Manufacturing (Leather)

Cutting and stitching
Cutting tables 450
Marking, buttonholing skiving, sorting and counting 450
Stitching
Light materials 300
Dark materials 1000
Making and finishing
Nailers, sole layers, welt beaters and scarfers,
trimmers, welters, lasters, edge setters,
600
sluggers, randers, wheelers, treers, cleaning,
spraying, buffing, polishing, embossing

Shoe Manufacturing (Rubber)

Washing, coating, mill run compounding 100
Varnishing, vulcanizing, calendering, upper and sole cutting 300
Sole rolling, lining, making and finishing process 500
Soap Factories
Kettle houses and ancillaries, glycerine evaporation and distillation
and continuous indoor soap making
General areas 150
Control panels 200 to 300

Batch or continuous soap cooling, cutting and drying, soap milling and
plodding
4536 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Table 8.1.10: Recommended Values of Illumination for Industrial Buildings and

Processes (contd.)

Area or Activity Illuminance

(lux)

General areas 150

Control panels and key equipment 200 to 300

Soap stamping, wrapping and packing, granules making, granules

storage and handling, filling and packing granules

General areas 150

Control panels and machines 200 to 300

Edible products processing and packing 200

Textile Mills (Cotton)

Bale breaking and picking 150

Carding and drawing 200

Slubbing, roving, spinning, spooling 200

Beaming and slashing on comb

Grey goods 200

Denims 300
Weaving

Patterned cloth and fine counts, light 300

Patterned cloth and fine counts, dark 500

Plain grey cloth 200

Cloth inspection 700

Textile Mills (Silk and Synthetics)

Manufacturing
Soaking, fugitive tinting, conditioning, setting or twist 200
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4537

Table 8.1.10: Recommended Values of Illumination for Industrial Buildings and

Processes (contd.)

Area or Activity Illuminance

(lux)

Textile Mills (Silk and Synthetics) (contd.)

Winding, twisting, rewinding and coining, quilting and
slashing
Light thread 200
Dark thread 300
Warping (silk or cotton system) on creel, on running ends, on reel, 300
on beam, on warp at beaming
Healding (drawing-in) 700
Weaving 300 - 500
Inspection 1000

Textile Mills (Woollen and Worsted)

Scouring, carbonizing, testing, preparing, raising, brushing, 150
pressing, back-washing, gilling, crabbing and blowing
Blending, carding, combing(white), tentering, drying and
200
cropping

Spinning, roving, winding, warping, combing (coloured) and 450

twisting

Healding (drawing-in) 700

Weaving
Fine worsteds 700
Medium worsteds and fine woollens 450
Heavy woollens 300

Burling and mending 700

Perching
Grey 700
Final 2000
4538 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Table 8.1.10: Recommended Values of Illumination for Industrial Buildings and

Processes (contd.)

Area or Activity Illuminance

(lux)

Wood Working
Rough sawing and bench work 150
Sizing, planing, rough sanding, medium machine and bench 200
work glueing, veneering
Fine bench and machine work, fine sanding and finishing 300

Table 8.1.11: Recommended Values Table 8.1.12: Recommended Values

of Illumination for of Illumination for
Storage Buildings Outdoor Stadiums
Colour TV
broadcasting

Area or Activity Illuminan Area or Activity Illuminanc

ce (lux) e (lux)
Storage Rooms of Ware Football Stadium 1700
House
Cricket Stadium 2200
Inactive 50
Rough bulky 50
Medium 100
Fine 250

Table 8.1.13: Recommended Values Table 8.1.14: Recommended Values

of Illumination for of Illumination for
Outdoor open yards Roads
Illuminance Illuminance
Area or Activity Area or Activity
(lux) (lux)
Outdoor Car Parking Lot 100 Roads inside a Housing 50- 100
Area
Airport Apron 200
Roads in a Congested 50- 100
Container Yard 200
Town / City Area
Jetty 250
Wide Roads with dividers 100 - 120
Avenues 100 - 120
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4539

(d) Semi-indirect fittings: Semi-indirect fittings shall be used when a comfortable

brightness ratio between the ceiling and the luminaire is desirable but an
efficiency of illumination, higher than that obtainable from indirect fittings is
required.
(e) Indirect fittings: Indirect fittings shall be used in situations where an
environment of evenly distributed illumination is to be achieved.
(f) Angle lighting: Lighting on vertical surfaces shall be done avoiding shadows
using interior or exterior light fitting of appropriate type concentrated source
light fitting depending upon the place and the color tone required. However, if
creating shadows is necessary then appropriate type concentrated source light
fitting should be chosen depending upon the place.
1.2.7 Illumination of Exit Signs and Means of Escape
1.2.7.1 Exit signs
(a) All required exit signs shall be illuminated at night, or during dark periods within the
area served.
(b) Exit signs may be illuminated either by lamps external to the sign or by lamps
contained within the sign. The source of illumination shall provide not less than 50
lux at the illuminated surface with a contrast of not less than 0.5. Approved self-
luminous signs which provide evenly illuminated letters having a minimum
luminance of 0.2 cd/m2 may also be used.
(c) Exit signs within an area where the normal lighting may be deliberately dimmed or
extinguished, such as places of entertainment, shall be illuminated either by lamps
contained within the sign or by approved self-luminous signs.
1.2.7.2 Means of Escape Lighting
(a) The means of escape and exit access in buildings requiring more than one exit shall
be equipped with artificial lighting. The lighting facilities so installed shall provide
the required level of illumination continuously during the period when the use of the
building requires the exits to be available.
(b) The intensity of illumination at floor level by means of escape lighting shall not be
less than 10 lux, except that the minimum required floor level illumination of aisles
in assembly halls, theatres and cinema during projection of motion or still pictures by
directed light shall not be less than 2 lux.

(c) The illumination of exit signs and the lighting of the means of escape and exit access
shall be powered by an alternate or emergency electrical system to ensure continued
illumination for a duration of not less than 30 minutes after the failure of primary
power supply.
4540 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

1.2.8 Selection of Appropriate Type of Lamp

It is important to select appropriate types of lamps for each purpose. The lamps which are
used for various purposes are:

(i) General Service Lamps (GLS)/Incandescent Lamps

General Service Lamps (GLS) are well known Incandescent Lamps. These are available
in a number of watt ratings. However, most commonly used ratings are 40 W, 60 W, 100
W, 150 W and 200 W rated lamps are also used for special applications. These types of
lamps are produce heat and should be minimized while selecting for a particular design
because other better choices are available nowadays. For kitchen, cooking areas of a
hotel, serving counters of a food shop or hotel, porch these are often essential because of
the color temperature. For living room, toilet, corridor, veranda, bed room these have
been used for long but from energy saving point of view other lamps which perform
better in terms of light output to watts ratio may be used. In general, the GLS type of
lamp may be used for almost all interior and exterior applications but from energy saving
point of view other lamps which perform better in terms of light output to watts ratio
should be used as much as possible.

(ii) Fluorescent Lamps (FL):

These are available in 20 W and 40 W ratings. These lamps are strongly recommended
for reading room, educational buildings, laboratories, office room, commercial space
applications, factory illumination, illumination of areas around industrial plant and
machineries, exterior lighting applications.

40 W FL should be used wherever possible because a 40 W FL is more energy efficient

compared to a 20 W FL. These are long life lamps, have wide applications and are
advantageous in many respects.

(iii) Compact Fluorescent Lamp( CFL) Energy Saving Lamps:

CFL Lamps are available in a number of watts ratings e.g., 4 W, 7 W, 11 W, 14 W and 24

W. CFLs have been finding wide application for almost all applications because of their
high Light output to watts ratio and also because of the attractive light color. CFL lamps,
therefore, should be widely used for energy saving purpose.

However, for reading areas, library areas, educational buildings, laboratories fluorescent
lights give better service and thus should be selected for these purposes. It is worthwhile
mentioning that Fluorescent lamps with high quality ballasts closely meet the energy
saving purpose.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4541

(iv) LED Lights:

Compact light fitting formed using a cluster of white LED is currently used to replace a
conventional lamp. An LED operates at very small amount of voltage. These are good for
lighting, energy efficient, have almost negligible heat dissipation. These are good for
relaxed environment interior lighting. LED lights are becoming more and more popular
because of much lower power consumption compared to other lamps.

(v) Halogen lamp:

Halogen lamps are used for spot lights, decorative lights in shops and commercial spaces,
inside show cases, stage lighting, and projection lights. Due to high temperature rise and
UV light output these should be avoided for interior lighting unless needed.

(vi) Mercury Vapour Lamp

These have been widely used for shops, streets, for high bay lighting, warehouse lighting
and similar special lighting. Most likely, this type of lamp will be discontinued within
next five to six years due some of it’s ill effects. Metal halide lamp is coming up as a
better alternative to mercury vapour lamp.

(vii) Metal Halide Lamp:

These are available in a number of watts ratings e.g., 150 W, 200 W, 250 W, 500 W,
1000 W, 2000 W. Good for exterior lighting, indoor and outdoor athletic facilities, for
high bay lighting, warehouse lighting. These are required where massive flood lighting is
required from high altitudes for coverage of large areas.
(viii) HP Sodium Lamp:

These are available in a number of watts ratings e.g., 40 W, 50 W, 70 W, 100 W, 150 W,

250 W, 400 W, 1000 W. Good for exterior lighting, Lighting for areas where higher
concentration of vehicles and people exist e.g., Street lighting, building exterior lighting,
security lighting.

(ix) Low Pressure Sodium Lamp:

For outdoor lighting such as street lights and security lighting where faithful color
rendition is considered unimportant. This type of lamps may be used for street lights,
observatory, parking lot and similar types of areas.

(x) Solar PV Cell Powered LED Lights:

These fittings require a solar panel, a storage battery system apart from the cluster of
LEDs. For outdoor lighting such as street lights, security lighting, outdoor parking area,
this type of light fitting may be used.
4542 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

1.3 ELECTRICAL AND ELECTRONIC INSTALLATIONS IN BUILDINGS

1.3.1 List of Symbols used for Electrical Drawings

A list of general graphical symbols used for electrical drawings is given in Table 8.1.15.
These are given as guideline. In case of justified reasons a designer may modify certain
symbol.

Table 8.1.15: Symbols used for Electrical Drawings

Serial No. Description Symbol

1 Main Distribution Board (MDB)

2 Floor Distribution Board (FDB)

3 Distribution Board (DB)

4 Sub-distribution Board (SDB)

5 Branch Distribution Board (BDB)

6 Switch Board (SB)

7 Telephone Outlet (PSTN)

8 Telephone Outlet (PABX)

9 Change over switch

E
10 Energy meter
A
11 Ammeter
V
12 Voltmeter
P.F
13 Power factor meter

14 Circuit breaker

15 Fuse

16 Ceiling mounted Incandescent light fitting

17 Wall mounted bracket light fitting

 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4543

Serial No. Description Symbol

18 Ceiling fan

19 Exit light pendant

20 Exit light-wall mounted

21 2 pin socket Outlet (single phase)

22 3 pin 13A switched socket Outlet (single phase)

23 Weatherproof and waterproof socket outlet

SPST Single – pole, one-

24
way switch

25 DPST Two - pole, one-

way switch

TPST Three - pole, one-

26
way switch

27 SPDT Two – way switch

28 Push button switch

29 Buzzer

30 Single fluorescent lamp on ceiling

31 Double fluorescent lamp on ceiling

32 Double fluorescent lamp on wall

33 Spot light
4544 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Serial No. Description Symbol

34 Wall mounted bracket fan

35 Exhaust fan

36 Pull box

37 TV socket outlet

38 Fire Alarm bell

39 Fire detector

40 Smoke detector

41 Speaker

42 Microphone

43 Conduit, concealed in ceiling or in wall

Conduit, concealed in floor or through under

44
ground

45 Telephone conduit

46 Television antenna conduit

47 Earth Electrode

1.3.2 Estimating the Load of a Building/Complex

Estimating the total load of a building has to be started with the listing of the connected
loads in a building. The steps are to list the loads in each of the rooms, in each of the
flats/offices of a floor, in each of the floors and the load of the total building. In this way
an account of the total building area/the total complex has to be prepared. Loads of the
Lift(s), water pump(s), bulk ventilating system in the basement and any other equipment
installed in the building must also be added. For completing the load calculation,
practical value of appropriate diversity factors will have to be applied at each stage.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4545

Estimating the total load of a complex consisting of a number of buildings has to be

started with the listing of the connected load of each of the buildings, they are lighting
load, water pump and any other equipment installed in the complex. For completing the
load calculation, practical value of appropriate diversity factors among the buildings will
have to be applied.
1.3.2.1 Maximum demand and diversity
Two items need to be determined, which are: (i) Maximum demand and (ii) Diversity
factor. These are needed in completing the load calculation and in the computation of
current.
In determining the maximum demand of an installation or parts thereof, diversity shall be
taken into account. Appendix A gives some information on the determination of the
maximum demand of an installation and includes the current demand to be assumed for
commonly used equipment together with guidance on the application of allowances for
diversity.
1.3.2.2 Estimation of load in kW, in kVA and in Amperes
An estimation of loads is necessary initially for design purposes and later for keeping a
track of the growth of load. Estimation of loads means estimation of watts or kilowatts in
small scale. In bigger scale the kVA is assessed together with the power factor. A
calculation of current is then to be performed for the selection of breakers/fuses and the
current carrying cables.
1.3.2.3 Estimation of electrical load in Watts
Energy efficient and energy saving should be considered in estimating the electrical load,
the watts rating of individual equipment/fittings connected to the system need to be listed
and added. Typical watt ratings of some of the equipment/fittings are shown in Table
8.1.16 which may be used for estimation if the actual values are not known or specified.

Table 8.1.16: Estimated Load for Different Fittings/Fixtures

Type of Fitting/Fixture Ratings Type of Fitting/Fixture Ratings

in Watts in Watts

CFL 5-65 15 A Socket outlets 1500

LED and Solar Panel Powered 10-60 Microwave Oven (domestic) 1200-
LED Security /Street Lights 1500

Fluorescent lamp with Washing machine (domestic) 350-500

accessories:

Nominal length 600 mm 20 Television (medium size) 120-200

4546 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Type of Fitting/Fixture Ratings Type of Fitting/Fixture Ratings

in Watts in Watts

Nominal length 1200 mm 40 Computer (without printer) 200

Photo copiers 1200- Computer with printer 700-800

1500

Ceiling fans 100 Window type A.C. machine 1500

(Max) (12000 BTU/hr)

Electric 1500 Split type A.C. machine 1300

(12000 BTU/hr)

Table fans 85 (Max) Geyser (water heater, 1000-

domestic) 1200

Pedestal fans 120 Toaster (domestic) 800-1000

(Max)
Exhaust fans 100 Electric calendar 700-1000
(Max)

5A socket outlets 300

1.3.2.4 Calculation of current

For the calculation of current (for the selection of cables and breakers) of the fluorescent
lamps the ratings are to be multiplied by a factor of 1.65 to take care of the power factor
and the starting current situation.

For the calculation of current (for the selection of cables and breakers) of the ceiling fans,
table fans, pedestal fans, exhaust fans the ratings are to be multiplied by a factor of 1.65
to take care of the power factor and the starting current situation.

For the calculation of current (for the selection of cables and breakers) of the small
inductive loads (up to 1.0 kW) the ratings are to be multiplied by a factor of 1.65 to take
care of the power factor and the starting current situation. The factor shall be higher for
higher rated motors.

1.3.2.5 Minimum load densities

While estimating the electrical load, the minimum load densities to be considered are
those shown in Table 8.1.17.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4547

1.3.3 Fittings, Fixtures and Accessories

Switch boards with back boxes and cover plates, ceiling roses, socket outlets with back
boxes, plugs, light fittings, fans, pull boxes with cover plates have been put in this
category, although there may be other items which may be included under electrical
accessories related to electrical and electronic installations in buildings.

1.3.3.1 Switch boards

Tumbler switches have been used for surface wiring and piano switches have been used
for concealed wiring. Now a day piano switches are also used with surface wiring. Piano
switches are mounted on either a plastic back box or a metal back box. These piano
switches are available in gangs. The other alternative is to have piano switches mounted
on a Perspex or Ebonite sheet which is then mounted on a metal back box.
The Switches must conform to the relevant BS standard. The minimum ampere rating of
switch shall not be below 5 A.

Switches may be Single Pole Single Throw (SPST) or Single Pole Double Throw (SPDT)
depending on the operation. For some application Double Pole Single Throw (DPST) and
Double Pole Double Throw (DPDT) are also available. Usually the DPST switches are
made for 10 A, 15 A and 20 A rating.

The phase (Live) wire (Brown PVC insulated cable) connection to the point must go
through the switch.

The metal / sheet steel back boxes of a switch board must have an earthing terminal to
terminate the Earth Continuity Conductor (ECC) coming from a BDB or an SDB.

Table 8.1.17: Minimum Load Densities

Type of Occupancy Unit Load

(Watts/m2)

Non A/C A/C

Residence/ Dwelling : Single family 20 75

Residence/ Dwelling : Multi-family (other than hotels) 20 75
Hospitals 32 80
Hotels, including apartment house (excluding any provisions 24 75
for electric cooking)
Office and commercial multi-storeyed buildings 28 75
Industrial building (excluding the loads for machines) 16 -
4548 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Type of Occupancy Unit Load

(Watts/m2)

Non A/C A/C

Departmental stores 28 75

Banks 20 75

Restaurants (excluding any provisions for electric cooking) 16 75

Barber shops and beauty parlours 32 75

Schools and colleges 12 70

Parking area in commercial buildings 4 -

Warehouses, large storage areas 2 -

1.3.3.2 Socket outlets and plugs

In general, all socket outlets must be switched (combined) and shuttered.
(a) General requirements of socket outlets
Socket outlets shall be 13 A switched shuttered 3 pin flat pin type. All socket outlets
must be switched (combined) and shuttered and shall be for 3 pin Flat pin type
(rectangular cross section) 13 A plugs fitted with tubular fuse.
The corresponding plugs must be fitted with fuse. The maximum fuse rating shall
be 13A for 13A Sockets. The fuse rating may be smaller depending upon the
current rating of the appliances used.
The phase wire (Brown cable) shall be connected to the L terminal of the socket outlet
through the combined switch and the neutral wire (Blue cable) shall be directly connected
to the N terminal of the socket. Earth Continuity Conductor (ECC) (Yellow + Green bi-
colour cable) for such a socket outlet shall be connected to the Earth terminal of the
socket.

The plug for each 13A socket outlet provided in a building for the use of domestic
appliances shall be provided with its own individual fuse. The feed cables for such a
circuit must have fuse or miniature circuit breaker (MCB) at the originating point in the
Distribution Board or Sub-Distribution Board or Branch Distribution Board. For some
high current applications, additional fuses/ circuit breakers adjacent to the sockets are
recommended.

Each socket outlet shall also be controlled by a switch which shall normally be located
immediately adjacent thereto or combined therewith.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4549

The phase (Live) wire (Brown PVC insulated cable) connection to the socket outlet must
be through the switch.
Copper size of the Earth Continuity Conductor (ECC) for such a socket outlet shall not be
smaller in size than 1.5 mm2 PVC insulated cable.
(b) 15 A/20 A rated socket outlets
(c) Round pin socket outlets of 15 A/20 A rating may be used for air conditioner
outlets and water heater outlets under special circumstances, for air conditioner outlets
(requiring 15 A or 20 A), 15 A/20 A rated socket outlets for round pin plugs may be used
along with a circuit breaker or fuse protection in a box adjacent to the sockets..
Each 15 A/20 A socket outlet provided in a building for the use of domestic appliances
such as air-conditioner, water cooler, etc. shall be provided with its own individual fuse.
The feed cables for such a circuit must have fuse or miniature circuit breaker (MCB) at
the originating point in the Distribution Board or Sub-Distribution Board or Branch
Distribution Board. For some high current applications, additional fuses/circuit breakers
adjacent to the sockets are recommended.
Each socket outlet shall also be controlled by a switch which shall normally be located
immediately adjacent to the Socket or shall be combined with the Socket.
The corresponding plugs for 15 A should be fitted with fuse. The maximum fuse rating
shall be 15 A for 15 A Sockets. For a 15 A rated socket outlet a 15 A rated fuse or a 15 A
circuit breaker must be placed adjacent to the socket.
For a 20 A rated socket outlet a 20 A rated fuse or a 20 A circuit breaker must be placed
adjacent to the socket.
Wiring for sockets shall be radial type of wiring. However, ring type wiring may be used
by strictly following the rules given in IEE Wiring regulations BS 7671 and by using
appropriate size of cable.
(d) Earth Continuity Conductor (ECC) for a socket
The ECC for a socket outlet shall not be smaller in size than 1.5 mm2 PVC insulated
annealed copper cable. The colour of the ECC cable insulation shall be Yellow + Green
bi-colour.
(e) Mounting height of a three pin switched socket outlet
Three pin switched shuttered socket outlets shall be mounted on a wall at a height 250
mm above floor level. Switched shuttered socket outlets are essential for safety in
particular for the safety of infants.
For certain applications like computers, printers, UPS, IPS such sockets may be mounted
at a higher level for the ease of operation.
4550 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(f) Restriction on mounting socket outlets in wet places

No socket outlets shall be provided inside bath rooms/toilets or any other place where
floor may remain wet.

(g) 5 A rated 2 pin socket outlets

5 A rated 2 pin socket outlets may be used along with the light and fan switch boards
only. Such sockets shall not be used as socket outlets at the skirt level.

(h) Number of socket outlets in a room/in a building

The number of socket outlets in a building depends upon the specific requirements of
occupants and the type of building. Adequate number of 13 A switched flat pin
(rectangular cross section pin) shuttered socket outlets shall be provided and arranged
around the building to cater to the actual requirements of the occupancy.

15 A round pin (rectangular cross section pin) socket outlets shall be provided for
specially Air-conditioners and water heaters of such ratings only.

For residential buildings, the minimal guidelines given in Table 8.1.18 shall be used to
determine the required number of 13 A switched flat pin (rectangular cross section pin)
shuttered socket outlets, when actual requirements cannot be ascertained. All socket
outlets shall conform to BDS 115.

Table 8.1.18: Minimum Number of 13 A flat pin Socket Outlets

Location No. of Switch Socket Outlets

Bed room 2

Living room 3

Drawing room 3

Dining room 1

Toaster/Snack toaster 1
Kitchen 1

Bathroom 0

Verandah 1
Refrigerator 1

Air-conditioner one for each room

 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4551

(i) Restriction on installation of two socket outlets in room fed from two phases
Installation of two socket outlets in a room fed from two different phases should be
avoided as far as possible. However, in unavoidable cases, the minimum distance
between two such socket outlets in a room fed from two different phases must not be less
than 2 m under any circumstances.
(j) Exterior/outdoor sockets
Socket outlets in exposed places where chances of dripping/falling rain water exist should
not be placed. In case of necessity, weather proof/waterproof covered socket outlets may
be mounted with appropriate precautions. In such a case the back box should preferably
be of bakelite or Acrylic or plastic material.
(k) Exterior/outdoor switches
Switches in exposed places where chances of dripping/falling rain water exist should not
be placed. In case of necessity, weather proof/waterproof covered switches may be
mounted with appropriate precautions. In such a case the back box should preferably be
of bakelite or Acrylic or plastic material.
1.3.3.3 Ceiling rose
A ceiling rose is needed for terminating the point wiring for a Light or a Fan in the
ceiling.
(a) A ceiling rose shall not be installed in any circuit operating at a voltage
normally exceeding 250 volts.
(b) Normally, a single pendant be suspended from only one ceiling rose using a
flexible cord. A ceiling rose shall not be used for the attachment of more than
one outgoing flexible cord unless it is specially designed for multiple pendants.
(c) A ceiling rose shall not contain a fuse terminal as an integral part of it.
(d) The ceiling rose shall conform to BS 67.
(e) Luminaire supporting couplers are designed specifically for the mechanical
support as well as for the electrical connection of luminaires and shall not be
used for the connection of any other equipment.

1.3.3.4 Light fitting

Switches shall be provided for the control of every light fitting. A switch may control an
individual light point or a group of light points.
Where control at more than one position is necessary for a lighting fitting or a group of
lighting fittings, as many two-way or intermediate switches may be provided as the
required number of control positions.
4552 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
In industrial premises light fittings shall be supported by suitable pipe/conduits, brackets
fabricated from structural steel, steel chains or similar materials depending upon the type
and weight of the fittings. Where a lighting fitting is to be supported by one or more
flexible cords, the maximum weight to which the twin flexible cords may be subject are
shown in Table 8.1.19.
Table 8.1.19: Maximum Permissible Weight to which Twin Flexible Cords may be
Subject
Nominal Cross-sectional Area Number and Diameter Maximum Permissible
of Twin Flexible Cord (mm2) (mm) of Wires Weight (kg)

0.5 16/0.2 2
0.75 24/0.2 3
1.0 32/0.2 5
1.5 48/0.2 5.3
2.5 80/0.2 8.8
4 128/0.2 14

For a Light fitting with shade, no flammable shade shall form part of the light fitting and
the shade shall be well protected against all risks of fire. Celluloid shade or lighting
fitting shall not be used under any circumstances.
(a) Lighting point
At each fixed lighting point one of the following accessories shall be used
(i) one ceiling rose conforming BS 67
(ii) one luminaire supporting coupler conforming BS 6972 or BS 7001
(iii) one batten lamp holder conforming BS 7895, BS EN 60238 or BS EN 61184
(iv) one luminaire designed to be connected directly to the circuit wiring
(v) one suitable socket-outlet
(vi) one connection unit conforming BS 5733 or BS 1363-4.
A lighting installation shall be appropriately controlled e.g., by a switch or combination
of switches to BS 3676 and/or BS 5518, or by a suitable automatic control system, which
where necessary shall be suitable for discharge lighting circuits.
(b) Wires/cables used inside light fittings and any other fitting
Wires/cables used inside a light fitting or any other fittings are mostly flexible types. In
some cases single core PVC insulated wiring cables mostly 1.5 mm2 are used. In such
cases the cables must be of high quality in terms of insulation and must have appropriate
copper cross section. Such cables are usually terminated in a ceiling rose.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4553

1.3.3.5 Fans
(a) Ceiling fan
Ceiling fans including their suspension shall conform to BDS 818.

With respect to the position of a lighting fitting, the positioning of a fan shall be such so
that it does not throw any shadow on the working plane is not acceptable. The unit
module area shall be so chosen that the required number of fans could be suitably located,
to avoid creation of pockets receiving little or no air circulation.

In general, fans in large halls may be spaced at 3 to 3.5 m in both the directions in the
horizontal plane. If building modules do not lend themselves to proper positioning of the
required number of ceiling fans, other types of fans, such as air circulators or wall
mounted bracket fans shall have to be installed for the areas uncovered by the ceiling
fans. In such cases, necessary electrical outlets shall have to be provided for the purpose.
Table 8.1.20 gives the recommended areas to be served by different sizes of ceiling fans
where the height of fan blades is at 2.5 m above the finished floor level.

Table 8.1.20: Recommended Fan Sizes in Rooms

Room Area (m2) Fan Sweep

Up to 6 915 mm
Over 6 to 9 1220 mm
Over 9 to 12 1442 mm

Wiring for a ceiling fan outlet from the switch board up to the ceiling fan outlet shall be
done through pre-laid 18 mm dia PVC conduits using 1.5 mm2 PVC insulated 2 cables of
Brown and Blue insulation. A high quality ceiling rose is to be installed at the ceiling fan
point for the termination of the wiring and the connection of the two wires of the Fan.

A fan hook is required to be placed during casting of the roof. The fan hook is to be made
using a 12 mm dia MS rod having at least 600 mm on both sides and shall be placed
above the MS rod mesh of the roof slab.

(b) Wall mounted bracket fan

For Wall mounted bracket fans shall be mounted on the wall using appropriate rowel
bolts. Wiring for a Wall mounted bracket fan outlet from the switch board up to the
Wall mounted bracket fan outlet shall be done through pre-laid 18 mm dia PVC conduits
using 1.5 mm2 PVC insulated 2 cables of Brow and Blue insulation. A high quality
ceiling rose is to be installed at the ceiling fan point for the termination of the wiring and
the connection of the two wires of the Fan.
4554 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(c) Pedestal fans and table fans

These items are movable and no fixed connections are necessary. Sockets will be used to
energize these fans.

(d) Installation/mounting of ventilating fans or exhaust fans

Exhaust fans are necessary for spaces, such as toilets, kitchens, canteens and godowns to
provide the required air changes. Since the exhaust fans are located generally on the outer
walls of a room, appropriate openings in such walls shall be provided right from the
planning stage. The sizes and the rpm of the exhaust fans will vary according to the
application and the volume for which a fan used. In some applications (such as some
industries, big size gas generator room etc.) high rpm fans are essential. In all cases
appropriate types of fan need to be chosen and appropriate arrangement need to be made
so that rain water cannot get inside the rooms.

(e) Installation/mounting of ceiling fans

Ceiling Fans shall be suspended from Fan hooks that are to be placed in position during
casting of the Roof.

(f) Fan hooks

Fan hooks may be concealed (hidden) or may be exposed type. Fan hooks shall be made
using MS rods of 12 mm diameter. The diameter of this rod shall not be below 10 mm
under any circumstances.

(g) Ceiling roses for fan points

Appropriate type of ceiling roses must be provided at the fan points for the termination of
the Fan point wiring cables. Connection to the Ceiling Fans will go from the ceiling
roses.

(h) Cutout box/circuit breaker box

If the BDB or the SDB from which a 3-pin switched shuttered socket receives power is at
a significant distance away and the load connected to the socket needs special care an
additional cutout box or a circuit breaker box may be placed adjacent to the socket. Such
a cutout Box or a Circuit Breaker box shall be placed inside a 18 SWG Sheet Steel
(coated with two coats of synthetic enamel paint) of appropriate size with appropriate
Perspex cover plate. Such a box may be surface fitted or may be concealed fitted. The
box shall have a brass terminal for the termination of the ECC.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4555

1.3.4 Distribution Wiring in a Building

1.3.4.1 General
Loads are separated into known and unknown loads.

General illumination is a known load, whether derived from detailed lighting layout, or
developed from watts per square meter calculation. Similarly fans are also known loads.
Besides these two types, there may be some other known loads.

Number, rating and layout of outlets for general illumination, fans and other known loads
should accurately be distributed among a number of branch circuits. These branch
circuits should then be carefully loaded with due regard to voltage drop, operating
voltage and possible increase in lighting levels in future. On the other hand the sockets
are unknown loads. Socket loads will be determined from projections based on the utility
of the building and type of applications.

Every installation shall be divided into small circuits (following the rules given in this
document) to avoid danger in case of a fault, and to facilitate safe operation, inspection,
maintenance and testing. For the establishment of the circuits appropriate type of wiring
is needed and appropriate terminations/connections/junctions of these circuits are needed.
At the same time appropriate types of protection against faults must be given at different
levels. These are to be achieved through installation of appropriate distribution wiring in
the building.

1.3.4.2 Distribution board

A Distribution Board is the junction point of the incoming line and the outgoing lines for
the distribution of Electricity throughout the building. The incoming as well as the
outgoing lines must have Circuit Breaker protection or Fuse protection. The junctions and
terminations of the incoming and outgoing cables are made through copper bars
containing bolts and nuts for cable lugs known as bus-bars. A Distribution board may be
named as MDB or FDB or DB or SDB or BDB.
(a) MDB stands for Main Distribution Board. This is the distribution box where the
main incoming cable enters and terminates from the main service feed
connection of a large building. The FDBs get feed from MDB.
(b) FDB stands for Floor Distribution Board located in each of the floors of a
multistoried building. The DBs get feed from FDB. Usually, more than one FDB
are needed.
(c) DB is the abbreviation for Distribution Board. This may be the box where the
main incoming cable enters and terminates from the main service feed
connection. The SDBs get feed from a DB.
4556 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(d) SDB is used to represent Sub- Distribution Board. This board is located in the
same floor of a building and connected to the DB. Usually more than one SDB
are needed. The BDBs get feed from SDB.

(e) BDB stands for Branch-Distribution Board located in the same floor of a
building and connected to the SDB. Usually more than one BDB are needed.

(f) EDB, EFDF, ESDB, EBDB Sections of DB, FDB, SDB, BDB receiving feed
from the Emergency Bus-bar which in turn is getting feed from standby
generator through changeover switch. These may be separate DBs placed by the
corresponding normal supply DBs.

Each of these distribution boards must have busbars for Line, neutral and
earthing for a single phase box. A 3-phase distribution board must have busbars
for Line 1, Line 2, and Line 3, neutral and earthing.

These boxes shall be made with sheet steel of not less than 18 SWG thicknesses
and must be appropriately paint finished to match the wall paint.

1.3.4.3 Circuit wiring

(a) Separate branch circuits for separate control
Separate branch circuits shall be provided for different parts of a building area which
need to be separately controlled. A branch circuit should be independently working and
should not be affected due to the failure of another branch circuit.

The number of final circuits (also termed as sub-circuits or circuits) required and the
points supplied by any final circuits shall comply with

(i) the requirement of over-current protection,

(ii) the requirement for isolation and switching, and

(iii) the selection of cables and conductors.

All final circuits shall be wired using loop wiring system; no joint box shall be used.

Sufficient number of 18 SWG sheet steel made (painted with two coats of grey synthetic
enamel paint) pull boxes, with ebonite/perspex sheet cover plate, must be given on the
walls near the ceiling. If brick walls are not available, pull boxes must be given in the
ceilings.

(b) For domestic and office buildings

5A Light/Fan Circuits must be used for all Domestic and Residential buildings. 5A
Light/Fan Circuits are also to be used for Office and commercial Buildings. The
corresponding circuit wire in the BDB/ SDB/ DB then shall be not less than 1.5 mm2.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4557

(c) For office and commercial buildings having large open floor areas
Under unavoidable circumstances, in case of difficulties in forming 5 A light/fan circuits
for office and commercial buildings having large open floor areas, 10 A light/fan circuits
may be used. The corresponding circuit wire in the BDB/SDB/DB then shall be not less
than 2.5 mm2. However, use of 5 A light/fan circuits is still emphasized.
(d) For industrial/factory buildings having large open floor areas
For industrial/factory buildings having large open floor areas, 10 A light/fan circuits may
be used.

(e) For industrial/factory buildings/warehouses having too large open floor areas
For industrial/factory buildings/warehouses having large open floor areas, efforts should
be given to use circuits not exceeding 10 A. The corresponding circuit wire in the
BDB/SDB/DB then shall be not less than 2.5 mm2.

For Industrial/Factory Buildings having very large open floor areas, 15 A light/fan
circuits may be used as exceptional cases only. The corresponding circuit breaker in the
BDB/SDB/DB then shall be not less than 4 mm2.

Increase in the sizes of the above mentioned cables may be required if the distance is too
long. Voltage drop calculation will give the guidance in that case.

(f) Separate branch circuits from Miniature Circuit Breaker (MCB)

Separate branch circuits shall be provided from miniature circuit breaker (MCB) of a
BDBD/SDB or fuse of the fuse distribution boards (FDB) for light/fan.

Separate branch circuits shall be provided from miniature circuit breaker (MCB) of a
BDBD/SDB or fuse of the Fuse distribution boards (FDB) for automatic and fixed
appliances with a load of 500 watt or more and socket outlets. Each automatic or fixed
appliance shall be served by a protected socket circuit.

(g) Less than 50% loading of circuits with more than one outlet
Circuits with more than one outlet shall not be loaded in excess of 50% of their current
carrying capacity.

(h) Branch circuits must have spare capacity to permit at least 20% increase in
load

Each branch circuit running between a DB and a SDB, between a SDB and a BDB must
have spare capacity to permit at least 20% increase in load before reaching the level of
maximum continuous load current permitted for that circuit
4558 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(i) One spare circuit must be allowed in the distribution board for each five
circuits in use.

At least one spare circuit must be allowed in the distribution board for each five circuits
in use. Additional space for a circuit breaker along with the provision for connecting a
pair of outgoing cables shall be kept.
(j) Each final circuit shall be connected to a separate way in a distribution board
Where an installation comprises more than one final circuit, each final circuit shall be
connected to a separate way in a distribution board. The wiring of each final circuit shall
be electrically separate from that of every other final circuit, so as to prevent unwanted
energization of a final circuit.

(k) Size of cables in a branch circuit shall be at least one size larger than that
needed for the computed load current

Size of cables to be used in a branch circuit shall be at least one size larger than that
computed from the loading if the distance from the over-current protective device to the
first outlet is over 15 m.

(l) 4 mm2 (7/0.036) and 6 mm2 (7/0.044) wiring cable for a 15 A socket outlet
branch circuit
The minimum size of wiring cable used for a 15 A socket outlet branch circuit shall be 4
mm2 (7/0.036). When the distance from the over-current protective device to the first
socket outlet on a receptacle circuit is over 30 m the minimum size of wire used for a 15
A branch circuit shall be 6 mm2 (7/0.044).
(m) Length of a lighting circuit
The length of a lighting circuit shall be limited to a maximum of 30 m, unless the load on
the circuit is so small that voltage drop between the over-current protective device and
any outlet is below 1 percent.
(n) Use of common neutral for more than one circuit is prohibited
Each circuit must have its own neutral cable. Use of common neutral cable for more than
one circuit is not permitted.
(o) Following the appropriate new colour codes of cables
During wiring, correct colour codes of the insulation of the cables must be used.
Previously, for a single phase circuit red colour insulation was used for the live wire and
the black colour insulation for the neutral and green + yellow bi-colour insulation was
used for the ECC. Previously, for a three phase circuit red colour was used for the live
(L1), Yellow colour for the live (L2), Blue colour for the live (L3) cable and the black
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4559

colour for the neutral and green + yellow bi-colour for the ECC. This colour code of
cables shall now be replaced by the current IEC cable colour code standards, Table 8.1.21
and Figure 8.1.1. The current IEC colour code is recommended to be followed in
Bangladesh.

Table 8.1.21: New introduced Colour Codes of Cables Following IEC Standards

Item Pre-1977 IEE Pre-2004 IEE Current IEC

Protective earth (PE) Green Green/yellow Green/yellow

bi-colour
bi-colour
Neutral (N) Black Black Blue
Single phase: Line (L) Red Red Brown
Three-phase: L1
Three-phase: L2 Yellow Yellow Black
Three-phase: L3 Blue Blue Grey

Figure 8.1.1 Existing and harmonised colour code by IEC recommended for use in
Bangladesh.

The above mentioned colour coding must be indicated in the design drawing. This should
also be mentioned in the specification.
(p) Balancing of circuits in three phase SDBs, DBs, FDBs, and MDBs.
In a 3 phase distribution system special care must be taken during wiring to obtain
balancing of loads among the three phases.
In a 3 phase SDB, DB, FDB, MDB connections of the circuits to the bus-bars must be
made in such a way so that the load current remains balanced among the three lines
during low load as well as full load. After completing the installation balancing should be
checked by clamp meter current measurement of each phase.
4560 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

The above mentioned current balancing must be indicated in the SDB (if 3 phase), DB,
FDB, and MDB circuit diagram of design drawing. This should also be mentioned in the
specification.

1.3.5 Electrical Layout and Installation Drawings

An electrical layout drawing shall be prepared after proper locations of all outlets for
lamps, fans, fixed and transportable appliances, motors etc. have been selected. This is
the beginning of the electrical distribution design work. This job must be done with due
importance prior to starting the construction and installation work. Strong emphasis is
given on this work in this document.

1.3.5.1 Locating positions of the points on the plan of the building

At the beginning, the Light points, Fan points, Socket points, Switch Boards, BDBs,
SDBs, FDBs. DBs and MDBs shall be located on each plan based on convention,
suitability, application and safety view point.

Conduit layout and cable layout shall then be shown on the drawing.

1.3.5.2 Light and fan circuits must not be mixed with the socket circuits
In designing the wiring layout, power (socket) and heating (socket) sub-circuits shall be
kept separate and distinct from light and fan sub-circuits.
All wiring shall be done on the distribution system with main and branch distribution
boards placed at convenient positions considering both physical aspects and electrical
load centres. All types of wiring whether concealed or surface, shall be as near the ceiling
as possible. In all types of wiring due consideration shall be given to neatness and good
appearance.

1.3.5.3 Balancing of circuits in three phase distribution boxes is a must

Balancing of circuits in three phase installations shall be arranged in the drawing and also
must be done during physical connection.

1.3.5.4 Single phase socket outlets receiving connection from two different phases
Single phase socket outlets receiving connection from two different phases located in the
same room is to be avoided. However, if it is essential to have such socket connection
these must be located 2 m or more apart.

1.3.5.5 Electrical Layout drawings for industrial premises

Electrical layout drawings for industrial premises shall indicate the relevant civil
structure/barrier/duct and mechanical equipment/duct.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4561

1.3.5.6 Preparation of detailed circuit diagram

Circuit diagrams of each of the Light and Fan circuits must first be prepared based on the
selection whether it is 5A or 10A circuit. The cable size of each of the circuit’s size of the
ECC must be shown in the drawing. The circuit diagrams of the BDBs, SDBs, DBs,
FDBs, and MDBs etc. are then to be prepared and presented in the form of single line
drawings indicating the cable sizes of each interconnection and the sizes of the ECCs.
The distribution of BDBs, SDBs, DBs, FDBs, MDBs etc. are two be shown in a
distribution drawing indicating the cable sizes of each interconnection and the sizes of the
ECCs.

1.3.5.7 Preparation of electrical distribution and wiring design drawing by an

experienced Engineer

Electrical Distribution and Wiring Design drawing of building must be prepared by an

eligible Engineer as mentioned in Table 2.3.4 Chapter 3 Part 2.

1.3.6 Electrical Wiring in the Interior of Buildings

1.3.6.1 Surface wiring or exposed wiring

Wiring run over the surface of walls and ceilings, whether contained in conduits or
not, is termed as surface wiring or exposed wiring.

Single core PVC insulated cupper through PVC channels or through PVC conduits or
through GI pipes of approved quality may be used for surface wiring.

Surface wiring using twin core flat PVC insulated cupper on wooden battens used to be
used long back. This is almost discontinued and discouraged now a day.

PVC conduits or GI pipes, when used for surface wiring, shall be clamped with saddles at
a spacing not exceeding 600 mm, to the wall or ceiling using plastic rowel plugs with
countersunk galvanized screws.

(a) Surface wiring using wood battens

The wood batten used in this method shall be of good quality wood with a minimum
thickness of 12 mm. They shall be installed exposed and run straight on the ceiling or
wall surfaces. Battens on walls shall be run either horizontally or vertically, and never at
an angle. Battens on ceilings shall run parallel to the edges in either orthogonal direction,
and not at an angle, they shall be fixed to the wall or ceiling by rowel plugs and
countersunk galvanized screws. Cables shall be fixed to the battens by using galvanized
steel clips or brass link clips or PVC clips of required size at a spacing not exceeding
100 mm.
4562 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(b) Surface wiring using PVC conduits

PVC conduits or GI pipes, when used for surface wiring, shall be clamped with saddles at
a spacing not exceeding 600 mm, to the wall or ceiling using plastic rowel plugs with
countersunk galvanized screws.

The conduits placed concealed inside roof or in wall must have 20 SWG GI pull wires
placed during laying of the pipes for pulling the cables later.

(c) Surface wiring using PVC channels

Surface wiring may be done using single core PVC insulated cables placed inside surface
fixed PVC channels of appropriate size. Fixing of channels must be done using screws in
rowel plugs inserted into drilled holes on the walls/ceilings. The channels must be placed
in a straight line with adequate number of screws so that no sag is observed. Cables must
not be stressed in the bends. Adequate space must exist inside the channel to put the
cables in position without difficulty.

Surface wiring using flexible chords, clips and nails shall not be used in general.
(d) Surface wiring using Round core flexible cable with plastic clips and nails
Surface wiring using exposed Round core flexible cable with plastic clips and long nails
have been used for extending a point wiring, for extending a socket wiring due to shift,
for add a circuit wiring.
This is not recommended for regular wiring. Instead of using this method, one should go
for the recommended surface wiring using single core PVC cables with PVC channels or
single core PVC cables with PVC conduits as mentioned above in this document.
For a length of not exceeding 1 m this may be used only for shifting an existing
Light/Fan point or for shifting an existing socket point only under unavoidable
circumstances.
1.3.6.2 Concealed wiring
The wires in this type of wiring shall be placed inside GI conduits or PVC conduits that
are buried in roofs and in brick/concrete walls. The conduits in the walls shall be run
horizontally or vertically, and not at an angle.
Conduits in concrete slabs shall be placed at the centre of thickness and supported during
casting by mortar blocks or 'chairs' made of steel bars or any other approved means. All
conduits shall be continuous throughout their lengths.
Appropriate planning should be made in which there shall be adequate spare capacity in
the conduits placed in roof slabs so that unforeseen situation during execution of the
installation can be taken care of. Conduits will run through the roof and then bend
downward for going up to the outlets, DBs, switch boards, sockets.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4563

In a column structure building having no permanent walls, switch boards and socket
boards, pull boxes shall be placed in columns and must be done during the casting of
columns.

Concealed wiring through floors and upward mounting of PVC/GI pipes from the floor is
strongly discouraged because of the occurrence of condensation and accumulation of
water from condensation eventually leading to damaging of the simple PVC insulated
cable insulation. This method should not be followed as a general practice.

Underground cables for electrical distribution in the premises/garden/compound of the

building shall be encased in GI or PVC pipes and laid in earth trenches of sufficient
depth. Armoured cables need not be encased in conduits except for crossings under road,
footpath, walkway or floors.
The conduits placed concealed inside roof or in wall must have 20 SWG GI pull wires
placed during laying of the pipes for pulling the cables later.

1.3.6.3 Wiring inside suspended ceilings (false ceilings)

Wiring inside suspended ceilings (false ceilings) shall be surface wiring through conduits
or through PVC channels mentioned under the heading of surface wiring methods.

Cables shall not be placed loosely and haphazardly on the suspended ceilings. Placing
naked cables inside the suspended ceiling is not permitted.

Cable joints with PVC tape wrapping is not allowed for connection of a fitting from the
ceiling rose or from a junction box inside the gap space.

1.3.6.4 Wiring through cable tray

Wiring for connections to some machines may be carried through a cable tray suspended
from the ceiling. This is very rare for a domestic building. However in a commercial /
office or industrial building this technique may be needed. In special circumstances
Cables may be pulled through pre laid GI/ PVC pipes under the floor where there will be
no chances of water accumulation in the floor or condensation.

1.3.6.5 Mounting height of light and fan switch boards

Light and fan switch boards shall be placed 1220 mm above floor level in the residential
buildings (i.e, the clearance between the floor and the bottom of the switch board
shall be 1220 mm).

This above mentioned height shall be 1300 mm above floor level in the office buildings,
commercial buildings and industrial buildings. However, the minimum height shall not
be below 1220 mm.
4564 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

1.3.6.6 Restriction on the use of plastic/PVC insulated flexible chords/cables

Plastic/PVC insulated flexible chords/cables shall not be used for wiring of light/fan
points or for wiring of sockets, or for wiring of any sub circuits.

1.3.6.7 Cable joints and cable joint boxes in concealed and surface wiring
Both the Brown (L) and Blue (N) cables of a final circuit shall run from a BDB/SDB up
to the switch board without a joint. Similarly, both the Brown (L) and Blue (N) cables of
a point shall run from the point up to the switch board. Cable joints are to be made in the
switch board back box. Where the above methods are not implementable, joints shall be
made using approved cable joint methods.

1.3.7 Methods of Point Wiring and Circuit Wiring

1.3.7.1 Methods of Point Wiring

Wiring between a light/fan point and its corresponding switch board is termed as Point
Wiring. The load of such a point is not in excess of 100 watts in general, and in special
cases this may be up to 200 watts. Wiring for a light/fan point shall be made using one of
the following two methods: (i) Surface wiring or (ii) Concealed wiring. For wiring of a
point one brown and one blue PVC insulated copper cable shall run between a point and
its switch board. Cable joints inside conduits or within channels are forbidden. The
current carrying capacity for such a circuit shall not be more than 5 A for a residential or
a commercial (business/mercantile) building. The minimum size of a cable for such
wiring shall be 1.5 mm2.
Common neutral shall not be used under any circumstances.
1.3.7.2 Methods of Circuit Wiring
Wiring between a switch board and a BDB/SDB/DB will be called Circuit Wiring.
Circuit wiring shall be done with a live cable a neutral cable and an ECC cable for a
single phase circuit. Sometimes this circuit is also referred to as sub-circuit.
An ECC must be provided with each circuit. The ECC at the switch board end shall be
terminated in the earth terminal of the metal part of the switch board using a brass
screw/bolt and a nut. The BDB/SDB/DB end of the ECC shall be terminated in the
earthing busbar of the BDB/SDB/DB.

The ECC in this case shall be PVC insulated copper cable of appropriate size but with
yellow + green bi-colour insulation.

For each circuit, the live cable must be drawn using brown colour insulated PVC cable
and the neutral cable shall be drawn using blue colour insulated PVC cable.
Common neutral shall not be used under any circumstances.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4565

The minimum sizes of cable for various uses shall be as follows:

(a) For a 5 A circuit protected by a 5 A circuit breaker or fuse shall not be below 1.5
mm2

(b) For a 10 A circuit protected by a 10 A circuit breaker or fuse shall not be below
2.5 mm2.
(c) For a 15 A circuit protected by a 15 A circuit breaker or fuse shall not be below
4 mm2.

(d) For a 20 A circuit protected by a 20 A circuit breaker or fuse shall not be below
6 mm2.
The above mentioned sizes must be increased for long cables as mentioned elsewhere in
this document.
In general, the minimum size of cable for a particular circuit shall depend on the rating of
the fuse or circuit breaker used for the protection of that circuit. A voltage drop check is
to be made for each length of the circuit to ensure that the voltage drop at the farthest end
of the load from the main distribution point does not exceed 2.5 percent.
Sockets shall get direct connection from the BDB/SDB through breaker/fuse protection.
Depending on the assessed requirements sockets may be grouped/looped at the socket
end. Such grouping shall not exceed 3 numbers of sockets in one circuit.

1.3.8 Feeder Wiring between SDB and BDB, DB and SDB, FDB to DB, MDB to
FDB etc.
Wiring between a BDB and an SDB, an SDB and a DB, a DB and an FDB, an FDB and
an MDB needs special attention and the rules are similar to Circuit Wiring. ECC must be
present for each of the feed connections. The ECC in this case also shall be PVC
insulated copper cable of appropriate size but with Green + Yellow bi-colour insulation.
At both ends the ECC must be terminated at the earthing busbar.

Appropriate cable lugs/cable sockets must be used for terminating the L1, L2, L3, N and
E connections on the busbars of both the boards. The sizes of the cables must be chosen
to match with the rating of the circuit breaker/fuse ratings as mentioned above.

Circuit breakers/fuses must be provided at the outgoing and incoming sides of each of the
busbars of each BDB/SDB/DB/FDB boxes.

1.3.9 Conduits, Channels, Cables, Conductors and related Accessories

Conduits, Cables, Conductors and Accessories are important parts of an electrical

distribution installation.
4566 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

1.3.9.1 Conduits and conduit fittings

Cables of an electrical distribution installation are drawn through electrical conduits. For
the installation of conduits various types of fittings are needed. For the two types of
commonly used conduits, PVC and Metal, fittings should be as under.

(a) PVC conduits

(i) PVC conduits and conduit fittings shall be of heavy wall water grade type. All bends
shall be large radius bends formed by heat or by mechanical bending machine. The
cross-section of the conduit shall remain circular at the bend and the internal
diameter shall not be reduced due to bending. PVC pipe fittings shall be sealed with
PVC solvent cement or adhesive for PVC of approved quality.

(ii) Conduits installed in floors, if installed, shall have a slope of at least 1:1000 towards
floor mounted pull box or cable duct.

(iii) Conduits placed concealed inside roof or in wall must have 20 SWG GI pull wires
placed during laying of the pipes for pulling the cables later.
(iv) Water grade PVC conduits must be used for both concealed and surface wiring.
Water grade PVC conduits of different diameters shall be used as per necessity.

(v) Appropriate high grade bends and circular boxes must be used with the PVC pipes.

(vi) 18SWG metal sheet made and synthetic enamel paint coated quality boxes of
matching sizes shall be used as pull boxes and junction boxes. Appropriate pull-box
covers of ebonite or perspex sheet shall be fitted with GI machine screw and washer.
(vii) The PVC conduits placed concealed inside roof or in wall must have 20 SWG GI
pull wires placed during laying of the pipes for pulling the cables later.

(b) PVC channels

PVC channels should be used only for extension work in an already installed building. A
design drawing should not show use of such wiring except inside a false ceiling. Even
inside the false ceiling this item should be used for lengths. For long distances PVC
conduits should be used. High quality PVC channels of sufficient thickness should be
used and fixed in a neat manner. For large number of cables and for thick cables PVC
channels should not be used.

(c) PVC flexible pipes/conduits

PVC flexible conduits shall be used with surface wiring only and only in places where
PVC bends cannot be used. Except special circumstances flexible PVC conduits shall not
be used.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4567

(d) Metal/steel conduits

Galvanized Iron (GI) conduits shall be made using at least 16 SWG sheet. The conduits
shall have seamless joint along the length and must be suitable for making bends. No
projections are allowed inside the conduits. Metal conduits must be threaded for end to
end joints using sockets. In case of necessity, threads will be cut at the end of short
pieces. Sharp edges at the ends must be properly treated so that cable injury does not take
place during cable pulling.

(e) Pull boxes

(i) Pull boxes/Joint boxes must be placed closed to the ceiling where conduits from the
ceiling are going downward toward a switch box or are going toward a socket box or
are going toward a BDB/ SDB/ DB / FDB.
(ii) Pull boxes are extremely essential for pulling the cables without injuring the cables
and thus should not be avoided under any circumstances. These are also essential for
future maintenance and extension work.

(iii) Pull boxes/Joint boxes must be placed in the ceiling of office/factory building where
conduits are running over a long distance between two walls (terminal points) and
where fixed walls are not available and also where heavy beams are used. In case of
big cross section beams pull boxes/joint boxes shall be placed closed to the beams.

(iv) Pull boxes/Joint boxes must be made with 18 SWG GI sheet or with 18 SWG MS
sheet but coated with two coats of Grey Synthetic Enamel paint.

(v) Covers of pull boxes should be ebonite or perspex sheet of not less than 1/8 inch
thickness.

(f) Metal Boxes for Switch Boards

Metal Boxes for Switch Boards must be made with 18 SWG GI sheet or with 18 SWG
MS sheet but coated with two coats of Grey Synthetic Enamel paint. A Switch Board
Metal Box must have a small Copper / Brass earthing busbar for terminating the ECCs.

(g) Switches for operating light and fan points

Switches for operating Light and Fan points must be of 5A rating. These switches are
usually SPST type. However, for special applications like stairs and some other places
these may be SPDT type.

Switches for operating Light and Fan points may be of Gang type or may be isolated
type. The isolated types are to be mounted on an ebonite top plate which is again fitted on
the above mentioned Metal boxes for Switch Boards.
4568 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(h) Mounting regulators of ceiling fans

Metal Boxes for Mounting Inductor Regulators of Ceiling Fans must be made with 18
SWG GI sheet or with 18 SWG MS sheet but coated with two coats of Grey Synthetic
Enamel paint. Metal Boxes for mounting regulators of ceiling fans must have a small
copper/brass earthing busbar for terminating the ECCs.
However, such regulators may be placed inside the 18 SWG GI sheet or MS sheet made
Metal Boxes for Switch Boards. In such a case arrangements must be made so that the
PVC insulated point and circuit wiring cables and their joints inside the switch board do
not touch a regulator. This may be done by appropriately dressing the cables and
fastening the cables by using polymer cable fasteners.

1.3.9.2 Cables and conductors

For application in building wiring, PVC insulated stranded cables shall be used for Live
and Neutral Wires for single phase and 3-lines (L1, L2, L3) and one neutral for 3-phase.
For ECC also PVC insulated stranded cables shall be used. As a result, use of bare
conductors is non-existent.

(a) Cables
Conductors of a PVC insulated cable, thin or thick, shall be copper. Cable containing
Aluminum conductors may be used for thick cable of size more than 35 mm2 but copper
is always preferred.

Cables for power and lighting circuits shall be of adequate size to carry the designed
circuit load without exceeding the permissible thermal limits for the insulation. The
voltage drop shall also be within the specified limit of 2.5 percent from a distribution
point up to their farthest end of the load point. Recommended sizes (in mm2) of copper
conductors are as follows:

1, 1.5, 2.5, 4, 6, 10, 16, 25, 35, 50, 70, 95, 120, 150, 185, 240, 300, 400, 500,
630, 800, 1000

For final circuit/sub-circuit and for Light/fan point wiring the cable nominal cross-section
of the cable shall not be less than 1.5 mm2 for copper conductors.

Standard copper conductor sizes of cables which should be used for electrical
installations/distribution in buildings are given below. Conductors of sizes other than the
sizes listed below are not recommended.

(b) Phase and neutral cables shall be of the same size

In the wiring of the sub-circuit/circuit and all other circuits inside a building the Phase
cable and the neutral cable shall be of the same size.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4569

(c) Flexible cables/flexible cords

The minimum cross-sectional area of conductors of flexible cables/flexible cords shall be
0.5 mm2 for copper conductors. Flexible cable or cords shall not be used as fixed wiring
unless contained in an enclosure affording mechanical protection.

Flexible cables/flexible cords may be used for connections to portable equipment. For the
purpose of this regulation an electric cooker of rated input exceeding 3 kW is not
considered to be portable. The flexible cord shall be of sufficient length so as to avoid
undue risk of damage to the outlet, cord or equipment and of being a hazard to personnel.
(d) Treatment of cable ends/cable terminations
All stranded conductors must be provided with cable sockets/cable lugs of appropriate
size fitted using appropriate hand press tool or hand crimp tool or hydraulic press tool
depending on the size of the cable. This is necessary for termination of the cable ends on
bus-bars.

(e) Jointing of cables in wiring

Cable joints for the PVC insulated cables used in circuit wiring (thin cables) are to be
made through porcelain/PVC connectors with PIB tape wound around the connector
before placing the cable inside the box joint/pull box.

1.3.10 Conduits through the Building Expansion Joints

Conduits shall not normally be allowed to cross expansion joints in a building. Where
such crossing is found to be unavoidable, special care must be taken to ensure that the
conduit runs and wiring are not in any way put to strain or are not damaged due to
expansion/contraction of the building structure. In unavoidable situations, PVC conduit
through an oversize flexible PVC conduit may be used with pull boxes on both sides of
expansion joints.

1.3.11 Types of Electrical Wiring for Exterior Lighting and other exterior
purposes

1.3.11.1 Electrical wiring for garden lighting

For garden lighting PVC insulated PVC sheathed underground cables shall be used. For
protection purpose these may be drawn through PVC pipe of appropriate dimension so
that adequate clearance remains for the ease of pulling. In general, no junction of cables
shall be provided in underground level. However, in case of necessity, metal sleeve cable
ferrule joints using Crimp Tool or hydraulic press and heat shrink insulated sleeve shall
be used on top.
4570 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

1.3.11.2 Electrical wiring for street lighting

For street lighting PVC insulated PVC sheathed underground cables shall be used. For
protection purpose these may be drawn through PVC pipe of appropriate dimension so
that adequate clearance remains for the ease of pulling. In general, no junction of cables
shall be provided in underground level. However, in case of necessity, metal sleeve cable
ferrule joints using Crimp Tool or hydraulic press and heat shrink insulated sleeve shall
be used on top. Joining the cables at the bottom of a street pole must be done inside a
metal joint box located sufficiently above the street level so that water cannot reach the
box even during the worst rain/flood situation.
1.3.11.3 Electrical wiring for boundary light
For boundary lighting PVC insulated PVC sheathed underground cables shall be used.
For protection purpose these may be drawn through PVC pipe of appropriate dimension
so that adequate clearance remains for the ease of pulling. In general, no junction of
cables shall be provided in underground level. However, in case of necessity, metal
sleeve or cable ferrule joints using Crimp Tool or hydraulic press and heat shrink
insulated sleeve shall be used on top. However, for the portion of the cable running
concealed through a wall, PVC insulated cables through PVC conduits may be used.
1.3.12 Branch Distribution Boards, Sub-distribution Boards, Distribution Boards,
FDBs and MDBs
1.3.12.1 Enclosure/box
Enclosures for sub-distribution boards located inside the building shall be dust-proof and
vermin-proof using sheet steel fabrication of a minimum thickness of 20 SWG. The
boards shall be safe in operation and safe against spread of fire due to short circuit.
1.3.12.2 Size of the enclosure of a BDB/SDB/DB/FDB/MDB
Table 8.1.22 provides a guidance of sizes of enclosures for SDB containing miniature
circuit breakers or fuses. However, the size will depend on the number and size of the
circuit breakers or the fuses the number of outgoing cables and their sizes, the size of the
busbars and the type of insulators used for the busbars.
Table 8.1.22: Recommended Enclosure Sizes for MCB's and Fuses
Dimensions (mm) No. of MCB's or
Fuses

Height Width Depth

350 390 120 up to 12

480 390 120 up to 24

610 390 120 up to 36

740 390 120 up to 48
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4571

1.3.12.3 Location
A Sub-distribution board (SDB) shall be located as close as possible to the electrical load
centre for that SDB. This is also applicable for determining the locations of FDBs, DB
and BDBs. These boards shall never be located on water soaked or damp walls.
1.3.12.4 Wiring of sub-distribution boards
(a) In wiring a sub-distribution board, total load of the consuming devices shall be
distributed, as far as possible, evenly between the numbers of ways of the board,
leaving the spare way(s) for future extension.
(b) All connections between pieces of apparatus or between apparatus and terminals on a
board shall be neatly arranged in a definite sequence, following the arrangements of
the apparatus mounted thereon, avoiding unnecessary crossings.
(c) Cables shall be connected to terminals only by soldered or welded lugs, unless the
terminals are of such form that it is possible to securely clamp them without cutting
away the cable strands.

1.3.13 Electrical Services Shafts, Bus Ducts, L.T. Riser Cables and L.T. Busbar
Trunking
1.3.13.1 Vertical service shaft for electrical risers
For buildings over six-storey or 20 m high there shall, in general, be a minimum of one
vertical electrical service shaft of (200 mm x 400 mm) size for every 1500 m2 floor area.
The electrical service shaft shall exclusively be used for the following purposes:
(a) Electric supply feeder cables or riser mains
(b) Busbar Trunking
(c) telephone cables
(d) Data Cables
(e) fire alarm cables
(f) CCTV cables
(g) Other signal cables
(h) Area fuse/circuit breakers
(i) Floor Distribution board/sub-distribution boards for individual floors.
The construction of the floors of the duct area shall be constructed in such a way so that
the remaining empty open space after putting the cables/busbar trunking/ pipes/ conduits
in position is filled up with RCC slab(s) or any other non-inflammable material so that
fire or molten PVC cannot fall from one floor to the next lower floor(s). For this purpose
arrangements need to be made during floor casting.
4572 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Free and easy access to the electrical shaft room in each floor must be available for
operation, maintenance and emergency shut downs.

Vertical cables other than electrical cables shall be placed at a sufficient distance from the
nearest electrical cable. A vertical separating brick wall between electrical and non-
electrical wall is preferable.

Vertical Service Shaft for Electrical Risers as mentioned above must not be placed
adjacent to the Sanitary Shafts. They should be placed at significant separation in order to
ensure that the Vertical Service Shaft for Electrical Risers remains absolutely dry.

1.3.13.2 LT Riser main cables

(a) For low rise building riser main cables will serve to bring L.T. connection to the
floor distribution boards (FDBs) of each floor from the main distribution board. For
a 5 storied building or lesser having a floor space of less than 600 m2 in each floor
the riser cables may be PVC insulated cables through PVC or GI pipes.

(b) For bringing the riser main cables a common vertical wall and holes or slots in the
floors must be given by the building construction people.

(c) However, for larger floor area or for higher buildings PVC insulated PVC sheathed
underground cables must be used with protection and spacing.

(d) For more than 9 storied building Busbar preferably sandwiched copper busbar
trunking should be used for safety reasons.

(e) PVC insulated PVC Sheathed underground cables must be used as Riser Main
Cables. These cables shall be placed in or pulled through a PVC pipe of higher
diameter so that the cable can be easily pulled through it. The PVC pipes must be
fixed vertically in a straight line on the wall of the shaft using appropriate saddles.
However, in some cases PVC insulated PVC Sheathed underground cables may be
directly fixed on the wall using appropriate saddles with 37mm spacing between two
adjacent cables. Sheet metal made Joint Boxes (with ebonite cover plates) must be
placed at each floor tapping point.

(f) The cable work shall be done neatly so that no suspended cables are seen around the
place and no suspended flexible pipes are seen.

(g) Each riser cable must have appropriate fuse or circuit breaker protection at the source
busbar junction and also at the tap off point.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4573

1.3.13.3 LT Busbar Trunking

For high rise buildings, LT (0.4KV TP&N) busbar trunking sytem is used instead of riser
main cables to minimize space in the vertical electrical shaft, to minimize the risk of
spreading of fire from one floor to another due to electrical short circuit in one of the
cables or sparks, to have a neat distribution system. Most part of the busbar trunking shall
be installed vertically. The horizontal portion of the busbar trunking shall usually connect
the vertical portion with the Substation LT panel.

(a) Busbar trunking are specially useful to minimize space and to minimize risks of
spreading fire (during accidents) which may happen with bundles of insulated
cables. The conductors supported by insulators inside the busbar trunking shall
be copper of solid rectangular cross-section. The copper bars are insulated. A
busbar trunking system shall be laid with minimum number of bends for
distribution system. Typical rating of feeder busbar trunking for 3-phase- 3-wire
or 3-phase- 4-wire system shall range from 200 amperes to 3000 amperes
although lower amperes are not impossible.

(b) Horizontal busbar trunking of suitable size may be provided along the roads for
a group of buildings to be fed by a single substation but with heavy weather
(moisture and water) protection and covered with appropriate weather resistant
water proof material. Extreme care need to be taken in these cases for protection
against moisture, water and outside weather.

(c) Busbar trunking shall be placed in a dry place and must not be installed in a
place which is even slightly exposed to weather/moisture/ spray or sprinkle of
water.

1.3.13.4 LT Busducts

In certain applications, especially in factory lighting and factory power distribution of

large area factories Busducts are used. In most cases, these Busducts are suspended from
ceiling. Busducts offer safe, reliable, neat distribution system in these cases. The choice
will depend on the floor area, type of machineries, type of jobs and other factors.

Appropriate circuit protection using adequate number of circuit breakers of appropriate

rating is needed. In most cases these busducts are horizontally mounted/suspended. The
busbars shall be copper. The rating shall depend on the current on each segment and the
current carried by each segment.
4574 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

1.3.14 L T Main Incoming Cable and Service Connection

(a) Overhead service connection to a building shall be achieved with PVC insulated
Cables with GI support wire (similar to catenary) or catenary wire (mainly for single
phase consumers). The overhead service connection shall be led into buildings via
roof poles or service masts made of GI pipe at least 38 mm in diameter having a
goose neck bend at the top and installed on the outer wall. The alternative is to have
underground cable connection.
(b) Underground PVC insulated PVC sheathed water proof cables shall be placed in
underground cable trench or pulled through a PVC pipe of higher diameter placed in
a cable trench so that the cable can be easily pulled through it. PVC insulated
stranded annealed copper ECC cables matching with the main cable size shall run
along the Main incoming cable with termination at the earthing busbar at both end.
Each of the PVC pipes must have 18 SWG GI pull wires placed during laying of the
pipes for pulling the cables later.
(c) For main incoming thick underground cables joints are strongly discouraged and
should be avoided as far as possible. However, for unavoidable cases joints must be
made through sleeve or ferrule of appropriately matched size fitted with hydraulic
press following neat processing of the cable ends. Appropriate fusible heat shrink
cover must be used over such junction.
For thick cables running through conduits as vertical risers, these joints must be put
inside metal joint/pull boxes with covers.
(d) Special forms of construction, such as flame proof enclosures, shall be adopted
where risk of fire or explosion exists near a place where thick incoming cable or riser
cables are placed.
(e) The Underground service cable shall be laid in conformity with the requirements of
Sec 1.3.24 titled “Laying of LT underground Cables”, of this Chapter.
(f) The power and telecommunication or antenna cables must be laid separately
maintaining sufficient distance.
(g) The fire alarm and emergency lighting circuits shall be segregated from all other
cables and from each other in accordance with BS 5839 and BS 5266.
Telecommunication circuits shall be segregated in accordance with BS 6701 as
appropriate.
(h) Where a wiring system is located in close proximity to a non-electrical service both
the following conditions shall be met:
 The wiring system shall be suitably protected against the hazards likely to arise
from the presence of the other service in normal use, and
 Appropriate protection against indirect contact shall be taken.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4575

(i) A wiring system shall not be installed in the vicinity of a service which produces
heat, smoke or fume likely to be detrimental to the wiring, unless protected from
harmful effects by shielding arranged so as not to affect the dissipation of heat from
the wiring.
(j) Where a wiring system is routed near a service liable to cause condensation (such as
water, steam or gas services) precautions shall be taken to protect the wiring system
from deleterious effects.
(k) No cable shall be run in a lift (or hoist) shaft unless it forms part of the lift
installation as defined in BS 5655.
1.3.15 Design for Electrical Wiring
Design of Electrical wiring must be done following the provisions provided in this
Chapter. Detailed design drawings must be prepared by eligible Engineer for complete
execution of the electrical works mentioned in this document and any other new items
arising because of the evolution of new technologies in the near future.
Typically, there must be conduit layout drawing(s) indicating the conduit layouts, the
locations of the switch boards, locations of the sockets, locations of the BDBs, locations
of the SDBs, locations of the DBs, locations of the FDBs, location of the MDB, location
of the Main incoming cable.
A distribution diagram of the BDBs, SDBs up to MDBs as applicable indicating the
ampere rating of the incoming MCB/MCCB, interlinking cable sizes and the ECCs must
be presented.
Detailed circuit diagrams of the circuits and the BDBs, SDBs, MDBs as applicable must
be presented.

Detailed drawings of earthing and earth inspection pits and any other complicated parts
must be presented. The contractor shall prepare as built drawings after completing a
project.

1.3.15.1 Design for electrical wiring in bedrooms and drawing rooms

The location of a switch board must be near the entrance door of a bedroom like any
other room. The location of the wall mounted light fittings must be chosen based on the
possible locations of furniture which is also needed in other rooms. Sufficient number of
3-pin 13 A switched shuttered flat pin sockets must be provided in a bed room. The same
principles are applicable for a Living room.

Design must be made in such a way that sufficient clearance (space) is left inside the
concealed conduits (i) for the ease of pulling the cables and also for adding few more
cables in case of necessity during future modification.
4576 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

For bedrooms and drawing rooms the light plus fan sub circuits for shall not be of more
than 5A rating.

Generally, single core PVC insulated stranded electrolytic annealed copper cables shall
be used in concealed wiring technique or in the other methods.

1.3.15.2 Design for electrical wiring in a kitchen.

The sensitive item in a kitchen is placing 3-pin 13 A switched shuttered flat pin sockets
on wall of the kitchen side table near the wall. Good distance must be maintained
between the kitchen water tap and the socket. The socket for the refrigerator (if any) shall
also be a 3-pin 13 A switched shuttered flat pin socket, and may be placed at the same
level as the other socket. For the ease of operation a 3-pin 13 A switched shuttered flat
pin socket for this purpose may be placed at the bottom level height of a switch board
provided this is acceptable in terms of aesthetics.

For kitchens, the light plus fan sub circuits for shall not be of more than 5A rating.

1.3.15.3 Switches for toilets and bath rooms

Switches for toilet lights and toilet ventilating fans must be placed outside the toilets
adjacent to the entrance door but must not be placed inside the toilet. The same rule
should be followed for bath rooms. Using ceiling mounted chord switch at the entrance
path of the door of a toilet is a good idea for small toilets attached to bed rooms. Ceiling
mounted chord switches may be used with a chord suspended from the ceiling near the
opening of the door.

1.3.15.4 Design for electrical wiring in office rooms

The location of a switch board must be near the entrance door of an office room. The
location of the light fittings must be chosen based on the possible locations of work table,
furniture. Sufficient number of 3-pin 13 A switched shuttered flat pin sockets must be
provided in each office room. In this regard special consideration needs to be given on
the possible location of computers and other office equipment.

Sufficient conduits and cables must be left for future modification as often rearrangement
of cables needs to be made.

Generally, single core PVC insulated stranded electrolytic annealed copper cables shall
be used for wiring by using the concealed wiring technique or the other two methods
mentioned in the wiring section.

In case of special requirements, PVC insulated PVC sheathed Stranded Electrolytic

Annealed Copper Cables may be used for wiring through conduits or other methods.

For Offices the sub circuits for shall not be of more than 5 A rating.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4577

1.3.16 Temporary Electrical Connection for a Building Construction Site

Temporary connections are needed for a building construction site. A fuse distribution
board containing incoming cut out fuse, outgoing cutout fuses plus busbars or distribution
boards containing in coming circuit breakers, outgoing circuit breakers plus busbars of
appropriate rating must be installed for such connections. Such boards shall be installed
in a dry place so that rain water or waters coming from a construction zone cannot reach
such boards.

1.3.17 Temporary Electrical Connection for an Outdoor Concert

Temporary connections are needed for an outdoor concert stage for special lighting, for
various display systems, for high power audio systems. A fuse distribution board
containing incoming cut out fuse, outgoing cutout fuses plus busbars or a distribution
board containing in coming circuit breakers, outgoing circuit breakers plus busbars of
appropriate rating must be installed for such connections. Such boards shall be installed
in a dry place and shall be mounted at a safe height above ground so that rain water or
waters coming from anywhere cannot reach such boards. Such boards shall not be
installed near flammable materials.

Cables of appropriate types and appropriate ratings must be used for such applications.
Appropriate type of sockets, preferably flat 3-pin switched shuttered 13 A sockets should
be used for distribution.

1.3.18 11 kV/ 0.4 kV Electrical Substation in a Building

1.3.18.1 General
According to the rule of the distribution companies of Bangladesh, 11 kV/ 0.4 kV
Electrical substations shall be required for a building if the load requirement of the
building exceeds 50 kW. In most cases, substations are required for Multi-storied
residential, Multi-storied Commercial buildings, Multi-storied Office building and
Industries.
To determine the rating of the substation required, a load factor of at least 80% shall be
applied to the estimated load of the building. The future expansion requirements should
definitely be taken into consideration.
1.3.18.2 Location of an electrical substation
In a multi-storied building, the substation shall preferably be installed on the lowest floor
level, but direct access from the street for installation or removal of the equipment shall
be provided. The floor level of the substation or switch room shall be above the highest
flood level of the locality. Suitable arrangements should exist to prevent the entrance of
storm or flood water into the substation area.
4578 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

The location of a substation will depend on (i) the feed point of the 11 kV Supply
Authority line and (ii) the location of the LT vertical riser cables.

It is preferable to locate the air-conditioning plant room (if any) adjacent to the electrical
substation in such a way that the distance from the controlling switchboard of the air-
conditioning plant rooms and corresponding switches in the electrical substation are kept
minimum.

In case of a building complex, or a group of buildings belonging to the same

organization, the substation should preferably be located in a separate building and
should be adjacent to the generator room, if any. Location of substation in the basement
floor and on the floors above ground floor level (GFL) preferably be avoided. If Sub-
Station it to be installed on the basement floor or the floors above ground floor level
(GFL) special safety measures is to be taken by the user or owner. Measures are as
follows:

(i) No objection certificate stating the Sub-Station safe by the Fire Service and
Civil Defense Department.

(ii) Certification of the building consultant stating safe, proper ventilation, easy
entrance and exit and safe load bearing capacity of the floors above the ground
floor level (GFL).

(iii) Proper undertaking of the Sub-Station user or owner as the case may be,
Stating safety and liability will be ensured by them.
In case the electric substation has to be located within the main building itself for
unavoidable reasons, it should be located on ground floor or assessment floor or the
floors above the ground floor (GFL) with easy access from outside.
1.3.18.3 Height, area, floor level and other requirements of a substation room

(a) The minimum height of a substation room should be 3.0 m to 3.6 m depending upon
the size of the transformer.

(b) The recommended area required for substation and transformer rooms for different
capacities are given in Table 8.1.23 for general guidance. Minimum recommended
spacing between the transformer periphery and walls should be :
(i) 0.75 m for Transformer installed in a room with wall on two sides.
(ii) 1.0 m for Transformer installed in a room with wall on three sides.
(iii) 1.25 m for Transformer installed in an enclosed room.
(iv) 1.5 m distance from one to another transformer for multiple transformers in
room for 11 kV voltage level and 2.5 m distance for higher level of voltage.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4579

(c) For transformers having large oil content (more than 2000 litres), soak pits are to be
provided.

The areas given in Table 8.1.23 hold good if they are provided with windows and
independent access doors in accordance with local regulations.

All the rooms shall have significant ventilation. Special care should be taken to ventilate
the transformer rooms and where necessary louvers at lower level and exhaust fans at
higher level shall be provided at suitable locations in such a way that cross ventilation is
maintained. Fans should be provided so that the transformer gets air supply from the fans.

The floor level of the substation should be high. Arrangement shall be made to prevent
storm water entering the transformer and switch rooms through the soak pits, if floor
level of the substation is low.

Substation of higher voltage may also be considered to the basement floor having proper
and safe building design.

Table 8.1.23: Recommended Area for Transformer and Substation of Different

Capacities

Capacity of Transformer Area Total Substation Area (with HT, LT

Transformer 2
(m ) Panels & Transformer Room but
(kVA) without Generators), (m2)

1 × 150 12 45

1 × 250 13 48

2 × 250 26 100

1 × 400 13 48

2 × 400 30 100

3 × 400 40 135

2 × 630 26 100

3 × 630 40 190

2 × 1000 40 180

3 × 1000 45 220
4580 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

1.3.18.4 11kV/0.4kV Distribution transformer for the substation of a building

An 11 kV/0.4kV indoor distribution Transformer is a major part of an indoor substation.
These Substations may be installed inside the building itself or may be housed in a
separate building adjacent to the building.
For small to moderate power rating up to 2 MW, two types of indoor transformers have
been widely used in recent years. These are (i) Oil Type Natural Cooled transformer and
(ii) Cast Resin Dry Type Natural Cooled transformers.
In most cases Oil Type Natural Cooled transformer may be used for substations if
adequate space is available to accommodate the transformer.
Cast Resin Dry Type Natural Cooled transformers should be used (i) in places where
stringent protection against spread of fire is needed and (ii) in places where space saving
is of utmost importance.
Choice of oil type or dry type transformers
Dry type transformer should be installed where risk of spreading of fire is high and where
flammable materials are to be kept around the substation.
For Hospital buildings, Multistoried Shopping Centers Dry type transformers should be
used to for minimizing fire risks.
An industrial buildings containing inflammable materials, chemical and having the
substation in the same building dry type transformers should be used for minimizing fire
risks.

1.3.18.5 Type of connection between a substation transformer and its LT panel

Connection between a substation transformer and its LT panel can be established a) by

using NYY underground LT Cables or b) by using ceiling suspended busbar trunking.
For small size transformers the first method should be used although there is no
restriction in using the second method. However, for big substations the second method is
safer and at the same time gives a neat solution.

1.3.18.6 Ventilation of a substation

In an electrical substation significant amount of forced ventilation is very much needed
apart from natural ventilation. Exhaust fans (minimum 450 mm dia) must be provided in
sufficient numbers on all sides of the substation above the lintel level. Grill fitted
windows having window panes must be provided on all sides for natural ventilation. The
windows must have sun sheds so that no rain water can enter inside the substation.

If due to space constraint or due to any other difficulties, sufficient number of windows
and ventilating fans cannot be installed, high velocity forced ventilation using ducts must
be provided.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4581

1.3.18.7 Layout of a substation

(a) In general, substation HT to LT transformer shall be placed in one corner of the

room so that the HT side remains away from the passage of the persons.

(b) The HT metering panel shall be located near the exterior of the substation room near
the exit gate and also shall be convenient for the HT cable entry.

(c) The HT Panel shall be located near the exterior, just after or adjacent to the HT
panel.

(d) LT panel shall remain at a sufficient distance from the transformer but not too far
away from the transformer. On the other hand, the location of the LT panel should
such that the riser main cable can have their way upward or outward within very
short distance.
(e) In allocating the areas within a substation, it is to be noted that the flow of electric
power is from supply company network to HT room, then to transformer and finally
to the low voltage switchgear room. The layout of the rooms shall be in accordance
with this flow.

(f) All the rooms shall have significant ventilation. Special care should be taken to
ventilate the transformer rooms and where necessary louvers at lower level and
sufficient number of high speed exhaust fans at higher level shall be provided at
suitable locations in such a way that cross ventilation is maintained. Sufficient
numbers of ceiling fans must be provided so that the transformer gets air supply from
ceiling fans.

(g) The 11 kV/0.4 kV substation shall not be placed in a basement.

(h) The substation shall preferably be placed in ground floor. Placing a substation on any
other floor other than ground floor shall be avoided.

(i) The substation room and the areas adjacent to cable routes must have adequate fire
alarm and fire extinguishing/fighting system appropriate for extinguishing fire due to
electrical system, cable burning and oil burning.

1.3.19 Standby Power Supply

1.3.19.1 Provision for standby power supply

Provision should be made for standby power supply, in buildings, where interruption of
electrical power supply would cause significant discomfort, result in interruption of
activities, major production loss, cause hazard to life and property and cause panic. The
standby power supply may be a petrol engine or diesel engine or gas engine generator or
an IPS or a UPS.
4582 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

1.3.19.2 Capacity of a standby generating set

The capacity of standby generating set shall be chosen on the basis of essential light load,
essential air-conditioning load, essential equipment load and essential services load,
essential lift (s), one or all water pumps and other loads required as essential load. Table
8.1.24 shows recommended room area for different sizes of generators as a general
guidance. Minimum recommended spacing between the generator periphery and walls
need to be included:

(i) 1.0 m for generator installed in an enclosed room.

(ii) 1.25 m distance from one to another generator for multiple generators in the
room.

1.3.19.3 Generator room

The generating set should preferably be housed in the substation building or should be
placed adjacent to the substation room to enable transfer of electrical load (Change over)
with negligible voltage drop as well as to avoid transfer of vibration and noise to the main
building. The generator room should have significant amount of ventilation and fitted
with a number of ceiling fans. Appropriate type and number of firefighting equipment
must be installed inside the generator room. The generator engine exhaust should be
appropriately taken out of the building and should preferably be taken out through any
other side except South. The generator oil tank should be place away from the control
panel side. In case of gas engine generator extra precaution must be taken regarding
ventilation, leakage to prevent explosion.

The standby generator room should preferably be located outside the building. In the case
of a gas engine driven generator, the generator must be located outside the building with
adequate ventilation and windows. In general the generator room must have adequate
ventilation and fans for continuous cooling.

The generator shall be placed either on the ground floor or in the first basement. Location
of generator in the basement floor preferably be avoided. If generator is to be installed on
the basement floor special safety measures is to be taken by the user or owner as per
manufacturer’s safety specification.
A continuous running generator must be located outside the building. Other rules
mentioned above for standby generator are strictly applicable for this case.

For both the standby and continuous running generators the generator room and the areas
adjacent to cable routes must have adequate fire alarm and fire extinguishing/fighting
system appropriate for extinguishing fire due to cable burning and fuel burning.
Generators must be installed on shock absorbing mounting bases.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4583

1.3.19.4 Changeover switch of a generator

A standby generator, if needed, is to be connected at the supply input point after the
energy meter and after the main incoming switch or the main incoming circuit breaker,
but through a changeover switch of appropriate rating. The rating of such a switch shall
be at least 1.25 times the rating of the main incoming circuit breaker. The changeover
switch shall be of such a type so that when moved to the mains position, there is no
chance that the generator will be connected and vice versa.

The Changeover Switch may be manual type with knife switch type switching or may be
automatic type with magnetic contactors. In both the cases the Changeover Switch shall
be properly made so that there is no chance of loose connection or spark.

The wiring for this purpose shall be made following the standard practices mentioned
under the heading of wiring using cables of appropriate size.

Table 8.1.24: Recommended Area for Standby Generator Room

Capacity (kW) Area (m2)

1 × 25 20
1 × 48 24
1 × 100 30
1 × 150 36
1 × 300 48
1 × 500 56

1.3.19.5 Installation of an IPS or a UPS

(a) For safety purpose size of a UPS should be kept as small as possible.

(b) For the installation of a 200 - 600 VA IPS a 5A circuit must be made with the light
points and fan points of different rooms to be brought under the control of the IPS.
This circuit must have 3A Fuse protection using fuse cutout box. Wiring and
connection has to be made following the wiring rules given in the wiring sections of
this document. Cables of appropriate size must be used for wiring.

(c) For the installation of a 600 - 700 VA IPS a 5A circuit must be made with the light
points and fan points of different rooms to be brought under the control of the IPS.
This circuit must have 5A fuse protections or 5A circuit breaker protection. Wiring
and connection has to be made following the wiring rules given in the wiring
sections of this document. Cables of appropriate size must be used for wiring.
4584 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(d) For the installation of an IPS of higher capacity, a BDB with multiple outgoing
circuits each not exceeding 5 A shall be used with cutout - fuse protection at both
incoming and outgoing sides. Cables of appropriate size must be used for wiring of
each circuit.

(e) Battery maintenance (checking water level, temperature rise and the condition of the
terminals) should be done at least every 15 days. Connection of the Battery terminals
should be made properly and checked periodically for loose connection and
deposition of sulphate. Battery of an IPS must be kept in a safe place so that short
circuit between the battery terminals does not occur. Inflammable materials must not
be kept in the vicinity of the IPS or battery.

(f) Safety issues must be taken into consideration in placing an IPS in a room. Same
points shall apply for the installation of an UPS.

1.3.19.6 Installation of a solar photovoltaic system on top of a building

Building should be provided with solar photovoltaic system. For installation of a solar
photovoltaic system, necessary precaution needs to be taken. Separate wiring and
protection system must also be ensured.

Installation of solar water heaters on the roof tops of the residential and commercial
buildings:
Buildings or apartments where hot water will be required, use of solar water heaters
instead of electric and gas water heaters should be made mandatory. Flat plate heat
collectors or vacuum tube solar water heaters of various capacities are available in the
market.
The integral parts of a conventional solar photovoltaic system are:
(a) Solar photovoltaic panel(s)
(b) Battery charge controller
(c) Inverter
(d) Cables between the solar photovoltaic panel(s) and the battery charge controller
(e) Cables between the battery and the battery charge controller
(f) Cables between the inverter and the distribution board (DB/SDB/BDB)
(g) Other cables and accessories.
For the installation of a solar photovoltaic system of higher capacity, a DB with multiple
outgoing circuits each not exceeding 5 A shall be used with cutout - fuse protection at
both incoming and outgoing side. Copper cables of appropriate size must be used for
wiring of each circuit.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4585

Battery maintenance (checking water level, temperature rise and the condition of the
terminals) should be done at least every 15 days. Connection of the battery terminals
should be made properly and checked periodically for loose connection and deposition of
sulphate.

Batteries of a solar photovoltaic system must be kept in a safe place so that short circuit
between the battery terminals does not occur. Inflammable materials must not be kept in
the vicinity of the IPS or battery. In most cases for roof top solar panels, the battery room
shall be placed inside a roof top room with adequate natural ventilation and forced
cooling using ceiling fans. Because of the roof top location of the Solar panels, the room
temperature is expected to be higher.

Safety issue must be taken into consideration in placing the batteries of a solar
photovoltaic system.
For a residential flat system building, one or two circuits for each flat shall come from the
DB of the photo-voltaic source at roof top to each flat depending on the requirement.
Connection to load in each flat will be done through a changeover switch for each circuit.
For a commercial/office building, one or two circuits for each office/office area shall
come from the DB of the photo-voltaic source at roof top to each flat depending on the
requirement. Connection to load in each flat will be done through a changeover switch
for each circuit.
Conduit based riser system must carefully be installed, separately for this system only,
during the construction of the building to bring down the cables from the roof top DB
room up to each flat/office/office area. Special care must be taken during installation so
that rain water can under no circumstances get into the conduit and cable system.
1.3.19.7 Installation of a Solar Photovoltaic System on the exterior Glass of a
Building having Large Glass area Facade
For semitransparent solar panels mounted on exterior glass of multistoried building
similar process and precautions mentioned above must be followed.
1.3.20 Electrical Distribution System
1.3.20.1 Design, selection and choice of the type of connection
(a) In the planning and design of an electrical wiring installation, due consideration shall
be given to prevailing conditions. Advice of a knowledgeable and experienced
electrical design engineer must be sought from the initial stage up to the completion
of the installation with a view to have an installation that will prove adequate for its
intended purpose, and which will be safe and will be efficient.
(b) All electrical apparatus shall be suitable for the voltage and frequency of supply of
this country mentioned earlier.
4586 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(c) The number and types of connection required e.g., single-phase two-wire AC or
three-phase four-wire AC shall be assessed, both for the supply source and for the
internal circuits needed within the installation.
(d) The following characteristics of the supply shall be ascertained :
(i) nominal voltage(s)
(ii) current and frequency
(iii) prospective short circuit current at the origin of the installation
(iv) type and rating of the over-current protective device acting at the origin of the
installation
(v) suitability for the requirements of the installation, including the maximum
demand
(vi) expected maximum value of the earth loop impedance of that part of the system
external to the installation.
(e) In case of connected loads of 50 kW and above, HT 11 kV three-phase supply line
with substation must be installed because of the requirement of the distribution
companies although the use of HT supply will involve higher expenses due to
installation of a distribution transformer, HT metering Panel, HT panel and LT Panel
at the consumer's premises.
In this respect, the rules of the electrical distribution authorities will be the ultimate
deciding factor.
1.3.20.2 Equipment and accessories
(a) High Voltage Switchgear
The selection of the type of high voltage switchgear for any installation should consider
the following:
(i) voltage of the supply system,
(ii) the prospective short circuit current at the point of supply,
(iii) the size and layout of electrical installation,
(iv) the substation room available, and
(v) the types machineries of the industry (if applicable).
(b) Guidelines on Various Types of Switchgear Installation
(i) Banks of switchgears shall be segregated from each other by means of fire
resistant barriers in order to prevent the risk of damage by fire or explosion
arising from switch failure. Where a bus-section switch is installed, it shall also
be segregated from adjoining banks in the same way.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4587

(ii) In the case of duplicate or ring main supply, switches with interlocking
arrangement shall be provided to prevent simultaneous switching of two
different supply sources.
(c) Low Voltage Switchgear
(i) Switchgear and fusegear must have adequate breaking capacity in relation to the
capacity of the transformers.
(ii) Isolation and protection of outgoing circuits forming the main distribution
system may be effected by means of circuit breakers, or fuses or switch fuse
units mounted on the main switchboard. The choice between alternative types of
equipment will take the following points into consideration:
(iii) In certain installations supplied with electric power from remote transformer
substations, it may be necessary to protect main circuits with circuit breakers
operated by earth leakage trips, in order to ensure effective earth fault
protection.
(iv) Where large electric motors, furnaces or other heavy electrical equipment are
installed, the main circuits shall be protected by metal clad circuit breakers or
conductors fitted with suitable instantaneous and time delay overcurrent devices
together with earth leakage and backup protection where necessary.
(v) In installations other than those mentioned above or where overloading of
circuits may be considered unlikely, HRC type fuses will normally afford
adequate protection for main circuits separately as required; the fuses shall be
mounted in switch fuse units or with switches forming part of the main switch
boards.
(vi) Where it is necessary to provide suitable connection for power factor
improvement capacitors at the substation bus, suitable capacitors shall be
selected in consultation with the capacitor and switchgear manufacturer and
necessary switchgear/feeder circuit breaker shall be provided for controlling the
capacitor bank(s).
1.3.21 Transformers
(a) Where two or more transformers are to be installed in a substation to supply an LT
distribution system, the distribution system shall be divided into separate sections
each of which shall normally be fed from one transformer only unless the LT
switchgear has the requisite short circuit capacity.
(b) Provision may, however, be made to interconnect busbar sections through bus
couplers to cater for the failure or disconnection of one transformer which need to be
executed with much care using locking system.
4588 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(c) The transformers, which at any time operate in parallel, shall be so selected as to
share the load in proportion to their respective ratings. Appropriate protection must
be provided and appropriate arrangements need to be made.

(d) When a step-up transformer is used, a linked switch shall be provided for
disconnecting the transformer from all poles of the supply, including the neutral
conductor.

1.3.22 Precautions regarding Rotating Machines

(a) All equipment including cables, of every circuit carrying the starting, accelerating
and load currents of motors, shall be suitable for a current at least equal to the full
load current rating of the motor. When the motor is intended for intermittent duty
and frequent stopping and starting, account shall be taken of any cumulative effects
of the starting periods upon the temperature rise of the equipment of the circuit.

(b) The rating of circuits supplying the rotors of slip ring or commutator of a motor or an
induction motor shall be suitable for both the starting and loaded conditions.
(c) Every electric motor having a rating exceeding 0.376 kW shall be provided with
control equipment incorporating means of protection against overcurrent.

(d) Every motor shall be provided with means to prevent automatic restarting after a
stoppage due to drop in voltage or failure. This requirement does not apply to any
special cases where the failure of the motor to start after a brief interruption of the
supply would be likely to cause greater danger. It also does not preclude
arrangements for starting a motor at intervals by an automatic control device, where
other adequate precautions are taken against danger from unexpected restarting.

1.3.23 LT Energy Meters

LT energy meters shall be installed in residential buildings at such a place which is

readily accessible to the owner of the building and the Authority. Installation of digital
energy meters at the users’ premises is a requirement of the distribution Companies.

LT energy meters should be installed at a height where it is convenient to note the meter
reading but should not be installed at a level less than 1.5 meter above the ground.

The energy meters should either be provided with a protective covering, enclosing it
completely except the glass window through which the readings are noted, or shall be
mounted inside a completely enclosed panel provided with hinged or sliding doors with
arrangement for locking. Earthing terminal must be provided if a metal box is used. Such
an earthing terminal must be connected to the ECC.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4589

1.3.24 Laying of LT underground Cables

PVC-PVC NYY underground LT cables shall be laid using one of the three methods.

(a) In the first method, brick wall prepared 900 mm deep trenches with cover plates
shall be used for placing the cables at the bottom of the trench.

(b) In the second method, 900 mm deep trenches prepared by ground excavation
(underground direct burial method) shall be used for placing the cables on top of
a 75 mm sand layer. In this second method (underground direct burial method),
two layers of brick on top, marking tape and then back filling the trench will
have to be done. The depth of the trench in general shall be 900 mm.

(c) In the third method, pre-laid PVC pipes having sufficient clearance compared to
the cable size (s) may be required at places. The PVC pipes must be laid in
trenches of the 900 mm depth. For pre-laid PVC pipe ducts, brick wall made
underground inspection pits will be required at an interval of at least 10 m for
cable pulling and future extensions or alterations.
1.3.25 Laying of HT Underground Cables

The HT underground armoured cables shall be laid using one of the three methods.
In the first method (i) brick wall prepared 900 mm deep trenches with cover plates shall
be used for placing the cables at the bottom of the trench.
In the second method, 900 mm deep trenches prepared by ground excavation
(underground direct burial method) shall be used for placing the cables on top of a 75 mm
sand layer. In this second method (underground direct burial method), two layers of brick
on top, marking tape and then back filling the trench will have to be done. The depth of
the trench in general shall be 900 mm.
In the third method, pre-laid PVC pipes having sufficient clearance compared to the cable
size(s) may be required at places. The PVC pipes must be laid in trenches of the 900 mm
depth.
For pre-laid PVC pipe ducts, brick wall made underground inspection pits will be
required at an interval of at least 10 m for cable pulling and future extensions or
alterations.
PVC pipe having sufficient clearance may be used for bringing the cable up to the trench
of the metering panel or HT panel.
The PVC pipes must have 18 SWG GI pull wires placed during laying of the pipes for
pulling the cables later.
Methods of installation of cables and conductors in common use are specified in Table
8.1.25.
4590 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

1.3.26 Main Switch and Switchboards

1.3.26.1 Metal clad enclosed type

All main switches shall be either metal clad enclosed type or of any other insulated
enclosed type and the circuit breakers shall be fixed at close proximity.

1.3.26.2 Circuit breakers on each live conductor

There shall be circuit breakers or miniature circuit breakers or load break switch fuses on
each live conductor of the supply mains at the point of entry. The wiring throughout the
installation shall be such that there is no break in the neutral wire in the form of a switch
or fuse unit or otherwise.

1.3.26.3 Location

(a) The location of the main board shall be such that it is easily accessible for firemen
and other personnel to quickly disconnect the supply in case of emergencies.

(b) Main switchboards shall be installed in boxes or cupboards so as to safeguard against

operation by unauthorized personnel.

(c) Open type switchboards shall be placed only in dry locations and in ventilated rooms
and they shall not be placed in the vicinity of storage batteries or exposed to
chemical fumes.

(d) In damp situation or where inflammable or explosive dust, vapour or gas is likely to
be present, the switchboard shall be totally enclosed or made flame proof as may be
necessitated by the particular circumstances.

(e) Switchboards shall not be erected above gas stoves or sinks, or within 2.5 m of any
washing unit in the washing rooms or laundries.

(f) In case of switchboards being unavoidable in places likely to be exposed to weather,

to drip, or in abnormally moist atmosphere, the outer casing shall be weather proof
and shall be provided with glands or bushings or adapted to receive screwed conduit.

(g) Adequate illumination shall be provided for all working spaces about the
switchboards, when installed indoors.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4591

Table 8.1.25: Different ways of Installation of Cables and Conductors in Common

Use

Type Description Example

A Cables enclosed in conduit

B Cables enclosed in trunking

C Cables enclosed in underground

conduit, ducts, and cable ducting.

D Two or more single-core cables

contained in separate bores of a
multi-core conduit and intended
to be solidly embedded in
concrete or plaster or generally
incorporated in the building
structure.
E Sheathed cables clipped direct to
a nonmetallic surface.

F Sheathed cables on a cable tray.

G Sheathed cables embedded direct

in plaster.

Single-core Mutli-core
4592 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Type Description Example

H Sheathed cables suspended from
or incorporating a catenary wire.

J Sheathed cables in free air. Vertical surface of a wall

or open cable trench
For cables in which the
20 mm min.
conductor cross-sectional area 20 mm min.

does not exceed 185 mm2, S is

equal to twice the overall
diameter of the cable. For cables s
in which the conductor cross-
sectional area exceeds 185 m2, S
s
is about 90 mm. For two cables
in horizontal formation on
brackets fixed to a wall, S may
have any lesser value. Single-core Multi-core

K Single and multi-core cables in Two single-core cables with

enclosed trench 450 mm wide by surfaces separated by a
600 mm deep (minimum distance equal to one
dimensions) including 100 mm diameter; three single-core
cover. cables in trefoil and
touching throughout. Multi-
core cables or groups of
single-core cables separated
by a minimum distance of
50 mm.
L Single and multi-core cables in Single-core cables
enclosed trench 450 mm wide by arranged in flat groups of
600 mm deep (minimum two or three on the vertical
dimensions) including 100 mm trench wall with surfaces
cover. separated by a distance
equal to one diameter with
a minimum separation of
50 mm between groups.
Multi-core cables installed
singly separated by a
minimum* distance of 75
mm. All cables spaced at
least 25 mm from the
trench wall.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4593

Type Description Example

M Single and multi-core cables in Single-core cables

enclosed trench 600 mm wide by arranged in groups of two
760 mm deep (minimum or three in flat formation
dimensions) including 100 mm with the surfaces separated
cover. by a distance equal to one
diameter or in trefoil
formation with cables
touching. Groups
separated by a minimum*
distance of 50 mm either
horizontally or vertically.
Multi-core cables installed
singly separated by a
minimum* distance of 75
mm either horizontally or
vertically. All cables
spaced at least 25 mm
from the trench wall.
* Larger spacing to be used where practicable.

1.3.27 Mounting of Metal clad switchgear

A metal clad switchgear shall be mounted on hinged type metal boards or fixed type
metal boards.

(a) Hinged type metal boards shall consist of a box made of sheet metal not less than
2 mm thick and shall be provided with a hinged cover to enable the board to swing
open for examination of the wiring at the back. The joints shall be welded. The board
shall be securely fixed to the wall by means of rag bolt plugs, or wooden plugs and
shall be provided with locking arrangement and an earthing stud. All wires passing
through the metal board shall be protected by a rubber or wooden bush at the entry
hole. The earth stud should be commensurate with the size of the earth lead(s).

(b) Fixed type metal boards shall consist of an angle or channel steel frame fixed on the
wall at the top, if necessary.

(c) There shall be a clearance of one meter at the front of the switchboards.
4594 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

1.3.28 Wooden Boards as Main Boards or Sub-Boards Containing Fused Cutouts

and Main Switches

Use of Wooden Board is discouraged because of the fear of break out of fire from a spark
or from an overheated cable. However, for small installations, not exceeding 15A SP,
connected to a single-phase 230 V supply, wooden boards may be used as main boards or
sub-boards containing fused cutouts and main switches of appropriate ratings may be
used. Such a board shall be made using seasoned teak or other approved quality timber.

1.3.29 Location of Distribution Boards

The distribution boards shall be located as near as possible to the centre of the load they
are intended to control.

(a) They shall be fixed on suitable stanchion or wall and shall be accessible for
replacement of fuses. All switches and circuit breakers used as switches shall be
located so that they may be operated from a readily accessible place. They shall be
installed such that the center of the grip of the operating handle of the switch or
circuit breaker, when in its highest position, is not more than 2.0 m and the bottom of
the panel shall be more than 0.45m above the floor or working platform.

(b) They shall be either metal clad type, or all insulated type. But if exposed to weather
or damp situations, they shall be of the weather proof type and if installed where
exposed to explosive dust, vapour or gas, they shall be of flame proof type. In
corrosive atmospheres, they shall be treated with anticorrosive preservative or
covered with suitable plastic compounds.

(c) Where two or more distribution fuse boards feeding low voltage circuits are fed from
a supply of medium voltage, these distribution boards shall be:
(i) fixed not less than 2 m apart, or

(ii) arranged so that it is not possible to open two at a time, namely, they are
interlocked, and the metal case is marked "Danger 415 Volts" and identified
with proper phase marking and danger marks, or

(iii) installed in rooms or enclosures accessible to authorized persons only.

(d) All distribution boards shall be marked "Lighting" or "Power", as the case may be,
and also be marked with the voltage and number of phases of the supply. Each shall
be provided with a circuit list giving diagram of each circuit which it controls and the
current rating for the circuit and size of fuse element.
(e) Distribution boards must be easily accessible for the ease of maintenance and
switching off during accidents.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4595

1.3.30 Over-current and Short Circuit Protection of Circuits

(a) Appropriate protection shall be provided at the distribution boards for all circuits and
sub-circuits against short circuit and over-current. The installed protective devices
shall be capable of interrupting any short circuit current that may occur, without
causing any danger. The ratings and settings of fuses and the protective devices shall
be coordinated so as to obtain absolute certain discrimination of the faulty area only
during a fault.

(b) Where circuit breakers are used for protection of main circuit and the sub-circuits,
discrimination in operation shall be achieved by adjusting the protective devices of
the sub-main circuit breakers to operate at lower current settings and shorter time-lag
than the main circuit breaker.
(c) A fuse carrier shall not be fitted with a fuse element larger than that for which the
carrier is designed.

(d) The current rating of fuses shall not exceed the current rating of the smallest cable in
the circuit protected by the fuse.

1.3.31 Fire Alarm and Emergency Lighting Circuits

Fire alarm and emergency lighting circuits shall be segregated from all other cables and
from each other in accordance with BS 5839 and BS 5266. Telecommunication circuits
shall be segregated in accordance with BS 6701 as appropriate.

1.3.32 Earthing
1.3.32.1 General

Earthing refers to connecting the exposed conductive part of electrical equipment and
also the extraneous conductive parts of earthed bodies like water pipe to the general mass
of the earth to carry away safely any fault current that may arise due to ground faults. The
object of an earthing system is to provide a system of conductors, as nearly as possible at
a uniform and zero, or earth, potential. The purpose of this is to ensure that, in general, all
parts of equipment and installation other than live parts shall be at earth potential, thus
ensuring that persons coming in contact with these parts shall also be at earth potential at
all times.
1.3.32.2 Earthing used in electrical installation for buildings

The usual method of earthing is to join the exposed metal work to earth via a system of
earth continuity conductors (ECC) connected to an earth electrode buried in the ground
through a system of earth lead wires. In conjunction with a fuse, or other similar device,
this then forms a protective system.
4596 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Thus, if a live conductor accidentally comes into contact with an exposed metal, the fuse
or protective device operates. As long as the overall resistance of the protective system is
low, a large fault current flows which blows the fuse. This cuts off the supply and
isolates the faulty circuit, preventing risk of shock, fire, or damage to equipment/
installation.
In Electrical installation for buildings, following types of earthing systems are required to
be installed:
(i) L.T. circuit/system earthing,
(ii) Equipment earthing (LT side),
(iii) Substation neutral earthing,
(iv) Substation LT system earthing, and
(v) H.T. circuit earthing for a substation.
The purpose of L.T. circuit/system earthing is to limit excessive voltage from line
surges, from cross-overs with higher voltage lines, or from lightning, and to keep
noncurrent carrying enclosures and equipment at zero potential with respect to
earth.
Earthing the system helps facilitate the opening of overcurrent protection devices in
case of earth faults. Earthing associated with current carrying conductors is
normally essential for the protection and safety of the system and is generally
known as circuit/ system earthing, while earthing of non-current carrying metal
work and conductor is essential for the safety of human life, animals, and property
and it is generally known as equipment earthing.
1.3.32.3 Arrangements of earthing systems:
(a) The value of resistance from the consumer's main earthing terminal to the
earthed point of the supply, or to earth, is in accordance with the protective and
functional requirements of the installation, and expected to be continuously
effective.

(b) Earth fault currents and earth leakage currents likely to occur are carried
without danger, particularly from the point of view of thermal, thermo-
mechanical and electromechanical stresses.

(c) Where a number of installations have separate earthing arrangements,

protective conductors running between any two of the separate installations
shall either be capable of carrying the maximum fault current likely to flow
through them, or be earthed within one installation only and insulated from the
earthing arrangements of any other installation.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4597

1.3.32.4 Integral parts of an earthing system

The integral parts of an Earthing System are:
(a) Earth electrode(s) buried under the ground
(b) Earth lead cables/wires connecting the earth electrode(s) with the earthing
busbar system. Earth lead cables/wires are also need to interconnect the earth
electrodes when there are more than one earth electrode.
(c) Earth continuity conductors (ECC) for linking earthing busbar at the substation
LT panel or main distribution DB of a building.
(d) Earth electrode clamp.
Connections of (i) Earth continuity conductors (ECC), (ii) Earth lead cables/wires and
(iii) Earth electrode(s) must be made in appropriate and long lasting manner because poor
connection or loss of connection will render the earthing system ineffective.
1.3.32.5 Earth continuity conductors (ECC)
ECC runs along the circuits/sub-circuits, socket circuits, interlinking circuits between a
BDB and a SDB, between a SDB and a DB, between a DB and a FDB, between a FDB
and a MDB, between a MDB and the LT panel earthing busbar of the substation. At each
point an ECC shall be terminated in a copper earthing busbar. In metal switch boards
back boxes and in metal socket back boxes appropriate copper or brass bolt nut
termination shall be provided.
ECC of an earthing system joins or bonds together all the metal parts of an installation.
PVC insulated wiring copper cables of appropriate size having Green + Yellow bi-colour
insulation shall be used as ECC.
The minimum size of the ECC shall be same as cross-sectional area of the phase
conductor for the PVC insulated wiring copper cables of appropriate size having Green +
Yellow bi-colour insulation.
1.3.32.6 Earth lead cable/wire
Earth Lead cable/wire runs between an earth electrode and the earthing busbar of the
MDB/DB or between an earth electrode and the LT panel earthing busbar of the
substation.
Often more than one earth electrodes are needed. In such a case duplicate earth lead
cables/wires from each earth electrode must be brought to the MDB/DB or to the LT
panel earthing busbar of the substation and properly terminated. In addition, in the
case of multiple earth electrodes, they must be interlinked by additional earth lead
cables/wires.
PVC insulated wiring copper cables of appropriate size having Green + Yellow bi-colour
insulation shall be used as earth lead wire. At both ends of the earth lead cable/wire,
copper cable lugs must be fitted using crimp tools or hydraulic press.
4598 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

The minimum size of the earth lead wire shall be 2 numbers of 1.5 mm2 PVC insulated
wiring copper cables of appropriate size having Green + Yellow bi-colour insulation.

The ends of the earth lead wires shall be terminated using crimp tool fitted cable lugs for
fitting on the busbar or with the Earth Electrode Clamp.

(a) An earth lead cable/wire establishes connection between the main earthing busbar
and the earth electrode(s). The earth lead wire shall be brought to one or more
connecting points, according to size of installation; the copper wire earthing leads
shall run from there to the electrodes. Usually more than one earth lead wires are
needed for one earth electrode to make sure that this link never fails.

(b) Earth lead cable/ wires shall one of the following types:

(i) PVC insulated cable

(ii) stranded copper cables without insulation

(iii) copper strips (copper bars)

(iv) PVC insulated cable is preferable in most cases.

(v) Earth lead wires shall run through PVC pipe from the earth electrode up to
the earthing busbar of the MDB/DB or LT Panel.

(c) Earth lead cables/ wires shall run, at least, 2 in parallel (at least) down to the earth
electrode so as to increase the safety factor of the installation. The two cables shall
be terminated in two seperate cable lugs and bolts at both ends. Copper wire used as
earthing lead must not be smaller than single core stranded 2 × 4 mm2 PVC insulated
cables (i.e. 2 nos. of single core 4 mm2 PVC insulated cables in parallel). Depending
on the current capacity of the Main incoming line the size will have to be raised.

Earth lead cables/wires shall be pulled from the earth electrode up to the terminating
earthing busbar through PVC conduits or GI pipes of appropriate dimension.

Table 8.1.26: Minimum Cross-sectional Area of Copper ECCs in Relation to the

Area of Associated Phase Conductors
Cross-sectional Area of Phase Minimum Cross-sectional Area of the
Conductor(s) (mm2) Corresponding Earth Conductor (mm2)

Less than 16 Same as cross-sectional area of phase

conductor
16 or greater but less than 35 16 mm2
35 or greater Half the cross-sectional area of phase
conductor
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4599

1.3.32.7 Earth electrodes and their installation

The earth electrode shall, as far as practicable, penetrate into moist soil (which will
remain moist even during the dry season) preferably below ground water table. The
resistance of an earthing system after measured after the installation of earth electrodes
(individually or combined as a single group) shall be around one ohm.

The types of earth electrodes are to be used for earthing of electrical installations of a
building and their sizes shall be as under:

(a) Copper rod earth electrode: shall have a minimum diameter of 12.5 mm of
minimum length of 3.33 m. Multiple copper rod earth electrodes may have to be
installed to achieve an acceptable value of earthing resistance of around 1 ohm.

(b) Copper plate earth electrodes: shall be 600 mm x 600 mm x 6 mm minimum in

size. The copper plate shall be buried at least 2 m below the ground level.
Multiple Copper plate earth electrodes may have to be installed to achieve an
acceptable value of earthing resistance of around 1 ohm.
(c) Galvanized Iron (GI) pipes: GI pipe earthing shall have a minimum diameter of
38 mm and of minimum length of 6.5m. Multiple GI pipes Earth Electrode may
have to be installed to achieve an acceptable value of earthing resistance of
around 1 ohm.

Schematic drawings of typical earthing systems are shown in Figures 8.1.2 to 8.1.4. For
the installation of the earthing system the following points shall be considered.

(a) For installing a copper rod earth electrode, a 38 mm GI pipe shall be driven
below ground up to a depth of 5 m and shall be withdrawn. The 12 mm dia
copper rod earth electrode of 4 m length shall then be easily driven into that hole
up to a depth of 3.6 m and 0.33 m shall be left for placing inside the earthing pit
described below.

(b) For installing a 600 mm x 600 mm x 6 mm Copper plate 2 m below the ground
level earth excavation will have to be done. The earth lead wire shall come via
an earthing pit.

(c) GI pipe earth electrodes driven by tube well sinking method are suggested. For
this purpose 38 mm dia GI pipes are recommended for domestic buildings. For
large plinth area buildings and multi-storied buildings 50 mm dia GI pipes are
recommended. The length of GI pipe to be driven below the ground level
depends on the earthing resistance which in turn depends on the availability of
water table during the dry season in this country. However, except the high land
and mountains, this depth varies between 12 m to 25 m.
4600 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
(d) Multiple numbers of GI pipe earth electrodes need to be used and connected in
parallel in order to lower the earthing resistance measured with an earth
resistance measuring meter. This is applicable for copper rod earyhing and plate
earthing also.
(e) If multiple rod, pipe, or plate electrodes of one grounding system are installed to
meet the earth resistance requirements, they shall not be less than 1.8 m apart.
Two or more grounding electrodes that are bonded together shall be considered
a single grounding electrode system.
(f) If multiple rod, pipe, or plate electrodes of one grounding system are installed to
meet the earth resistance requirements, they shall not be less than 1.8 m apart.
Two or more grounding electrodes that are bonded together shall be considered
a single grounding electrode system.

Figure 8.1.2 Copper Rod Earthing Figure 8.1.3 Copper Plate Earthing

(a) (b)
Figure 8.1.4 Pipe Earthing; (a) Type 1; (b) Type 2
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4601

1.3.32.8 Brass clamps/terminals on earth electrodes (earth electrode clamp)

(a) A brass clamp must be fitted on top of a GI pipe earth electrode to terminate the
earth lead wire and to maintain electrical contact with the earth electrode and also to
terminate the earth lead wire coming from the earthing busbar of the LT panel/
MDB/DB. This is needed to establish long lasting and firm connection between the
earth electrode and earth lead wire, which in turn means connection between the
earth electrode and earthing busbar of an LT panel or MDB/DB.
(b) The Brass clamp shall be made using at least 9.5 mm thick and at least 50 mm wide
Brass plate bent and shaped properly to fit tightly around the GI pipe earth electrode
and shall have sufficient length (at least 35 mm) on both sides for fixing bolts and
cable lugs. This clamp shall have two hexagonal head 9.5 mm bolts on one side and
two hexagonal head 9.5 mm bolts on the other side, Figure 8.1.4(a). Sufficient space
should be available for fixing the cable lugs of the earth lead wires. After fitting the
lugs of the earth lead cables the brass clamp and the GI pipe head should be coated
with two coats of synthetic enamel paint on top of one undercoat paint layer.
(c) An alternative to this clamp is to use a 9.5 mm (at least) thick brass plate having 4
holes for fitting four hexagonal brass bolts on the four corners for fitting the cable
lugs of the earth lead wires as shown in Figure 8.1.4(b). The brass plate is welded to
a GI pipe socket and threaded on top of the earth electrode (pipe).
1.3.32.9 Earthing busbars
A copper earthing busbar shall be provided inside the LT Panel or MDB/DB of a
building. The earth lead wire coming from the Earth Electrode (s) shall be terminated on
this busbar using cable lugs (cable lugs must be fitted using crimp tools or hydraulic
press) and brass bolts and nuts.
Copper earthing busbar shall also be provided inside the DBs, FDBs, SDBs and BDBs.
Hexagonal head brass screw, nuts and washers are needed for fixing the ECC and earth
lead cables with this busbar
1.3.32.10 Earthing pit
An earthing pit shall be constructed around the top of the Earth Electrode, below the
ground level using 250 mm brick walls on a CC floor with a 150 mm thick RCC slab
cover on top having lifting hooks. The top of the earth electrode (in case of pipe earthing)
shall remain 375 mm above the top of the bottom CC floor of the pit. The minimum
inside dimension of the earthing pit shall be 600 mm × 600 mm × 600 mm. The outside
as well as the inside of the walls of the pit and the floor of the pit shall be cement mortar
plastered. The inside shall be net cement finished. The top of the RCC slab pit cover shall
remain 38 mm above the ground level. The pit shall be made in such a way that water
cannot get in to the pit. One earthing pit is needed for one earth electrode.
4602 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

1.3.33 Lightning Protection of Buildings

Whether a building needs protection against lightning depends on the probability of a

stroke and acceptable risk levels. Assessment of the risk and of the magnitude of the
consequences needs to be made. As an aid to making a judgment, a set of indices is given
in Table 8.1.27 below for the various factors involved.

Table 8.1.27 (a): Index Figures Associated with Lightning Protection Design

Index A: Use of Structure Index Index B: Type of Construction Index

Houses and similar buildings 2 Steel framed encased with 1

nonmetal roofa

Houses and similar buildings 4 Reinforced concrete with 2

with outside aerial nonmetal roof

Small and medium size 6 Brick, plain concrete, or 4

factories, workshops and masonry with nonmetal roof
laboratories

Big industrial plants, telephone 7 Steel framed encased or 5

exchanges, office blocks, hotels, reinforced concrete with metal
blocks of flats roof

Places of assembly, for 8 Timber formed or clad with any 7

example, places of workshop, roof other than metal or thatch
halls, theatres, museums,
exhibitions, department stores,
post offices, stations, airports,
stadiums

Schools, hospitals, children's 10 Any building with a thatched 10

homes and other such structures roof

a
A structure of exposed metal which is continuous down to ground level is excluded
from the table as it requires no lightning protection beyond adequate earthing
arrangements.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4603

Table 8.1.27 (b): Index Figures Associated with Lightning Protection Design
Index C : Contents or Index Index D : Degree of Isolation Index
Consequential Effects

Ordinary domestic or office 2 Structure located in a large area having 2

building, factories and workshops structures or trees of similar or greater
not containing valuable materials height, e.g. a large town or forest

Industrial and agricultural 5 Structure located in an area with a 5

buildings with specially few other structures or trees of
b
susceptible contents similar height

Power stations, gas works, 6 Structure completely isolated or 10

telephone exchanges, radio exceeding at least twice the height of
stations surrounding structures or trees

Industrial key plants, ancient 8 Index E : Type of Terrain Index

monuments, historic buildings,
museums, art galleries

Schools, hospitals, children's and 10 Flat terrain at any level 2

other homes, places of assembly
b
This means specially valuable plant Hilly terrain 6
or materials vulnerable to fire or the
Mountainous terrain 300 m and above 8
results of fire.
Table 8.1.27 (c) : Index Figures Associated with Lightning Protection Design
Index F : Height of Structure Index Index G : Lightning Prevalence Index

Up to 9 m 2 Number of thunderstorm days

per year:
9-15 m 4 Up to 3 2
15-18 m 5 4-6 5
18-24 m 8 7-9 8
24-30 m 11 10-12 11
30-38 m 16 13-15 14
38-46 m 22 16-18 17
c
46-53 m 30 19-21 20
c
Structures higher than 53 m require Over 21 21
protection in all cases
4604 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

1.3.33.1 Degree of Isolation

The relative exposure of a particular building will be an element in determining whether
the expense of lightning protection is warranted. In closely built-up towns and cities, the
hazard is not as great as in the open country.
1.3.33.2 Type of terrain
In hilly or mountainous areas, buildings are more susceptible to damage due to lightning
than buildings in the plains or flat terrain. In hilly areas, a building upon high ground is
usually subject to greater hazard than one in a valley or otherwise sheltered area.
1.3.33.3 Height of structure
Height of the structure is an important factor for the purpose of lightning protection.
Taller structures are subject to greater hazards than smaller structures and, therefore,
lightning protection is more desirable for tall structures.
1.3.33.4 Lightning prevalence
The number of thunderstorm days in a year varies in different parts of a country.
However, the severity of lightning storms, as distinguished from their frequency of
occurrence, is usually much greater in some locations than others. Hence, the need for
protection varies from place to place, although not necessarily in direct proportion to the
thunderstorm frequency.
1.3.33.5 Risk assessment
"Risk Index" is the sum of the indices for all the factors, as given in Table 8.1.27. A few
examples of calculation of Risk Index are given in Table 8.1.28, based on a marginal
Risk Index of 40.
1.3.33.6 Integral parts of a lightning protection system
A smallest complete lightning protection system shall consist of (i) An air spike or air
terminal, (ii) A down conductor, (iii) A roof conductor and (iv) An earth electrode.
An air spike or air terminal is that part which is intended to intercept lightning discharges.
It consists of a vertical thick conductor of round cross section mounted on the highest
part of the building to protect the required area. However, in general there may be more
than one air spike or air terminal. In such a case roof conductors (made with copper strips
or PVC insulated Annealed Stranded copper cables) need to be used to interconnect the
Air Spikes or Air Terminals. Usually, for each Air Spike or Air Terminal there shall be
one down conductor (made with copper strips or PVC insulated Annealed Stranded
copper cables) going down up to the Earth Electrode pit and connected to the Earth
Electrode. In all junctions, appropriate type of copper or brass junction plates or brass
clamps must be used to ensure low resistance, firm and long lasting connection.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4605

Table 8.1.28: Example of Calculation of Risk Index

Total
Example A B C D E F G Index Recommendations
Figure

Small residential building 2 4 2 2 2 2 21 35 No protection

in a thickly populated needed, in general
locality (height less than
10 m)

Office building in a 7 2 2 2 2 5 21 41 As the figure is

locality (height 20 m) around 40, need
of protection will
depend upon the
importance of the
building

Hotel building (height 7 2 2 10 2 16 21 60 Protection

31m) exceeding twice the essential
height of surrounding
structures

Building of historical 8 4 8 10 2 30 21 83 Protection

importance completely essential
isolated (height > 55 m)

Structure of high historical - - - - - - - - Protection essential

importance as the height
(height > 55 m) exceeds 53 m

Structure, such as hydro- 7 2 6 2 6 4 21 48 Protected by

electric power stations, surroundings
sufficiently protected by
means of surrounding
structures, for example,
high vertical cliffs, high
metallic structures or earth
wire of transmission
system (height 15 m)
4606 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
(a) Air spike/air terminal
An air spike or air terminal shall be made with copper rod of minimum 12 mm diameter
with tin coating on top. The terminal shall have a copper/brass base plate for mounting on
top of roof, column, parapet wall using rowel bolts. The minimum dimension of such a
base plate shall be 152 mm x 152 mm x 13 mm. The length and width may need to be
increased depending on the number of connection of the down conductors and the roof
conductors. Such connections are to be made using hexagonal head brass bolts and nuts
of 10mm diameter with brass washers. Minimum height of the air terminal shall be 300
mm above the highest point of the building fulfilling all the conditions of NFPA 780.
(b) Down conductor
A Down Conductor shall be made with copper strip or Stranded PVC insulated annealed
copper cable.
(c) Roof conductor
A Roof Conductor shall be made with copper strip or Stranded PVC insulated annealed
copper cable. This shall run along the periphery of the roof to link all air spikes and all
down conductors installed on top of a building. The joints shall be made using clamps
made of copper strips (of 1/8 inch minimum thickness) and appropriate brass bolts and
washers of 3/8 inch minimum diameter.
(d) Earth electrode
The Earth Electrode is exactly of the same type as the Earth Electrode of the Electrical
Distribution (Electrical Installation for Buildings) system described earlier in this
document. Considering the practical situation in this country and Pipe Earth Electrodes
are suggested. For each Air spike one Earth Electrode is an ideal solution.
(e) Earth inspection boxes
A 18 SWG GI sheet made Earth Inspection Box must be provided for each down
conductor 1000 mm above the plinth level of the building (concealed inside the wall)
which will contain a copper strip made clamp on the insulation peeled down conductor to
check the continuity of the Earth Lead Down Conductor and the Earth Electrode and also
to measure the Earth Resistance of the system. The box shall have a GI sheet made cover
plate.
(f) Earthing pit
Earthing pits shall be provided as described in the earthing topic above.
1.3.33.7 Number of lightning arrestors required and their installation
Number of Lightning Protection Air Spikes in a building will depend on the nature of the
roof top, on the total area of the roof top, on the height of the building, height of the
adjacent buildings, height of the nearby towers or other similar structures. However, as a
thumb rule, for every 80 m2 area at least one air spike should be chosen at the beginning.
During placement of the air spikes the total number may have to be increased or adjusted.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4607

1.3.33.8 Protection zone

The zone of protection is the space within which an air spike provides protection by
attracting the stroke to itself. It has been found that a single vertical conductor attracts to
itself strokes of average or above average intensity which in the absence of the conductor
would have struck the ground within a circle having its centre at the conductor and a
radius equal to twice the height of the conductor. For weaker than average discharges the
protected area becomes smaller. For practical design it is therefore assumed that
statistically satisfactory protection can be given to a zone consisting of a cone with its
apex at the top of the vertical conductor and a base radius equal to the height of the
conductor. This is illustrated in Figure 8.1.5. A horizontal conductor can be regarded as a
series of apexes coalesced into a line, and the zone of protection thus becomes a tent-like
space (Figure 8.1.6).

(a) When there are several parallel horizontal conductors the area between them
has been found by experience to be better protected than one would expect
from the above considerations only. The recommended design criterion is that
no part of the roof should be more than 9 m from the nearest horizontal
conductor except that an additional 0.3 m may be added for each 0.3 m or part
thereof by which the part to be protected is below the nearest conductor.

(b) The earth termination is that part which discharges the current into the general
mass of the earth. In other words, it is one or more earth electrodes. Earth
electrodes for lightning protection are no different from earth electrodes for
short circuit protection systems. The total resistance of an electrode for a
lightning protection system must not exceed 10 ohms for buildings up to 10
storied and 2 ohms for high rise buildings.

Figure 8.1.5 Protected zone for Figure 8.1.6 Protected zone for horizontal
vertical conductors conductors
4608 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(c) The down conductor is the conductor which runs from the air termination to the
earth termination. A building with a base area not exceeding 100 m2 shall be
provided with one down conductor. For a larger building, there shall be one
down conductor for the first 80m2 plus a further one for every
100 m2 or part thereof in excess of the first 80 m2. Alternatively, for a larger
building one down conductor may be provided for every 30 m of perimeter.
Ideally, every air spike should have a down conductor going down up to the
earth electrode.
(d) The material used for lightning conductors must be copper. The criterion for
design is to keep the resistance from air termination to earth electrode to a
negligible value.
(e) Recommended dimensions for various components of lightning arrester are
given in Table 8.1.29. Larger conductors should however be used if the system
is unlikely to receive regular inspection and maintenance.

Table 8.1.2 9: Sizes of the Components of Lightning Protection Systems

Components Minimum Dimensions

Air terminals 12 mm dia

Copper strip 20 mm W x 3 mm T
Copper and phosphor bronze rods 12 mm dia

PVC insulated stranded annealed copper cable (minimum size) 19 strands of 1.8 mm dia

Down Conductors
Copper strip 20 mm x 3 mm

PVC insulated stranded annealed copper cable (minimum size) 19 strands of 1.8 mm dia

Earth Electrode

Hard drawn copper rods for driving into soft ground 12 mm dia
Hard drawn or annealed copper rods for indirect driving 12 mm dia
or laying in ground

Phosphor bronze for hard ground

12 mm dia
Copper clad steel for hard ground
50 mm dia
GI pipe
38 mm/50 mm dia
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4609

(f) External metal on a building should be bonded to the lightning conductor with
bonds at least as large as the conductor.

(g) When a lightning conductor carries a stroke to earth, it is temporarily raised to

a potential considerably above that of earth. There is, therefore, a risk that the
discharge will flash over to nearby metal and cause damage to the intervening
structure. This can be prevented by either, (i) providing sufficient clearance
between conductor and other metal or (ii) by bonding these together to ensure
that there can be no potential difference between them. The necessary clearance
is obtained from :
H
D  0.3 R  (8.1.1)
15 n

Where,

D = Clearance in metres

R = Resistance to earth in ohms

H = Height of building in metres

n = Number of down electrodes

Since it is often impracticable to provide the necessary clearance, the alternative

technique of bonding is preferred.

(h) Surge arrester selection

A surge arrester is a protective device for limiting surge voltages by discharging, or
bypassing, surge current through it. It also prevents continued flow of follow-through
current while remaining capable of repeating these functions. It is used to protect
overhead lines, transformers and other electrical apparatus mostly in an outdoor
substation from lightning voltages traveling through the overhead lines.

(i) Horn-gap lightning arresters

Horn-gap lightning arresters are commonly used for low and medium voltage overhead
lines. The rating of the surge arrester shall be equal to or greater than the maximum
continuous phase to ground power frequency voltage available at the point of application.

(j) Design of lightning arrester using rolling sphere method

Lightning arrester (including number and height) can also be designed and installed by
using rolling sphere method following NFPA 780. Minimum height of the air terminal
shall be in accordance with Sec 1.3.33.6.
4610 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

1.3.34 Telecommunications in Buildings

1.3.34.1 General

Placing concealed 2 pair indoor cables is needed to get (ii) telephone lines of the wired
telephone companies inside rooms of a building and (ii) to get the PABX lines of the
building /offices in the building to the respective rooms under the PABXs. In addition to
this, 10/20/50 pair telephone cables are required to be brought in to the PABX room(s) of
the building. Conduits are to be installed for both of these two categories. For the entry of
10/20/50 pair cables, conduits through straight and easy path (in most cases, through one
side of the vertical electrical duct) need to be brought in.

1.3.34.2 Concealed telecommunication cable wiring

2 pair PVC insulated PVC sheathed annealed copper telecommunication cable shall be
drawn through sufficient number of pre-laid 19/25/38 mm PVC conduits to establish
telecommunication network inside a building. A clearance of at least 40 percent must be
maintained inside the PVC conduits. Sufficient number of 18 SWG GI sheet made pull
boxes (with Perspex sheet / ebonite sheet cover plates) at all suitable places must be
placed for the ease of pulling these cables.

2 pair PVC insulated PVC sheathed annealed copper telecommunication cable shall be
used for wiring between a Telephone DP/Patch panel and a telecommunication outlet.
The extra pair shall remain for future maintenance. The minimum size of the copper wire
of this cable shall be 0.5 mm. The copper shall be preferably tinned.

1.3.34.3 Surface telecommunication cable wiring

Surface wiring should not be a choice during designing a building wiring. However, if the
building is already constructed or under compulsory conditions or for extension of an
existing network one may go for surface wiring. The same 2 pair PVC insulated PVC
sheathed annealed copper telecommunication cable shall be used for this purpose. Wiring
shall be done either by using channels or by using PVC conduits following the power line
surface wiring methods mentions earlier.

1.3.34.4 Telecommunications outlets

Wall mounted Telecommunication outlets shall contain RJ11 or RJ45 connectors/jacks

(shuttered). For simple telephone connection RJ11 shuttered jacks are sufficient. The
outlet box shall have a back-box which may be made of the same polymer material as the
front panel or shall be made using 18 SWG GI sheet or 18 SWG MS sheet but painted
with two coats of synthetic enamel paint.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4611

1.3.34.5 Telephone DP room, patch panel room and digital PABX room

Telephone DP room, Patch Panel Room and PABX room should be located near the
vertical riser duct of the building so that the incoming 50/100 pair underground telephone
cable can be terminated in the DP/MDF or patch panel for distribution among the flats of
a multistoried residential building or among the offices of a multistoried
commercial/office building.

If a digital telephone PABX is to be installed then this can be installed in the same room.
A separate earth electrode with earth lead wire will be required for the PABX.
1.3.35 Television Antennas/Cable Television system

In a multistoried residential/office building, television antennas shall be placed at one

suitably sited antenna location on roof top and connect these to individual flats/
residences/offices in the same building by coaxial cables through concealed conduits.

1.3.35.1 Cable work for television antennas/cable television system

Vertical duct and easy entry to each flats/ offices must be provided as sharp bending of
these cables is difficult and harmful to the cables. These cables must not be placed in the
same conduit with power cables. A distance of at least 350 mm must be maintained if a
portion runs in parallel with the power cable conduits.
RF and Video cables shall be PVC sheathed Co-axial Cables shall be made with solid
Copper centre conductor, foamed polythene insulated and further sealed Alluminium foil
taped and Copper wire braided.
1.3.35.2 Television antenna outlets/cable television system outlets

Wall mounted television coaxial cable outlets shall contain high quality coaxial
connectors/jacks. The outlet box shall have a back-box which may be made of the same
polymer material as the front panel or 18 SWG GI sheet or 18 SWG MS sheet made but
painted with two coats of synthetic enamel paint.

1.3.36 Data Communication Network for LAN and Internet Services inside a
Building

Data Communication Network for LAN and Internet Services inside a Building may be
installed using Cat 6 unshielded twisted pair (UTP) cables in a concealed manner
following the concealed wiring power cables installation procedure mentioned in the
wiring methods section of this document. Each of the cables will be terminated at one end
at the 8P8C (RJ45) connector based data socket outlet board in the required rooms at the
power socket level. On the other end, the cable will be terminated in the patch panel.
From the patch panel up to the data socket outlet the cable shall be in one piece i.e., no
4612 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

joints will be allowed. As a result the concealed conduit work needs to be done carefully
to have a straight line path and without any bend in the roof slab. Sufficient pull boxes
will be required in the roof slab. Pull box will also be needed close to the vertical bend
near the bend and ceiling at any downward drop of the conduit. The conduits must have
20 SWG GI pull wires during laying for pulling the cables later.

Because of the nature of these cables more clearances are needed inside the PVC conduits
compared to the power cables. If the conduits are running parallel to the power cables
then there should be at least a distance of 410 mm between these two.

Recently Cat. 7 cables are emerging as a better choice in place of Cat. 6 cables.

1.3.37 Fire Detection and Alarm System inside a Building

The major parts of a Fire Detection and Alarm System inside a Building may be listed as
(a) A number of different types of Fire Detectors/ detection devices wired in a number
of radial circuits

(b) Manual call points

(c) A central control panel for fire detection

(d) A number of alarm sounders/alarm devices wired in a number of radial circuits

(e) Cables for wiring the fire detectors/detection devices

(f) Cables for wiring the alarm sounders/alarm devices

Control Panel

The control panel will indicate in which detection circuit (zone) an alarm or fault
condition has been generated and will operate common or zonal sounders and auxiliary
commands (for example door release or fire brigade signaling).

Detectors

A number of types of detectors (smoke detectors, heat detectors, ionization smoke

detectors, optical beam smoke detectors, opto-heat detectors) for the installation

Alarm Devices

Alarm devices fall into two types, audible and visual. The audible types are most
common, with a variety of types being available from bells to all kinds of different
electronic sounders including those containing pre-recorded spoken messages. The choice
of device is dependent on local preference, legal requirement and the need to have a tone
distinct from all other building audible alarms.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4613

Speech alarms or links to PA systems overcome some of the complacent responses to

warning tones and can be used to good effect when carrying out regular fire tests in
buildings where there are many people unfamiliar with the regular routines - such as
hotels. Finally visual alarms are to be used where the hard of hearing may be occupying a
building or where the ambient noise is such (above 90 dBA) that audible warning may
not be heard, where hearing protectors are in use or where the sounder levels would need
to be so high that they might impair the hearing of the building occupant.

Audible and Visual Alarm Devices

The audible types are most common, with a variety of types being available from bells to
all kinds of different electronic sounders including those containing pre-recorded spoken
messages. The choice of device is dependent on local preference, legal requirement and
the need to have a tone distinct from all other building audible alarms.

Cables for Fire Detectors

BS 5839-1 introduced more onerous requirements for the types of cables used in fire
detection and alarm systems. Fireproof cables should now be used for all parts of the
system and enhanced fire resistance cables should be used where there is a requirement to
ensure cable integrity over a longer period of time. For example when connecting to
alarm sounders or where connection between sub-panels provides any part of alarm
signal path.

Fire alarm cables should be segregated from the cables of other systems; they should be
clearly marked, preferably coloured red and should be routed through parts of the
building that provide minimum risk. This latter point is particularly relevant where the
use of the building is being changed - for example if a fuel store is being moved.

Specific Areas of Application for Fire Detection and Alarm Equipment

The BS 5839 suite of standards relate to specific areas of application for fire detection
and alarm equipment. Specifically part 1 relates to public premises and part 6 relates to
residential premises. BS5839-1 is a comprehensive code of practice for fire detection and
alarm systems, the requirements relate to both life and property protection and the
standard includes much advice and comment with is very useful in informing the building
owner or system specifier of the background to the requirements.

Codes of Practice for Different Types of Fire Protection Systems

The parts of BS7273 are codes of practice for different types of fire protection systems.
Generally this is considered separately to fire alarm systems but there may be occasions
where a tradeoff can be made between the two systems, or where the two systems interact
and must be interfaced.
4614 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Standards Related to Design and Performance of Items of Equipment that Make up a Fire
Detection and Alarm System
The EN 54 suite of standards relates to the design and performance of items of equipment
that make up fire detection and alarm system. Each part relates to a different piece of
equipment, for example part 3 relates to alarm devices, part 11 to call points, part 4 to
power supplies etc.
Fire Detection Zones
Fire detection zones are essentially a convenient way of dividing up a building to assist in
quickly locating the position of a fire. BS 5839-1 has some specific recommendations
with respect to detection zones.
Wiring of the fire detection and alarm system will be done using the concealed wiring
and the surface wiring methods described in the power line wiring section of this
document.
1.3.38 CCTV System inside a Building
Installation of cable network for CCTV System inside a Building shall be done following
the guidelines given for cable work for television antennas/cable television system earlier
in this document.
For wiring of the power lines required for the Installation of CCTV system inside a
building will be done using the concealed wiring and the surface wiring methods
described in the power line wiring section of this document.
1.3.39 Design and Installation of Access Control System
Wiring of the Installation of access control systems will be done using the concealed
wiring and the surface wiring methods described in the power line wiring section of this
document.
1.3.40 Installation of Electronic Security Systems
Wiring of the installation of electronic security systems will be done using the concealed
wiring and the surface wiring methods described in the power line wiring section of this
document.
1.3.41 Qualification of the Contractor of Electrical and Electronic Engineering
Works in a Building
A Contractor who will be working with the electrical and electronic engineering works in
a building must have appropriate ABC license from the electrical licensing board of
government of Bangladesh.
The contractor must have sufficient number of well trained and experienced technicians
to execute the job. For big volume of work, the contractor must have at least one
Electrical Engineer assigned for the job.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4615

1.3.42 Inspection and Testing

1.3.42.1 General

Every installation shall, on completion and before being energized, be inspected and
tested. The methods of test shall be such that no danger to persons or property or damage
to equipment occurs even if the circuit tested is defective.

1.3.42.2 Periodic inspection and testing

Periodic inspection and testing shall be carried out in order to maintain the installation in
a sound condition after putting it into service. Where an addition is to be made to the
fixed wiring of an existing installation, the latter shall be examined for compliance with
the recommendations of the Code.

1.3.42.3 Checking the conformity with the Bangladesh Standard

The individual equipment and materials which form part of the installation shall generally
conform to the relevant Bangladesh Standard (BDS) wherever applicable. If there is no
relevant Bangladesh standard specification for any item, these shall be approved by the
appropriate authority.

(i) Inspection of the colour identification of cables of wiring

For single phase, Brown for Live, Blue for Neutral, Green + Yellow bi-colour
for ECC. For three phase, Brown for L1, Black for L2, Grey for L3, Blue for
Neutral and Green + Yellow bi-colour for ECC and Earth Lead Wire.

(ii) Inspection of earthing terminal, earthing bus

Inspection should be made to check whether brass made earthing terminals have
been provided inside the metal back boxes of the switchboards and socket
boards (welded or screwed to the metal back box) and whether the ECCs of the
sub circuit have been terminated in these terminals. Inspection should be made
to check whether at least one copper earthing busbar has been provided in the
BDBs, SDBs, FDBs, DBs, MDBs and the LT panel and whether ECCs have
been appropriately terminated in these busbars using hexagonal head brass bolt
and nuts. Also it should be checked whether the Earth Lead Wires have been
properly terminated in the LT Panel / MDB / DB as appropriate.

(iii) Insulation Tests

Insulation test is one of the most important tests for Electrical Installations in a
Building.
4616 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Insulation resistance test shall be made on all electrical equipment, using a self-
contained instrument such as the direct indicating ohm-meter of the generator
type. DC potential shall be used in these tests and shall be as follows or an
appropriate Meggar:

Circuits below 230 volts 500 volts Meggar

Circuits between 230 volts to 400 volts 1000 volts Meggar

The minimum acceptable insulation resistance value is 5 mega ohms for LT
lines. Before making connections at the ends of each cable run, the insulation
resistance measurement test of each cable shall be made. Each conductor of a
multi-core cable shall be tested individually to all other conductors of the group
and also to earth. If insulation resistance test readings are found to be less than
the specified minimum in any conductor, the entire cable shall be replaced.
All transformers, switchgears etc. shall be subject to an insulation resistance
measurement test to ground after installation but before any wiring is connected.
Insulation tests shall be made between open contacts of circuit breakers,
switches etc. and between each phase and earth.
(iv) Earth Resistance Test and the Continuity Resistance Test
Earth resistance tests shall be made on the system, separating and reconnecting
each earth connection using earth resistance meter.
The electrical resistance of the Earth Continuity Conductor of different segment
shall be measured separately using sensitive digital Ohm meter or by means of
resistance bridge instrument. The resistance of the Earth Lead Wire shall be
measured from the earthing busbar of the LT Panel/MDB/DB and the earth
electrode(s). The electrical resistance of any section shall not exceed 1 ohm.
Where more than one earthing sets are installed, the earth resistance between
two sets shall be measured by means of sensitive digital Ohm meter or by means
of resistance bridge instrument. The earth resistance between two sets shall not
exceed 1 ohm.

Operation Tests
Current load measurement shall be made on equipment and on all power and
lighting feeders using Clamp on Ammeters.

The current reading shall be taken in each phase wire and in each neutral wire
while the circuit or equipment is operating under actual load conditions.

Clamp on Ammeters are required to take current readings without interrupting a

circuit.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4617

All light fittings shall be tested electrically and mechanically to check whether
they comply with the standard specifications.

Fluorescent light fittings shall be tested so that when functioning no flickering or

choke singing is felt.

(v) Inspection of the Installation

On completion of wiring a general inspection shall be carried out by competent
personnel in order to verify that the provisions of this Code and that of the
Electricity Act of Bangladesh have been complied with. A certificate may be
issued on satisfactory completion of the work in a format as shown in Appendix
C. Items to be inspected are detailed in the following sections.

Inspection of Substation Installations

In substation installations, it shall be checked whether:

 The installation has been carried out in accordance with the approved
drawings;

 Phase to phase and phase to earth clearances are provided as required;

 All equipment are efficiently earthed and properly connected to the required
number of earth electrodes;

 The required ground clearance to live terminals is provided;

 Suitable fencing is provided with gate with lockable arrangements;

 The required number of caution boards, firefighting equipment, operating

rods, rubber mats, etc., are kept in the substation;

 In case of indoor substation sufficient ventilation and draining arrangements

are made;

 All cable trenches have covers of noninflammable material;

 Free accessibility is provided for all equipment for normal operation;

 All name plates are fixed and the equipment are fully painted;

 All construction materials and temporary connections are removed;

 Oil level , busbar tightness, transformer tap position, etc. are in order;

 Earth pipe troughs and cover slabs are provided for earth electrodes/earth
pits and the neutral and LA earth pits are marked for easy identification;
4618 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

 Earth electrodes are of GI pipes or CI pipes or copper plates. For earth

connections, brass bolts and nuts with lead washers are provided in the
pipes/plates;

 Earth pipe troughs and oil sumps/pits are free from rubbish, dirt and stone
jelly and the earth connections are visible and easily accessible;

 HT and LT panels and switchgears are all vermin and damp-proof and all
unused openings or holes are blocked properly;

 The earth busbars have tight connections and corrosion free joint surfaces;
 Control switch fuses are provided at an accessible height from ground;

 Adequate headroom is available in the transformer room for easy topping-

up of oil, maintenance, etc.;
 Safety devices, horizontal and vertical barriers, busbar covers/shrouds,
automatic safety shutters/door interlock, handle interlock etc. are safe and
in reliable operation in all panels and cubicles;
 Clearances in the front, rear and sides of the main HT and LT and subswitch
boards are adequate;

 The switches operate freely; the 3 blades make contact at the same time, the
arcing horns contact in advance; and the handles are provided with locking
arrangements,

 Insulators are free from cracks, and are clean;

 In transformers, there is no oil leak;

 Connections to bushing in transformers are light and maintain good contact;

 Bushings are free from cracks and are clean;

 Accessories of transformers like breathers, vent pipe, buchholz relay, etc.
are in order;

 Connections to gas relay in transformers are in order;

 In transformers, oil and winding temperature are set for specific
requirements to pump out;

 In case of cable cellars, adequate arrangements exist to pump off water that
has entered due to seepage or other reasons; and

 All incoming and outgoing circuits of HT and LT panels are clearly and
indelibly labeled for identifications.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4619

Inspection of Low Tension (LT) Installation

In Low Tension (LT) or Medium Voltage (MV) Installations, it shall be checked
whether:
 All blocking materials that are used for safe transportation in switchgears,
contactors, relays, etc. are removed;
 All connections to the earthing system have provisions for periodical
inspection;
 Sharp cable bends are avoided and cables are taken in a smooth manner in
the trenches or alongside the walls and ceilings using suitable support
clamps at regular intervals;
 Suitable linked switch or circuit breaker or lockable push button is provided
near the motors/apparatus for controlling supply to the motor/apparatus in
an easily accessible location;
 Two separate and distinct earth connections are provided for the motor
apparatus;
 Control switch fuse is provided at an accessible height from ground for
controlling supply to overhead travelling crane, hoists, overhead busbar
trunking;
 The metal rails on which the crane travels are electrically continuous and
earthed and bonding of rails and earthing at both ends are done;
 Four-core cables are used for overhead travelling crane and portable
equipment, the fourth core being used for earthing, and separate supply for
lighting circuit is taken;
 If flexible metallic hose is used for wiring to motors and other equipment,
the wiring is enclosed to the full lengths, and the hose secured properly by
approved means;
 The cables are not taken through areas where they are likely to be damaged
or chemically affected;
 The screens and armours of the cables are earthed properly;
 The belts of belt driven equipment are properly guarded;
 Adequate precautions are taken to ensure that no live parts are so exposed
as to cause danger;
 Installed Ammeters and voltmeters work properly and are tested; and
 The relays are inspected visually by moving covers for deposits of dusts or
other foreign matter.
4620 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Inspection of Overhead Lines

For overhead lines, every care must be taken so that:
 All conductors and apparatus including live parts thereof are inaccessible;
 The types and size of supports are suitable for the overhead lines/conductors
used and are in accordance with approved drawing and standards;
 Clearances from ground level to the lowest conductor of overhead lines,
sag conditions, etc. are in accordance with the relevant standard;
 Where overhead lines cross the roads suitable grounded guarding shall be
provided at road crossings,
 Where overhead lines cross each other or are in proximity with one another,
suitable guarding shall be provided at crossings to protect against possibility
of the lines coming in contact with one another;
 Every guard wire shall be properly grounded/earthed;
 The type, size and suitability of the guarding arrangement provided shall be
adequate;
 Stays cables must be provided suitably with the overhead line carrying
poles as required and shall be efficiently earthed at the bottom and shall be
provided with suitable stay insulators of appropriate voltages;
 Anti-climbing devices and Danger Board/Caution Board Notices are
provided on all HT supports;
 Clearances along the route are checked and all obstructions such as
trees/branches and shrubs are cleared on the route to the required distance
on either side;
 Clearance between the live conductor and the earthed metal parts are
adequate; and
 For the service connections tapped off from the overhead lines, cutouts of
adequate capacity are provided.
Inspection of Lighting Circuits
The lighting circuits shall be checked to see whether:
 Wooden boxes and panels are avoided in factories for mounting the lighting
boards, switch controls, etc.;
 Neutral links are provided in double pole switch fuses which are used for
lighting control, and no fuse is provided in the neutral;
 The plug points in the lighting circuit are all 3-pin type, the third pin being
suitably earthed;
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4621
 Tamper proof interlocked switch socket and plug are used for locations
easily accessible;
 Lighting wiring in factory area is enclosed in conduit and the conduit is
properly earthed, or alternatively, armoured cable wiring is used;
 A separate earth wire is run in the lighting installation to provide earthing
for plug points, fixtures and equipment;
 Proper connectors and junction boxes are used wherever joints are in
conductors or cross over of conductors takes place;
 Cartridge fuse units are fitted with cartridge fuses only;
 Clear and permanent identification marks are painted in all distribution
boards, switchboards, sub-main boards and switches as necessary;
 The polarity has been checked and all fuses and single pole switches are
connected on the phase conductor only and wiring is correctly connected to
socket outlets;
 Spare knockouts provided in distribution boards and switch fuses are
blocked;
 The ends of conduits enclosing the wiring leads are provided with ebonite
or other suitable bushes;
 The fittings and fixtures used for outdoor use are all of weatherproof
construction, and similarly, fixtures, fittings and switchgears used in the
hazardous area are of flameproof application;
 Proper terminal connectors are used for termination of wires (conductors
and earth leads) and all strands are inserted in the terminals;
 Flat ended screws are used for fixing conductor to the accessories;
 Flat washers backed up by spring washers are used for making end
connections.
Accessibility of Connections and Cable joints for Inspection
Except for the following, every connection and joint shall be accessible for
inspection, testing and maintenance:
 A compound-filled or encapsulated joint
 A connection between a cold tail and a heating element (e.g. a ceiling and
floor heating system, a pipe trace-heating system)
 A joint made by welding, soldering, brazing or compression tool
 A joint formatting part of the equipment complying with the appropriate
product standard.
4622 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

1.4 Related Codes and Standards

Significant modification, upgradation and additions of the previous electrical engineering

section of BNBC of 1993 have been incorporated in this updated version. While making
changes and additions, the following documents/regulations/codes have been taken as
reference/guiding sources:
(a) Bangladesh Electricity Act.
(b) IEE wiring Regulation (17th edition) BS: 7671 2008 including all parts.
(c) British Standards (BS).
In addition to these, the following documents/regulations/codes have also been taken as
references as required:
(a) National Building Code of India - 2005.
(b) Building Code of Pakistan - latest version.
(c) National Electrical Code of USA.
(d) International Electrotechnical Commission (IEC) Standards.
(e) ISO 50001 Standard for Energy Management System.
(f) Verband Deutscher Elektrotechniker (Association of German Electrical
Engineers) (VDE).
However, efforts have been be given to accept a significant part of rules and practices
mentioned in IEE wiring Regulation (17th edition) BS: 7671 2008 including all parts with
necessary modifications for our system and suitable for our country.
While preparing this document the following Standards and practices are kept in mind.
(a) For having safe domestic electrical systems, domestic electrical installations shall be
designed and installed according to the "fundamental principles" given in British
Standard BS 7671 Chapter 13. These are similar to the fundamental principles
defined in international standard IEC 60364-1. It is necessary to apply British
Standard BS 7671 (the "Wiring Regulations"), including carrying out adequate
inspection and testing to this standard of the completed works.
 To meet the above mentioned requirements the following rules and
guidance shall be followed.
 The rules of the IEE wiring regulations (BS 7671), colloquially referred to
as "the regs" (BS 7671: 2008, 17th Edition).;
 The rules of an equivalent standard approved by a member of the European
Economic Area (e.g., DIN/VDE 0100);
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4623

(b) Guidance given in installation manuals that is consistent with BS 7671, such as the
IEE On-Site Guide and IEE Guidance Notes 1 to 7.

(c) Installations in commercial and industrial premises must satisfy the requirements set
in Electricity at Work Regulations 1989 (UK) and must follow recognised standards
and practices, such as BS 7671 "Wiring Regulations".

Apart from these, some modifications had to be made considering the weather and other
local conditions, practices and previous experiences in this country.

1.5 List Of Related Appendices

Appendix A Maximum Demand and Diversity

Appendix B Useful Tables Relating to Conductor Sizes

Appendix C Completion Certificate Form

4624 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

PART VIII
Chapter 2
Air-Conditioning, Heating And Ventilation
2.1 General

2.1.1 Purpose

The purpose of this Chapter is to provide minimum standards for regulating and
controlling the design, construction, installation, quality of materials, location, operation,
performance, maintenance and use of air conditioning, heating and ventilation systems to
ensure acceptable conditions of air inside the building required for human health, safety
and welfare with energy conservation.

2.2 Scope

2.2.1 The provisions of this Code shall apply to erection, installation, alteration,
repair, relocation, replacement, addition to, use and maintenance of any air-conditioning,
heating and ventilation systems.

2.2.2 Additions, alterations, repairs and replacement of equipment or systems shall

comply with the provisions for new equipment and systems except as otherwise provided
in Sec 2.2.2.1.

2.2.3 Where, in any specific case, different sections of this Code specify different
materials, methods of construction or other requirements, the most restrictive one shall
govern. Where there is a conflict between a general requirement and a specific
requirement, the specific requirement shall be applicable.

2.2.4 The regulations of this Code are not intended, and shall not be understood to
permit violation of the provisions of other ordinances, regulations or official requirements
in force.

2.3 Application

It shall be unlawful to install, extend, alter, repair or maintain air-conditioning, heating

and ventilation systems in or adjacent to buildings except in compliance with this Code.

2.3.1 Existing Systems

Existing Installations: Air-conditioning, heating and ventilation systems in existence at

the time of adoption of this Code may have their use, maintenance or repair continued if
the use, maintenance or repair is in accordance with original design and location and no
hazard to life, health or property has been created by such system.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4625

Additions, Alterations or Repairs: Additions, alterations or repairs may be made to any

air-conditioning, heating or ventilation system without requiring the existing system to
comply with all the requirements of this Code, provided the addition, alteration or repair
conforms to the requirements of a new system. Additions, alterations or repairs shall not
make an existing system unsafe, create unhealthy or overloaded conditions.

Changes in Building Occupancy: Air-conditioning, heating and ventilation systems which

are a part of any building or structure undergoing a change in use or occupancy, as
defined in the Building Code, shall comply with all requirements of this Code which may
be applicable to the new use, or occupancy.

Maintenance: All air-conditioning, heating and ventilation systems, materials and

appurtenances, both existing and new, and all parts thereof shall be maintained in proper
operating condition in accordance with the original design and in a safe and hazard free
condition. All devices or safeguards which are required by this Code shall be maintained
in conformance with this Code. The owner or the owner's designated agent shall be
responsible for maintenance of the systems and equipment.

Moved Buildings: Air-conditioning, heating and ventilation systems of a building or a

structure if moved to another premises shall comply the provisions of this Code for new
installations.

2.3.2 Alternative Materials and Methods of Construction

The provisions of this Code are not intended to prevent the use of any material or method
of construction not specifically prescribed by this Code, provided any such alternative
material and/or method of construction has been approved and the use authorized by the
Authority.

The Authority shall require that sufficient evidence or proof be submitted to substantiate
any claims made regarding the use of alternatives.

2.3.3 Modifications

Whenever there are practical difficulties involved in carrying out any of the provisions of
this Code, the Authority, within the limitations set forth in Part 2 may allow
modifications for individual cases. The modifications shall be in conformity with the
intent and purpose of this Code and that such modification shall not lessen health, life and
fire safety requirements.
4626 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
2.4 Terminology
This Section provides an alphabetical list of the terms used in and applicable in this
Chapter of the Code. In case of any conflict or contradiction between a definition given in
this Section and that in Part 1, the meaning provided in this Section shall govern for
interpretation of the provisions of this Chapter.
ABSORPTION A process whereby a material extracts one or more substances
present in an atmosphere or mixture of gases or liquids
accompanied by the material’s physical and/or chemical changes.
ABSORPTION A refrigerating system in which refrigerant gas evaporated in the
REFRIGERATING evaporator is absorbed in the absorber by an absorbent solution.
SYSTEM This also includes a generator for separation of refrigerant from
the absorbent solution, a condenser to liquefy the refrigerant and
an expansion device.
ADSORPTION The action, associated with the surface adherence, of a material in
extracting one or more substances present in an atmosphere or
mixture of gases and liquids, unaccompanied by physical or
chemical change.
AIR CHANGE Introducing new, cleansed, or recirculated air to conditioned
space, measured by the number of complete changes per unit time.
AIR TERMINALS A round, square, rectangular, or linear air outlet or inlet device
used in the air distribution system.
AIR, OUTSIDE External air; atmosphere exterior to refrigerated or conditioned
space; ambient (surrounding) air.
AIR, The part of return air passed through the air-conditioner before
RECIRCULATED being resupplied to the conditioned space. Also known as AIR,
RETURN.
AIR, RETURN See AIR, RECIRCULATED.
AIR- The process of treating air so as to control simultaneously its
CONDITIONING temperature, humidity, purity, distribution, pressure and air
movement to meet the thermal requirements of the space.
AIR-HANDLING Equipment comprised of cooling and/or heating coil and a blower
UNIT or fan with electric motor used for the purpose of cooling/heating
and distributing supply air to a room, space or area.
BLOWER A fan used to force air under pressure.
BOILER A closed vessel in which a liquid is vaporized.
BRINE Any liquid cooled by the refrigerant and used for the heat
transmission without a change in its state. This also includes
chilled water.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4627

CHIMNEY Primarily a vertical shaft enclosing at least one flue for conducting
flue gases to the outdoors.
COIL A cooling or heating element made of pipe or tubing.
CONDENSER A heat exchanger in which the refrigerant, compressed to a
(Refrigerant) suitable pressure, is condensed to liquid by rejecting heat to an
appropriate external cooling medium.
When the condenser rejects heat to air, the condenser is termed as
air coled condenser.
When the condenser rejects heat to water, the condenser is termed
as water cooled condenser.
When the condenser rejects heat to glycol (brine), the condenser is
termed as glycol cooled condenser.
CONDENSING A condensing unit is a complete set consisting of compressor(s)
UNIT and condenser(s) with or without receiver. It may be air cooled or
water cooled.
CONTROL Any device for regulating a system or component in normal
operation, manual or automatic.
COOLING An enclosed device for evaporatively cooling water by contact
TOWER with air.
DAMPER A device for regulating the flow of air or other fluid.
DEHUMIDIFICAT Condensation of water vapour from air by cooling below the dew
ION point.
DEW POINT The temperature at which condensation of moisture begins when
TEMPERATURE the air is cooled at same pressure.
DRY BULB The temperature of air as registered by a thermometer, taken in
TEMPERATURE such a way as to avoid errors due to radiation.
DUCT SYSTEM A continuous passageway for the transmission of air which, in
addition to the ducts, may include duct fittings, dampers, plenums,
grilles and diffusers.
ENERGY The ratio between refrigeration capacity of a complete air
EFFICIENCY conditioning unit in btu/hr with the power consumption in watt.
RATIO
ENTHALPY A thermal property indicating quantity of heat in the air above an
arbitrary datum, in kilo joules per kg of dry air (or btu per pound
of dry air).
EVAPORATIVE The removal of sensible heat from the air by the adiabatic
AIR COOLING exchange of heat between air and a water-spray or wetted surface,
wherein the evaporating water absorbs the sensible heat of air.
4628 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

EVAPORATOR A heat exchanger in which liquid refrigerant, after reducing its

(refrigerant) pressure (expansion), is evaporated by absorbing heat from the
medium to be cooled.
EXFILTRATION The phenomenon of inside air leaking out of an air conditioned space.
FAN An air moving device comprising of a wheel or blade, and housing
or orifice plate.
FAN, A propeller or disc type wheel within a cylinder and including
TUBEAXIAL driving mechanism supports for either belt drive or direct
connection.
FILTER A device to remove solid particles from a fluid.
FIRE DAMPER A closure which consists of a normally held open damper installed
in an air distribution system or in a wall or floor assembly and
designed to close automatically in the event of a fire in order to
isolate the conditioned space from the fire zone.
FIRE A construction assembly that acts as a barrier against spread of fire
SEPARATION and may not be required to have a fire resistance rating or fire
protection rating.
GLOBAL Global warming potential of a chemical compound is its relative
WARMING contribution to global warming compared to Carbon Dioxide
POTENTIAL (CO2).
(GWP) Global warming can make our planet and its climate less
hospitable and more hostile to human life. Thus it is necessary to
reduce reduction in emission of greenhouse gases such as CO2,
SOX, NOX and refrigerants. Long atmospheric life time of
refrigerants results in global warming unless the emissions are
controlled. GWP values of some of the refrigerants are given
below. The values indicated are for an integration period of 100
years.
Refrigerant GWP values
R-11 4,000
R-12 2,400
R-22 1,700
R-123 0.02
R-134a 1,300
R-407A 2,000
R-407C 1,600
R-410A 1,890
R-744 (CO2) 1.00
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4629

HUMIDITY Water vapour within a space.

HUMIDITY, The ratio of partial pressure or density of water vapour in air to the
RELATIVE saturation pressure or density, respectively, of water vapour at the
same temperature.
HYDRONIC Of, relating to, or being a system of heating or cooling that
involves transfer of heat by a circulating fluid (as water or vapour)
in a closed system of pipes.
INDOOR AIR Air quality that refers to the nature of conditioned air that
QUALITY (IAQ) circulates throughout the space/area where one works, lives, that
is, the air one breathes when indoors.
It not only refers to comfort which is affected by temperature,
humidity, air movement and odors but also harmful biological
contaminants and chemicals present in the conditioned space. Poor
IAQ may be a cause of serious health hazard. Carbon dioxide has
been recognized as the surrogate ventilation index.
INFILTRATION The phenomenon of outside air leaking into an air conditioned space.
INSULATION, A material having a relatively high resistance to heat flow and
THERMAL used principally to retard heat flow.
INTEGRATED It is the part-load efficiency figure of the chiller at the ARI
PART LOAD 550/590 standard rating point, measured in kW/ton, according to
VALUE (IPLV) the following standard formula
1
IPLV 
0 . 01 0 . 42 0 . 45 0 . 12
  
A B C D
where, A = kW/ton at 100% load
B = kW/ton at 75% load
C = kW/ton at 50% load
D = kW/ton at 25% load
MECHANICAL A refrigerating system in which the gas evaporated in the
REFRIGERATION evaporator is compressed by mechanical means usually by a
EQUIPMENT compressor. This also includes condenser and expansion device.
NON-STANDARD It is the part-load efficiency figure of the chiller at the rating
PART LOAD conditions other than the ARI standard rating point but within
VALUE (NPLV) prescribed limits. The rating points are actually values at which
the chiller will actually be operating.
OVERALL HEAT The time rate of heat flow per unit area (normal to the flow) from
TRANSFER the fluid on the warm side of a barrier to the fluid on the cold side,
COEFFICIENT (U) per unit temperature difference between the two fluids.
4630 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

OZONE Ozone depletion potential of a chemical compound is its relative

DEPLETION contribution to the depletion of the ozone layer compared to CFC-
POTENTIAL 11. ODP values of some of the refrigerants are as follows
(ODP)
Refrigerant ODP values

R-11 1.0
R-12 1.0
R-22 0.05
R-123 0.02
R-134a 0
R-407A 0
R-407C 0
R-410A 0

PACKAGED AIR An encased assembly of equipment/machinery for thermal

CONDITIONER conditioning (cooling/heating) of air along with cleaning and
circulation of air to maintain internal thermal environment of an
air conditioned space. It includes a prime source of refrigeration
for cooling and dehumidification with or without internal and
external air distribution ducting. It may also include means for
heating, humidifying and ventilating air. These units may be floor
mounted, wall mounted or ceiling mounted type. They may
provide free delivery or ducted delivery of conditioned air.
These machines are equipped with air cooled or water cooled
condenser(s). These machines are equipped with reciprocating,
rotary or scroll compressor(s).
PLENUM An air compartment or chamber to which one or more ducts are
connected and which forms part of an air distribution system.
POSITIVE The supply of outside air by means of a mechanical device, such
VENTILATION as a fan.
PSYCHROMETRY The science involving thermodynamic properties of moist air and
the effect of atmospheric moisture on materials and human
comfort. It also includes methods of controlling properties of
moist air.
PSYCHROMETRIC A chart graphically representing the thermodynamic properties of
CHART moist air.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4631

REFRIGERANT The fluid used for heat transfer in a refrigerating system, which
absorbs heat at a low temperature and a low pressure of the fluid
and rejects heat at a higher temperature and a higher pressure of
the fluid, usually involving changes of phase of the fluid.
REHEATING The process by which air, which has been cooled down in order to
condense out part of the moisture it contains, is heated again in
order to raise its temperature to a suitable level.
RETURN AIR These are fittings fixed at the openings through which air is taken
GRILLE out from the air-conditioned enclosure by an air-conditioning plant
or unit.
ROOM AIR- A factory made, encased assembly designed as a self-contained
CONDITIONER unit primarily for mounting in a window or through the wall or as
a console. It is designed to provide free delivery of conditioned air
to an enclosed space, room or zone (conditioned space). It
includes a prime source of refrigeration for cooling and
dehumidification and means for the circulation and cleaning of air.
It may also include means for heating, humidifying, ventilating or
exhausting air.
SHADE FACTOR The ration of instantaneous heat gain through fenestration with
shading device to that through the fenestration without shading device.
SUPPLY AIR The air that has been passed through the conditioning apparatus
and taken through the duct system and distributed in the
conditioned space.
SPLIT AIR A split package air conditioner is same as the packaged air
CONDITIONER conditioner excepting that the condenser or the condensing unit is
built as a separate package for remote field installation and
interconnecting refrigerant pipes between indoor unit and outdoor
unit is considered as a package. The indoor units may be floor
mounted, wall mounted, ceiling mounted (concealed) and may be
free blow type or ducted type.
SUPPLY AIR These are fittings fixed at the openings through which air is
DIFFUSERS/ delivered into the air-conditioned enclosure by an air-conditioning
GRILLES plant or unit.
TEMPERATURE, The temperature of air as registered by a thermometer.
DRY BULB
TEMPERATURE, The temperature at which water, by evaporating into air, may
WET BULB bring the air to saturation adiabatically at the same temperature.
Wet-bulb temperature (without qualification) is the temperature
indicated by a wet bulb psychrometer constructed and used
according to specifications.
4632 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

THERMAL Thermal transmission per unit time through unit area of the given
TRANSMIT- building unit divided by the temperature difference between the air
TANCE or some other fluid on either side of the building unit in ‘steady
state’ conditions.
THERMAL Storage of thermal energy, sensible, latent or combination thereof
ENERGY for use in central system of air conditioning or refrigeration. It
STORAGE uses a primary source of refrigeration for cooling and storing
thermal energy for reuse at peak demand or for backup as planned.
VARIABLE A variable refrigerant flow (VRF) air conditioning system is
REFRIGERANT similar to a split air conditioning system excepting that it is of
FLOW (VRF) larger capacity and covers multiple zones/areas simultaneously. It
SYSTEM is consisted of one or more outdoor condensing units, multiple
indoor units, interconnected refrigerant pipes between outdoor
unit(s) and indoor units, etc. all considered as a single package.
The condensing units contain at least one inverter controlled
rotary/scroll compressor or digital scroll compressor. The
objective of using inverter controlled compressor or digital scroll
compressor is to regulate capacity of air conditioning system, in
response to the load requirements, by regulating refrigerant flow
through the indoor units. The indoor units may be floor mounted,
wall mounted, ceiling mounted (concealed) and may be free blow
type or ducted type.
VENTILATION The process of supplying and/or removing air by natural or
mechanical means to or from any space. Such air may or may not
have been conditioned.
WATER The treatment of water circulating in a hydronic system, to make it
CONDITIONING suitable for air conditioning system due to its effect on the
economics of the air conditioning plant.
Untreated water used in air conditioning system may create
problems such as scale formation, corrosion and organic growth.
Appraisal of the water supply source including chemical analysis
and determination of dissolves solids is necessary to devise a
proper water conditioning program.

2.5 General Provisions

2.5.1 Air conditioning, heating and ventilation system shall be designed, constructed,
installed, operated and maintained in accordance with good engineering practice such as
described in the ASHRAE (American Society of Heating, Refrigerating and Air-
conditioning Engineers) Handbooks, HI (Hydraulic Institute of USA) manuals and
relevant chapters of this Code.
2.5.2 All electrical work in connection with air-conditioning, heating and ventilation
system shall be carried out in accordance with the provisions of latest Bangladesh
Electricity Act and the provisions of any of its regulations and bye-laws, and shall also
comply with the requirements of Chapter 1.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4633

2.5.3 All plumbing work in connection with air-conditioning, heating and ventilation
system shall be carried out in accordance with the provisions and guidelines of ASHRAE
handbooks and HI manuals.
2.5.4 All gas and fuel piping in connection with air-conditioning, heating and
ventilation system shall be carried out in accordance with the provisions of Chapter 8.
2.5.5 Fire Safety: Installations of equipment of air-conditioning, heating and
ventilation system shall conform to the requirements of Part 4 of this Code.

2.6 Planning

2.6.1 General
2.6.1.1 All relevant aspects of air-conditioning, heating and ventilation system
installations shall be analyzed and evaluated properly during the planning stage of the
building in order to determine the necessary provisions to be kept in the building for
proper and safe installation of the system machinery, equipment and other facilities.
2.6.1.2 Necessary particulars of electrical requirements of air-conditioning, heating or
ventilation system shall be determined early in the planning stage to include it in the
electrical provisions of the building.
2.6.1.3 Where necessary, all plans, calculations, specifications and data for air-
conditioning, heating and ventilation system serving all buildings and all occupancies
within the scope of the Code shall be supplied to the Authority, for review purposes.
2.6.1.4 Design air conditioning, heating and ventilation system taking consideration
for energy efficiency and energy conservation. Provide data to design architect to keep
provisions in the building for reduction of energy usage required for operation of air-
conditioning system. Optimize the design by coordinating the design with the design
architect at the early stage i.e. in the schematic design phase and continually improve
design during the design development process.
2.6.2 Building Planning
2.6.2.1 Orientation of building
Effect of orientation of building and arrangement of rooms/spaces shall be analyzed in
the planning stage of the building to find out the most effective plan of the building in
terms of building use, application of air-conditioning, heating and ventilation system and
reduction of energy consumption.
2.6.2.2 Building design and use of materials
Analysis shall be carried out in the design stage for selection of appropriate shading
devices and other materials as set forth in Sec 2.7.1 so as to take advantage of reduction
in energy consumption related air-conditioning, heating and ventilation system. Selection
of glazing materials shall be in compliance with Sec 2.12.2.4.
4634 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

2.6.2.3 Equipment space

Requirements of space for erection and installation of air-conditioning, heating and
ventilation system equipment and machinery (ducting, cooling, heating and air-
conditioning equipment; refrigerating machinery, boiler etc.) shall be determined during
the planning stage of the building so that it can be incorporated in the building planning
effectively. Requirements of equipment/machinery space shall be determined taking
consideration of actual equipment and machinery space; clearance space for operation;
maintenance and fire prevention requirement; access space and other requirements of this
Code. Building plan shall also include adequate provisions for transportation of
equipment and machinery to and from equipment/machinery room, installation of
outdoor air inlets and exhaust air outlets. Planning for equipment space shall take into
consideration of different parameters described in Sections 2.5 and 2.6.
2.6.2.4 Equipment space planning for central air conditioning plant
(a) In selecting the location for plant room, the aspects of efficiency, economy and good
practice should be considered and wherever possible it shall be made contiguous
with the building. This room shall be located as centrally as possible with respect to
the area to be air conditioned and shall be free from obstructing columns.
(b) In case of large capacity water cooled chiller installations (500 TR and above), it is
advisable to have a separate isolated equipment room where possible. The clear
headroom below soffit of beam should be minimum 4.5 m for centrifugal chillers,
and minimum 3.6 m for reciprocating and screw type chillers.
(c) The floors of the equipment rooms should be light colored and finished smooth. For
floor loading, the air conditioning engineer should be consulted.
(d) Supporting of pipe within plant room spaces should be normally from the floor.
However, outside plant room areas, structural provisions shall be made for
supporting the water pipes from the floor/ceiling slabs. All floor and ceiling supports
shall be isolated from the structure to prevent transmission of vibrations.
(e) Equipment rooms, wherever necessary, shall have provision for mechanical
ventilation. In hot climate, evaporative air-cooling may also be considered.
(f) Plant machinery in the plant room shall be placed on plain/reinforced cement
concrete foundation and provided with anti-vibration supports. All foundations
should be protected from damage by providing epoxy coated angle nosing.
Requirements of seismic restraint supports may also be considered.
(g) Equipment room should preferably be located adjacent to external wall to facilitate
equipment movement and ventilation.
(h) Wherever necessary, acoustic treatment should be provided in plant room space to
prevent noise transmission to adjacent occupied areas.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4635

(i) Air conditioning plant room should preferably be located close to main electrical
panel of the building in order to avoid large cable lengths.
(j) In case the air conditioning plant room is located in basement floor, equipment
movement route shall be planned to facilitate future replacement and maintenance.
Service ramps or hatch in ground floor slab should be provided in such cases.
(k) Floor drain channels or dedicated drainpipes in slope shall be provided within plant
room space for effective disposal of waste water. Fresh water connection may also
be provided in the air conditioning plant room.
(l) Thermal energy storage: In case of central plants, designed with thermal energy
storage its location shall be decided in consultation with the air conditioning
engineer. The system may be located in plant room, on rooftop, in open space near
plant room or buried in open space near plant room. For roof top installations,
structural provision shall take into account load coming due to the same. For open
area surface installation horizontal or vertical system options shall be considered and
approach ladders for manholes provided. Buried installation shall take into account
loads due to movement above, of vehicles, etc. Provision for adequate expansion
tank and its connection to thermal storage tanks shall be made.

2.6.2.5 Space planning for air cooled chillers

(a) Air Cooled chiller shall be installed where adequate open space is available for heat
transfer of air cooled condensers of the chiller.
(b) Where such space is available on ground, it can be installed on ground provided
noise and hot air from the chiller do not create any problem to the adjoining building.
(c) Roof of the building is a suitable location for installation of air cooled chiller. When
it is intended to install air cooled chiller on roof, prior planning is a must. The roof
shall be structurally strong enough to withstand the dynamic load of the chiller along
with chilled water pumps, pipes, valves and associated equipment required for this
purpose. Advice from an air conditioning engineer shall be taken at the planning
stage.
(d) Vibration from the machine shall not transmit to the roof structure. Chiller shall be
installed on seismic restraint type vibration isolators.
(e) Noise of the air cooled chiller shall be attenuated so that it does not transmit to the
occupied area. A low speed condenser fan with acoustically treated fan cylinder shall
be preferable. Similarly acoustically encased compressors shall also be preferable.

2.6.2.6 Planning equipment room for air handling units and package units
(a) This shall be located as centrally as possible to the conditioned area and contiguous
to the corridors or other spaces for carrying air ducts. For floor loading, air
conditioning engineer shall be consulted.
4636 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(b) In the case of large and multistoried buildings, independent air handling unit should
be provided for each floor. The area to be served by air-handling unit should be
decided depending upon the provision of fire protection measures adopted. Air
handling unit rooms should preferably be located vertically one above another.

(c) Provision should be made for the entry of fresh air. The fresh air intake shall have
louvers having rain protection profile, with volume control damper and bird screen.

(d) In all cases air intakes shall be so located as to avoid contamination from exhaust
outlets or to the sources in concentrations greater than normal in the locality in which
the building is located.

(e) Exterior openings for outdoor air intakes and exhaust outlets shall preferably be
shielded from weather and insects.

(f) No air from any dwelling unit shall be circulated directly or indirectly to any other
dwelling unit, public corridor or public stairway.

(g) All air handling unit rooms should preferably have floor drains and water supply.
The trap in floor drain shall provide a water seal between the air-conditioned space
and the drain line.

(h) Supply/return air duct shall not be taken through emergency fire staircase.

Exception: Ducts can be taken inside the fire stair provided fire isolation of ducts at
wall crossings is (are) carried out.

(i) Waterproofing of air handling unit rooms shall be carried out to prevent damage to
floor below.
(j) The floor should be light colored, smooth finished with terrazzo tiles or the
equivalent. Suitable floor loading should also be provided after consulting with the
air conditioning engineer.
(k) Where necessary, structural design should avoid beam obstruction to the passage of
supply and return air ducts. Adequate ceiling space should be made available outside
the air handling unit room to permit installation of supply and return air ducts and
fire dampers at air handling unit room wall crossings.
(l) The air handling unit rooms may be acoustically treated, if located in close proximity
to occupied areas.
(m) Access door to air handling unit room shall be single/double leaf type, airtight,
opening outwards and should have a sill to prevent flooding of adjacent occupied
areas. It is desired that access doors in air conditioned spaces should be provided
with tight sealing, gaskets and self-closing devices for air conditioning to be
effective.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4637

(n) Air handling unit rooms shall be separated from the air conditioned space by 4 hour
fire rated walls and 2-hour fire rated door. Fire/smoke dampers shall be provided in
supply/return air duct at air handling unit room wall crossings and the annular space
between the duct and the wall should be fire-sealed using appropriate fire resistance
rated material.

(o) Fire isolation shall be provided for vertical fresh air duct, connecting several air
handling units.

2.6.2.7 Planning of pipe shafts

(a) The shafts carrying chilled water pipes should be located adjacent to air handling
unit room or within the room.

(b) Shaft carrying condensing water pipes to cooling towers located on roof/terrace
should be vertically aligned.

(c) All shafts shall be provided with fire barrier at floor crossings in accordance with the
provisions of Chapter 4.
(d) Access to shaft shall be provided at every floor.

2.6.2.8 Planning for supply air ducts and return air

(a) Duct supports, preferably in the form of angles of mild steel supported using stud
anchors shall be provided on the ceiling slab from the drilled hole. Alternately, duct
supports may be fixed with internally threaded anchor fasteners and threaded rods
without damaging the slabs or structural members.

(b) If false ceiling is provided, the supports for the duct and the false ceiling shall be
independent. Collars for grilles and diffusers shall be taken out only after false
ceiling/boxing framework is done and frames for fixing grilles and diffusers have
been installed.
(c) Where a duct penetrates the masonry wall it shall either be suitably covered on the
outside to isolate it from masonry or an air gap shall be left around it to prevent
vibration transmission. Further, where a duct passes through a fire resisting
compartment/barrier, the annular space shall be sealed with fire sealant to prevent
smoke transmission (see also Part 4 of this Code).
2.6.2.9 Space planning for cooling tower
(a) Cooling towers are used to dissipate heat from water cooled refrigeration, air
conditioning and industrial process systems. Cooling is achieved by evaporating a
small proportion of re-circulating water into outdoor air stream. Cooling towers are
installed at a place where free flow of atmospheric air is available.
4638 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(b) Cooling towers shall be installed at least 3 m above the bases of the chillers. Cooling
tower shall preferably be installed on the roof of the concerned building. In special
cases it may be installed on ground or on any elevated platform or on the roof of the
adjacent building provided the moisture laden discharge air from the cooling towers
do not pose any problem to other buildings. Cooling tower should be so located as to
eliminate nuisance from drift to adjoining structures.

(c) Any obstruction to free flow of air to the cooling tower shall be avoided.

(d) Structural provisions for the cooling tower shall be taken into account while
designing the building. Wind speed shall be taken into consideration while designing
the foundations/supports for cooling towers. Vibration isolation shall be an important
consideration in structural design.

(e) Special design requirements are necessary where noise to the adjoining building is to
be avoided. Special provisions shall be included in the design to reduce water droplet
noise.

(f) Provisions for make-up water tank to the cooling tower shall be made. Make-up
water tank to the cooling tower shall be separate from the tank serving drinking
water.

(g) Make-up water having contaminants or hardness, which can adversely affect the
refrigeration plant life, shall be treated.

2.6.2.10 Building structure

Structural design requirements viz. load on the floor or ceiling; punches in the roof, floor
and walls; vertical shaft for pipe risers and duct risers; concrete ducts etc. shall be
determined in the planning stage to make adequate provisions in the structural design and
to keep such provisions in the building. The structural design shall consider static and
dynamic loads of equipment and machinery including vibration of machinery.

2.6.2.11 Design drawings

For the purpose of effective installation of air-conditioning, heating and ventilation

system, working drawings showing layout of machinery, equipment, ducts, pipes etc.,
details of builders' works, holes and/or punches in roof, floors, walls, supports for
machinery/equipment etc. shall be prepared prior to finalization of building design
drawings. Such drawings/documents shall be properly stored for future reference.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4639

2.7 Air-Conditioning System Design

2.7.1 Building Design Requirements

2.7.1.1 Glazing

(a) Building design shall consider all the aspects for reduction of heat transfer through
the glazing. Building orientation shall be such that, if possible, glazing in walls
subject to direct and intensive sun exposure shall be avoided. In case where it is not
possible to do so, necessary protective measures shall be taken to reduce heat
transfer through the glazing. Such protective measures may be in the form of sun
breakers, double glazing, heat resistant glass or application of other shading devices.

(b) When sun breakers are used, it shall preferably be 1m away from the wall face, with
free ventilation, particularly from bottom to top, being provided for cooling of sun
breakers and window by free convection. Conduction from sun breakers to main
building shall be the minimum. Sun breakers shall shade the maximum glazed area
possible, especially for the altitude and azimuth angle of the sun. Sun breakers shall
preferably be light and bright in colour so as to reflect back as much of the sunlight
as possible.

(c) Where the above protection is in the form of reflective surfaces, adequate care shall
be taken to avoid any hazard to the traffic surrounding the building and people on the
road because of the reflected light from the surfaces.

(d) Application of any protection shall not restrict entry of light to a limit demanding
artificial lights.

2.7.1.2 Roof insulation

(a) Construction of exposed roofs shall be such that the heat transmission through the
roof is not excessive. Where required the overall heat transfer coefficient (U) of the
roof exposed to sun shall be reduced effectively by using appropriate construction
materials and/or proper type of insulation material (s). The overall thermal
transmittance from the exposed roof should be kept as minimum as possible and
under normal conditions, the desirable value should not exceed 0.58 W/m²/⁰C.

(b) Under-deck or over-deck insulation shall be provided for exposed roof surface using
suitable Insulating materials. Over-deck insulation shall be properly waterproofed to
prevent loss of insulating properties.

(c) The ceiling surface of floors which are not to be air conditioned may be suitably
insulated to give an overall thermal transmittance not exceeding 1.16 W/m²/⁰C.
4640 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

2.7.2 Design Conditions

2.7.2.1 Inside design conditions

(a) For comfort air-conditioning, the inside design conditions shall be selected with an
objective to reduce energy consumption in the operation of the air-conditioning
system. Acceptable values of inside design conditions for summer are provided in
Table 8.2.1. Unless otherwise specifically required, the design calculations shall be
based on the normal practice values of Table 8.2.1.

Table 8.2.1: Inside Design Conditions of Some of Applications for Summera

Sl. No. Use Category of Space Indoor Design Conditions

Dry Bulb Relative
Temperature (oC) Humidity (%)

1. Restaurants, Cafeteria and Dining Hall 23 ~ 26 55 ~ 60

2. Kitchens 28 ~ 31 --
3. Office buildings 23 ~ 26 50 ~ 60

4. Bank/Insurance/Commercial building 23 ~ 26 45 ~ 55

5. Departmental stores 23 ~ 26 50 ~ 60
6. Hotel guest rooms 23 ~ 26 50 ~ 60

7. Ball room/meeting room 23 ~ 26 40 ~ 60

8. Class rooms 23 ~ 26 50 ~ 60
9. Auditoriums 23 ~ 26 50 ~ 60

10. Recovery rooms 24 ~ 26 45 ~ 55

11. Patient rooms 24 ~ 26 45 ~ 55

12. Operation theatres 17 ~ 27 45 ~ 55

13. Delivery room 20 ~ 23 45 ~ 55

14. ICU/CCU 20 ~ 23 30 ~ 60

15. New born Intensive care 22.5 ~ 25.5 30 ~ 60

16. Treatment room 23 ~ 25 30 ~ 60

17. Trauma room 17 ~ 27 45 ~ 55

18. Endoscopy/Bronchoscopy 20 ~ 23 30 ~ 60
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4641

Sl. No. Use Category of Space Indoor Design Conditions

Dry Bulb Relative
Temperature (oC) Humidity (%)

19. X-ray (diagnostic & treatment) 25.5 ~ 27 40 ~ 50

X-ray (surgery/critical area and
20. 21 ~ 24 30 ~ 60
catherization)
21. Laboratory (diagnostics) 22.5 ~ 24.5 30 ~ 60
22. Art Galleries/Museums 17 ~ 22 40 ~ 55
23 Libraries 20 ~ 22 45 ~ 55
24. Radio studio/Television studio 23 ~ 26 45 ~ 55
25. Telephone terminal rooms 22 ~ 26 40 ~ 50
26. Airport terminal/ bus terminal 23 ~ 26 50 ~ 60

Note:
a The room design dry bulb temperature should be reduced when hot radiant panels are
adjacent to the occupant and increased when cold panels are adjacent, to compensate
for the increase or decrease in radiant heat exchange from the body. A hot or cold
panel may be un-shaded glass or glass block windows (hot in summer, cold in winter)
and thin partitions with hot or cold spaces adjacent. Hot tanks, furnaces, or machines
are hot panels.

(b) To avoid thermal shock, the difference between the dry bulb temperatures of outdoor
air and indoor air shall not exceed 11oC. If it is absolutely necessary to have a
difference more than 11oC, there shall have adequate provision for ante-room to
reduce the effect of thermal shock.
(c) For air-conditioning systems other than comfort air-conditioning, design conditions
required by the specific processes involved or applications may be adopted. When
required, proper protective measures shall be taken for persons working therein.
(d) Velocity of air in an air-conditioned space, in the zone between the floor level and
the 1.5 m level, shall be within 0.12 m/s and 0.25 m/s for comfort applications for
commercial buildings, and for other applications it shall not exceed 0.5 m/s.
2.7.2.2 Outside design conditions
(a) The outside design conditions for summer months for different cities are provided in
Table 8.2.2. Selection of outside design conditions from this table shall be based on
requirements of the application and the percent of time the outside air temperature is
allowed to exceed the outside design conditions.
4642 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(b) In case of stringent design conditions a meteorologist with experience in applied

climatology may be consulted to evaluate conditions such as; the formation of heat
sinks in urban areas; the duration of extreme temperatures; project sites located
remotely from reporting stations.

2.7.2.3 Ventilation air

(a) Every space served by the air-conditioning system shall be provided with outside
fresh air not less than the minimum amount mentioned in Table 8.2.3. If adequate
temperature regulation along with efficient filtration of air and absorption of odour
and gas are provided, the amount of fresh air requirement may be reduced. However,
in no case the outdoor air quantity shall be lower than 2.5 l/s per person.

(b) In hospital operation theaters, a large quantity of outdoor air supply is recommended
to overcome explosion hazard of anesthetics and to maintain sterile conditions.
However, if adequate filtration with efficient absorption of anesthetics and laminar
flow of supply air is provided, outside air requirement may be substantially reduced.
Recirculation of air shall comply with the requirements of Sec 2.11.3.6.

2.7.3 Noise and Vibration

2.7.3.1 General

Air-conditioning, heating and ventilation system design and installations shall consider
all the aspects of noise and vibration control related to the system and shall conform to
the requirements of Chapter 3 of this Part. Selection and installation of equipment for air-
conditioning, heating and ventilation system shall be such that noise and vibration
transmitted to the space served by the system shall not exceed the recommended value for
the space served.

2.7.3.2 Equipment room

Equipment room for installation of air handling units, refrigeration machinery, pumps,
boilers, blowers and other equipment, which produce noise and vibration, shall not
preferably be located adjacent to any acoustically sensitive area. Location of the
equipment room shall be such that direct transmission of noise and vibration from the
equipment room to acoustically sensitive areas do not occur. Appropriately designed
sound barriers shall be used to restrict transmission of noise from equipment room to any
acoustically sensitive areas, wherever necessary. Similarly, adequate measures shall be
taken to restrict transmission of vibration from equipment room to other rooms.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4643

2.7.3.3 Selection of equipment

Where possible, the equipment shall be selected which produce low sound power level
consistent with the required performance and ensuring operation at maximum efficiency.
Noise levels shall be reduced by appropriate shrouding of the equipment, if necessary.
Equipment shall be so oriented that the noise will be radiated away from the likely areas
of complaint.
Table 8.2.2: Outside Design Conditions for Different Stationsa

Cooling DB/MWBb Evaporation, WB/MDBc Range

Station
0.4% 1% 2% 0.4% 1% 2% of

DB MWB DB MWB DB MWB WB MDB WB MDB WB MDB DBd

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14)

Barisal 35.5 28.5 34.5 28.5 34.0 28.0 30.0 33.0 29.5 33.0 29.0 32.0 5.0

Bogra 36.5 28.5 35.5 28.5 34.5 28.0 31.5 33.5 30.0 33.0 29.0 33.0 5.5

Chandpur 35.5 28.5 34.5 28.5 34.0 28.0 29.5 33.0 29.5 33.0 29.0 32.5 5.0

Chittagong 34.0 28.5 33.5 28.5 33.0 28.0 29.5 32.5 29.0 32.5 28.5 32.0 4.5

Comilla 35.0 27.5 34.5 27.5 34.0 27.5 29.0 33.0 28.5 32.5 28.0 32.0 5.5

Cox’s Bazar 34.0 27.5 33.5 27.5 33.0 27.5 29.0 31.0 29.0 30.0 29.0 30.0 5.0

Dhaka 35.55 27.5 35.0 27.0 34.5 27.0 29.0 33.0 28.5 29.0 28.5 29.0 5.0

Dinajpur 36.0 28.5 35.0 28.0 34.5 28.0 30.0 32.5 29.0 33.0 29.0 33.0 5.5

Faridpur 36.5 28.5 35.5 28.0 34.5 28.0 29.5 33.0 29.0 33.0 29.0 33.0 5.0

Ishurdi 37.5 27.0 36.5 27.0 35.5 28.0 30.0 34.5 29.0 33.5 29.0 33.5 6.0

Jessore 38.0 28.5 37.0 28.5 36.0 28.0 30.0 35.0 30.0 35.0 29.5 34.0 6.5

Khulna 36.5 29.0 36.0 28.0 35.5 28.0 30.0 34.0 30.0 34.0 29.5 33.5 5.0

Mongla 37.0 31.0 36.0 30.5 35.0 30.0 33.0 34.0 32.5 34.0 32.0 33.5 5.0

Mymensingh 35.0 28.0 34.0 28.0 33.5 27.5 29.5 33.0 29.0 32.5 28.5 32.0 4.5

Patuakhali 35.5 28.5 35.0 28.5 34.5 28.5 30.0 33.0 30.0 33.0 29.5 32.5 5.0

Rajshahi 35.5 29.0 34.5 28.5 34.0 29.0 31.5 33.0 31.0 32.5 30.0 31.5 5.0

Rangamati 35.5 26.0 34.5 27.0 34.0 27.5 28.5 33.5 28.0 32.5 28.0 32.5 6.0

Rangpur 35.5 28.5 34.5 28.0 34.0 28.0 29.5 30.5 29.5 30.0 29.5 30.0 5.0

Sylhet 35.5 27.0 34.5 27.0 34.0 26.5 28.5 32.5 28.0 32.5 28.0 32.5 5.5

Tangail 36.0 27.5 35.5 27.5 34.5 27.5 29.0 33.5 28.5 33.0 28.5 33.0 5.5
4644 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Notes:
a This table has been prepared by statistical analysis of weather data of ten years,
recorded three hourly by trained observers of Bangladesh Meteorological Department.
b The dry bulb (DB) temperatures presented in column-2, 4 & 6 represent values
which have equaled or exceeded by 0.4%, 1%, and 2% of the total hours during the
summer months of May through September. The coincident mean wet bulb
temperatures (MWB) listed in columns 3, 5 & 7 are the mean of all wet bulb
temperatures occurring at the specific design dry bulb temperatures. These values shall
be used for cooling load calculation.
c Wet bulb (WB) temperatures presented in column-8, 10 & 12 represent values
which have been equaled or exceeded by 0.4%, 1% and 2% of the total hours during
the summer months of May through September. The coincident mean dry bulb
temperatures (MDB) listed in columns 9, 11 & 13 are the mean of all dry bulb
temperatures occurring at the specific design wet bulb temperatures. These values shall
be used for selection of Cooling Tower, evaporative cooling equipment, fresh air
cooling and other similar equipment.
d Mean daily range temperatures presented in column-14 are the difference
between the average daily maximum and average daily minimum temperatures during
the warmest months at each station.

Table 8.2.3: Minimum Ventilation Rates for Air Conditioned Spaces

Occupancy Classification Outdoor Outdoor Default Exhaust

Airflow Rate in Airflow Occupant Airflow
Breathing Rate in Densitya Ratea
Zone Breathing
Zonea
l/s per person l/s per m2 No./100 m2 l/s per m2

Correctional facilities

Cells without plumbing 2.5 0.6 25

fixtures -
g
Cells with plumbing fixtures 2.5 0.6 25 5.0
Dining halls (see food and beverage service)
Guard stations 2.5 0.3 15 -
Day room 2.5 0.3 30 -

Booking/waiting 3.75 0.3 50 -

 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4645

Occupancy Classification Outdoor Outdoor Default Exhaust

Airflow Rate in Airflow Occupant Airflow
Breathing Rate in Densitya Ratea
Zone Breathing
Zonea
l/s per person l/s per m2 No./100 m2 l/s per m2

Dry cleaners, laundries

Coin-operated dry cleaner 3.75 - 20 -

Coin-operated laundries 3.75 0.3 20 -

Commercial dry cleaner 15 - 30 -

Commercial laundry 12.5 - 10 -

Storage, pick up 3.75 0.6 30 -

Education

Auditoriums 2.5 0.3 150 -

Corridors (see public spaces)
Media center 5 0.6 25 -
Sports locker roomsg - - - 2.5
Music/theater/dance 5 0.3 35 -
Smoking lounges 30 70 -
Day care (through age 4) 5 0.9 25 -
Classrooms (ages 5-8) 5 0.6 25 -
Classrooms (age 9 plus) 5 0.6 35 -
Lecture classroom 3.75 0.3 65 -
Lecture hall (fixed seats) 3.75 0.3 150 -
Art classroomg 10 0.9 20 3.5

Science laboratoriesg 5 0.9 25 5.0

Wood/metal shopsg 5 0.9 20 2.5

Computer lab 5 0.6 25 -

Multiuse assembly 3.75 0.3 100 -

Locker/dressing roomsg - - - 1.25

4646 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Occupancy Classification Outdoor Outdoor Default Exhaust

Airflow Rate in Airflow Occupant Airflow
Breathing Rate in Densitya Ratea
Zone Breathing
Zonea
l/s per person l/s per m2 No./100 m2 l/s per m2

Food and beverage service

Bars, cocktail lounges 3.75 0.9 100 -

Cafeteria, fast food 3.75 0.9 100 -

Dining rooms 3.75 0.9 70 -

Kitchens (cooking)b - - - 3.5

Hospitals, nursing and convalescent homes

Autopsy rooms - - - 2.5

Medical procedure rooms 7.5 - 20 -

Operating rooms 15 - 20 -

Patient rooms 12.5 - 10 -

Physical therapy 7.5 - 20 -

Recovery and ICU 7.5 - 20 -

Hotels, motels, resorts and

dormitories

Multipurpose assembly 2.5 0.3 120 -

Bathrooms/toilet-privateg - - - 12.5/25f

Bedroom/living room 2.5 0.3 10 -

Conference/meeting 2.5 0.3 50 -

Dormitory sleeping areas 2.5 0.3 20 -

Gambling casinos 3.75 0.9 120 -

Lobbies/pre-function 3.75 0.3 30 -

 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4647

Occupancy Classification Outdoor Outdoor Default Exhaust

Airflow Rate in Airflow Occupant Airflow
Breathing Rate in Densitya Ratea
Zone Breathing
Zonea
l/s per person l/s per m2 No./100 m2 l/s per m2

Offices

Conference rooms 2.5 0.3 50 -

Office spaces 2.5 0.3 5 -
Reception areas 2.5 0.3 30 -
Telephone/data entry 2.5 0.3 60 -
Main entry lobbies 2.5 0.3 10 -

Private dwellings, single and

multiple

Garages, common for multiple

- - - 3.75
unitsb
Garages, separate for each
- - - 50 l/s per car
dwellingb
Kitchensb - - - 12.5/50f
Living areasc 0.35 Air Change - Based upon -
per Hour (ACH) number of
but not less than bedrooms.
7.5 l/s per First bedroom
person 2 persons; each
additional
bedroom 1
person
Toilet rooms and bath roomsg - - - 10/25f

Public spaces

Corridors - 0.3 - -
Elevator car - - - 5.0
Shower room (per shower
- - - 25/10f
head)g
4648 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Occupancy Classification Outdoor Outdoor Default Exhaust

Airflow Rate in Airflow Occupant Airflow
Breathing Rate in Densitya Ratea
Zone Breathing
Zonea
l/s per person l/s per m2 No./100 m2 l/s per m2

Smoking lounges 30 - 70 -
Toilet rooms - publicg - - - 25/30e
Places of religious worship 2.5 0.3 120 -
Courtrooms 2.5 0.3 70 -
Legislative chambers 2.5 0.3 50 -
Libraries 2.5 0.6 10 -
Museums (children's) 3.75 0.6 40 -
Museums/galleries 3.75 0.3 40 -
Retail stores, sales floors and showroom
floors

Sales (except as below) 3.75 0.6 15 -

Dressing rooms - - - 1.25
Mall common areas 3.75 0.3 40 -
Shipping and receiving - 0.6 --
b
Smoking lounges 30 - 70 -
Storage rooms - 0.6 --
Warehouses (see storage) - - - -

Specialty shops

Automotive motor-fuel
- - - 7.5
dispensing stationsb
Barber 3.75 0.3 25 2.5
Beauty and nail salonsb 10 0.6 25 3.0
b
Embalming room - - - 10.0
Pet shops (animal areas)b 3.75 0.9 10 4.5

Supermarkets 3.75 0.3 8 -

 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4649

Occupancy Classification Outdoor Outdoor Default Exhaust

Airflow Rate in Airflow Occupant Airflow
Breathing Rate in Densitya Ratea
Zone Breathing
Zonea
l/s per person l/s per m2 No./100 m2 l/s per m2

Sports and amusement

Disco/dance floors 10 0.3 100 -

Bowling alleys (seating areas) 5 0.6 40 -
Game arcades 3.75 0.9 20 -
Ice arenas without combustion
- 0.30 - 2.5
engines
Gym, stadium, arena (play
- 0.30 - -
area)
Spectator areas 3.75 0.3 150 -
Swimming pools (pool and
- 2.4 --
deck area)
Health club/aerobics room 10 0.3 40 -
Health club/weight room 10 0.3 10 -

Storage

Repair garages, enclosed

- - - 3.75
parking garages b,d
Warehouses - 0.3 - -

Theaters

Auditoriums (see education) - - --

Lobbies 2.5 0.3 150 -
Stages, studios 5 0.3 70 -
Ticket booths 2.5 0.3 60 -

Transportation

Platforms 3.75 0.3 100 -

Transportation waiting 3.75 0.3 100 -
4650 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Occupancy Classification Outdoor Outdoor Default Exhaust

Airflow Rate in Airflow Occupant Airflow
Breathing Rate in Densitya Ratea
Zone Breathing
Zonea
l/s per person l/s per m2 No./100 m2 l/s per m2

Workrooms

Bank vaults/safe deposit 2.5 0.3 5 -

Darkrooms - - - 5.0
Copy, printing rooms 2.5 0.3 4 2.5
c
Meat processing 7.5 - 10 -
Pharmacy (prep. area) 2.5 0.9 10 -
Photo studios 2.5 0.6 10 -
Computer (without printing) 2.5 0.3 4 -

a Based upon net occupiable floor area.

b Mechanical exhaust required and the recirculation of air from such spaces is
prohibited. All air supplied to such spaces shall be exhausted, including any air in
excess of that required by this table.
c Spaces unheated or maintained below 50°F are not covered by these requirements
unless the occupancy is continuous.
d Ventilation systems in enclosed parking garages shall comply with Sec 2.11.3.8.
e Rates are per water closet or urinal. The higher rate shall be provided where periods
of heavy use are expected to occur, such as toilets in theaters, schools and sports
facilities. The lower rate shall be permitted where periods of heavy use are not
expected.
f Rates are per room unless otherwise indicated. The higher rate shall be provided
where the exhaust system is designed to operate intermittently. The lower rate shall
be permitted where the exhaust system is designed to operate continuously during
normal hours of use.
g Mechanical exhaust is required and recirculation is prohibited except that
recirculation shall be permitted where the resulting supply air-stream consists of not
more than 10 percent air re-circulated from these spaces (see Sec 2.11.3.6, items a
and c).
h For nail salons, the required exhaust shall include ventilation tables or other systems
that capture the contaminants and odors at their source and are capable of exhausting
a minimum of 25 l/s per station.
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2.7.3.4 Noise control

(a) Air Ducts: Air ducts shall be so designed and installed to avoid any transmission of
noise and vibration which may be picked up by the duct system from equipment
room or adjoining rooms. Duct system shall not allow cross talk or noise transfer
from one occupied space to another.

Duct system shall be appropriately designed, constructed and installed to obtain

adequate attenuation of noise required to maintain recommended noise level in the
air-conditioned space.

Duct construction and installation shall be such that drumming effect of duct walls
and noise transmission through the duct walls can be minimized to the approved
level.

(b) Plenum Chamber: If required, properly designed plenum chamber, lined with
approved sound absorbed material, and/or sound attenuators shall be used for
attenuation of noise.

(c) Flow Control Devices: Air dampers and other flow control devices shall be so
selected that noise generation does not exceed approved levels.

(d) Air Terminals: Air terminals shall be selected for the approved noise generation
characteristics.

(e) Piping: Velocity of fluids in piping shall be so selected that noise generation does
not exceed approved levels.

(f) Chiller and Refrigeration Equipment: Chiller(s) and refrigeration equipment(s) shall
be so selected and installed that the combined effect of noise level does not exceed
65 dBA or approved levels at the property boundary line. Where ever possible
refrigerant compressors may be encased in acoustically treated enclosures to reduce
noise transmission. Similarly, low speed condenser fans may be used to have
reduced noise generation. Fan cylinders may be acoustically treated to reduce noise
transmission.

(g) Cooling Tower: Cooling Towers(s) shall be so selected and installed that the
combined effect of noise generation does not exceed 65 dBA or approved levels at
the proper boundary level. Where ever possible, fan cylinders shall be acoustically
treated to reduce noise transmission. Floating mats may also be used to reduce water
droplet noise.
4652 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

2.7.3.5 Vibration control

(a) Appropriately designed vibration isolators shall be installed under the machinery to
restrict vibration transmission to structures. Similarly vibration isolators shall also be
used between machinery and all pipe work and duct work including the supports
when applicable.

(b) Where ever necessary “Inertia Block” with spring vibration isolators shall be used to
restrict vibration transmission to structures.

(c) Spring vibration isolators shall be earthquake restraint type.

2.8 Air Distribution System

2.8.1 Duct Work

2.8.1.1 General
(a) Supply air, return air and outside air for air-conditioning, heating and ventilation
systems shall be conducted through duct systems. Ducts and plenums shall be of
independent construction or shall be formed by parts of the building structure.
(b) Supply and return air plenums shall be limited to uninhabited crawl spaces, areas
above a ceiling or below the floor, or attic spaces. Plenums shall be limited to one
fire area. Fuel-fired equipment shall not be installed within a plenum. Venting
systems and exhaust ducts shall not be extended into or through ducts or plenums.
(c) Prohibited Use: Exits and exit access corridors shall not be used as supply or return
air ducts or plenums.
Exception: The restriction on the use of the space between the corridor ceiling and
the floor or roof structure above as return air plenum shall not apply when the
corridor is not required to be of fire resistance rated construction or is separated from
the plenum by fire resistance rated construction or is located within a dwelling unit.
(d) Flood Proofing: For building located in a flood hazard zone, plenum spaces shall be
either placed above the base flood elevation or protected so as to prevent water from
entering or accumulating within the plenum space during floods up to the base flood
elevation.

2.8.1.2 Material
(a) All ducts, duct connectors, associated fittings and plenums used to convey supply air,
return air, and outdoor air for air-conditioning, heating and ventilation system shall
be constructed of steel, aluminum alloy or some other approved metal. Ducts,
plenums and fittings may be constructed of concrete, clay or ceramics when installed
in the ground or in a concrete slab, provided the joints are tightly sealed.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4653

(b) When gypsum products are exposed in ducts or plenums, the air temperature shall
neither be lower than 10oC nor be higher than 52oC and the moisture content shall be
controlled so as not to adversely affect the material. Gypsum products shall not be
exposed in ducts serving evaporative coolers.

2.8.1.3 Combustibles within ducts or plenums

Plenums shall be constructed with non-combustible materials. Materials exposed within
ducts or plenums shall have a flame spread index of not more than 25, and smoke
developed rating of not more than 50 when tested in accordance with ASTM E84.
Exceptions:

(i) Return air and outside air ducts, plenums and concealed spaces which serve a
dwelling unit may be of combustible construction.
(ii) Air filters serving dwelling unit.

(iii) Air filters used as water evaporation medium in an evaporative cooler.

(iv) Charcoal filters when protected with an approved fire suppression system.
(v) Exposed electric cables installed in concealed space used as plenums exhibit a
flame propagation of not more than 1.5 m and produce smoke having a peak
optical density not greater than 0.5 and average optical density not greater than
0.15 when tested in accordance with UL910.

(vi) Nonmetallic fire sprinkler piping in the plenum exhibit a flame propagation of
not more than 1.5 m and shall produce smoke having a peak optical density not
greater than 0.5 and average optical density not greater than 0.15 when tested in
accordance with UL1820.

2.8.1.4 Duct construction

(a) Ducts shall be of square, rectangular, round or oval cross-section. Construction of

required size of duct shall be as per good practice described in ASHRAE Handbooks
and SMACNA (Sheet Metal and Air-conditioning Contractors' National Association,
USA) duct construction standards.

(b) Joints of duct systems shall be made substantially airtight by means of tapes, mastics,
gasketing or other means and shall have no opening other than those required for
proper operation and maintenance of the system. Access openings shall be provided
in the duct system for periodic cleaning of the system. Removable grilles requiring
only the loosening of catches or screws for removal may be considered as access
openings. Walk in access doors shall be so constructed that the door may be readily
opened from the inside without the use of keys.
4654 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(c) Vibration isolators installed between equipment and metal ducts (or casings) or
between two sections of the ducts where duct crosses building expansion joint, shall
be made of an approved flame retardant fabric or shall consist of sleeve joints with
packing of approved material having flame spread rating of not more than 25 and a
smoke developed rating of not more than 50 when tested in accordance with ASTM
E84. Vibration isolation connectors constructed of fabric shall not exceed 250 mm in
length.

2.8.1.5 Duct coverings

(a) Supply and return air ducts and plenums of a cooling or heating system shall be
insulated with approved quality insulating material of adequate thickness required as
per location of the duct system and temperatures of air inside and around the duct
system. Insulation shall be of such quality and thickness to prevent the formation of
condensation on the exterior or interior walls of any duct.

(b) Materials used within the ducts and plenums for insulation, sound absorption or other
purposes shall have a mold, humidity and erosion resistant face that meets the
requirements of accepted standards. These materials when exposed to air velocities
within the ducts in excess of 10 m/s shall be fastened with both adhesive and
mechanical fasteners, and exposed edges shall have adequate treatment to withstand
the operating velocity.

(c) Duct coverings, duct linings, vapour barrier facings, tapes, adhesives used in duct
system shall have a flame spread rating not over 25 and a smoke development rating
no higher than 50 when tested as a composite installation:

Exceptions:

(i) Duct coverings shall not be required to meet these requirements where they are
located entirely outside of a building, do not penetrate a wall or roof, and do not
create an exposure hazard.
(ii) Duct covering having a flame spread index not exceeding 50 and a smoke
density not greater than 100 may be used in dwelling/apartment houses where
duct system serves not more than one dwelling unit.

(d) Duct coverings, linings, including associated tapes and adhesives shall be interrupted
at least 1 m from heat source in a duct system such as electric resistance heaters, fuel
burning heaters or furnaces and at the area of a fire damper or fire door, where the
duct penetrates a fire separation. Interior insulation and acoustical linings shall be
placed so as not to interfere with positive closing of fire dampers or other closures.

(e) Service openings shall not be concealed.

 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4655

2.8.1.6 Duct installation

(a) An air distribution system shall be designed and installed as per good practice
described in ASHRAE Handbooks and SMACNA Handbook so as to meet the
requirement of proper distribution of air as per provisions of this Code. The
installation of an air distribution system shall not affect the fire protection
requirements specified in this Code.

(b) Ducts and all parts of the duct system shall be substantially supported and securely
fastened to the structural members of the building with approved devices of
noncombustible material designed to carry the required loads. Duct supports shall
not lessen the fire protections of structural members. Ducts shall be braced and
guyed to prevent lateral or horizontal swing.

(c) Hangers shall have sufficient strength and durability to properly and safely support
the duct work. Hangers shall have sufficient resistance to the corrosive effect of the
atmosphere to which they will be exposed. Hangers shall not be used in direct
contact with a dissimilar metal that would cause galvanic action in the hanger, duct,
fastenings, or structure.

(d) Ducts shall not be hung from or supported by suspended ceilings.

(e) Metal ducts shall not usually be installed within 100 mm of the ground. Metal ducts
not having an approved protective coating, when installed in or under concrete slab
shall be encased in at least 50 mm of concrete. Metallic ducts having an approved
protective coating and nonmetallic ducts shall be installed in accordance with the
manufacturer's installation instructions.

(f) When ducts penetrate any masonry wall, it shall either be lined with felt to isolate it
from the masonry, or an air gap shall be left around it.

(g) All underground ducts located in a flood hazard zone shall be capable of resisting
hydrostatic and hydrodynamic loads and stresses, including the effects of buoyancy,
during the occurrence of flooding to the base flood elevation.

(h) Ducts installed in locations where they are subject to mechanical damage by vehicles
or from other causes shall be protected by approved barriers.

2.8.1.7 Fire damper

(a) Fire dampers shall be provided at locations where air distribution systems penetrate
assemblies that are required to be fire resistance rated by this Code.
4656 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Exceptions:

(i) Fire dampers are not required in the following cases:

(ii) Where an exhaust duct penetrates a fire resistance rated shaft wall and the sub-
duct extends not less than 560 mm vertically upward.

(iii) At penetrations of tenant separation and corridor walls in buildings equipped

throughout with an automatic sprinkler system installed in accordance with the
Code.

(iv) Where the ducts are constructed of steel and are part of an engineered smoke
removal system.

(v) At penetration of corridor walls where the ducts are constructed of steel and do
not have openings which communicate the corridor with adjacent spaces or
rooms.

(vi) At penetrations of a roof assembly where ducts are open to the atmosphere.

(vii) In hazardous exhaust systems.

(viii) Where ceiling dampers are installed in accordance with the building code.

(ix) In garage exhaust or supply shafts which are separated from all other building
shafts by not less than 2-hour fire resistance rated fire separation assembly.

(x) In ducted air-conditioning, heating and ventilation systems penetrating walls

with a 1 hour fire resistance rating or less. Where fire dampers will interfere
with the operation of the smoke control system, approved alternative
protective devices shall be utilized.

(b) Fire dampers shall comply with UL555 and bear the label of an approved agency.
Fire dampers shall be installed in accordance with the manufacturing installation
instructions.

(c) Fire dampers shall be accessible. Suitable openings with tightly fitted covers shall be
provided to make fire dampers accessible for inspection and this shall be large
enough to permit maintenance and resetting of the damper.

(d) Ductwork shall be connected to fire damper sleeves or assemblies in such a way that
collapse of the ductwork will not dislodge the damper.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4657

2.8.1.8 Automatic shutoff

(a) Each single air distribution system providing air-conditioning, heating or ventilation
air in excess of 1000 l/s in various occupancies, shown below, shall be equipped with
an automatic shutoff provision activated by smoke detectors. When the system
serves more than one occupancy, automatic shutoff must be provided.

Type of Subdivision Type of Subdivision

Occupancy Occupancy

A A5 G G2
B All (B1, B2 & B3) H H2
C All (C1, C2, C3, C4 & C5) I I1, I2, & I3
D All (D1 & D2) J All (J1, J2, J3 & J4)
E E1 & E3 L L
F F1 & F2

Exceptions:
(i) Automatic shutoff need not be installed when all rooms have direct exit to the
exterior of the building.
(ii) Automatic shutoff need not be installed in systems specifically designed for
smoke control.
(b) Smoke Detection: Smoke detectors required by Sec 2.5.1.8 shall be installed in the
main return-air duct ahead of any outside air inlet or they may be installed in each
room or space served by the return air duct. Detectors shall also be installed in the
supply duct, downstream of the filters. Activation of any detector shall cause the air
moving equipment to automatically shut down.
2.8.2 Air Terminals
2.8.2.1 Registers, grilles and diffusers
Supply air registers, grilles and diffusers; and return air grills shall be installed in
accordance with the manufacturer's installation instructions. Selection and installation of
registers, grilles and diffusers shall comply with the requirements of air distribution
system.
2.8.2.2 Ventilating ceilings
Perforated ceilings may be used for air supply except in exit corridors which are required
to be of fire resistive construction. Ceiling material shall be of Class-I flame spread
classification on both sides in accordance with requirements of this Code. All wiring shall
be in enclosures regardless of the voltage carried. Suspended ventilating ceiling supports
shall be of non-combustible materials.
4658 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

2.8.2.3 Visual duct openings

Duct openings in bathrooms, toilets and changing rooms shall prevent visual observation
from adjoining rooms.
2.8.2.4 Capped opening
All duct openings shall be capped during construction.
2.8.2.5 Return air intake and outside air intake
Return air and outside air intake openings shall be located in accordance with the
requirements of Sec 2.6.2.7.
2.8.2.6 Exhaust openings
Outside exhaust openings shall be located so as not to create nuisance. Exhaust air shall
not be directed onto walkways.
2.8.2.7 Opening protection
Outside air intake and exhaust openings shall be protected with corrosion-resistant
screens, louvers or grilles. Openings shall be protected against all local weather
conditions. Exhaust openings shall have provision to prevent back draft under wind
conditions.
2.8.3 Exhaust Air Systems
2.8.3.1 General
(a) Exhaust air systems serving kitchens or toilets and/or bathrooms shall be
independent exhaust systems and shall not be combined with exhaust air ducts
serving other areas, except at immediately before the point of final delivery to the
outside, such as at the base of a roof ventilator or when all interconnected systems
are equipped with suitable back pressure devices to prevent passage of odours from
one system to another when the fan is not in operation.
(b) Exhaust ducts shall have provision for removal of condensates where this may be a
problem, such as for swimming pools and shower exhausts and for these applications
duct joints shall be water tight.

(c) Construction and installation of exhaust air ducts for toilet, bathrooms and
swimming pools shall be in accordance with the provisions of Sec 2.5.1.
(d) Design, construction and installation of exhaust air systems for exhaust of harmful
and hazardous gases and industrial/process exhaust gases shall be in accordance with
the provisions of Sec 2.8.4.
(e) Design, construction and installation of kitchen exhaust system shall be in
accordance with the provisions of Sec 2.8.5.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4659

2.9 Air-Conditioning Equipment

2.9.1 General
2.9.1.1 Scope
Air-conditioning, heating and ventilation equipment shall conform to the requirements of
this Code.
Equipment shall not be installed or altered in violation of this Code. Defective materials
or parts shall be replaced in such a manner as not to invalidate any approval.
2.9.1.2 Approval
When required each appliance shall be approved by the building official for safe use or
comply with applicable nationally recognized standard. For this purpose installers shall
furnish satisfactory evidence that the appliance is constructed in conformity with the
requirements of this Code. The permanently attached label of an approved agency may be
accepted as such evidence.
2.9.1.3 Labeling
All mechanical equipment and appliances shall bear permanent and legible factory
applied name plate on which shall appear construction and operation data including
safety requirements.
2.9.1.4 Testing
Where required an approved agency shall test a representative sample of the mechanical
equipment or appliance being labeled to the standard or standards pertinent to the
equipment or appliance. The approved agency shall maintain a record of all tests
performed. The records shall provide sufficient detail to verify compliance with the test
standard.
2.9.1.5 Equipment installation
(a) General: Mechanical equipment and appliances shall be installed in accordance with
the manufacturer's installation instructions for the labeled equipment. Connections to
mechanical equipment or appliances, such as fuel supply, electrical, hydronic piping,
vent and ducts shall conform to the requirements of this Code.
(b) Clearance: Appliances shall be installed with the minimum clearances to
combustibles for which the appliance has been tested as specified by the
manufacturer.
(c) Anchorage of Appliances: Appliances designed to be fixed in position shall be
securely fastened in position. Supports for appliances shall be designed and
constructed to sustain vertical and horizontal loads within the stress limitations
specified in the Code.
4660 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(d) Noise and Vibration: Equipment noise and vibration transmitted to the occupied
space shall not exceed the recommended value for the space. Selection and
installation of equipment shall be in accordance with Sec 2.4.3.

(e) Identification of Equipment: When more than one air-conditioning, heating,

refrigerating or ventilation systems are installed on the roof of a building or within
the building, each equipment shall be identified as to the area or space served by the
equipment.

2.9.1.6 Access

All mechanical equipment and appliances shall be accessible for inspection, service,
repair and replacement without removing permanent construction. Unless otherwise
specified not less than 750 mm of working space and platform shall be provided to
service the equipment or appliance.

Appliance controls, gauges, filters, blowers, motors and burners shall be accessible. The
operating instructions shall be clearly displayed near the appliance where they can be
read easily.

2.9.1.7 Location

(a) Remote Location: Where an appliance is located in a remote location, a walkway

having a minimum width of 600 mm shall be provided, leading from the access
opening to the appliance.

(b) Hazardous Location: Appliances installed in garages, warehouses, or other areas

where they may be subject to mechanical damage shall be installed behind suitable
protective barriers or at a suitable height above the floor or located out of the normal
path of vehicles to guard against such damages.

Air-conditioning or heating equipment located in a garage and which generates a

glow, spark or flame capable of igniting flammable vapours shall be installed in such
a way that the pilots and burners or heating elements and switches are at least 450
mm above the floor level.

Where such appliances installed within a garage are enclosed in a separate approved
compartment having access only from outside of the garage such appliances may be
installed at floor level, provided the required combustion air is taken from and
discharged to the exterior of the garage.

Heating equipment located in rooms where cellulose nitrate plastic or other explosive
materials are stored or processed shall comply with the requirements of Part 4 of this
Code.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4661

(c) Outdoor Installation: Mechanical equipment and appliance located outdoors shall be
approved for outdoor installation. Mechanical equipment and appliances installed
outdoors shall conform to the requirements of Sec 2.6.1.5.

Where appliances are located within 3 m of a roof edge or open side of a drop greater
than 600 mm, guards shall be provided. Height of the guard shall be a minimum of
900 mm and a maximum of 1050 mm above the surface.

Equipment that are located outdoors and may be adversely affected by sun and/or
water shall be adequately protected. Access shall be possible under all weather
conditions. All outdoor installed equipment shall be so located that the sound level
shall not be more than 65 dB when measured anywhere on the property boundary
line.

2.9.1.8 Electrical installations

(a) Equipment regulated by this Code requiring electrical connections of more than 50
volts shall have a positive means of disconnect adjacent to and in sight from the
equipment served. A 230 volt AC grounding type receptacle shall be located within 8
m of the equipment for service and maintenance purposes. The receptacle need not
be located on the same level as the equipment. Low voltage wiring of 50 volts or less
within a structure shall be installed in a manner to prevent physical damage.

(b) Permanent lighting shall be provided to illuminate the area in which an appliance is
located. For remote locations, the light switch shall be located near the access
opening leading to the appliance.

Exceptions:

Lighting fixtures need not be installed when the fixed lighting for the building will
provide sufficient light for safe servicing of the equipment.

2.9.1.9 Condensate wastes

Condensates from air cooling coils, fuel burning condensing appliances and the overflow
from evaporative coolers and similar water supplied equipment shall be collected and
discharged to an approved plumbing fixture and disposal area. The waste pipe shall have
a slope of not less than 1 in 100 and shall be of approved corrosion resistant material and
approved size. Condensate or waste water shall not drain over a public way.

2.9.1.10 Personnel Protection

A suitable and substantial metal guard shall be provided around exposed flywheels, fans,
pulleys, belts and moving machinery which are portions of air-conditioning, heating and
ventilation system.
4662 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

2.9.2 Cooling by Refrigeration

2.9.2.1 General

(a) Scope: Every air cooling system and equipment using refrigerant coils, chilled water
coils and brine coils shall conform to the requirements of this Section and to the
applicable requirements of Sections 2.6.1 and 2.7.

(b) Use of Group 2 Refrigerants: Direct refrigerant systems containing Group

2 refrigerants shall not serve an air-cooling or air-conditioning system used for
human comfort.

2.9.2.2 Installation

(a) Clearance from Ground: When cooling equipment other than ducts and piping is
suspended from the under floor construction, a clearance of at least 150 mm shall be
provided between the base of the equipment and the ground.

(b) Exterior Wall Installation: All equipment mounted on exterior wall at a height of 6 m
or more above the ground shall be provided on a platform not less than 750 mm in
depth, with 1 m high handrails on operation and control side of the equipment. The
platform shall be accessible through catwalk not less than 450 mm wide and handrail
of 1 m high from inside the building or from roof access.

Exceptions:

Equipment located on exterior wall but removable from inside may not require
platform and catwalk.
2.9.2.3 Access
(a) Cooling Units: Except for piping, ducts and similar equipment that does not require
servicing or adjusting, an unobstructed access and passageway not less than 600 mm
in width and 2 m in height shall be provided to every cooling unit installed inside
buildings.
Exception:
The access opening to a cooling unit located in an attic space may be reduced to 750
mm in length and width, provided the unit can be replaced from this opening or
another opening into this space or area.
(b) Attic or Furred Space Installation: Access to and working platforms for cooling units
or cooling system compressors located in an attic or furred space shall be provided
with a solid continuous flooring not less than 600 mm in width from the access
opening to the required working space and platform in front of the equipment when
access opening is located more than 1 m away from working space.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4663

(c) Filters, Fuel Valves and Air Handlers: An unobstructed access space not less than
600 mm in width and 750 mm in height shall be provided to filters, fuel control
valves and air handling units. Refrigerant, chilled water and brine piping control
valves shall be accessible.

Exception:

An access opening from the unobstructed access space which opens directly to such
equipment may be reduced to 375 mm in the least dimension if the equipment can be
serviced, repaired and replaced from this opening without removing permanent
construction.

(d) Refrigeration Machinery Room Installations: Access to equipment located in a

refrigeration machinery room shall comply with Sec 2.7.

(e) Roof or Exterior Wall Installation

(i) Equipment installed on the roof or on an exterior wall shall be accessible under
all weather conditions. A portable ladder or other portable temporary means may
be used for access to equipment located on the roof, or on exterior wall of a
single-storey portion of the building.

(ii) Platform: When the roof has a slope greater than 4 in 12 a level working
platform at least 750 mm in depth shall be provided along the control or
servicing sides of the unit. Sides of a working platform facing the roof edge
below shall be protected by a substantial railing of minimum 1 m in height with
vertical rails not more than 525 mm apart, except that parapets at least 600 mm
in height may be utilized in lieu of rails or guards.

(iii) Catwalk: On roofs having slopes greater than 4 in 12, a catwalk at least 400 mm
in width with substantial cleats spaced not more than 400 mm apart shall be
provided from the roof access to the working platform at the appliance.

2.9.2.4 Working space

Equipment requiring access thereto, as specified in Sec 2.6.2.3, shall be provided with an
unobstructed space on the control or servicing side of the equipment of not less than 750
mm in depth and 2 m in height. Working space for equipment located in a machinery
room shall comply with Sec 2.7.

Exception:

The height of the working space may be reduced to 750 mm for an air handling unit, air
filter or refrigerant, chilled water piping and brine piping control valves.
4664 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
2.9.2.5 Lighting in concealed spaces
When access is required to equipment located in an under floor space, attic or furred
space, a permanent electric light outlet and lighting fixture shall be installed in
accordance with Sec 2.6.1.8.
2.9.2.6 Condensate control
When a cooling coil or cooling unit is located in the attic or furred space where damage
may result from condensate overflow, an additional water tight pan of corrosion resistant
metal shall be installed beneath the cooling coil or unit to catch the overflow condensate
due to clogged primary condensate drain, or one pan with a standing overflow and a
separate secondary drain may be provided in lieu of the secondary drain pan. The
additional pan or the standing overflow shall be provided with a drain pipe, minimum 19
mm nominal pipe size, discharging at a point which can be readily observed. This
requirement is in addition to the requirements for condensate waste piping set forth in
Sec 2.6.1.9.
2.9.2.7 Return air and outside air
(a) Source: A cooling unit shall be provided with outside air, return air, or both. Cooling
systems regulated by this Code and designed to replace required ventilation shall be
arranged to deliver into the conditioned space not less than the amount of outside air
specified in Building Code.
(b) Prohibited Sources: The outside air or return air for a cooling system or cooling unit
shall not be taken from the following locations:
(i) Closer than 3 m from an appliance vent outlet, a vent opening or a plumbing
drainage system or the discharge outlet of an exhaust fan, unless the outlet is 1
m above the outside air inlet.
(ii) Where it will pick up objectionable odours, fumes or flammable vapours; or
where it is less than 3 m above the surface of any abutting public way or
driveway; or where it is in a horizontal position in a sidewalk, street, alley or
driveway.
(iii) A hazardous or insanitary location or a refrigeration machinery room;
(iv) An area the volume of which is less than 25 percent of the entire volume served
by such system, unless there is a permanent opening to an area the volume of
which is equal to 25 percent of the entire volume served.
(v) A room or space having any fuel burning appliances therein, except when 75
percent of the conditioned air is discharged back into the same room or space
and air inlets are not located within 3 m of firebox or draft diverter of fuel
burning appliance and the room has a volume exceeding 1 m3 for each 100 watts
fuel input rate of all fuel burning appliance therein.
(vi) A closet, bathroom, toilet or kitchen.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4665

(c) Return Air Limitation: Return air from one dwelling unit shall not be discharged into
another dwelling unit through the cooling system.

2.9.2.8 Air velocity

Cooling systems shall be designed and constructed so that velocity through filters does
not exceed the filter manufacturer's recommendation.

2.9.2.9 Screen

Required outside air inlets shall be covered with screen having 6 mm openings.

Exception:

An outside air inlet serving a nonresidential portion of a building may be covered with
screen having opening larger than 6 mm but not larger than 25 mm.

2.9.2.10 Duct system

If ducts are required for circulation of air, the duct system shall be constructed and
installed in accordance with Sec 2.5.1. Selection and installation of registers, diffusers
and grilles shall conform to the requirements of Sec 2.5.2.

2.9.3 Evaporative Cooling

2.9.3.1 General

(a) Scope: Where possible evaporative cooling system may be installed. Evaporative
cooling systems shall comply with this Section.

(b) Outside Air: Evaporative cooling system shall be provided with outside air as
specified in Sec 2.6.2.7

(c) Air Ducts: Air duct systems for evaporative cooling shall comply with Sec 2.5.1.

2.9.3.2 Location

Evaporative cooler shall normally be installed outdoor. It may be installed indoor if duct
is provided between cooler and outside air intake.

Evaporative cooling systems shall be installed in a manner to minimize the probability of

damage from an external source.

2.9.3.3 Access

Evaporative coolers shall be accessible for inspection, service and replacement without
removing permanent construction.
4666 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

2.9.3.4 Installation

An evaporative cooler supported by the building structure shall be installed on a

substantial level base and shall be secured directly or indirectly to the building structure
by suitable means to prevent displacement of the cooler.

An evaporative cooler supported directly by the ground shall rest on a level concrete slab.
The upper surface of the concrete slab shall not be less than 75 mm above the adjoining
ground level.

An evaporative cooler supported on an above ground platform shall be elevated at least

150 mm above the adjoining ground level.

Openings in the exterior walls shall be flushed in an approved manner in accordance with
this Code.
2.9.4 Heating Equipment
2.9.4.1 General
(a) Scope: Provisions of this Section shall apply to all electric, hot water or steam air
heating systems.
(b) Outside Air: Heating system shall be provided with outside air as specified in
Sec 2.6.2.7.
(c) Air Ducts: Air ducts for heating systems shall comply with the applicable provisions
of Sec 2.5.1.
2.9.4.2 Location
(a) Steam shall not be used in heating coil of air handling unit when it is located inside
the building but not installed in a machinery room.
(b) All fuel burning equipment such as boilers shall not be installed inside a building and
shall be installed inside a machinery room.
(c) Appliances generating a glow, spark or flame capable of igniting flammable vapours
shall not be located in places where such vapours exist.
2.9.4.3 Access
All appliances shall be accessible for inspection, services, repair and replacement without
removing permanent construction. On control and servicing side(s) of the appliance, an
unobstructed working space of not less than 750 mm in width and 1250 mm in height
shall be provided.
2.9.4.4 Installation
All heating appliances shall be installed as per applicable provisions of Sec 2.6.1.5.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4667

2.9.4.5 Controls

(a) In case of air-conditioning plants where heating or reheating is required, a safety

device shall be incorporated in the installation to cut off automatically the source of
heating, such as steam, hot water or electricity by means of a suitable thermostat or
some other device, as soon as the temperature of the room reaches a predetermined
high level not exceeding 44oC, unless a higher temperature is required for an
industrial process carried out in the air-conditioned enclosure. In no case the outlet
temperature of the heater shall exceed 90oC.
(b) In the case of air-conditioning plants where heating or reheating by means of an
electrical heater designed to operate in an air current is done, the system shall be
equipped with a safety device to cut off the electricity to the heating device
whenever there is failure of the air flow in which the heater is required to operate.

The surface temperature of all electrical heaters used in air-conditioning systems

shall be limited preferably to 400oC, and in no case more than 538oC when measured
in still air.

2.9.4.6 Boilers and Furnaces

(a) Steam and hot water boilers and furnaces used for air-conditioning systems shall be
designed, constructed and installed in conformance with the requirements of
acceptable standards in this regard and the appropriate Boiler Code.

(b) Boilers and furnaces shall be installed in a machinery room having:

(i) A sufficiently large floor area to permit accessibility for inspection and servicing
of the appliance and to provide adequate clearance to satisfy requirements of fire
safety. The volume of the room for housing central heating furnaces shall be at
least 12 times the total volume of the furnace. The volume of the room for
housing central heating boilers shall be at least 16 times the total volume of the
boiler. If the ceiling height of the room or space is greater than 2.5 m, the
volume shall be calculated on the basis of 2.5 m height.
(ii) A permanent opening or opening connecting with the outdoors or with some
space that freely connects with outdoors,
(iii) A knockout panel to act as explosion relief panel to prevent damage to structure
in case of any explosion in boiler rooms,
(iv) Boiler rooms and furnace rooms shall be protected with an automatic fire
suppression system installed in accordance with the Code.
(c) Before commissioning of the boiler a certificate of compliance from the Chief
Inspector of Boiler shall be obtained.
4668 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

2.9.5 Air Handling Unit

2.9.5.1 General

Air handling units shall comply with the applicable requirements as set forth in
Sections 2.6.1 and 2.6.2.

2.9.5.2 Location

Air handling unit rooms shall, as far as possible, be centrally located with the equipment
room contiguous to the corridors or other spaces for running of air ducts.

Air handling unit rooms shall be located in areas where reasonable sound levels can be
tolerated. Air handling unit rooms shall not preferably be located adjacent to conference
rooms, sound recording studios, broadcasting studios, bed rooms and other acoustically
sensitive areas. If it is absolutely necessary to locate air handling unit room adjacent to
the above acoustically sensitive areas, adequate acoustic treatment in the air handling
units, supply and return air ducts, air handling unit rooms shall be provided. In such case,
the access door to the air handling unit room shall be of single leaf type properly
acoustically treated and shall have a door sill. The door shall open outwards.

In case of multi-storied buildings and for large capacity plant, independent air handling
unit room(s) shall be provided for each floor when design calls for the same. The area
served by each air handling unit shall conform to the fire protection measures adopted.

2.9.5.3 Access

Floor area of the air handling unit room shall be sufficient to allow proper layout of
equipment with adequate access space and working space for proper operation and
maintenance.

2.9.5.4 Installation

Air handling units shall be installed on vibration isolators to restrict transmission of

vibration to the building structure. The base of the air handling unit shall be minimum 75
mm above the adjoining floor level. All air handling unit rooms shall have properly
installed floor drains.

2.9.6 Packaged Air-conditioners

2.9.6.1 General

Packaged air-conditioners shall comply with the applicable requirements set forth in
Sections 2.6.1 and 2.6.2.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4669

2.9.6.2 Prohibited use

Packaged air-conditioners shall not be used for,
(a) Operation theatres where provisions for high percentage of fresh air and high quality
filtration of air are required.
(b) Special applications like sterile rooms for hospitals and clean rooms where high
efficiency filtration is required.
(c) Sound recording studios and other areas where criteria for acoustics are stringent.
Exceptions:
Single package units when installed far away from the air-conditioned space and are
provided with properly designed sound attenuators that maintains the desired sound
level inside the conditioned space.
(d) Area requiring close and independent control of temperature and relative humidity.
Exception: Computer room air-conditioning.
(e) Internal zones where no exposed wall is available for installation of room air-
conditioners or no external platform is available for installation of outdoor installed
unit.
(f) The width of the area is such that throw of air from the air-conditioner cannot cover
the required area.
2.9.6.3 Installation
(a) Wall punches for room air-conditioners shall have proper sealing and resilient pad
around the body of the unit to avoid leakage of air and vibration transmission.
(b) Outdoor units shall be installed keeping adequate space for condenser air flow. The
discharge of condenser air shall not create any disturbance to the adjacent rooms or
buildings.
(c) Refrigerant pipes and condensate drain pipes shall be properly installed and shall
have proper insulation to avoid condensation on pipes. Indoor installations shall
comply with the requirements of Sec 2.9.2.6.
2.9.7 Accessory Equipment

2.9.7.1 Air curtain

(a) Where Required: In super markets, departmental stores, commercial buildings and
other applications where the continuous movement of people and/or equipment
through the door requires that the door be remained open continuously, adequately
sized air curtains may be used to restrict entry of unconditioned air to conditioned
space.
4670 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(b) Installation: Air curtains shall be installed in such a way as to cover the whole width
of the door. The width and velocity of air jet shall be sufficient to restrict the entry of
unconditioned air to the conditioned space. The unit shall have provisions to control
the jet velocity with respect to pressure and velocity of air in the unconditioned
space.
2.9.7.2 Air filters
(a) Air supplied to any space for cooling, heating or ventilation shall be adequately
filtered before its point of discharge into the space. Minimum filtration efficiency
shall be in accordance with good engineering practice for the space served, as
recommended in ASHRAE Handbook.
(b) Access: Adequate access to facilitate servicing of filters shall be provided. Doors,
ladders, electric lighting etc. shall be provided where necessary. A device for
indicating differential pressure across the filter bank shall preferably be fitted to
determine the need for filter change.
(c) Electrostatic Filters: Electrostatic filters when used shall be electrically interlocked
so that power supply is disconnected when access door is opened.
2.9.8 Piping System
2.9.8.1 Material
Piping material for air-conditioning, heating and ventilation system shall be metallic
only.
Exception: Condensate drain and waste water drain piping for cooling units may be
nonmetallic.
2.9.8.2 Support and anchors
Adequately designed piping supports shall be used at approved space intervals to prevent
undue stress on the pipe and building structure. Piping shall also be adequately anchored.
Pipes shall not be supported or hanged from another pipe.

2.9.8.3 Expansion and contraction

Piping shall be installed with provisions to take care of expansion and contraction of the
piping because of temperature changes of the fluid it conveys.

2.9.8.4 Pipe covering

(a) All pipes likely to achieve a surface temperature during normal operation exceeding
70oC and are exposed to human contact or surface temperature lower than the dew
point temperature of the surrounding air, shall be insulated with approved material
suitable for the operating temperature of the system. The insulating material and its
thickness shall be as recommended in ASHRAE Handbook.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4671

(b) Insulation and covering on pipes in which the temperature of the fluid exceeds
120oC:
(i) Shall be of noncombustible material.
(ii) Shall not produce flame and smoke, glow or smoulder when tested in
accordance with the latest standard in this regard at the maximum temperature to
which such insulation or covering is to be exposed in service.
Combustible insulation and covering shall have a flame spread rating throughout the
material, not exceeding 25 units in buildings of noncombustible construction, when
pipes run in a horizontal or vertical service space. When pipes run in a room or space
other than service space, the pipe covering shall have a flame spread rating not
exceeding that required for the interior finish of the ceiling of the room or space.
Exception:
Pipe coverings may have a flame spread rating more than 25 and smoke developed
index more than 100 when pipes are enclosed within walls, floor slabs or non-
combustible raceways or conduits.
2.9.8.5 Steam or hot water bare pipes passing through a storage space shall be protected
to prevent direct contact between the surface of pipe and the material stored.
Bare pipes containing steam or fluid at temperature above 120oC and passing through a
combustible floor, ceiling or wall shall have a sleeve of metal at least 50 mm larger in
diameter than pipe, packed with noncombustible material.
Minimum clearance between bare pipe and combustible materials shall not be less than
15 mm when temperature of steam or water in the pipe does not exceed 120oC and shall
not be less than 25 mm for temperatures exceeding 120oC.
2.9.8.6 All piping shall be marked with approved makings for type of fluid carrying
with direction of flow.

2.9.9 Split Air-Conditioners

2.9.9.1 General
Split air-conditioners shall comply with the applicable requirements set forth in
Sections 2.6.1 and 2.6.2.
2.9.9.2 Prohibited Use
Split air-conditioners shall not be used for,
(a) Operation theatres where provisions for high percentage of fresh air and high quality
filtration of air are required.
(b) Special applications like sterile rooms for hospitals and clean rooms where high
efficiency filtration is required.
(c) Sound recording studios and other areas where criteria for acoustics are stringent.
4672 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Exceptions:

Split air conditioners when installed far away from the air-conditioned space and are
provided with properly designed sound attenuators which can maintain the desired
sound level inside the conditioned space.

(d) Area requiring close and independent control of temperature and relative humidity.

Exception: Computer room air-conditioning.

(e) Internal zones where no exposed wall is available for installation of room air-
conditioners or no external platform is available for installation of outdoor installed
unit.

(f) The width of the area is such that throw of air from the air-conditioner cannot cover
the required area.
2.9.9.3 Installation

(a) Wall punches for room air-conditioners shall have proper sealing and resilient pad
around the body of the unit to avoid leakage of air and vibration transmission.
(b) Outdoor units shall be installed keeping adequate space for condenser air flow. The
discharge of condenser air shall not create any disturbance to the adjacent rooms or
buildings.

(c) Refrigerant pipes and condensate drain pipes shall be properly installed and shall
have proper insulation to avoid condensation on pipes. Indoor installations shall
comply with the requirements of Sec 2.9.2.6.

2.9.10 Variable Refrigerant Flow (VRF) System

2.9.10.1 General

Variable refrigerant flow (VRF) air-conditioning system shall comply with the applicable
requirements set forth in Sections 2.6.1 and 2.6.2.

2.9.10.2 Prohibited Use

VRF system shall not be used for,

(a) Operation theatres where provisions for high percentage of fresh air and high quality
filtration of air are required.

(b) Special applications like sterile rooms for hospitals and clean rooms where high
efficiency filtration is required.

(c) Sound recording studios and other areas where criteria for acoustics are stringent.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4673

Exceptions:
VRF system when installed far away from the air-conditioned space and are
provided with properly designed sound attenuators that maintains the desired sound
level inside the conditioned space.
(d) Area requiring close and independent control of temperature and relative humidity.
2.9.10.3 Installation
(a) Wall punches for room air-conditioners shall have proper sealing and resilient pad
around the body of the unit to avoid leakage of air and vibration transmission.
(b) Outdoor units shall be installed keeping adequate space for condenser air flow. The
discharge of condenser air shall not create any disturbance to the adjacent rooms or
buildings.
(c) Refrigerant pipes and condensate drain pipes shall be properly installed and shall
have proper insulation to avoid condensation on pipes. Indoor installations shall
comply with the requirements of Sec 2.9.2.6.

2.10 Refrigerating Equipment

2.10.1 General
2.10.1.1 Scope
In addition to other provisions of this Code, refrigerating systems and equipment shall
conform to the requirements of this Section.
2.10.1.2 Approval
All refrigerating equipment and components shall comply with relevant internationally
recognized Standards. The listing and label, attached to the equipment, of an approved
agency may be accepted as evidence of compliance with applicable internationally
recognized Standards.
2.10.1.3 Installation
Refrigerating equipment shall be installed to conform to the provisions of Sec 2.6.1 and
the manufacturer's installation instructions.
2.10.1.4 Access
Access for refrigerating units shall be provided as for cooling units and cooling systems
set forth in Sections 2.6.1.6 and 2.6.2.3.
2.10.1.5 Working space and working platform
Working space and working platform shall be provided as for cooling units and cooling
systems set forth in Sec 2.6.2.4.
4674 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

2.10.1.6 Prohibited location

Refrigerating systems and portion thereof shall not be located in an elevator shaft, dumb
waiter shaft or a shaft having moving objects therein, or in a location where it will be
subject to mechanical damage.

2.10.1.7 Condensate control

Piping and fittings which convey refrigerant, brine, chilled water or coolant, which
generally reach a surface temperature below the dew point of the surrounding air and
which are located in spaces or areas where condensation could cause a hazard to the
building occupants, structure, electrical or other equipment shall be insulated to prevent
such damage.

2.10.2 Absorption Refrigerating Equipment

2.10.2.1 Location

Fuel burning absorption systems shall not be installed in the following locations:

(a) In any room or space less than 300 mm wider than the units installed therein, with a
minimum clear working space of not less than 75 mm along the sides, back and top
of the unit.

(b) In a hazardous location.

(c) In a surgical operating room or medical treatment room.

(d) In any occupancy group unless separated from the rest of the building by not less
than a one hour fire resistive occupancy separation.

Exceptions:

A separation shall not be required for equipment serving only one dwelling unit.

(e) In a room used or designed to be used as a bedroom, bathroom, closet or in any

enclosed space with access only through such room or space.
(f) In a room from where noise and vibration may be transmitted to acoustically
sensitive areas.

Absorption systems containing Group 2 refrigerants shall not be located in any building
unless installed within a refrigeration machinery room provided as per Sec 2.7.3.3.

Absorption systems containing more than 9 kg of a Group 2 refrigerant shall be located

not less than 6 m from any door, window or ventilating air inlet to a building.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4675

2.10.2.2 Installation

Fuel burning absorption systems located outside of a building shall be completely

enclosed in a weather proof housing of approved materials, unless approved for outdoor
installation. The housing shall not be larger than necessary to properly cover and provide
a minimum 150 mm clearance around the unit or units enclosed therein, including all
controls and draft diverters.

An absorption system supported from the ground shall rest on a concrete slab. The upper
surface of the concrete slab shall be at least 75 mm above the adjoining ground level.

2.10.2.3 Pressure relief devices

An absorption system shall be equipped with a factory installed pressure relief device,
either a fusible plug, a rupture member or a pressure relief valve.

2.10.2.4 Combustion air

A fuel burning absorption system shall be provided with adequate combustion air
including venting appliances.

2.10.2.5 Steam or hot water absorption system

All absorption systems using steam or hot water as energy source shall be installed in a
machinery room unless the manufacturer has certified it suitable for outdoor installation.
The machinery room shall comply with the provisions of Sec 2.7.3.3.

2.10.3 Mechanical Refrigerating Equipment

2.10.3.1 General

(a) Scope: Mechanical refrigerating equipment shall comply with the provisions of
Sec 2.7.1.

Refrigerating systems and equipment, including the replacement of parts and

alteration, shall comply with the provisions of this Section.

(b) Supports: Supports for compressors, condensing units and chillers shall be designed
to safely carry the equipment. Supports from buildings or parts of buildings that are
of noncombustible construction shall be noncombustible.

A compressor or portion of condensing unit supported from the ground shall rest on
a concrete or other approved base. The upper surface of the concrete base shall be at
least 75 mm above the adjoining ground level.
4676 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(c) Ventilation of Rooms Containing Condensing Units: Rooms or spaces other than a
refrigeration machinery room complying with the requirements of this Section, in
which any refrigerant containing portion of a condensing unit is located, shall be
provided with one of the following means of ventilation:

(i) Permanent gravity ventilation openings of not less than 0.2 m2 net free area
opening directly to the outside of the building or extending to the outside of the
building by continuous ducts,

(ii) A mechanical exhaust system arranged to provide at least 3 complete air change
per hour and to discharge to the outside of the building.

Exception:

Mechanical exhaust system shall not be required if the room or space has a
volume exceeding 40 m3 per kW of the unit or where such room or space has
permanent gravity ventilation openings of 0.2 m2 minimum total area to the
other rooms or spaces exceeding 40 m3 per kW.

(d) Compressor Near Exits: Refrigerant compressors of more than 4 kW rating shall be
located at least 3 m from an exit unless separated by a one hour fire resistive
occupancy separation.

2.10.3.2 Refrigerants

(a) Classification: Refrigerants listed in Tables 8.2.4 and 8.2.5 or other refrigerants
equivalent in safety to life, limb, health or property shall only be used in refrigerating
equipment.

Note: Bangladesh is a signatory to the Montreal Protocol which proclaims phasing

out of the use of some refrigerants viewed as responsible for depletion of the ozone
layer and/or causing global warming. If at the time of using this Code, any of the
refrigerants mentioned in Tables 8.2.4 and 8.2.5 is prohibited from use by the
Government, the relevant row or rows of these two tables shall be deemed to be
deleted. Likewise, if any safer substitutes to these refrigerants are available and
permitted by the Government, these shall be included in the list of refrigerants
permitted by this Code. In general, preference shall be given to equipment using
refrigerants having relatively lower Ozone Depletion Potential and Global Warming
Potential.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4677

Table 8.2.4: Group-I Refrigerant Classification, Amount and Occupational

Exposure Limit (OEL)

Refrigerant Name Refrigerant Degrees of Max. Quantity OELe

Designation Classificationf Hazarda in Space
Intended for
Human
Occupancy
(g/m3)

R-11d Trichlorofluoromethane A1 2-0-0b 6.2 1,000

R-12d Dichlorodifluoromethane A1 2-0-0b 90 1,000
d b
R-13 Chlorotrifluoromethane A1 2-0-0 - 1,000
R-13B1d Bromotrifluoromethane A1 2-0-0b - 1,000
b
R-14 Tetrafluoromethane A1 2-0-0 400 1,000
R-22 Chlorodifluoromethane A1 2-0-0b 210 1,000
-
R-32 Difluromethane
(Methylene chloride) A2 77 1,000

R-113 Trichlorotrifluoroethane A1 2-0-0b 20 1,000

R-114 Dichlorotetrafluoroethane A1 2-0-0b 140 1,000
b
R-115 Chloropentafluoroethane A1 2-0-0 760 1,000
R-123 Dichlorotrifluoroethane B1 2-0-0b 57 1,000
b
R-134a Tetrafluoroethane A1 2-0-0 210 1,000
R-407C R-32/125/134a A1 2-0-0b 270 1,000
b
R-500 R-12/152a A1 2-0-0 120 1,000
R-502 R-22/115 A1 2-0-0b 330 1,000
c
R-717 Ammonia B2 3-3-0 0.22 25
R-744 Carbon dioxide A1 2-0-0b 72 5,000

Notes :

a Degrees of hazard are for health, fire, and reactivity, in accordance with NFPA 704.
b Reduction to 1-0-0 is allowed if analysis satisfactory to the code official shows that
the maximum concentration for a rupture or full loss of refrigerant charge would
not exceed the IDLH, considering both the refrigerant quantity and room volume.
c For installations that are entirely outdoors, use 3-1-0.
4678 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

d Class 1 ozone depleting substance; prohibited for new installations.

e Occupational Exposure Limit based on OSHA PEL.
f The capital letter designates the toxicity of the refrigerant at 400 ppm by volume.
The number denotes the flammability of the refrigerant.
Class A: Toxicity not identified
Class B: Evidence of toxicity identified.
Class 1: No flame propagation in air at 65⁰F and 14.7 psia.
Class 2: Lower flammability limit (LML) greater than 0.00625 lb/ft3 at 70⁰F and
14.7 psia and heat of combustion less than 8174 Btu/lb.
Class 3: Highly flammable as defined by LFL less than or equal to 0.00625
lb/ft3 at 70⁰F and 14.7 psia or heat of combustion greater than or equal
to 8174 Btu/lb.

Table 8.2.5: Group 2 Refrigerants

Refrigerant Designation Name

R-40 Methyl chloride

R-611 Methyl format
R-717 Ammonia
R-764 Sulphur dioxide

(b) Group 1 Refrigerants

(i) Direct Systems: The maximum amount of Group 1 refrigerants in direct systems
shall not exceed that set forth in Table 8.2.4.
(ii) Indirect Systems: The amount of Group 1 refrigerants used in indirect systems
shall be unlimited.
(iii) General: Condensing units or combinations of refrigerant interconnected
condensing units totaling 75 kW or more rating which contain a Group 1
refrigerant shall be enclosed in a refrigeration machinery room.
Exception:
The requirement shall not apply when the condensing unit is located outside of a
building or on the roof of a building and not less than 6 m from a door, window or
ventilating air opening in a building or when the condensing unit located in the
building is exclusively used for ice making or cold storage together with the usual
accessory rooms in connection therewith.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4679

(c) Group 2 Refrigerants: A mechanical refrigerating system or unit refrigerating system

containing a Group 2 refrigerant shall not be located within a building unless all
refrigerant containing portions of the system are enclosed in a refrigeration
machinery room. Such system when installed outside of a building shall be located at
least 6 m from an exit door, window or ventilating air inlet in a building.

Exception:

This shall not apply to a building used exclusively for ice making, cold storage or for
the manufacturing or processing of food or drink, provided the occupant load does
not exceed one person per 10 m2 of floor area served by such system. Portions of
refrigerating systems containing Group 2 refrigerants shall not be located in an exit.

Direct refrigeration systems containing Group 2 refrigerants shall not serve an air
cooling or air-conditioning system used for human comfort.

2.10.3.3 Refrigeration machinery room

(a) General: Required refrigeration machinery rooms shall be of at least one hour fire
resistive construction. All doors shall be tight fitting. Every door shall be clearly
labeled "Machinery Room". The room shall have no openings that will permit the
passage of escaping refrigerant to the other parts of the building. There shall be no
direct opening between a refrigeration machinery room containing Group 2
refrigerant and a room or space in which there is an open flame, spark producing
device or heating surface hotter than 426oC. A refrigeration machinery room
containing Group 2 refrigerants shall have at least two means of escape located at
least one-fifth the perimeter of the room apart. Refrigeration machinery rooms
containing Group 1 refrigerant shall have at least one exit door. Size of the exit
door shall be at least 1 m by 2 m.
A refrigeration machinery room door shall open in the direction of escape.
An unobstructed working space of at least 750 mm in width and at least 2100 mm
in height shall be provided around two adjacent sides of all moving machinery in a
refrigeration machinery room.
(b) Refrigeration Machinery Room Ventilation: Refrigeration machinery room shall be
provided with either mechanical or gravity ventilation.
(i) Mechanical exhaust system shall be a separate and individual system of
ventilation serving no other area and shall exhaust air to outdoors at the rate
of 12 air changes per hour. Exhaust air outlet shall not be located within 6m
from any exterior door, window or ventilation air inlet in any building.
Provisions shall be made for makeup air to replace that being exhausted.
Control switch for exhaust system shall be located within the machine room
and shall be readily accessible.
4680 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(ii) Area of gravity ventilation openings to outside of the building shall not be
less than one twentieth of the floor area of the machinery room but shall be
more than 0.65 m2. Approximately one-half of the openings shall be located
within 300 mm of the floor and one half within 300 mm of the ceiling of the
machinery room.
(c) Equipment in a Refrigeration Machinery Room: Combustion air shall not be taken
from a refrigeration machinery room. Electrical equipment, switch or control panel
other than those used exclusively for air-conditioning, heating and ventilation
system shall not be located in a refrigeration machinery room. This provision shall
not apply to electrical lighting fixtures for machinery room and switches thereof.

A readily accessible single emergency refrigeration control switch shall be

provided to shut off all electrically operated machineries in a refrigeration
machinery room, except the exhaust ventilation system complying with Sec 2.7.3.3.
Such switch shall be located outside the machinery room, within a distance of 3 m
from the machinery room exit.

(d) First Aid Facility: Each refrigeration machinery room shall be provided with first
aid boxes. Refrigeration machinery room containing Group 2 refrigerants shall be
provided with two gas masks.

2.10.3.4 Refrigerant piping and equipment

(a) Materials: Materials used in the construction and installation of refrigerating

systems shall be suitable for the refrigerant in the system, and no material or
equipment shall be installed which will deteriorate due to the chemical action of the
refrigerant or the compressor oil, or combination of both.
(b) Erection of Refrigerant Piping: Refrigerant piping and tubing shall be installed in
such a way so as to prevent excessive vibration and strains at joints and
connections. Adequate type of supports shall be used at points as required but not
exceeding 4.5 m apart.
Refrigerant piping and tubing shall be installed in such a way so that it is not
subject to damage from an external source.
Copper tubing containing other than Group 1 refrigerant shall not be located in a
public hallway, lobby or stairway or a building unless enclosed in iron or steel
piping and fittings or in rigid metal conduit.
Iron or steel refrigerant piping placed underground shall be coated with sufficient
asphalt paint or equivalent material to inhibit corrosion.
(c) Refrigerant Containers: A refrigerant receiver or evaporator or condenser shall be
constructed in accordance with approved standards.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4681

(d) Valves and fittings: All valves and fittings shall be of approved type rated for the
maximum operating pressure of the system.

(e) Pressure Limiting Device: A pressure limiting device shall be installed on a

positive displacement refrigerant compressor which is a portion of:

(i) A refrigerating system containing Group 2 refrigerant.

(ii) An air cooled refrigerating system containing Group 1 refrigerant of 7.5 kW

or more rating.

(iii) A water cooled refrigerating system containing Group 1 refrigerant of 2.25

kW or more rating.

A stop or shutoff valve shall not be placed between a pressure limiting device
required by this Section and the compressor it serves.
(f) Pressure Relief Valves: The following compressors of the positive displacement
type shall be equipped with a pressure relief valve:

(i) A compressor of 15 kW or more rating which is a portion of a refrigeration

system containing Group 1 refrigerant and operating at a pressure exceeding
103 kPa in the high pressure side of the system.

(ii) A compressor which is a portion of a refrigerating system containing a Group 2

refrigerant.

A pressure relief valve shall be connected to the refrigerant discharge side of the
compressor it serves, between such compressor and a stop valve. A stop or
shutoff valve shall not be located between a pressure relief valve required by
this Section and the compressor it serves.
A pressure relief valve required by this Section that terminates outside shall
discharge at a location at least 4.5 m above the adjoining ground level and at
least 6 m from a window, ventilating opening or exit from a building.
(g) Pressure Relief Devices for Pressure Vessels: A pressure vessel over 150 mm
diameter which may be shutoff by valves from other parts of the system shall be
equipped with a pressure relief device(s) or rupture member complying with the
requirements of this Code.
(h) Manual Discharge of Group 2 Refrigerant: A refrigerating system located in a
building and containing carbon dioxide or Group 2 refrigerant shall be equipped
with approved means for manual discharge of the refrigerant to the atmosphere.
The discharge pipe shall terminate outside of the building not less than 2 m above
the highest structure on the building and at least 6 m from any window, ventilating
opening or exit from a building.
4682 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

2.10.3.5 Storage of refrigerants

Refrigerants not contained in refrigeration system regulated by the Code shall be stored
in original containers kept in machinery room. The total amount shall not exceed 135 kg.

A portable refrigerant container shall not be connected to the refrigerating system for a
period longer than is necessary to charge or discharge the refrigerating system.

2.10.4 Cooling Tower

2.10.4.1 Location

Cooling Tower shall not be located where warm and humid air discharge from cooling
tower is likely to cause damage to building structure.

2.10.4.2 Installation

Cooling tower located at roof shall meet the requirements of structures as specified in this
Code. Clearances for air suction and discharge shall be maintained in accordance with the
recommendation of the manufacturer of the cooling tower.

Wind speed shall be taken into consideration while designing the foundation/supports for
cooling tower.

Necessary vibration isolators shall be installed to restrict transmission of machine

vibration to the structure.

2.10.4.3 Access

An easy access to cooling tower located at roof shall be provided.

2.10.4.4 Waste water disposal

Cooling towers or evaporative condensers which are equipped with a positive water
discharge to prevent excessive build-up of alkalinity and are used for water cooled
condensing units or absorption units shall discharge the water into an approved disposal
system.

2.10.4.5 Piping connections

Water supply, waste water piping and other piping connections shall comply with the
provisions of the Code.

2.10.4.6 Noise

Cooling tower noise shall not be more than 65 dBA or that approved by the jurisdiction at
the property boundary line. If necessary, the fan cylinder may be covered with acoustic
materials to attenuate noise. Similarly floating type mat may be used to reduce the water
droplet noise.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4683

2.10.4.7 Safety
Cooling tower fan shall be protected by a strong metal screen so that no external object
and/or bird can come in contact with the fan blades.
An electric isolating switch shall be installed, in a locked enclosure, at a suitable location
near the cooling tower to disconnect power to the cooling tower fan when maintenance
works are to be carried out.
Each cooling tower shall be provided with a securely fixed ladder to facilitate
maintenance works.

2.11 Ventilation Systems

2.11.1 General
2.11.1.1 Scope
The provisions of this Section shall govern the ventilation of spaces within a building
intended for human occupancy.
2.11.1.2 Where required
Every space intended for human occupancy shall be provided with ventilation by natural
or mechanical means during the periods when the room or space is occupied.
2.11.2 Natural Ventilation
2.11.2.1 Sources
Natural ventilation of an occupied space shall be through windows, doors, louvers,
skylights or other openings to the outdoor. Such ventilating openings shall open to the
sky or a public street, space, alley, park, highway, yard, court, plaza or other approved
space which comply with the requirements of the building code.
2.11.2.2 Area of ventilating openings
The minimum ventilating opening to the outdoors shall be four percent of the floor area
being ventilated.

(a) Adjoining Spaces: Where rooms and spaces without openings to the outdoors are
ventilated through an adjoining room, the unobstructed opening to the adjoining
rooms shall be at least eight percent of the floor area of the interior room or space,
but not less than 2.33 m2. The ventilation openings to the outdoors shall be based
on the total floor area being ventilated.
(b) Opening below Grade: Openings below grade shall be acceptable for natural
ventilation provided the outside horizontal clear space measured perpendicular to
the opening is one and one-half times the depth below the average adjoining grade.
4684 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

2.11.2.3 Contaminants exhausted

Naturally ventilated spaces having contaminants present shall comply with the
requirements of Sec 2.8.4.

2.11.2.4 LP-gas distribution facilities

LP-gas distribution facilities shall be provided with air inlets and outlets arranged so that
air movement across the floor of the facility will be uniform. The total area of both inlet
and outlet openings shall be at least 0.70 percent of the floor area. The bottom of such
openings shall not be more than 150 mm above the floor.

2.11.3 Mechanical Ventilation

2.11.3.1 Where required

Mechanical ventilation shall be provided in all occupiable rooms or spaces where the
requirements for natural ventilation are not met; in all rooms or spaces, which because of
the nature of their use or occupancy, involve the presence of dust, fumes, gases, vapours,
or other noxious or injurious impurities, or substances which create a fire hazard; where
space temperature is more than 40o C; where relative humidity of inside air is more than
70 percent; where job conditions require ventilation; or where required as per provisions
of this Code.

2.11.3.2 Ventilation system

Mechanical ventilation shall be provided by a method of supply air and return or exhaust
air. The amount of supply air shall be approximately equal to the amount of return and
exhaust air; however, the system shall not be prohibited from producing a negative or
positive pressure. The ventilation system ducts and equipment shall be designed and
installed in accordance with Sec 2.5.

2.11.3.3 Ventilation air quantity

The minimum amount of air circulation rate for ventilation shall be determined based on
the occupant load/space area and use of the building in accordance with Table 8.2.6. The
air circulation rate specified in the Table 8.2.6 shall be equal to the combined total of
outside air and re-circulated air. The occupant load shall be determined in accordance
with the data provided in Table 8.2.3.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4685

Table 8.2.6 Required: Minimum Air Circulation Rate for Mechanical Ventilation of
Non-Air Conditioned Space

SI. Application Air SI. Application Air

No. Change No. Change
per Hour per Hour

1 Assembly rooms 4-8 28 Hospitals-sterilizing 15-25

2 Bakeries 20-30 29 Hospital-wards 6-8

3 Banks/building 4-8 30 Hospital domestic 15-20

societies

4 Bathrooms 6-10 31 Laboratories 6-15

5 Bedrooms 2-4 32 Launderettes 10-15

6 Billiard rooms 6-8 33 Laundries 10-30

7 Boiler rooms 15-30 34 Lavatories 6-15

8 Cafes and coffee bars 10-12 35 Lecture theatres 5-8

9 Canteens 8-12 36 Libraries 3-5

10 Cellars 3-10 37 Living rooms 3-6

11 Churches 1-3 38 Mushroom houses 6-10

12 Cinemas and theatres 10-15 39 Offices 6-10

13 Club rooms 12, Min 40 Paint shops 10-20

(not cellulose)
14 Compressor rooms 10-12
41 Photo and X-ray 10-15
15 Conference rooms 8-12
darkroom
42 Public house bars 12, Min
16 Dairies 8-12 43 Recording control rooms 15-25
17 Dance halls 12, Min 44 Recording studios 10-12
18 Dye works 20-30 45 Restaurants 8-12
19 Electroplating shops 10-12 46 School rooms 5-7
20 Engine rooms 15-30 47 Shops and 8-15
Supermarkets
21 Entrance halls 3-5
48 Shower baths 15-20
4686 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

SI. Application Air SI. Application Air

No. Change No. Change
per Hour per Hour
22 Factories and work 8-10 49 Stores and 3-6
shops Warehouses
23 Foundries 15-30 50 Squash courts 4, Min
24 Garages 6-8a 51 Swimming baths 10-15
25 Glass houses 25-60 52 Toilets 6-10
26 Gymnasium 6, Min 53 Utility rooms 15-20
27 Hair dressing saloon 10-15 54 Welding shops 15-30

Note: The ventilation rates may be increased by 50 percent where heavy smoking
occurs or if the room is below ground.
a
Only outdoor air and no recirculation shall be done.

2.11.3.4 Minimum outdoor air

The minimum amount of the outdoor air shall be in accordance with Table 8.2.3.
Mandatory requirement: in no case the ventilation air quantity shall be lower than 2.5 l/s
per person.
2.11.3.5 Air temperature
The temperature differential between ventilation air and air in the conditioned space shall
not exceed 5.5oC.
Exception:
Ventilation air that is part of the air-conditioning system.
2.11.3.6 Recirculation
(a) Amount of Recirculation: Not more than 67 percent of the required ventilation air
specified in Table 8.2.6 shall be permitted for recirculation, when the concentration
of particulates is less than specified in Table 8.2.7. Air in excess of the required
ventilation air shall be permitted to be completely recirculated. Air shall not be
recirculated to another dwelling unit or occupancy of dissimilar use.
Not more than 85 percent of the required ventilation air shall be permitted for
recirculation when the system is equipped with effective adsorption or filtering
equipment so that the condition of the air supplied to the room or space is within
the quality limitations of Table 8.2.7.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4687

Table 8.2.7: Maximum Allowable Contaminant Concentrations

Contaminant Annual Short Term Level Averaging

Average Period
(not to be
(arithmetic
exceeded more (hours)
mean)
than once a year)
µg/m3 µg/m3
Particulates 60 150 24
Sulfur oxides 80 400 24
Carbon monoxide 20,000 30,000 8
Photochemical oxidant 100 500 1
Hydrocarbons (not including 1,800 4,000 3
methane)
Nitrogen oxides 200 500 24
Odour -- Essentially --
unobjectionablea
Note: a Judged unobjectionable by 60 percent of a panel of 10 untrained subjects.

(b) Prohibited Use of Recirculated Air: Air drawn from mortuary rooms, bathrooms or
toilets or any space where an objectionable quantity of flammable vapours, dust,
odours, or noxious gases is present shall not be recirculated. Air drawn from rooms
that must be isolated to prevent the spread of infection shall not be recirculated.
Exception:
Air drawn from hospital operating rooms may be recirculated, if the following
requirements are met:
(i) A minimum of twenty five total air changes per hour shall be provided, of which
five air changes per hour shall be outdoor air.
(ii) All fans serving exhaust systems are located at the discharge end of the
system.
(iii) Outdoor air intakes shall be located at least 7.5 m from exhaust outlets of
ventilation systems, combustion equipment stacks, medical surgical vacuum
systems, plumbing vent stacks or from areas which may collect vehicular
exhaust and other noxious fumes. The bottom of outdoor air intakes serving
central systems shall be located at least 2 m above ground level, or if installed
above roof, at least 1 m above roof level.
(iv) Positive air pressure shall be maintained at all times in relation to adjacent
areas.
4688 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(v) All ventilation or air-conditioning systems serving such rooms shall be

equipped with a filter bed of 25 percent efficiency upstream of air-
conditioning equipment and a filter bed of 99 percent efficiency downstream
of the supply fan, any recirculating spray water systems and water reservoir
type humidifiers. All filter efficiencies shall be average atmospheric dust spot
efficiencies tested in accordance with the latest ASHRAE standard.
(vi) Duct linings shall not be used in air-conditioning and ventilation systems
serving such rooms unless terminal filters of at least ninety percent efficiency
are installed downstream of linings.
(vii) Air supplied shall be delivered at or near the ceilings and all exhaust air shall
be removed near floor level, with at least two exhaust outlets not less than 75
mm above the floor.
(c) Swimming Pool Area Recirculation: Return air from a swimming pool and deck
area shall be permitted to be recirculated in accordance with Sec 2.8.3.6 when such
air is dehumidified to maintain the relative humidity of the area at 60 percent or
less. The return air shall only be recirculated to the area from which it was
removed.
2.11.3.7 Ventilation in uninhabited spaces
Uninhabited spaces, such as crawl spaces or attics, shall be provided with natural
ventilation openings as required by the Code or such spaces shall be mechanically
ventilated. The mechanical ventilation system shall be a mechanical exhaust and supply
air system. The exhaust rate shall be 0.1 litre per square metre of horizontal area. The
ventilation system shall operate when the relative humidity exceeds 70 percent in the
space.
2.11.3.8 Ventilation in enclosed parking garages

Mechanical ventilation systems for enclosed parking garages shall be permitted to

operate intermittently where the system is arranged to operate automatically upon
detection of vehicle operation or the presence of occupants or sensing the CO (carbon
monoxide) concentration level by approved automatic detection devices.
Average concentration of CO shall not exceed 35 ppm with a maximum of 200 ppm.
Automatic operation of the system shall not reduce the ventilation air flow rate below
0.25 litre per m2 of the floor area and the system shall be capable of producing a
ventilation air flow rate of 7.6 litre per m2 of floor area. In no case the outdoor air
quantity shall be lower than 5 litre per m2 of floor area.

Connecting offices, waiting rooms, ticket booths and similar uses that are accessory to a
public garage shall be maintained at a positive pressure.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4689

2.11.4 Mechanical Exhaust

2.11.4.1 Where required

All rooms and areas having air with dust particles sufficiently light enough to float in the
air, odours, fumes, spray, gases, vapours, smoke, or other noxious or impurities in such
quantities as to be irritating or injurious to health or safety or which is harmful to building
and materials or has substances which create a fire hazard, and rooms or areas as
indicated in Table 8.2.6 shall have air exhausted to the outdoors in accordance with this
Section.

2.11.4.2 Design of exhaust system

(a) General: The design of the system shall be such that the emissions or contaminants
are confined to the area in which they are generated by currents, hoods or
enclosures and shall be exhausted by a duct system to a safe location or treated to
remove contaminants. Ducts conveying explosives or flammable vapours, fumes or
dusts shall extend directly to the exterior of the building without entering other
spaces. Exhaust ducts shall not extend into or through ducts or plenums.

Exception:

Ducts conveying vapour or fumes having flammable constituents less than 25

percent of their lower flammability limit (LFL) may pass through other spaces.

Separate and distinct systems shall be provided for incompatible exhaust materials.

Contaminated air shall not be recirculated to occupied areas unless contaminants

have been removed. Air contaminated with explosive or flammable vapours, fumes
or dusts; flammable or toxic gases; or radioactive material shall not be recirculated.

(b) Exhaust Air Inlet: The inlet to the exhaust system shall be located in the area of
heaviest concentration of contaminants.

(c) Velocity and Circulation: The velocity and circulation of air in work areas shall be
such that contaminants are captured by an air stream at the area where the
emissions are generated and conveyed into a product - conveying duct system.
Mixtures within work areas where contaminants are generated shall be diluted
below 25 percent of their lower explosive limit or lower flammability limit with air
which does not contain other contaminants.

2.11.4.3 Make up air

Make up air shall be provided to replenish air exhausted by the ventilating system. Make
up air intakes shall be located so as to avoid recirculation of contaminated air within
enclosures.
4690 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

2.11.4.4 Hoods and enclosures

Hoods and enclosures shall be used when contaminants originate in a concentrated area.
The design of the hood or enclosure shall be such that air currents created by the exhaust
systems will capture the contaminants and transport them directly to the exhaust duct.
The volume of air shall be sufficient to dilute explosive or flammable vapours, fumes or
dusts as set forth in Sec 2.11.4.2.

2.11.4.5 Exhaust outlets

The termination point for exhaust ducts discharging to the atmosphere shall not be less
than the following:

(a) Ducts conveying explosive or flammable vapours, fumes or dusts: 9 m from

property line; 3 m from opening into the building; 2 m from exterior walls or roofs;
9 m from combustible walls or openings into the building which are in the direction
of the exhaust discharge; 3 m above adjoining grade.

(b) Other product conveying duct outlets: 3 m from property line; 1 m from exterior
wall or roof; 3 m from openings into the buildings; 1 m above adjoining grade.

(c) Domestic kitchen, bathroom, domestic clothes dryer exhaust duct outlets: 1 m from
property line; 1 m from opening into the building.

(d) Outlets for exhausts that exceed 80oC shall be in accordance with the relevant code.

2.11.4.6 Motors and fans

(a) General: Motors and fans shall be sized to provide the required air movement.
Motors in areas which contain flammable vapours and dusts shall be of a type
approved for such environments. A manually operated remote control device shall
be installed to shutoff fans or blowers in flammable vapour or dust system. Such
control device shall be installed at an approved location.

Electrical equipment used in operations that generate explosive or flammable

vapours, fumes or dusts shall be interlocked with the ventilation system so that the
equipment cannot be operated unless the ventilation fans are in operation. Motors
for fans used to convey flammable vapours or dusts shall be located outside the
duct and shall be protected with approved shields and dust proofing. Motors and
fans shall be accessible for servicing and maintenance.

(b) Fans: Parts of fans in contact with explosive or flammable vapours, fumes or dusts
shall be of nonferrous or non-sparking materials or their casing shall be lined or
constructed of such material. When the size and hardness of materials passing
through a fan could produce a spark, both the fan and the casing shall be of non-
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4691

sparking materials. When fans are required to be spark resistant, their bearings shall
not be within the air stream, and all parts of the fan shall be grounded. Fans in
systems handling materials that are likely to clog the blades, and fans in buffing or
woodworking exhaust systems, shall be of the radial blade or tube axial type.

Equipment used to exhaust explosive or flammable vapours, fumes or dusts shall

bear an identification plate stating the ventilation rate for which the system was
designed.

Fans located in systems conveying corrosives shall be of materials that are resistant
to the corrosion or shall be coated with corrosion resistant materials.

2.11.4.7 Exhaust systems of special areas

(a) Motor Vehicle Operation: In areas where motor vehicles operate for a period of
time exceeding 10 seconds, the ventilation return air shall be exhausted. In fuel
dispensing areas, the bottom of the air inlet or exhaust opening shall be located a
maximum of 450 mm above the floor.
(b) Spray Painting and Dipping Rooms: Rooms booth for spray painting or dipping
shall have mechanical exhaust systems which create a cross-sectional air velocity
of 0.5 m/s. The system shall provide a uniform exhaust of air across the width and
height of the room or booth. The exhaust system shall operate while spray painting
or dipping is being done.

(c) Motion Picture Projectors: Projectors equipped with an exhaust discharge shall be
directly connected to a mechanical exhaust system. The exhaust system shall
operate at an exhaust rate as indicated by the manufacturer's instructions.

Projectors without an exhaust shall have contaminants exhausted through a

mechanical exhaust system. The exhaust rate for electric arc projectors shall be a
minimum of 100 l/s per lamp. The exhaust rate for xenon projectors shall be a
minimum of 150 l/s per lamp. The lamp and projection room exhaust systems, if
combined or independent, shall not be interconnected with any other exhaust or
return system within the building.

(d) Dry Cleaning Equipment: Dry cleaning equipment shall be provided with an
exhaust system capable of maintaining a minimum air velocity of 0.5 m/s across
the face of the loading door.

(e) LP gas Distribution Facilities: LP gas distribution facilities that are not provided
with natural ventilation shall have a continuously operating exhaust system at the
rate of 5 l/s per square metre of floor area. The bottom of air inlet and outlet
openings shall not be more than 150 mm above the floor.
4692 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

2.11.4.8 Exhaust system ducts

(a) Construction: Ducts for exhaust systems shall be constructed of materials approved
for the type of particulates conveyed and as per latest standard in this regard. Ducts
shall be of substantial airtight construction and shall not have openings other than
those required for operation and maintenance of the system.

(b) Supports: Spacing of supports for ducts shall not exceed 3.7 m for 200 mm ducts
and 6 m for larger ducts unless justified by the design. The design of supports shall
assume that 50 percent of the duct is full of the particulate being conveyed.

(c) Explosion Venting: Ducts conveying explosive dusts shall have explosion vents,
openings protected by antiflash-back swing valves or rupture diaphragms.
Openings to relieve explosive forces shall be located outside the building.

(d) Fire Protection: Fire suppression system shall be installed within ducts having a
cross-sectional dimension exceeding 250 mm when the duct conveys flammable
vapours or fumes.

(e) Clearances: Ducts conveying flammable or explosive vapours, fumes or dusts shall
have a clearance from combustibles of not less than 450 mm.

2.11.5 Kitchen Exhaust Equipment

2.11.5.1 Kitchen exhaust ducts

(a) Materials: Kitchen exhaust ducts and plenums shall be constructed of at least
16 SWG steel or 18 SWG stainless steel sheet.

Joints and seams shall be made with a continuous liquid tight weld or braze made on
the external surface of the duct system. A vibration isolator connector may be used,
provided it consists of noncombustible packing in a metal sleeve joint of approved
design. Duct bracing and supports shall be of noncombustible material securely
attached to the structure and designed to carry gravity and lateral loads within the
stress limitations of the Building Code. Bolts, screws, rivets and other mechanical
fasteners shall not penetrate duct walls. Exhaust fan housings shall be constructed of
steel.

Exception:

Kitchen exhaust ducts which are exclusively used for collecting and removing steam,
vapour, heat or odour may be constructed as per provisions of Sec 2.4.1.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4693

(b) Corrosion Protection: Ducts exposed to the outside atmosphere or subject to a

corrosive environment shall be protected against corrosion. Galvanization of metal
parts, protection with noncorrosive paints and waterproof insulation are considered
acceptable methods of protection.
(c) Prevention of Grease Accumulation: Duct systems shall be so constructed and
installed that grease cannot become pocketed in any portion thereof, and the system
shall have a slope not less than 1 in 48 towards the hood or an approved grease
reservoir. Where the horizontal ducts exceed 23 m in length the slope shall not be
less than 1 in 12.
(d) Air Velocity: The air velocity in the duct shall be a minimum of 7.62 m/s and a
maximum of 12.7 m/s.
(e) Cleanouts and Other Openings: Duct systems shall not have openings other than
those required for proper operation and maintenance of the system. Any portion of
such system having sections inaccessible from the duct entry or discharge shall be
provided with adequate cleanout openings of approved construction spaced not
more than 6 m apart. The cleanout shall be located on the side of the duct having a
minimum opening dimension of 300 mm or the width of the duct when less than
300 mm.
(f) Duct Enclosure: The duct which penetrates a ceiling, wall or floor shall be enclosed
in a fire-resistant rated enclosure from the point of penetration in accordance with
the Code. The duct enclosure shall be sealed around the duct at the point of
penetration and vented to the exterior through weather-protected openings. The
clearance between the duct enclosure and the duct shall be at least 75 mm and not
more than 300 mm. Each duct enclosure shall contain only one exhaust duct.
Approved fire rated access openings shall be provided at cleanout points.
(g) Kitchen exhaust air flow rate shall be calculated based on the data provided in
Table 8.2.8.
2.11.5.2 Kitchen exhaust hoods
(a) A commercial exhaust hood shall be provided for each commercial cooking
appliance.
Exceptions:
(i) An appliance located within a dwelling unit and not used for commercial
purposes.
(ii) Completely enclosed ovens.
(iii) Steam tables.

(iv) Auxiliary cooking equipment that does not produce grease laden vapours,
including toasters, coffee makers and egg cookers.
4694 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(b) Domestic cooking appliances used for commercial purposes shall be provided with
a commercial exhaust hood. Domestic cooking appliances used for noncommercial
purposes shall be provided with ventilation in accordance with Sec 2.8.

(c) Hood Construction: The hood and other parts of the primary collection system shall
be constructed of galvanized steel, stainless steel, copper or other material
approved by the Building Official for the use intended. The minimum nominal
thickness of the galvanized steel shall be 1.2 mm (No. 18 SWG). The minimum
nominal thickness of stainless steel shall be 0.93 mm (No. 20 SWG). Hoods
constructed of copper shall be of copper sheets weighing at least 7.33 kg/m2. All
external joints shall be welded liquid tight. Hoods shall be secured in place in
noncombustible supports.

(d) Interior Surface: The interior surfaces of the hood shall not have any areas that can
accumulate grease.

Exception: Grease collection systems under fitters and troughs on the perimeter of
canopy hoods.

(e) Canopy Hoods: Canopy hoods shall be designed to completely cover the cooking
equipment. The edge of the hood shall extend a minimum horizontal distance of
150 mm beyond the edge of the cooking surface on all open sides and the vertical
distance between the lip of the hood and the cooking surface shall not exceed 1.22
m.

(f) Non-canopy Type Hoods: Hoods of the non-canopy type shall be located a
maximum of 900 mm above the cooking surface. The edge of the hood shall be set
back a maximum of 300 mm from the edge of the cooking surface.

(g) Hood Exhaust: The hood exhaust shall create a draft from the cooking surface into
the hood. Canopy hoods attached to wall shall exhaust a minimum of 500 l/s per m2
of the hood area. Canopy hoods exposed on all sides shall exhaust a minimum of
750 l/s per m2 of hood area. Hoods of the non-canopy type shall exhaust a
minimum of 460 l/s per lineal metre of cooking surface.

(h) Exhaust Outlet: An exhaust outlet within the hood shall be so located as to optimize
the capture of particulate matter. Each outlet shall serve not more than a 3.7 m
section of the hood.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4695
Table 8.2.8: Design Exhaust Air Flow in litre per second per kW of the Kitchen
Equipment
SI No. Kitchen Equipment Electricity based Gas based
Equipment Equipment

1 Cooking pot 8 12
2 Pressure cooker cabinet 5 -
3 Convection oven 10 -
4 Roasting oven (salamander) 33 33
5 Griddle 32 35
6 Frying pan 32 35
7 Deep fat fryer 28 -
8 Cooker/stove 32 35
9 Grill 50 61
10 Heated table/bath 30 -
11 Coffeemaker 3 -
12 Dish washer 17 -
13 Refrigeration equipment 60 -
14 Ceramic cooker/stove 25 -
15 Microwave oven 3 -
16 Pizza oven 15 -
17 Induction cooker/stove 20 -

2.11.5.3 Make up air

Make up air shall be supplied during the operation of the kitchen exhaust system. The
amount of make-up air shall be approximately equal to the amount of the exhaust air. The
make-up air shall be supplied in such a way as to avoid short circuiting and reducing the
effectiveness of the exhaust system. Windows and doors shall not be used for the purpose
of providing make up air.
2.11.5.4 Grease removal
The air exhausted in every commercial exhaust hood shall pass through approved grease
filters or grease removal device designed for the specific purpose. Grease removal
devices shall bear the label of an approved agency, and shall be installed in accordance
with the manufacturer's instructions for the labeled equipment. All grease filters shall be
accessible. Grease filters shall be installed at a minimum angle of 45o to the horizontal.
The filters shall be arranged so as to capture and drain grease to a point of collection.
4696 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

2.11.5.5 Motors, fans and safety devices

(a) Motors and fans shall be of sufficient capacity to provide required air movement.
Electrical equipment shall be approved for the class of use as provided in the Code.
Motors and fans shall be accessible for servicing and maintenance. Motors of the
exhaust fan shall not be installed within the ducts or under hoods.

(b) Commercial exhaust system hoods and ducts shall have a minimum clearance to
combustibles of 450 mm.

(c) Fire Suppression System Required: All commercial cooking surfaces, kitchen
exhaust systems, grease removal devices and hoods shall be protected with an
approved automatic fire suppression system as per the Code.

2.12 Energy Conservation

2.12.1 General

Air-conditioning, heating and ventilation systems of all buildings shall be designed and
installed for efficient use of energy as herein provided. Calculations of cooling and
heating loads shall be based on data which lead to a system with optimum energy use.

General standards of comfort or particular environmental requirements within the

building shall not be sacrificed in an endeavor to achieve low consumption of energy. For
special applications, such as hospitals, laboratories, thermally sensitive equipment,
computer rooms and manufacturing processes, the design concepts and parameters shall
conform to the requirements of the application at minimum energy levels.

2.12.2 Design Parameters

2.12.2.1 Outdoor design conditions

Unless specifically required, the outdoor design temperature shall be selected from
columns of 2 percent value of Table 8.2.2 for cooling.

2.12.2.2 Indoor design conditions

Indoor design temperature shall not be less than 24oC for cooling unless otherwise
required for specific application.

2.12.2.3 Humidity

The actual design relative humidity shall be selected from the range shown in Table 8.2.1
for the minimum total air-conditioning, heating and ventilation system energy use.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4697

2.12.2.4 Shading co-efficient of glazing

(a) The shading co-efficient (SC) and solar heat gain co-efficient (SHGC) shall be
selected so as to reduce total heat influx through the glazing.

(b) For any specific value of glazing to wall ratio (GWR) of any wall the shading co-
efficient and solar heat gain co-efficient shall be based on the Table 8.2.9(a).

Table 8.2.9(a): SHGC and SC Values Based on GWR Value

GWR SHGC SC GWR SHGC SC

10 0.85 0.98 60 0.33 0.38

20 0.60 0.69 70 0.31 0.36

30 0.50 0.57 80 0.30 0.34

40 0.40 0.46 90 0.27 0.31

50 0.35 0.40

Notes:
(i) Solar heat gain co-efficient (SHGC) = Shading Co-efficient (SC) x 0.87

(ii) Glazing to wall ratio (GWR) = Total glazing area on any wall divided by total
area of that wall including the glazing area.
(iii) The Visible Light Transmittance (VLT) of the glazing element shall not be lower
than 35 percent.

(c) For buildings with external shading in the form of overhang and/or vertical fins a
higher SHGC can be selected. The adjusted value of SHGC can be found out by
using the following equation:

SHGC adj  SHGC  A or B (8.2.1)

Values of A or B shall be taken from Table 8.2.9(b). Only higher of A & B shall be
taken when both overhang and fins are used.
4698 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Table 8.2.9(b): Correction Factor for Overhang Shading and Vertical Fins

Value of overhang Shading Shading Value of overhang Shading Shading

projection correction correction projection correction correction
factor or vertical factor for factor for factor or vertical factor for factor for
projection factor overhang (A) vertical fins (B) projection factor overhang (A) vertical fins (B)

0.0 0.00 0.00 0.6 0.28 0.24

0.1 0.05 0.04 0.7 0.33 0.28

0.2 0.09 0.08 0.8 0.38 0.32

0.3 0.14 0.12 0.9 0.43 0.36

0.4 0.19 0.16 1 or higher 0.47 0.40

0.5 0.24 0.20

Notes :

(i) Overhead projection factor is the ratio between depth of overhang and height of
window.

(ii) Fin projection factor is the ratio between depth of fin and length of fin.

(iii) Shading can only be counted if shade structure are placed over the window and
glazing.

2.12.3 System Design

2.12.3.1 Load variation

Consideration shall be given to changes in building load and the system designed, so that
maximum operational efficiency is maintained under part load conditions. The total
system shall be separated into smaller zones having similar load requirements, so that
each zone can be separately controlled to maintain optimum operating conditions by
reducing wastage of energy.

2.12.3.2 Temperature of cooling media

The temperature of refrigerant, chilled water or brine circulated within the system shall
be maintained at the level necessary to achieve the required output to match the
prevailing load conditions with the minimum expenditure of energy.

2.12.3.3 Energy recovery

Energy recovery system shall be adopted, where possible.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4699

2.12.4 Equipment and Control

2.12.4.1 General
Air-conditioning, heating and ventilation system shall be equipped with devices and
controls to automatically control the capacity of the system when the building
requirement reduces. The control system shall have devices to reduce energy use
considering the effect of building energy storage.
2.12.4.2 Cooling with outdoor air
Each air handling system shall have facility to use up to and including 100 percent of the
air handling system capacity for cooling with outdoor air automatically whenever the use
of outdoor air will result in lower usage of energy than would be required under normal
operation of the air handling system.
Exception:
Cooling with outdoor air is not required under any one or more of the following
conditions:
(a) Where the air handling system capacity is less than 2500 l/s or total cooling
capacity is less than 40 kW.
(b) Where the quality of outdoor air is so poor as to require extensive treatment of the
air.
(c) Where the need for humidification or dehumidification requires the use of more
energy than is conserved by outdoor air cooling on an annual basis.
(d) Where the use of outdoor air cooling would affect the operation of other systems so
as to increase the overall energy consumption of the building.
2.12.4.3 Mechanical ventilation
Each mechanical ventilation system shall be equipped with a readily accessible means for
either shutoff or volume reduction, and shutoff when ventilation is not required.
Automatic or gravity dampers that close when the system is not operating shall be
provided for outdoor air intakes and exhausts.
2.12.4.4 Maintenance
Heat exchange tubes shall be periodically cleaned to maintain its heat transfer
characteristics. Maintenance of all equipment shall be periodically done to maintain its
efficiency at satisfactory level.
2.12.4.5 Minimum equipment efficiencies
Cooling equipment shall meet or exceed the minimum efficiency requirements presented
in Tables 8.2.10 and 8.2.11. Heating and cooling equipment not listed here shall comply
with ASHRAE 90.1.
4700 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Table 8.2.10: Minimum Performance of Unitary Air Conditioning Equipment

Minimum Minimum Test

Equipment Class and Size Category
COP IPLV Standard

Unitary air cooled air conditioner

≥19 and <40 kW (≥5.4 and <11 tons) 3.08 -- ARI 210/240
≥40 to <70 kW (≥11 to <20 tons) 3.08 -- ARI 340/360
≥70 kW (≥20 tons) 2.93 2.99 ARI 340/360
Unitary water cooled air conditioner
<19 kW (<5.4 tons) 4.10 -- ARI 210/240
≥19 and <40 kW (≥5.4 and <11 tons) 4.10 -- ARI 210/240
≥<40 kW (≥11 tons) 3.22 3.02 ARI 210/240

Table 8.2.11: Minimum Performance of Chillers

Minimum Minimum Test

Equipment Class and Size Category
COP IPLV Standard

Air cooled chiller, electrically operated

<530 kW (<150 tons) 2.90 3.16 ARI 550/590
≥530 kW (≥150 tons) 3.05 3.32 ARI 550/590
Centrifugal water cooled chiller, electrically
operated
<530 kW (<150 tons) 5.80 6.09 ARI 550/590
≥530 and <1050 kW (≥150 and <300 tons) 5.80 6.17 ARI 550/590
≥1050 kW (≥300 tons) 6.30 6.61 ARI 550/590
Reciprocating compressor, water cooled
chiller, electrically operated
All Capacities 4.20 5.05 ARI 550/590
Rotary screw and scroll compressor, water
cooled chiller, electrically operated
<530 kW (<150 tons) 4.70 5.49 ARI 550/590
≥530 and <1050 kW (≥150 and <300 tons) 5.40 6.17 ARI 550/590
≥1050 kW (≥300 tons) 5.75 6.43 ARI 550/590
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4701

Minimum Minimum Test

Equipment Class and Size Category
COP IPLV Standard

Air cooled absorption, single effect

All Capacities 0.60 -- ARI 560
Water cooled absorption, single effect
All Capacities 0.70 -- ARI 560
Water cooled absorption, double effect,
indirect fired
All Capacities 1.00 1.05 ARI 560
Water cooled absorption, double effect, direct
fired
All Capacities 1.00 1.00 ARI 560

2.12.4.6 Controls

(a) All mechanical cooling and heating shall be controlled by a time clock that:

(i) Can start and stop the system under different schedules for three different
day-types per week.

(ii) Is capable of retaining programming and time setting during a loss of power
for a period of at least 10 hours, and

(iii) Includes an accessible manual override that allows temporary operation of

the system for up to 2 hours.

Exceptions: (i) Cooling systems < 28 kw (8 tons); (ii) Heating systems < 7
kw (2 tons)

(b) All heating and cooling equipment shall be temperature controlled. Where a unit
provides both heating and cooling, controls shall be capable of providing a
temperature dead band of 3°C (5°F) within which the supply of heating and cooling
energy to the zone is shut off or reduced to a minimum. Where separate heating and
cooling equipment serve the same temperature zone, thermostats shall be
interlocked to prevent simultaneous heating and cooling.

(c) All cooling towers and closed fluid coolers shall have either two speed motors,
pony motors, or variable speed drives controlling the fans.
4702 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

2.12.5 System Balancing

2.12.5.1 General
Construction documents shall require that all HVAC systems be balanced in accordance
with generally accepted engineering standards.
Construction documents shall require that a written balance report be provided to the
owner or the designated representative of the building owner for HVAC system servicing
zones with a total conditioned area exceeding 500 m2 (5000 ft2).
(a) Air System Balancing
Air systems shall be balanced in a manner to first minimize throttling loses. Then, for
fans with fan system power greater than 0.75 kW (1.0 hp), fan speed shall be adjusted to
meet design flow conditions.
(b) Hydronic System Balancing
Hydronic systems shall be proportionately balanced in a manner to first minimize
throttling loses; then the pump impeller shall be trimmed or pump speed shall be adjusted
to meet design flow conditions.
Exceptions:
(i) Impellers need not be trimmed nor pump speed adjusted for pumps with
pump motors of 7.5 kW (10 hp) or less.
(ii) Impellers need not be trimmed when throttling results in no greater than 5%
of the nameplate horse power draw, or 2.2 kW (3 hp), whichever is greater.
2.12.6 Condensers
2.12.6.1 Condenser locations
Care shall be exercised in locating the condensers in such a manner that heat sink is free
of interference from heat discharge by devices located in adjoining spaces and also does
not interfere with such other systems installed nearby.
2.12.6.2 Treatment water for condensers
All high-rise buildings using centralized cooling water system shall use soft water for the
condenser and chilled water-system.
2.12.7 Economizers
2.12.7.1 Air side economizer: Each individual cooling fan system that has a design
supply capacity over 1200 l/s (2500 cfm) and a total mechanical cooling capacity over 22
kW (6.3 tons) shall include either:
(a) An air economizer capable of modulating outside-air and return-air dampers to
supply 100 percent of the design supply air quantity as outside-air; or
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4703

(b) A water economizer capable of providing 100% of the expected system cooling load
at outside air temperature of 10°C (50°F) dry-bulb/7.2°C (45°F) wet-bulb and below:

Exception:

(i) Projects in the hot-dry and warm-humid climate zones are exempted.

(ii) Individual ceiling mounted fan systems <3200 l/s (6500 cfm) are exempted.
2.12.7.2 Where required by Sec 2.12.7.1 economizers shall be capable of providing
partial cooling even when additional mechanical cooling is required to meet the cooling
load.

2.12.8 Variable Flow-Hydronic Systems

2.12.8.1 Chilled or hot-water systems shall be designed for variable fluid flow and shall
be capable of reducing pump flow rates to no more than the larger of:
(a) 50 percent of the design flow rate, or

(b) The minimum flow required by the equipment manufacturer for proper operation of
the chillers or boilers.
2.12.8.2 Water cooled air-conditioning or heat pump units with a circulation pump
motor greater than or equal to 3.7 kW (5 hp) shall have two-way automatic isolation
valves on each water cooled air-conditioning or heat pump unit that are interlocked with
the compressor to shut off condenser water flow when the compressor is not operating.

2.12.8.3 Chilled water or condenser water systems that must comply with either Sec
2.12.8.1 or Sec 2 .12.8.2 and that have pump motors greater than or equal to 3.7 kW (5
hp) shall be controlled by variable speed drives.

2.12.9 Variable Air Flow Systems

2.12.9.1 Air conditioning air distribution system shall be designed for variable air flow
and shall be capable of reducing air flow by using any or all of the following devices:

(a) Variable speed drives for controlling speeds of fan motors,

(b) Variable air volume units/terminals,

(c) Dampers for regulating air flow through ducts. Dampers may preferable be motor
driven and modulating type.

2.12.9.2 Air handling units that has fan capacity greater than 7.5 kW shall be controlled
by variable speed drives.

Exception: Kitchen ventilation fans.

4704 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

2.13 Inspection, Testing and Commissioning

2.13.1 Inspection and Testing

2.13.1.1 General
All air-conditioning, heating and ventilation system shall be inspected and tested by the
Authority before the system is commissioned for normal operation. It should be ensured
that these are carried out thoroughly and that all data and results are properly
documented. It is recommended that whole inspection, testing and commissioning be
done under the guidance and control of a single Authority.
2.13.1.2 Inspection
All machinery, equipment and other accessories of the air-conditioning, heating and
ventilation system shall be inspected by the Authority to determine whether the system
components and the system as a whole has been installed as per design and provisions of
this Code; proper safety requirements have been maintained; and adequate fire protection
measures have been taken.
Inspection shall also be carried out on structural supports, hangers, fastening devices,
vibration isolators etc.
2.13.1.3 Testing
(a) General: All machinery, equipment and other accessories shall be tested as per
approved procedures. Tests shall be conducted to determine the strength capacity of
any item and performance of any machine and equipment. All test data shall be
properly documented.
(b) Pressure Testing of Piping: All field installed refrigerant and hydronic piping
system along with their valves and pipe fittings shall be tested at their approved test
pressures to determine whether the piping system can withstand the test pressures.
(c) Air Distribution System Testing: All ducting system shall be tested to determine
whether the duct system has any leakage at test pressures. All air terminals and air
dampers shall be tested for their flow characteristics.
(d) Machinery and Equipment: Tests shall be conducted on machinery and equipment
to determine whether these operate and function properly. All machinery and
equipment shall also be tested for their electrical power consumption characteristics
and overall performance. Before performance testing of the system all air
distribution system and hydronic system shall be properly balanced by approved
procedure.
(e) Safety Devices and Controls: Tests shall be carried out to determine whether the
safety devices and controls function properly.
(f) All air filters shall be tested in accordance with the latest standard.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4705

2.13.2 Commissioning

If the Authority becomes satisfied regarding satisfactory installation and performance of

the air-conditioning, heating and ventilation system after testing, the system shall be
commissioned following approved procedure. Before complete commissioning, all air
distribution systems and hydronic systems shall be properly balanced and all the controls
and their sensors shall be properly adjusted.

2.14 Operation and Maintenance

2.14.1 General

The owner of the building where the air-conditioning, heating and ventilation system is
installed, shall follow a properly designed operation procedure and maintenance
schedule.

2.14.2 Operation

A well sequenced operation procedure shall be followed to ensure effective operation of

the air-conditioning, heating and ventilation system, safety from hazard to personnel and
property. Operation procedure shall take account for saving in energy use.

All operational data of all the machinery and equipment shall be properly recorded for
determination of performance of the machinery, equipment and the system. These data
shall be properly preserved for future reference for maintenance purposes.

2.14.3 Maintenance
A well designed maintenance program for the air-conditioning, heating and ventilation
system shall be implemented in order to achieve the following:

(a) Optimum reliability and continuity of service.

(b) Extended longevity and economic life.

(c) Functional effectiveness, whereby the intended performance of mechanical

equipment and system can be fully attained.
(d) Minimum operating cost, attendant requirements, servicing and repairs.

(e) Safety from hazard to personnel and property.

Maintenance program and procedure shall comply with the instructions of machinery/
equipment manufacturers in this regard.
4706 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

PART VIII
Chapter 3
Building Acoustics
3.1 Purpose
The purpose of this Chapter is to provide codes, recommendations and guidelines for
fulfilling acoustical requirements in buildings.

3.2 Scope
This Chapter specifies planning, design and construction codes, recommendations and
guidelines on spatial, architectural and technical aspects of acoustics within or outside
buildings to ensure acoustical performance, comfort and safety. Planning and design
aspects are discussed generally and also particularly for buildings with different
occupancies.
3.3 Terminology

This Section provides meanings and definitions of terms used in and applicable to this
Chapter of the Code. The terms are arranged in alphabetical order. In case of any
contradiction between a meaning or a definition given in this Section and that in any
other part of the Code, the meaning or definition specified in this Section shall govern for
interpretation of the provisions of this Section.
BALANCED NOISE Balanced Noise Criteria (NCB) curves are used to specify
CRITERIA (NCB) acceptable background noise levels in occupied spaces (see
CURVES Appendix F).
BEL See sound pressure level.
CYCLE See Frequency.
dBA A sound pressure level measurement, when the signal has
been weighted with a frequency response of the A curve. The
dBA curve approximates the human ear and is therefore used
most in building acoustics.
DECIBEL (dB) See sound pressure level.
DIRECT SOUND Sound that travels directly from a source to the listener or
receiver. In a room, the sequence of arrivals is the direct
sound first, followed by sound reflected from room surfaces.
ECHO Echo is a reflection of a sound wave back to its source in
sufficient strength and with a sufficient time lag to be
separately distinguished. Usually, a time lag of at least 50 to
80 ms is required for hearing discrete echoes.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4707

EFFECTIVE The number for rating the noise of an individual aircraft

PERCEIVED NOISE flying overhead is the Effective Perceived Noise Level in
LEVEL IN DECIBEL decibels (unit, EPN dB). This value takes into account the
(EPN dB) subjectively annoying effects of the noise including pure
tones and duration. In principle, it is a kind of time-integrated
loudness level.
FLUTTER ECHO A quick succession of echoes; it may be present as a
disturbing phenomenon in small rooms or between a pair of
parallel reflectors. If the time between echoes is greater than
about 30 to 50 ms, the periodicity is audible as a distinct
flutter.
FREQUENCY The frequency of sound is the number of vibrations per
second of the molecules of air, generated by the vibrating
body. One complete movement to and fro of the vibrating
body is referred to as a 'cycle'. Frequency is expressed as the
number of cycles per second (cps); it is also referred to its
unit as Hertz (Hz).

IMPACT ISOLATION Impact Isolation Class (IIC) is a single-number impact

CLASS (IIC) isolation rating for floor construction. Tests are made with a
standard tapping machine and noise level measured in 1/3-
octave bands. These are plotted and compared to a standard
contour.

INTENSITY Intensity at a point is the average rate at which sound energy

is transmitted through a unit area around the point and
perpendicular to the direction of propagation of sound. It is
also known as sound intensity. Its units is W m-2.

L10 In environmental noise assessment, the A-weighted noise

level (unit dBA), with fast (F) time weighting, that is
exceeded by 10 percent of sated time period is known as L10.

L Aeq, T Expression for Equivalent Continuous A-Weighted Sound

Pressure Level for airborne sounds that are non-stationary
with respect to time. It is formed by applying A-weighting to
the original signal before squaring and averaging. Also
known as equivalent continuous sound level.
LOUDNESS Loudness is the sensation produced in the human ear and
depends on the intensity and frequency of sound. The unit of
loudness level is phon.
4708 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

NOISE Noise is defined as unwanted sound. Noise conditions vary

from time to time and a noise which may not be
objectionable during the day may be increased in annoying
proportions in the silence of the night, when quiet conditions
are essential.
NOISE EXPOSURE Noise exposure forecast at any location is the summation of
FORECAST (NEF) the noise levels in Effective Perceived Noise Level (unit EPN
dBA) from all aircraft types, on all runways, suitably
weighted for the number of operations during day time and
night time.
NOISE MAP A noise map is a graphic representation of the sound level
distribution existing in a given region, for a defined period.
NOISE REDUCTION Noise Reduction (NR) is a general term for specifying sound
(NR) insulation between rooms. It is more general than
Transmission Loss (TL). If all boundary surfaces in the
receiving room are completely absorbent, the NR will exceed
the TL by about 5 dB, i.e. NR = TL + 5dB.
PERCENTAGE The percentage of meaningless syllables correctly written by
SYLLABLE listeners is called Percentage Syllable Articulation (PSA).
ARTICULATION
(PSA)

REVERBERATION The prolongation of sound, as a result of successive

reflections in an enclosed space, when the source of the
sound has stopped, is called reverberation.

REVERBERATION The reverberation time of a room is defined as the time

TIME (RT) required for the sound pressure level in a room to decrease by
60 dB after the sound is stopped, and is calculated by the
formula
0 . 16 V
RT 
A  xV

Where, RT= reverberation time, s

V= room volume, m3
A= total room absorption, m2 sabin
x= air absorption coefficient
SIGNAL-TO-NOISE Signal-to-Noise Ratio (SNR) defined as the power ratio
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4709
RATIO (SNR) between a signal (meaningful information) and the
background noise (unwanted signal), which can be expressed
as
SNR = (Psignal /Pnoise)
where, P is average power

SNR can be obtained by calculating the square of amplitude

ratio:
SNR = (Psignal /Pnoise) = (Asignal /Anoise)2
where, A is root mean square (RMS) amplitude

In decibel, the SNR is defined as

SNRdB = 10 log10 (Psignal / Pnoise) = Psignal,dB - Pnoise,dB

which might be equivalently expressed in amplitude ratio as

SNRdB = 10 log10 (Asignal / Anoise)2 = 20 log10 (Asignal / Anoise)

SOUND FOCUS When a sound wave is reflected by a concave surface, large

AND DEAD SPOT enough compared to the wavelength, it concentrates on a spot
where sound pressure rises excessively. This is called a
'sound focus'. As a consequence, sounds become weak and
inaudible at some other spots, called 'dead spots'.
SOUND PRESSURE Sound Pressure Level or Sound Intensity Level is measured
LEVEL (SPL) in terms of the unit bel (B), which is defined as the logarithm
of the ratio of the sound pressure to the minimum sound
pressure audible to the average human ear. The unit decibel
(dB) is one-tenth of a bel (B). Thus,

Sound Pressure Level  log10 1 bcls  10 log10 1 dccibcls

10 10

where,
I = Sound Pressure in watt cm2, and
I 0 =Sound Pressure audible to the average human ear
taken as 10-16 watt/cm2.
4710 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

SOUND To avoid the misleading nature of an average transmission

TRANSMISSION loss (TL) value and to provide a reliable single figure rating
CLASS (STC) for comparing partitions, a different procedure for single
figure rating, called Sound Transmission Class (STC) rating,
of a partition is determined by comparing the 16 frequency
TL curve with a standard reference contour, the sound
transmission class contour. STC ratings of some common
walls and floors are given in Appendix E.

SPEECH The percentage of correctly received phrases is called

INTELLIGIBILITY Speech Intelligibility.

TRANSMISSION Transmission loss (TL) of a partition is a measure of its

LOSS sound insulation. It is equal to the number of decibels by
which sound energy is reduced in passing through the
structure. Units dB.

WAVELENGTH The wavelength of sound is the distance over which a

complete cycle occurs. It can be found by measuring distance
between the centres of compression of the sound waves. It is
dependent upon the frequency of the sound.

3.4 Building Acoustics: General Considerations and Provisions

Generalised considerations and provisions for planning and design of building are
furnished in this Section.

3.4.1 Classifications of Building Acoustics

3.4.1.1 Considering diversity of desired objectives and salient design features, building
acoustics can be broadly classified as,

(a) Acoustics for Speech

(b) Acoustics for Music

(c) Acoustics for Multipurpose

 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4711

Table 8.3.1 shows classifications of acoustics with brief description and examples of
spaces involved.

Table 8.3.1: Classifications of Building Acoustics, Brief Description and Examples of

Spaces Involved

Classifications Brief Description Examples of Spaces

(a) Acoustics Relates to speech with foremost objectives of Classroom, lecture

for Speech intelligibility. A space should have relatively hall, conference
lower reverberation time for speech. Generally, hall, recital hall,
it covers narrow range of frequency spectra in assembly hall,
lower-mid level (about 170 to 4,000 Hz, for an courtroom, audi-
average dynamic range of 42 dBA). torium for speech
etc.

(b) Acoustics Involves music with prime objectives of Music practice

for Music liveliness or reverberance, intimacy, fullness, booth, rehearsal
clarity, warmth, brilliance, texture, blend and room, band room,
ensemble. Music may include instrumental and listening booth,
vocal melody, or either of the two. A space orchestra, concert
requires relatively higher reverberation time for hall, symphony hall,
music. Generally, it involves broad range of cathedral etc.
frequency spectra (about 50 to 8,500 Hz, for an
average dynamic range of about 75 dBA).

(c) Acoustics Includes both speech and music acoustics to Multipurpose hall,
for fulfil objectives of the both at a rationally cinema, theatre,
Multipur- compromised level. Acoustics design of a opera house,
pose multipurpose space is quite challenging as the mosque (for speech
design objectives and measures vary remarkably and melodious
for speech and music. For example, there is a recitation), church,
significant variation in desired reverberation temple etc.
times of a space for speech and music.

3.4.1.2 A building or a building complex is usually a group of spaces or rooms

intended for various functions. Those spaces may require involvement of different types
of acoustics as stated in Table 8.3.1. For example, a school has spaces for speech (e.g.,
classroom), music (e.g., music room) and multipurpose (e.g., auditorium). Thus, a
building or a building complex should not be generally classified as a whole for a
particular type of acoustics, rather its spaces or rooms shall be classified individually and
appropriate acoustical design shall be considered accordingly.
4712 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

3.4.1.3 Spaces or rooms of a building or a building complex, if those even have

different types of acoustical requirements, shall be designed in such a way, so that those
can coexist and work as a whole.

3.4.2 Acoustical Planning and Design Targets

3.4.2.1 A space, involving either of the acoustical types stated in Sec 3.4.1, must
achieve few design targets. Some of these important design targets are mentioned below:

(a) Noise exceeding allowable limit should be controlled

(b) Speech intelligibility should be satisfactory

(c) Music should have liveliness, intimacy, fullness, clarity, warmth etc.

(d) The desired sound level must be optimum to be heard properly

(e) Diffusion of sound throughout the whole space

(f) There should be no defects such as echoes, flutter echoes etc.

3.4.2.2 Necessary planning and design measures shall be taken for achieving these
targets to optimum levels or standards as dictated in this Code.

3.4.3 Factors Affecting Acoustical Planning and Design

3.4.3.1 Among many, following are the most significant factors affecting acoustical
planning and design; noise, reverberation time, sound level and diffusion of sound.

3.4.3.2 For various types of building acoustics, as stated in Sec 3.4.1, the effects of
these factors might be different. These factors are dependent on different conditions, like
noise and sound level, room volume, building materials, surface materials, sound levels,
room geometry etc.

3.4.4 General Considerations and Provisions for Planning, Design, Assessment

and Construction

3.4.4.1 In Appendix F, a flow diagram summarises activities required for planning,

design, assessments and construction related to building acoustics.

3.4.4.2 Acoustical planning and design, including all parts and details, shall be
performed during design phase of any project and must comply with standards and codes
as dictated in this Code.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4713

3.4.4.3 During planning and design phase, the expected results for acoustical
performance of a space or a room or building, as dictated in different Sections of this
Chapter, shall be precisely analysed and assessed through standard practice, for example,
precise computational methods based on computer analysis, simulation and prediction
techniques.

3.4.4.4 Acoustical planning and design targets and expected results shall be clearly
specified and documented as a part of the design proposal.

3.4.4.5 Acoustical planning and design measures shall be compatible with

requirements of other environmental factors including natural light, ventilation and heat
for working in an overall synergy.

3.4.4.6 Acoustical planning and design measures shall be congenial to other design
parameters including function, structure and aesthetics for an overall harmony in design.

3.4.4.7 The proposal for acoustical design, materials, devices, supporting structures
and construction methods shall be safe for health during construction and post-
construction occupancy.

3.4.4.8 Acoustical materials, devices and supporting structures shall be safe in case of
disasters including earthquake and fire.
3.4.4.9 The acoustical design measures and materials shall be reasonably energy
efficient and compatible with Green Building practice.

3.4.4.10 Acoustical materials shall be eco-friendly, recyclable and should require

minimum maintenance. Those shall be compliant to sustainable acoustics in particular
and sustainable building practice in general.

3.4.4.11 It is recommended to conduct peer supervisions and periodic assessments at

different phases of construction process to rectify any drawback at its initial stage.

3.4.4.12 Post-construction and post-occupancy assessments shall be conducted and

findings shall be compared with expected results. Assessment shall include instrumental
measurements and opinion survey of occupants. If any discrepancy is found, the space
shall be modified until it reaches reasonably close to the expected result.

3.4.4.13 Preceding provisions shall be applicable for modifications of a space to

eliminate acoustical faults, retrofitting a space for acoustical performance or any other
acoustical design and construction activities.

3.4.4.14 Form G, Checklist: Acoustical Planning, Design and Post-occupancy

Assessments, as in Appendix G, shall be filled in and signed by the acoustical consultant
for each acoustical space or room or building of any project.
4714 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
3.5 Planning and Design For Noise Control

3.5.1 Types of Noise

3.5.1.1 Depending on location of source, noise might be of two types:
(a) Outdoor Noise.
Following are some common sources of outdoor noise:
(i) Traffic noise generated from air traffic, road traffic, rail traffic etc. (see
Appendix H)
(ii) Noise from zones and buildings within built-up areas, machinery,
appliances, construction activity, loudspeakers, people, animals etc.
(b) Indoor Noise.
Following are some common source of indoor noise:
(i) Household appliances, machinery, footsteps on floor, air conditioner duct
etc.
(ii) Activities performed by occupants, like people, pets etc.
3.4.2.2 Basing on transmission path, noise can be classified as
(a) Airborne Noise
Examples noise from appliances, car horn, telephone ring etc.
(b) Structure-borne Noise
Example footsteps, slamming of door, furniture movement, vibrating
mechanical equipment etc.

3.5.2 Design Sequence for Noise Control

3.5.1.1 In order to achieve noise control effectively, measures should be taken in the
following order:
(a) Suppression of noise generation at its source
(b) Layout planning
(c) Insulation design
(d) Absorption design

3.5.3 Planning and Design for Outdoor Noise Control

3.5.3.1 Planning to control outdoor noise is an integral part of country and town
planning ranging from regional to detailed zoning and three dimensional layouts of built
form and traffic routes.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4715

3.5.3.2 Noise causes more disturbances to people at rest than those at work. For this
reason, outdoor noise levels in various zones or areas should be considered in planning
and design with respect to critical hours of space occupancy (see Table 8.H.1,
Appendix H).

3.5.3.3 Planning and design of buildings shall consider all sources of noise mentioned in
Sec 3.5.1 and keep provisions to control those from transmitting in and around buildings.
For example, the orientation of buildings might be decided in way to reduce the noise
disturbance from noisy neighbourhood.

3.5.3.4 A noise survey shall be conducted and a Noise Map shall be prepared to
identify source, type, intensity, frequency and other parameters of noise in and around the
site of any specific project. Noise levels should be measured for pick and off pick hours
of both working and holidays, and also for 'Day Time' and 'Night Time' as defined in
'Noise Pollution (Control) Rules 2006' and its subsequent amendments by the
Government of the People's Republic of Bangladesh (see Table 8.H.1, Appendix H). The
noise levels shall be analysed statistically for value of L10, LAeg,T etc.

3.5.3.5 A Noise Map shall be used to examine compliance to the permissible upper
limit of noise levels set for different land use zones in the 'Noise Pollution (Control)
Rules 2006' and its subsequent amendments by the Government of the People's Republic
of Bangladesh (see Table 8.H.1, Appendix H). As references, intensity levels of some
common noise are shown in (see Table 8.H.3, Appendix H).

3.5.3.6 The planning should be undertaken in such a manner that the noise can be kept
at a distance. Quiet zones and residential zones should be placed with adequate setback
from noise sources, like airports, highways, railway lines and factories. It might be useful
to note that doubling the distance drops the sound pressure level by about 6 dBA.

3.5.3.7 Buildings (or parts of buildings) which are considered to be especially

susceptible to noise, including hospitals, research laboratories, recording studios or the
like, should not be sited near sources of noise.

3.5.3.8 It might be a preferable option to place a noise tolerant buffer zone, developing
green belt, public gardens etc. between a noisy zone and a quiet zone.

3.5.3.9 Noise barriers might be provided by placing buildings and occupancies less
susceptible to noise between the source and the more susceptible ones. Purpose built
noise barriers made of bricks, concrete, fibreglass, fibre reinforced plastic or other
materials can also be used to protect buildings from noise.
4716 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

3.5.3.10 If noise barriers (as stated in Sec 3.5.3.9) is neither attainable nor adequate, a
building itself should have all necessary measures to protect itself against outside noise.
The following might be some options:

(a) In zoning of spaces, noise tolerant spaces might be placed near a noise source,
while placing less-tolerant spaces at a distance.

(b) External walls or partitions should have appropriate Sound Transmission Class
(STC) to reduce external noise to the acceptable indoor background noise levels
(Tables 8.3.3 to 8.3.6, 8.E.1 and 8.E.2, Appendix E)

(c) Preferably, external walls near source of noise should not have any operable
window. However, to meet the demand of natural light, fixed widows allowing
only light might be placed with proper noise insulation measures.

(d) If need for operable windows allowing natural light and ventilation are
inevitable in external walls near source of noise, special measures should be
taken for restricting noise while allowing light and ventilation. Acoustic louvers,
active noise cancellation devices etc. are examples of these types of special
measures.

(e) If natural ventilation is required but natural light is not required, ventilation
ducts or chutes with lining of acoustic absorbers might be designed in a manner
to absorb noise while air flows through.

3.5.3.11 Following special provisions shall be applicable for air traffic noise:

(a) No building for human occupancy shall preferably be constructed, where NEF
value due to air traffic noise exceeds 40 EPN dBA. As a reference, typical noise
levels of some aircraft types are shown in Table 8.H.2, Appendix H.

(b) Educational institutions, hospitals, auditoriums etc. shall preferably be located at

places where the value of NEF is less than 25 EPN dBA.

(c) In areas exposed to less than 90 EPN dBA, all of the windows shall be closed
and properly sealed, having double glazing, in order to provide an acceptable
interior noise environment.

(d) Industrial and commercial activities generating high interior noise environments
might be located in areas exposed to noise levels greater than 90 EPN dBA.
(e) In airport areas of highest noise levels, sparsely manned installations like
sewage disposal plants, utility substations and similar other facilities might be
located.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4717

3.5.3.12 Following provisions shall be applicable for road traffic noise:

(a) For road traffic noise level, the value of L10 shall be limited to a maximum of 70
dBA for zoning and planning new buildings in urban areas, while dwellings are
proposed to have sealed windows.

(b) The maximum permissible upper limit of L10 shall be reduced to 60 dBA when
the dwellings are proposed to have open windows.

(c) Major new residential developments shall preferably be located in areas with L10
levels substantially lower than those specified above.

(d) Where L10 is greater than 70 dBA, design solutions such as barrier blocks, noise
buffers or purpose built noise barriers shall be utilized in order to reduce noise
levels at least to that level.
(e) Through traffic roads shall preferably be excluded from quiet and residential
zones to avoid excessive traffic noise.

(f) In the neighbourhood of residential, educational, institutional and health care

buildings, legislative control shall be exercised for road noise particularly from
vehicles as dictated in 'Noise Pollution (Control) Rules 2006' and its subsequent
amendments by the Government of the People's Republic of Bangladesh.

3.5.3.13 Following special provisions shall be applicable for rail traffic noise:

(a) No residential or public building, except for the railway station and its ancillary
structures, shall preferably be connected to the railway lines.

(b) Mercantile or commercial buildings should not abut the railway lines or the
marshalling yards. Only planned industrial zones may be located beside the
railway tracks.
(c) In order to reduce the high noise levels, produced at the arrival and departure of
trains, platforms in railway stations shall be treated with sound absorbing
materials particularly on the ceiling.

(d) The main platform floor shall be separated from the station building with a
minimum gap of 50 mm so that the ground or structure-borne vibrations are not
transmitted to the building.

(e) Windows and other openings shall preferably be placed as less as possible in the
facade along the railway tracks.

(f) Greenbelts, landscaping or any other form of barrier might be developed along
the railway lines.
4718 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

3.5.3.14 Construction noise shall be controlled according to the 'Noise Pollution

(Control) Rules 2006' and its subsequent amendments by the Government of the People's
Republic of Bangladesh.

3.5.4 Planning and Design for Indoor Noise Control

3.5.4.1 The allowable upper limits of indoor background noise levels (in dBA) are as
shown in Table 8.3.2 and Figure 8.D.1 in Appendix D. Design shall comply with
recommended range of Balanced Noise Criteria (NCB) Curve for different types of
activity.

Table 8.3.2: Allowable Upper Limit of Indoor Background Noise Levels and
Recommended Range of NCB Curves

Type of Space dBA NCB Curve

Broadcast and recording studios (distant microphone used) 18 10

Concert halls, opera houses, and recital halls 18-23 10-15

Large theatres and auditoriums, mosques, temples, churches and

<28 <20
other prayer spaces

Television and recording studio (close microphone used) <33 <25

Small theatres, auditoriums, music, rehearsal rooms, large

<38 <30
meeting and conference rooms

Bedrooms, hospitals, hotels, residences, apartments, etc. 33-48 25-40

Classrooms, libraries, small offices and conference rooms.

38-48 30-40
Living rooms, and drawing rooms in dwellings

Large offices, receptions, retail shops and stores, cafeterias,

restaurants, indoor stadiums, gymnasium, large seating-capacity 43-53 35-45
spaces with speech amplification

Lobbies, laboratory, drafting rooms, and general offices 48-58 40-50

Kitchens, laundries, computer and maintenance shops 53-63 45-55

Shops, garages, etc. (for just acceptable telephone conversation) 58-68 50-60

For work spaces where speech is not required 63-78 55-70

 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4719

3.5.4.2 Noise generated from within a building shall not be transmitted to

neighbourhood at a noise level higher than the allowable upper limit set for that zone (see
Table 8.H.1, Appendix H).
3.5.4.3 Buildings, in which there are some sources of noise, shall have buffers
separating the noise producing area from the other areas. The less vulnerable areas of the
building may be planned to act as noise buffers.
3.5.4.4 In the assessment of indoor noise levels, direct sound shall be separated from
reverberant sound.
3.5.4.5 The reverberant sound transmitted from one room to another shall be cut down
by employing suitable sound absorption materials and by structural and non-structural
partitions.

3.5.5 Sound Insulation

3.5.5.1 The recommended sound insulation criteria are classified in some Grades. The
STC value for airborne sound insulation is graded as stated below (see also, Figure 8.D.2,
Appendix D):
(a) Grade I STC = 55 Apply mainly to fully residential, quiet rural and suburban
areas and in certain luxury apartment buildings.

(b) Grade II STC = 52 Apply to residential spaces in relatively noisy

environments, typical of urban and suburban areas.

(c) Grade III STC = 48 Express minimal requirements applicable to very noisy
locations, such as commercial or business areas, like shop
houses with dwelling units on the upper floors, or
downtown areas.
3.5.5.2 Transmission of sound should be controlled with appropriate material, assembly
of building elements. Typical STC rating for different types of building element, like
stud partitions, masonry walls, doors, windows and interior partitions are shown in Table
8.E.1, Appendix E.
3.5.5.3 Recommended STC for partitions for specific occupancies are shown in Table
8.E.2, Appendix E.

3.5.6 Control of Structure-borne Impact Noise

3.5.6.1 Impact noise problems can be controlled in following ways:
(a) Preventing or minimising the impact by cushioning the impact with resilient
materials, like floor tiles of rubber and cork, carpeting on pads with desired
Impact Isolation Class (IIC). Criteria for airborne and impact sound insulation of
floor-ceiling assemblies between dwelling unit, Tables 8.3.3 and 8.3.4.
4720 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(b) Floating the floor for isolating the impacted floor from the structural floor by a
resilient element is extremely effective. This element can be rubber or mineral
wood pads, blankets or special spring metal sleepers.

(c) Suspending the ceiling and using an absorber in the cavity.

(d) Isolating all rigid structures, such as pipes, and caulking penetrations with
resilient sealant.

Table 8.3.3: Airborne Sound Insulation of Partitions between Dwelling Units

Apt. A Apt. B Grade II Apt. A Apt. B Grade II

STC STC

Bedroom to Bedroom 52 Bathroom to Living room 54

Living room to Bedrooma 54 Corridor to Living 52

rooma,c,d

Kitchenb to Bedrooma 55 Kitchen to Kitchene 50

Bathroom to Bedrooma 56 Bathroom to Kitchen 52

Corridor to Bedrooma,c 52 Corridor to Kitchena,c,d 52

Living room to Living room 52 Bathroom to Bathroom 50

Kitchenb to Living 52 Corridor to Bathrooma,c 48
rooma

Notes:

For Grade I, add 3 points; for Grade III, subtract 4 points.

a
Whenever a partition wall may serve to separate several functional spaces, the
highest criterion must prevail.
b
Or dining or family or recreation room.
c
It is assumed that there is no entrance door leading from the corridor to the living
unit.
d
Criterion applies to the partition. Doors in corridor partition must have the rating
of partition, not vice versa.
e
Double wall construction is recommended to minimise kitchen impact noise.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4721

Table 8.3.4: Airborne and Impact Sound Insulation of Floor-Ceiling between

Dwelling Units
Apt. A Apt. B Grade II Grade II Apt. A Apt. B Grade II Grade II
STC IIC STC IIC

Bedroom above Bedroom 52 52 Living room above Kitchenc,e 52 52

Living room above Bedrooma 54 57 Kitchen above Kitchenc 50 52

Kitchenb above Bedrooma,c 55 62 Bathroom above Kitchena,c 52 52

Family room above Bedrooma,d 56 62 Family room above Kitchena,c,d 52 58

Corridor above Bedrooma 52 62 Corridor above Kitchena,c 48 52

Bedroom above Living roome 54 52 Bedroom above Family roome 56 48

Living room above Living room 52 52 Living room above Family roome 54 50

Kitchen above Living rooma,c 52 57 Kitchen above Family roome 52 52

Family room above Living rooma,d 54 60 Bathroom above Bathroomc 50 50

Corridor above Living rooma 52 57 Corridor above Corridor 48 48

Bedroom above Kitchenc,e 55 50

Notes:

For Grade I, add 3 points; for Grade III, subtract 4 points.

a
Arrangement requires greater impact sound insulation than inverse, where a
sensitive area is above less sensitive area.
b
Or dining or family or recreation room.
c
It is assumed that the plumbing fixtures, appliances and piping are insulated with
proper vibration isolation.
d
The airborne STC criteria in this table apply as well to vertical partitions between
these two spaces.
e
This arrangement require equivalent airborne sound insulation than the converse.

3.5.7 Control of Electro-Mechanical System Noise

3.5.7.1 Mechanical noise is generated from mechanical devices like air-conditioning

and air-handling systems, lifts, escalators, pumps, electric generators etc.
4722 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

3.5.7.2 Mechanical noise problems can be controlled in following ways:

(a) Reducing the vibration of electro-mechanical equipment by damping and
isolation.
(b) Reducing the airborne noise by decoupling the vibration from efficient radiating
sources.
(c) Decoupling the vibrating source from the structure.
(d) In air-conditioning duct system, smooth transitions at changes of duct size, large
radius bends, lining with absorbing materials etc. are effective measures.
(e) Active noise cancellation technique, by producing a synthesised signal exactly
out-of-phase with the original noise signal to make the resultant signal
effectively zero, might be applied in special cases.

3.5.8 Occupational Noise Exposure

3.5.8.1 Protection against the effects of noise exposure shall be provided when the
sound level exceeds those shown in Table 8.3.5.
3.5.8.2 Exposure to impulsive or impact noise should not exceed 140 dBA peak sound
level.

Table 8.3.5: Permissible Noise Exposure

Sound Level Duration per Day Sound Level Duration per

dBA (slow Hour - Minute dBA (slow Day
response) response) Hour - Minute

85 16-00 98 2-50
86 13-56 99 2-15
87 12-08 100 2-00
88 10-34 101 1-44
89 9-11 102 1-31
90 8-00 103 1-19
91 6-58 104 1-09
92 6-04 105 1-00
93 5-17 106 0-52
94 4-36 107 0-46
95 4-00 108 0-40
96 3-29 109 0-34
97 3-02 110 0-30
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4723

Notes:

(i) The sound level should be measured on A scale at slow response.

(ii) When the daily noise exposure is composed of two or more periods of noise
exposure of different levels, their combined effect should be considered, rather than
the individual effect of each. If the sum of the following fractions: C1 /T1 + C2 /T2 +
..... Cn /Tn exceeds unity, then, the mixed exposure should be considered to exceed
the limit value. Cn indicates the total time of exposure permitted at that time.

3.6 Reverberation Time, Sound Pressure Level and Diffusion of Sound

3.6.1 General Considerations

(a) For an overall performing, comfortable and safe acoustical environment, along
with the issues of noise, other significant aspects of acoustics should be
considered. This shall include sound pressure level, reverberation time and
diffusion of sound.

(b) Speech intelligibility is a significant parameter to achieve satisfactory acoustical

design. Percentage Syllable Articulation (PSA) is an index for assessing speech
intelligibility. PSA can be expressed as

PSA = 96 ki kr kn ks (%) (for English Language)

PSA = 93 ki kr kn ks (%) (for Bangla Language)

Where,

ki, kr, kn and ks are the coefficient for average speech level, Reverberation
Time, Noise level/ Speech level and room shape, respectively (see Figure
8.I.1, Appendix I).

(c) For a PSA of 82%, almost a perfect Speech Intelligibility (nearly 100%) can be
achieved. However, in reality, there are some background noise (>20 dBA) and
reverberation time in different spaces, causing lower PSA. The minimum
admissible PSA should be 75% for a satisfactory Speech Intelligibility.

3.6.2 Reverberation Time

Spaces for various uses should be designed for recommended optimum reverberation
time to achieve a level of intelligibility and liveliness (see Figure 8.3.1).
4724 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
3.6.3 Sound Pressure Level

(a) In a space with a low background noise (<20 dBA) and a minimum
Reverberation Time (close to 0.0 s), a maximum Percentage Syllable
Articulation (PSA), and thus Speech Intelligibility can be achieved at sound
pressure level of speech ranging from 60 dBA to 70 dBA (see Figure 8.I.1,
Appendix I).
(b) For speech halls with higher background noise (>20 dBA), the recommended
Signal-to-Noise Ratio (SNR) is +15 dBA for children and at least +6 dBA for
adults.

Notes:
(i) The optimum RT for speech is shown here for English and Bangla language. It
might be noted that the recommended optimum RT for speech in Bangla ranges
from 0.5 s to 0.8 s.
(ii) The figure shows optimum RT for Western music and English vocals. For local
music of Bangladesh, optimum RT might be assumed from its typological
similarity to that of Western music.

Figure 8.3.1 Recommended optimum reverberation times for spaces of various uses
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4725
3.6.4 Diffusion of Sound

(a) Diffusion of sound should be achieved in any space, so that certain key
acoustical properties, like sound pressure level, reverberation time etc. are the
same anywhere in the space.
(b) There shall not be a difference greater than 6 dBA between sound pressure
levels of any two points in the audience area.

(c) Appropriate room geometry should be chosen to achieve diffusion of sound.

Figure 8.E.2, Appendix E shows recommended proportion of a space to avoid
standing wave, flutter echo etc., which are obstacles to achieve diffusion of
sound.

3.7 Speech Privacy

3.7.1 Principle of Speech Privacy between Enclosed Spaces

3.7.1.1 When noise carries information, productivity and noise are related inversely.
When noise does not carry information, it can be annoying, counterproductive or can be
useful as a masking sound, depending upon its frequency, intensity level and constancy.

3.7.1.2 The degree of speech privacy in a space is a function of following two factors:

(a) The degree of sound isolation provided by the barriers between rooms

(b) The ambient sound level in the receiving room

3.7.1.3 In case of an airtight barrier between two rooms, the sound intensity level of the
source room (1) and the receiving room (2) are related as,
IL2 = IL1 - NR

where, NR is reduction, IL2 and IL1 are sound intensity levels in the receiving
and source room respectively.

3.7.1.4 Transmitted noise level IL2 is not annoying to a majority of adults, if a properly
designed background sound is a maximum 2 dBA less than IL2. For example, a
transmitted noise IL2 of 40 dBA in a room with a background sound of at least 38 dBA
will not cause annoyance to most people.

3.7.1.5 The upper intensity level of usable background masking sound is usually taken
as about 50 dBA; any higher intensity level itself will cause annoyance.

3.7.2 Sound Isolation Descriptor

3.7.2.1 For speech sound, a descriptive scale is shown in Table 8.3.6

4726 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
3.7.2.2 Relation between barrier STC and hearing condition on receiving side with
background noise level at NC-25 is shown in Table 8.3.7

Table 8.3.6: Relative Quality of Sound Isolation

Ranking Descriptor Hearing Conditiona

6 Total privacy Shouting barely audible.

5 Excellent Normal voice levels not audible. Raised voices barely audible
but not intelligible.

4 Very good Normal voice levels barely audible. Raised voices audible but
largely unintelligible.

3 Good Normal voice levels audible but generally unintelligible.

Raised voices partially intelligible.

2 Fair Normal voice levels audible and intelligible some of the time.
Raised voices generally intelligible.

1 Poor Normal voice levels audible and intelligible most of the time.

0 None Normal voice levels always intelligible.

a
Hearing condition in the presence of ambient noise, if any.

Table 8.3.7: Barrier STC and Hearing Condition on Receiving Side with
Background Noise Level at NC-25

Descriptor
Barrier
Hearing Condition and Application
STC
Rankinga

25 Normal speech can be understood quite Poor/1 Space divider

easily and distinctly through the wall.

30 Loud speech can be understood fairly Fair/2 Room divider where

well. Normal speech can be heard but concentration is not
not easily understood. essential

35 Loud speech can be heard but not easily Very Suitable for offices
intelligible. Normal speech can be Good/4 next to quiet spaces
heard only faintly, if at all.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4727

Descriptor
Barrier
Hearing Condition and Application
STC
Rankinga

42-45 Loud speech can be faintly heard but Excellent/5 For dividing noisy and
not understood. Normal speech is quiet areas; party wall
inaudible. between apartments

46-50 Very loud sounds (such as loud singing, Total Music room, practice
brass musical instruments or a radio at Privacy/6 room, sound studio,
full volume) can be heard only faintly bedrooms adjacent to
or not at all. noisy areas
a
See Table 8.3.6.

3.7.3 Speech Privacy Design for Enclosed Space

3.7.3.1 Figure 8.J.1, Appendix J shows a Speech Privacy Analysis Sheet, which shall be
used to determine speech privacy rating number for design of enclosed space.
3.7.3.2 Following factors are involved in speech privacy rating of enclosed-space:
(a) Space rating of source room (Room No. 1)
(i) Speech effort - a measure of loudness of speech
(ii) Source room factor - gives the approximate effect of room absorption on the
speech level in the source room. The scale in Figure 8.J.1, Appendix J
represents average absorption. For live rooms the factor should be raised by
2 points and for dead room the factor should be lowered by 2 points. Factors
(a + b) give the approximate source-room voice level.
(iii) Privacy allowance-determines the measure of privacy required, such as
Normal Privacy and Confidential Privacy.
(b) Isolation rating of receiving room (Room No. 2)
(i) The STC rating of the barrier (see Tables 8.E.1 and 8.E.2, Appendix E)
(ii) Noise reduction factor A2/S indicates receiving room absorption, that is, the
difference between NR and TL, where A2 is the area of receiving room and S
is the area of the barrier between the rooms. Absorption is assumed to be
average. For live rooms the factor should be lowered by 2 points and for
dead room the factor should be raised by 2 points.

(iii) Recommended background noise level in the receiving room. As a

reference, Table 8.3.2 might be used.
4728 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
3.8 Sound Amplification System

3.8.1 Objectives and Design Criteria

3.8.1.1 A well designed sound amplification system should augment the natural
transmission of sound from source to listener with adequate loudness and diffusion. It
should never be used as a substitute for good building acoustics design, because it rarely
overcomes or corrects any serious deficiency; rather, it may amplify and exaggerate the
deficiency.

3.8.1.2 An ideal sound amplification system shall give the listener the desired loudness,
directivity, intelligibility and other acoustical qualities.

3.8.1.3 Spaces seating less than 500 (approximately, 1400 m3 volume) should not
require any sound amplification system if it is properly designed; since, a normal
speaking voice can maintain speech level of 55 to 60 dBA in this volume of space.

3.8.1.4 The central type amplification system is preferred, in which a loudspeaker or a

cluster of loudspeakers is placed directly above the source of sound to provide desired
realism and intelligibility. In case, the ceiling height is low and sound cannot reach all
listeners from a central type; a distributed system can be used with a number of
loudspeaker each serving a small area with low-level amplification. A distributed system
is particularly feasible in areas under the balcony.

3.8.1.5 A careful location of microphone should be chosen to avoid feedback of sound

from loudspeaker to the microphone.

3.9 Occupancy A: Residential Buildings

3.9.1 Controlling Noise

Controlling measures shall have to be taken against noise coming from outdoor and
indoor sources as specified in Sections 3.4 and 3.5.

3.9.2 Space Layout

(a) Quiet and noisy quarters shall be grouped and separated horizontally and
vertically from each other by rooms (or spaces) not particularly sensitive to
noise such as entry, corridor, staircase, wall closets or other built-in building
components.
(b) If a living room in one apartment is located adjacent to a living room in another
apartment, adequate sound insulation should be provided in separating wall.

(c) Bedrooms shall be located in a relatively quiet part of the building.

 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4729

(d) Bathrooms must be separated acoustically from living rooms both horizontally
and vertically.
If bathroom fixtures are installed along walls which separate living room and
bathroom, adequate sound insulation should be provided in separating wall.
(e) Measures should be taken to avoid transmission of footstep noise through floors.

3.9.3 Sound Insulation Factors

(a) Separation for Sound Insulation: The sound insulation criteria in residential units
are to be based on three grades:
(i) Grade I criteria apply mainly to fully residential, quiet rural and suburban
areas and in certain cases to luxury apartment buildings or to dwelling
units above the eighth floor of a high-rise building.
(ii) Grade II criteria apply to residential buildings built-in relatively noisy
environments typical of urban or suburban areas.
(iii) Grade III criteria express minimal requirements applicable to very noisy
locations, such as commercial or business areas (like shop houses with
dwelling units on the upper floors) or downtown areas.
(iv) Among the above three categories, Grade II covers the majority of
residential constructions and shall therefore be regarded as a basic guide.
(v) In all grades wall constructions and floor-ceiling assemblies between
dwelling units shall have STC ratings at least equal to the values given in
Tables 8.3.3 and 8.3.4.
(vi) An STC rating of not less than 45 dB is to be provided in walls and floors
of residential buildings, between dwelling units of the same building and
between a dwelling unit and any space common to two or more dwelling
units.
(vii) Table 8.E.2, Appendix E shows STC requirements for different spaces of
specific occupancies.
(b) Reduction of Airborne Noise : In case of air borne noise (between the frequency
range 100-31500 Hz), a sound insulation of 50 dB shall be provided in between
the living room in one house or flat and rooms/bed rooms in another. The value
shall be 35 dB in between different rooms of the same house. (See Appendix E
for airborne sound insulation properties of walls, doors and windows).
(c) Reduction of Airborne Noise Transmitted through the Structure: Exterior walls
shall be rigid and massive and have good sound insulation characteristics with as
few openings as possible. Windows with acoustic louvers might be used to
protect noise intrusion, while allowing ventilation.
4730 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Ventilation ducts or air transfer openings (ventilators), where provided, shall be

designed to minimize transmission of noise, if necessary, by installing some
attenuating devices.

(d) Construction of sound insulation doors shall be of solid core and heavy
construction with all edges sealed up properly. Hollow core wooden doors and
light weight construction shall be avoided because these are dimensionally
unstable and can warp, destroying the seal along the perimeter of the door.

(e) Rubber, foam rubber or foamed plastic strips, adjustable or self-aligning stops
and gaskets shall be used for sealing the edges of the doors. They shall be so
installed that they are slightly compressed between doors and stop when the
door is in a closed position. In simple cases the bottom edges shall have a
replaceable strip of felt or foam rubber attached to minimize the gap between
door and floor.

(f) Separation between the two faces of the door shall be carried through
uninterruptedly from edge to edge in both directions. Damping treatments shall
be inserted between individual layers of the doors. Ordinary doors with surface
leather padding shall not be used.
(g) Automatic damped door closers are to be used whenever applicable and
economically feasible in order to avoid the annoying sound of doors slamming.

(h) The difference between the TL of the wall and that of the door shall not exceed
10 dB.
(i) The floor of a room immediately above the bedroom or a living room shall
satisfy the Grade I impact sound insulation.

3.10 Occupancy B: Educational and Occupancy C: Institutional Buildings

3.10.1 Sources of Noise

3.10.1.1 Outdoor Noise: Measures shall be taken in planning and design to control noise
from external sources mentioned in Sections 3.4 and 3.5.
3.10.1.2 Indoor Noise:
The following sources of indoor noise shall be taken into consideration:
(a) Wood and metal workshops, machine shops, technical as well as engineering
testing laboratories, other machine rooms, typing areas etc. which produce
continuous or intermittent noises of disturbing nature,
(b) Music rooms,
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4731

(c) Assembly halls, particularly those which are attached to the main building,

(d) Practical work spaces, gymnasiums and swimming pools,

(e) School kitchen and dining spaces,

(f) Entry lobby, foyer, lounge, corridor and other circulation spaces.

3.10.2 Planning and Design Requirements

3.10.2.1 Site Planning: The school building shall be located as far away as possible
from the sources of outdoor noise such as busy roads, railways, neighbouring market
places or adjacent shopping areas as well as local industrial and small scale
manufacturing concerns.

Where the site permits, the building shall be placed back from the street, in order to make
use of the noise reducing effect of the increased distance between street line and building
line.

If adequate distance between the school/institution building and the noisy traffic route
cannot be provided, rooms which do not need windows or windowless walls of
classrooms shall face the noisy road.

Car parking areas shall preferably be located in remote parts of the site.

3.10.2.2 Activities and Space Layout: The minimum requirement for sound insulation in
educational buildings shall be as specified in Table 8.3.5.

3.10.2.3 Halls and Circulation Areas: The lobby, lounge areas etc. or other circulation
spaces and linking corridors shall be separated from teaching areas, lecture galleries or
laboratories. No direct window openings shall be placed along the walls of the corridors
or circulation areas.

Doors, ventilators and other necessary openings shall be designed with sufficient foam or
rubber seals, so that they are noise proof when closed.

3.10.2.4 Noise Reduction within Rooms: Lecture halls of educational institutions (with a
seating capacity of more than 100 persons) shall be designed in accordance with the
relevant acoustical principles.

Lecture halls with volumes of up to about 550 m3 or for an audience of up to about 150 to
200, shall not require a sound amplification system, if their acoustical design is based on
appropriate principles and specifications.

A diagonal seating layout shall preferably be used for rectangular lecture rooms of the
capacity mentioned above as it automatically eliminates undesirable parallelism between
walls at the podium and effectively utilizes the diverging front walls as sound reflectors.
4732 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
3.11 Occupancy D: Health Care Buildings

3.11.1 Sources of Disturbing Noise

3.11.1.1 Outdoor Noise: Sources of outdoor noise specified in Sec 3.4 shall be taken into
consideration for planning and design. Additionally, health care service facilities like
ambulance, medicine and equipment vans, store deliveries, laundry and refuse collection
trolleys are also frequent sources of noise. Health care buildings shall be sited away from
such sources as far as practicable.

3.11.1.2 Indoor Noise: Indoor noise sources include mechanical and mobile equipment
like X-ray and suction machines, drilling equipment etc. Planning and design shall take
into account the following sources of noise:

(a) The handling of sterilizing, as well as metal or glass equipment,

(b) Wheeled trolleys used for the purpose of carrying foods and medical supplies,

(c) Mechanical equipment like mechanical and electrical motors, machineries,

boilers, pumps, fans, ventilators, transformers, elevators, air-conditioning
equipment etc.

(d) Operational facilities like refrigerators, sterilizers, autoclaves etc. ,

(e) Patient service facilities including oxygen cylinders or tanks, saline stands,
carrier carts and instrument cases, etc.

(f) Maintenance work of engineering services like plumbing and sanitary fixtures or
fittings, hot and cold water and central heating pipes, air-conditioning ducts,
ventilation shafts etc., and

(g) Audible calling systems, radio and television sets.

3.11.2 Planning and Design Requirements

3.11.2.1 Site Planning: Site shall be selected to keep adequate distance from traffic noise
from highways, main roads, railroads, airports and noise originating from parking areas.
In addition to the requirements of Sec 4.4.3, the following requirements shall be fulfilled:

(a) In the selection of a site and site planning, consideration shall be given to:

(i) Distance from exterior noise,

(ii) Effect of high buildings adjacent to the site which can act as noise
reflectors, and

(iii) Traffic conditions surrounding the site.

 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4733

(b) Parking areas might be carefully located at the farthest possible corners of the
premises. If enough space is not available to provide facilities for the desired
number of vehicles, parking spaces shall be provided in more than one area.
Loading platforms and service entries are to be planned in such a manner as to
minimize noise in areas requiring silence.

(c) Closed courts shall preferably be avoided.

3.11.2.2 Activities and Space Layout: The following points might be given due
consideration in the planning and design of health care buildings.

(a) Rooms to be used for board meetings, conferences, counseling and instructional
purposes shall be grouped near public zones of the building in such a way that
spread of noise can be avoided.

(b) Long corridors might be avoided, as it may freely spread noise.

(c) The main kitchen might be housed in a separate building and connected to the
wards only by service lifts or a service stair. If this is impracticable, it shall be
planned beneath the wards, rather than above them.

(d) Mechanical plants might preferably be placed in separate buildings.

(e) Rooms housing equipment, operational facilities and patient service facilities
shall be designed for adequate sound insulation.

(f) Closed courts might be avoided, unless rooms facing the court are air-
conditioned with completely sealed and air tight windows.

(g) The units which are themselves potential sources of noise for example,
children's wards and outpatient departments, shall be treated with special care
regarding the protection against noise.

3.11.2.3 Noise Reduction in the Sensitive Area: In health care buildings, many
sensitive areas such as operation theatres, doctor's consultation rooms, intensive care
units and post-operative areas shall be provided with special noise control arrangements.

These rooms shall preferably be isolated in locations (or corners) surrounded by other
intermediate zones which ensure protection of the core area from outdoor noise.

A sound reduction of about 45 dBA between the consulting and the waiting rooms shall
be provided in order to weaken the transmission of sound.

A lobby like space in between the interconnecting and communicating doors shall be
provided.
4734 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
3.11.2.4 Sound Insulation Factors: The rooms and indoor spaces of a health care
building shall be treated with sound absorptive materials. Different STC ratings of walls
specified for separate components of buildings shall have to be considered as follows:
(a) For airborne noise, the average STC rating of wall and floors shall be 50 dB.
(b) An STC rating of 55 dB shall be required between rooms whose occupants are
susceptible to noise.
(c) In general an average STC of 45 dB is to be provided for corridor walls and for
walls between patient rooms.
(d) All doors shall be fitted with silent closers. Doors to opposite rooms might be
positioned in a staggered manner.
(e) For ward doors, a corresponding STC of 35 dB shall be provided.
(f) PVC mats, rubber mats or other resilient materials and rubber shod equipment
shall be used in utility rooms, ward kitchens and circulation areas as floor
coverings.
Other finish materials like rubber tile, cork tile, vinyl tile or linoleum which can
also help reduce the impact noise substantially shall be used alternatively.
(g) Mobile equipment, such as trolleys and bed, oxygen cylinder carriers and
stretchers shall be made relatively silent by means of non-friction wheels with
rubber tyre.
(h) Special treatments such as thin nonporous coverings or films over some soft
absorbent materials shall be used for good sound absorption when a washable
acoustical treatment is desired.
(i) Door and window curtains or screens, as well as bed sheets etc. shall be used
wherever the indoor openings are located to help reduce reverberation in the
hard surfaced surroundings. Curtain rails, rings and runners of silent type shall
be used so that they generate as little frictional noise as possible.
(j) Ventilation ducts and conduits shall be laid out in such a way that they do not
open an easy by-pass for spreading out any noise from other sources. These
conduits and ducts shall be completely sealed around the pipes where they pass
through walls and floors.
(k) Special care shall be taken to reduce noise of plumbing equipment and fixtures.
Specially made silencing pipes and flushing fixtures shall be used to reduce the
noise of water closet and cisterns in lavatories and toilets.
Ducts carrying waste or water pipes shall be properly lined with sound
insulation material to prevent noise from the pipes passing through duct walls
into the patients' wards or cabins or the spaces susceptible to noise.
(l) Wherever available, cisterns shall be used to replace the pressure operated
flushing system so that the disturbance becomes less irritating.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4735
3.12 Occupancy I: Assembly

3.12.1 General

Buildings of Occupancy I shall be designed both for transmission of noise through the
walls and openings and also for internal acoustics. Public address systems installed in
such buildings shall conform to the standards and specifications.

3.12.2 Sources of Noise

3.12.2.1 Outdoor Noise: The following sources of noise shall be taken into account in
planning and design:

(a) Traffic noise (air, road and rail) and noise from other outdoor sources entering
through walls, roofs, doors, windows or ventilation openings,

(b) Noise from any other gathering spaces, public meetings, outdoor activities and
crowds, particularly during the time of breaking of shows and performances,

(c) Noise produced from parking areas.

3.12.2.2 Indoor Noise: The following indoor noise sources shall be taken into account in
planning and design:
(a) Noise from other adjacent halls located within the same building used for similar
performance, or for seminar, symposium or general meetings,

(b) Noise produced from ticket counters, lobby or lounge areas, rehearsal rooms,
waiting areas and corridors,

(c) Noise generated from other ancillary services located within the building, like
cafeteria or snack bar, tea shop, post office, bank or the like,

(d) Noise generated from the mechanical or electrical equipment, air-conditioning

plants, ventilation channels and ducts, plumbing and water lines etc.

3.12.3 Planning and Design Requirements

3.12.3.1 Site Planning and Acoustical Requirements: The noise control of auditoria or
assembly halls shall begin with sensible site planning following the measures and
precautions stated below:

(a) The auditorium shall be effectively separated from all exterior and interior noise
and vibration sources as far as practicable;

(b) The assembly halls shall be protected from vehicular or air traffic, parking or
loading areas, mechanical equipment, electrical rooms or workshops.
4736 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

The following are the acoustical requirements for good hearing conditions in an
auditorium which shall be ensured in planning and design:

(a) Adequate loudness shall have to be ensured in every part of the auditorium;

(b) The sound energy shall be uniformly distributed in the hall;

(c) Optimum reverberation characteristics shall have to be provided;

(d) The hall shall be free of such acoustical defects as echoes, long delayed
reflections, flutter echoes, sound concentrations, distortions, sound shadow and
room resonance etc.;
(e) Noise and vibration shall be excluded or reasonably reduced in every part or the
hall room.

3.12.3.2 Activities and Space Layout in Divisible and Multi-purpose Auditoria

(a) A protective buffer zone of rooms between exterior noise source and auditorium
proper shall be designed.

(b) Rooms in the buffer zone (lobbies, vestibules, circulation areas, restaurants,
ticket counters, offices etc.) shall be shut off from the auditorium proper by
sound insulation doors.

(c) The purposes of the subdivided spaces shall be clarified, in order to establish the
predictable intensity of the various sound programs.

3.12.3.3 Noise Reduction within Rooms

(a) There shall not be any use of continuous, unrecognizable and loud background
noise.

(b) The ventilating and air-conditioning system shall be so designed that the noise
level created by the system is at least 10 dB below the permissible background
noise level specified in noise criteria level.

(c) In order to protect the hall from external noise the minimum sound reduction
value required in an auditorium is 65 dB for a concert hall and 60 dB for a
theatre. This reduction shall be provided on all sides.

3.12.3.4 Sound Insulation Factors

(a) Rooms in the buffer zone (lobbies, vestibules, circulation areas, restaurants,
counter and issue desk corners, office etc.) shall have sound absorbing ceilings
and carpeted floor. If the rooms are to be used for the purposes of verbal
instructions only, a moderate degree of sound insulation (STC 40 to 45 dB) shall
be accomplished by the movable partitions.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4737

(b) If audio equipment or loudspeakers are to be used, an acoustically more

effective, efficient partition system shall be used, with sound insulation of STC
45 to 50 dB.
(c) An insulation of STC 50 to 60 dB shall be provided if any section of the space is
selected for the performance of live music.
(d) All windows shall have to be eliminated from the main auditorium walls in
order to exclude excessive outdoor noises.
(e) Suspended ceilings shall accommodate the ventilating, air-conditioning and
electrical services above the room.
(f) In order to increase the effectiveness of the suspended ceilings the following
measures shall be taken :
(i) The ceiling membrane shall weigh not less than 25 kg/m2;
(ii) The ceiling membrane shall not be too rigid;

(iii) Noise transmission through the ceiling shall have to be avoided by the use
of a solid, airtight membrane;

(iv) Gaps between ceiling and surrounding structure shall be sealed;

(v) The air space between ceiling membrane and structural floor shall be
increased to a reasonable maximum;

(vi) An absorbent blanket is to be used in the air space above the ceiling;

(vii) The number of points of suspension from the structural floor above shall
be reduced to a minimum;

(viii) Hangers made of resilient substance shall be preferable to the rigid ones.

(g) In order to improve the airborne or impact sound insulation of a ceiling the
following specifications shall be followed:

(i) The ceiling membrane shall have a minimum of 25 mm solid cement

plaster layer with completely closed, airtight and sealed joints all around;
(ii) If further reduction of undesirable noise is desired within a sound insulated
room, sound absorptive treatment shall be provided along the underside of
the solid ceiling.
3.12.3.5 Masking Noise: The artificial noise produced by electronically created
background noise for the purpose of drowning out or masking unwanted noise, shall be
provided. The process shall effectively suppress minor intrusions which might interrupt
the recipient's privacy.
4738 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
3.12.3.6 The maximum permissible background noise levels in various occupancies are
specified in terms of Balanced Noise Criteria (NCB) curves. Each of the NCB curves is
expressed by the sound pressure level values in the important 1200-2400 Hz frequency
band. The NCB levels shall be used to specify the desirable lowest limit under which the
background noise must not fall. (See Table 8.3.1 and Figure 8.F.1, Appendix F).
Note: The general configuration of the NCB curves is quite similar to the noise rating
(NR) curves established by the International Organization for Standardization, used
mostly in the European practice.

3.13 Occupancy E: Business and Occupancy F: Mercantile Buildings

3.13.1 General
Buildings of Occupancy E and F shall be planned and designed to minimize noise from
external and internal sources.

3.13.2 Sources of Disturbing Noise

3.13.2.1 Outdoor Noise: The following sources of outdoor noise and those specified in
Sec 3.4 shall be taken into account in the planning and design of business and mercantile
buildings:
(i) Traffic,
(ii) Playgrounds,
(iii) Market places and shopping areas,
(iv) Crowds grouped around the buildings for business purpose or other.
3.13.2.2 Indoor Noise: The following sources of indoor noise shall be identified for
noise attenuation within buildings:
(a) Mechanical noise, caused by heating, ventilating and air-conditioning systems,
elevators, escalators and pneumatic tubes etc. ;
(b) Noise produced by office equipment or machines such as typewriters, printers,
teleprinters, reproduction, tabulating and punching machines etc.;
(c) Noise produced by mechanical amplifiers, for example in seminar halls,
conference rooms or staff training rooms or the like where public address system
is used;
(d) Machine noise generated from slide rooms, projection rooms and from
electrical and mechanical machines like generators, transformers, switch rooms
and electric substations etc. ;
(e) Typical office noise created by speech, voices in circulation areas, opening and
closing of doors etc. ;
(f) Plumbing systems, ventilation plants, lift machineries, air-conditioning and
cooling systems.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4739

3.13.3 Planning and Design Requirements

3.13.3.1 Site Planning: Rooms susceptible to noise shall be located away from the
sources of noise.
3.13.3.2 Activities and Space Layout: Spaces producing noise and those susceptible to
noise shall be separated as far as practicable. The effective length of long corridors shall
be minimized. Swing doors are to be provided at intervals.
3.13.3.3 Noise Reduction in the Sensitive Areas
(a) Open plan Offices
(i) The floor area may be carpeted in order to absorb airborne noise and
footstep noise. The carpet shall preferably be thick and placed on top of
resilient floors.
(ii) The entire portion of the ceiling shall be treated with sound absorption
materials. Such treatment shall be applied to the screens and nearby walls
also.
(iii) A highly sound absorptive ceiling with a sound absorption coefficient of
0.70 shall preferably be used to absorb 70 percent of the sound energy
reflecting 30 percent of it.
(iv) Moderately noisy office equipment (like typewriters, telephones, computers
etc.) shall be distributed as uniformly as possible all over the office space.
(v) Noisy office equipment shall be concentrated into specific areas of the
office space. The space shall be treated with maximum amount of sound
absorptive material and visually separated from the rest of the office.
(b) General Offices: Sound absorbent ceiling shall be provided in corridors. Hard
floor finishes and batten floors in corridors shall be avoided. Floor ducts shall be
planned on one side of corridors.
3.13.3.4 Reduction of Noise at Source: The following measures shall be undertaken to
reduce noise at source depending on the degree of noise reduction desired.
(a) The noise from slamming of doors shall be reduced by fitting automatic quiet
action type door closers. Continuous soft, resilient strip set into the door frames
as well as quiet action door latches shall be used.
(b) Machines like typewriters, calculators, printers etc. shall be fitted or installed
with resilient pads to prevent the floors or tables (on which they stand) from
acting as large radiating panels.
(c) Noises from ventilating systems, from a uniform flow of traffic or from general
office activities, shall be considered to generate an artificial masking noise. In
open plan offices the provision of a relatively high but acceptable degree of
4740 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

background noise (from the ventilating or air-conditioning system) shall be

provided, in order to mask undesirable office noises created by typewriters,
telephones, office machines or loud conversation and to provide a reasonable
amount of privacy.
The background noise masking system shall be introduced gradually without
disturbing the feeling of the occupants.
The air-conditioning system may be used to generate background masking noise
if the noise level from the ceiling fans, ducts etc. can be suitably reduced to
generate the desired frequency spectrum.
3.13.3.5 Sound Insulation Factors: The acoustical performance of the partitions dividing
rentable office spaces shall not exceed an STC rating of 25 to 30 dB, unless the
background noise is so high that it masks the sound coming through the lightweight
partition.
If lightweight partitions are employed for subdivision of large spaces into executive
cabins and secretarial areas, the following measures shall be taken to increase the
insulation factors:
(a) Sound barriers shall be provided up to above the false ceiling with a noise
reduction characteristic that will not be affected by ducts, conduits or other cable
lines including electricity and water piping installed in the ceiling space.
(b) Where construction of light weight partitions is considered essential, a double
skin panel shall be preferred.
The panels shall be installed apart from each other either by use of separate
framing or by use of elastic discontinuities in the construction. Sound absorbing
materials shall be provided in the air cavity between the panels so that more
insulation can be assured.
(c) All apertures, gaps and joints at side walls, floors and ceiling junctions shall be
properly sealed.
(d) A double panel hollow floor construction shall be employed with heavy sound
damping materials introduced between the panels for effective reduction of the
structure-borne noise transmitted from upper floors to the floors below,
particularly when lightweight floors are provided in multi-use spaces.
Lightweight materials having high natural frequencies may resonate or vibrate
due to an applied vibratory force, which may be caused by mechanical
equipment, road or rail traffic etc. These materials, if used for specific reasons,
shall be isolated from the source of noise in order to reduce the amount of
vibration transmitted to the building.
(e) The floor surfaces surrounding the office space may be lined with a carpet of
high sound absorption.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4741

(f) For sound adsorption with floor carpeting, the following characteristics shall be
maintained:
(i) Fibre type carpet shall not be used, as it has practically no effect on sound
absorption;
(ii) Hair, hair jute and foam rubber pads shall be used for higher sound
absorption than the less permeable rubber coated hair jute, sponge rubber
etc.;
(iii) To improve sound absorption the loop-pile fabrics with increased pile
height (with the density held constant) shall be applied;
(iv) The backing shall be more permeable for higher sound absorption.

3.14 Occupancy G: Industrial Buildings

3.14.1 General Noise Levels

In the noise control of industrial buildings the following requirements are to be fulfilled:
(a) An acceptable acoustical environment for individual workers and machine
operators;
(b) Speech communication among operators to the required degree;
(c) Protection of other workers or office employees (either close to the noise source
or at some other location within the same building);
(d) Prevention of noise transmission into adjacent buildings or into the surrounding
community.
3.14.1.1 Intermittent Noises : Intermittent noise in the form of isolated explosions, and
periodic noise related to pressure relief valves, hammering, grinding and sawing
operations etc. shall be identified for enforcing controlling measures.
3.14.1.2 Sources of Noise: The following sources of noise in industrial buildings and
manufacturing plants shall be identified and investigated to find whether the machines are
in smooth operation and producing minimal mechanical noise.
(a) Fabrication and assembly machines;
(b) Machines used for material transport and general plant services;
(c) Noise caused by impact and coupled with resonant response of the structural
members, connected to the impacting surfaces;
(d) High frequency sounds generated from grinders;
(e) Frictional noise occurring at the time of sawing, grinding or sanding, as well as
during the cutting on lathe machines and in brakes or from bearings;
4742 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(f) Noise generated from piping systems and valves;

(g) High velocity flow of air, steam or other fluids that undergo an abrupt change in
pipe diameter which give rise to turbulence and resultant noise, and noise
generated by rapid variation in air pressure caused by turbulence from high
velocity air, steam or gases;

(h) Unpleasant noise identified with rotating or reciprocating machines, which is

generated due to pressure fluctuation in the fluids inside the machines.

3.14.2 Hearing Damage Risk Criteria

When the sound level at a particular section in a factory or industrial building exceeds
the specified level in terms of magnitude and time (as shown in Table 8.3.5), feasible
engineering control shall be applied and implemented in order to reduce the sound to the
limits shown. Personal hearing protection equipment shall be provided and used if such
control fails to reduce sound levels.

3.14.3 Interference with Communication

In industries where the operator has to follow verbal instructions during operation of the
machine the background noise shall be reduced to an acceptable level.

Precautionary measures shall be taken so that the noise generated inside may not be the
cause of accidents by hindering communication or by masking warning signals.

3.14.4 Requirements for Noise Reduction

3.14.4.1 Noise Reduction by Layout and Location: Considerable noise reduction may be
achieved by a sensible architectural layout in noisy industrial buildings following the
steps mentioned below:

(a) Noisy areas shall be separated from spaces requiring silence.

(b) The office block is to be located in a separate building. If this is not possible, the
office space in a factory shall be segregated from the production area as far as
practicable.

(c) The office building shall not have a common wall with the production areas.
Where a common wall is unavoidable it should be of heavy construction (not
less than 375 mm thick).

(d) Electrically operated vehicles shall be used as far as practicable, since they
eliminate most of the noise normally associated with combustion engines.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4743

3.14.4.2 Noise Reduction at Source: In order to suppress the noise at the source
relatively silent machines and equipment shall be installed. Additionally the following
provisions shall be adhered to:
(a) Appropriate type of manufacturing process or working method shall be selected
which does not cause disturbing noise. Machine tools and equipment are to be
selected carefully in order to attain lower noise levels in the machine shop.
(b) Maintenance of vibrating and frictional machineries shall be ensured.
(c) Impact noises in general shall be reduced; soft and resilient materials shall be
applied on hard surfaces where impact noise can originate.
(d) Rubber tyres or similar other materials shall be fixed on the areas or surfaces
used for the handling and dropping of materials.
(e) The area of the radiating surface from which a noise is radiated shall be reduced
to a minimum.
(f) Resilient flooring (carpeting, rubber tile, cork tile, etc.) shall be used adequately
to reduce impact transmission onto the floor.
(g) Flexible mountings, anti-vibration pads, floating floors etc. shall be used to
prevent the transmission of vibration and shock from various machines into the
building or structure.
(h) Mechanically rigid connecting paths must be interrupted by resilient materials so
that the transmission of vibration and noise is reduced.
3.14.4.3 Isolator Specifications
(a) Isolators shall be made of resilient materials like steel (in the form of springs),
soft rubber and corks.
(b) Direct contact between the spring and the supporting structure shall be
eliminated, in order to reduce transmission of high frequencies by metal springs.

(c) Rubber or felt pads shall be inserted between the ends of the springs and the
surfaces to which they are fixed.
(d) Felt or cork shall be used under machine bases, as resilient mats or pads.

(e) If the equipment is massive like drop hammers causing serious impact vibration
(in larger manufacturing plants), it shall be mounted on massive blocks of
concrete, on its own separate foundation.

(f) The foundation shall have a weight 3 to 5 times that of the supported machines.

(g) A sound reduction of 5 to 10 dBA shall have to be realized from the vibration
isolation measures.
4744 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
3.14.4.4 Noise Reduction by Enclosures and Barriers: When the plant is large in which
the overall noise level results from many machines, an enclosure shall be provided.
(a) When only one or two machines are the dominant source of disturbing noise, the
noisy equipment shall be isolated in a small area of enclosure.
(b) The enclosure shall be in the form of close fitting acoustic box around the
machines. The box shall be of such character that the operator can continue with
his normal work outside the box.
(c) An enclosure around the offending unit shall be impermeable to air and lined
with sound absorbing materials such that the noise generated by machines is
reduced substantially.
(d) When the industrial plant is a large one in which the resultant noise level is
produced from a number of machines, enclosures shall be used either for
supervisory personnel or operators who are engaged in monitoring the automatic
machines. Such barriers may have inspection openings.
(i) Enclosures of this type shall ensure noise reduction of at least 30 dBA, and
shall be made of sheet metal lined inside with an appropriate insulation
material.
(ii) Where curtains are used to isolate the noisy equipment in a small area, they
shall be of full length i.e. from ceiling to floor and shall be made of fibre
glass cloth and lead or leaded vinyl.
(e) If the size of the machine is large and asks for more working spaces, thus not
permitting close fitting enclosures, the machine shall be housed in a separate
room or enclosure.
The inside of the enclosure shall be lined with sound absorbing materials in
order to reduce the contained noise.
(f) If after all these measures are taken the noise level still remains above a
tolerable degree, the workers shall be provided with earplugs for protection.

3.15 Acoustical Requirements of Special Occupancies

3.15.1 Susceptible Buildings

3.15.1.1 Recording and radio studios
A recording studio shall present optimum acoustical conditions. A differentiation shall be
made among the numerous various purposes of studio use.
(a) Particular attention shall be given to the following requirements:
(i) An optimum size and shape of the studio shall be established following the
design criteria;
(ii) A high degree of diffusion shall be secured;
(iii) Ideal reverberation characteristics shall be provided;
(iv) Noises and vibration shall be completely eliminated and acoustical defects
shall be totally prevented.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4745

(b) The acoustical treatments shall be uniformly and proportionately distributed

over the three pairs of opposite surfaces enclosing the studio.
(c) Portable acoustic screen and a reverberation chamber shall be provided so that
the desired reverberation condition can be achieved.
(d) Variable absorbers such as hinged or sliding panels, rotatable cylinders,
adjustable drapery etc. shall be fixed on wall surfaces and ceiling areas.
(e) All surfaces shall be carefully checked for echoes, flutter echoes etc.
(f) Parallel surfaces shall be eliminated or treated with highly absorptive acoustical
materials (throughout the frequency range between 63 and 8000 Hz).
3.15.1.2 Research laboratories
(a) In the selection of site, care shall be taken to ensure that no noise generating
installations exist in the vicinity.
(b) Location of laboratories shall be secluded from the noisy zones within the
building.
(c) A sound insulation of at least 35 dB shall be achieved by means of acoustic
partitions where offices are attached to the laboratory.
(d) Sound absorbing screens shall be used where scientists and researchers are
engaged in laboratory activities and desk work simultaneously.
(e) Transmission of noise through service ducts, pipes, lifts and staircases shall be
guarded.
(f) Double glazed windows shall be provided in the noise sensitive areas. There
shall be a minimum gap of 100 mm between the two glasses.
3.15.1.3 Music rooms
The following provisions shall apply to music rooms, including rehearsal rooms,
instructional space, practice booth etc.
(a) Acoustical conditions in practice booths and listening booths shall have a
reverberation time of 0.4 to 0.5 second.
(b) Adequate floor area, room height, room shape and volume must be established
to achieve proper reverberation.
(c) Sound absorbing materials shall be applied sufficiently so that the excessive
sound generated by bands or individual instruments can be soaked up.
(d) Parallelism between opposite surfaces shall be avoided.
(e) Entire surfaces of at least two adjacent walls and all the ceiling area shall be
treated with sound absorbing materials.
4746 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
3.15.1.4 Libraries
A quiet and peaceful interior shall be maintained inside libraries. The following
provisions are to be adhered to in planning and design:
(a) Screening and sound insulation measures shall be undertaken in and around the
reception/issue desk and photocopying facility areas.
(b) Stack rooms, store rooms and administrative offices shall be planned in such a
way that the audiovisual areas are properly isolated from external noises.
(c) Walls enclosing the library shall have a sound reduction value of not less
than 50 dB.
(d) Fanlights shall be double glazed and non-openable.
(e) Walls facing the corridors or other noisy areas shall not have fanlights or
borrowed lights unless they are double glazed.
3.15.1.5 Law courts and council chambers
(a) Entrance into court rooms and council chambers (especially from circulation
areas and gathering spaces) shall be through baffle lobbies, with two sets of
doors fitted with silencers.
(b) Offices shall be planned around the court rooms or chambers for further
protection against outdoor noise and the central rooms shall have a sound
insulation value of not less than 50 dB (provided by 225 mm thick brick wall) to
insulate against airborne noise in the corridors.
(c) The court and chamber rooms shall have floors finished with resilient materials.
(d) Ceiling and upper parts of the walls of lobbies and circulation areas shall have
sound absorbing treatments.

3.15.2 Public Address System

3.15.2.1 Design of public address systems shall take care of equipment choice,
positioning of the individual elements and other precautions to obtain optimum
performance of the system.
3.15.2.2 Passenger terminals and other public places equipped with public address
systems shall as far as practicable avoid the use of sound reflecting surfaces like hard
walls and floors. Reverberation time shall be reduced as far as possible by using sound
absorbing materials on walls and ceilings.
3.15.2.3 Reverberation built-up sound level shall not be relied upon. Direct sound shall
preferably be audible in all areas to be covered by the public address system.
3.15.2.4 Sound levels of the public address system in the areas covered shall be
adequately high to overcome background noise.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4747
3.16 Related References

Maekawa Z. and Lord P. 1994. Environmental and Architectural Acoustics. E&FN

SPON, UK (Table 8.3.2)

Grondzik, W. T., Kwok, A. G., Stein, B and Reynolds, J. S. 2006. Mechanical and
Electrical Equipment for Buildings. John Wiley & Sons, New Jersey. (Tables 8.3.3 to
8.3.6)

3.17 List of Related Appendices

Appendix D NC, NCB and Recommended Criteria for Sound Insulation

Appendix E STC, Aural Field and Proportion of Space

Appendix F Activity Flow Diagram: Planning, Design, Assessment and

Construction in Building Acoustics

Appendix G Checklist for Acoustical Planning, Design and Post-occupancy

Assessments

Appendix H Noise Levels and Subjective Evaluation

Appendix I PSA and Liveliness

Appendix J Speech Privacy Analysis Sheet

Appendix K Sound Absorption Coefficients

4748 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

PART VIII
Chapter 4
Lifts, Escalators and Moving Walks
4.1 General
4.1.1 Purpose
The purpose of this Chapter is to provide minimum standards for regulating and
controlling the design, construction, installation, quality of materials, location, operation,
maintenance and use of lifts, escalators and moving walks to ensure public safety and
welfare.
4.1.2 Scope
4.1.2.1 The provisions of this Chapter shall apply to the erection, installation, alteration,
repair, relocation, replacement, addition to, operation and maintenance of lifts, escalators
and moving walks.
4.1.2.2 Additions, alterations, repairs and replacement of equipment or systems shall
comply with the provisions for new equipment and systems.
4.1.2.3 Where, in any specific case, different sections of the Code specify different
materials or other requirements, the most restrictive one shall govern. Where there is a
conflict between a general requirement and a specific requirement, the specific
requirement shall be applicable.
4.1.2.4 It shall be unlawful to install, extend, alter, repair or maintain lift, escalator or
moving walk systems in or adjacent to buildings except in compliance with this Code.
4.1.3 Terminology
This Section provides an alphabetical list of the terms used in this Chapter of the Code. In
case of any conflict or contradiction between a definition given in this Section and that in
Part 1, the meaning provided in this Section shall govern for interpretation of the
provisions of this Chapter.
AUTOMATIC RESCUE A device meant to bring a lift stuck between floors due to
DEVICE loss of power, to the nearest level and open the doors in
order to allow trapped passengers to be evacuated. Such
a device may use some form of internal auxiliary power
source for such purpose, complying with all the safety
requirements of a lift during normal run. The speed of
travel is usually lower than the normal speed. In the case
of manual doors on reaching the level, the device shall
allow the door to be opened and in case of power
operated doors the device shall automatically open the
door.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4749

BALUSTER One of the slender upright supports of a hand rail.

BALUSTRADE A row of balusters meant for supporting moving hand

rails.

BASEMENT STOREY The lower storey of a building below or partly below the
ground level.
BOTTOM CAR The clear vertical distance from the pit floor to the
CLEARANCE lowest structural or mechanical part, equipment or device
installed beneath the car platform aprons or guards
located within 300 mm, measured horizontally from the
sides of the car platform when the car rests on its fully
compressed buffers.
BOTTOM CAR RUNBY The distance between the car buffer striker plate and the
striking surface of the car buffer when the car is in level
with the bottom terminal landing.
BOTTOM COUNTER The distance between the counter weight buffer striker
WEIGHT RUNBY plate and the striking surface of the counterweight buffer
when the car is in level with the top terminal landing.

BUFFER A device designed to absorb the impact of the falling car

or counter weight beyond its normal limit of travel by
absorbing and dissipating the kinetic energy of the car or
counterweight.
BUFFER, OIL A buffer using oil as a medium which absorbs and
dissipates the kinetic energy of the descending car or
counterweight.
Oil buffer stroke - The oil displacing movement of the
buffer plunger or piston, excluding the travel of the
buffer plunger accelerating device.
BUFFER, SPRING A buffer which stores in a spring the kinetic energy of
the descending car or counterweight.
 Spring buffer load rating - The load required to
compress the spring by an amount equal to its
stroke.
 Spring buffer stroke - The distance, the contact end
of the spring can move under a compressive load
until the spring is compressed solid.
4750 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

CALL INDICATOR A visual and audible device in the car to indicate to the
attendant the lift landings from which the calls have been
made.

CAR BODY WORK The enclosing body work of the lift car which comprises
the sides and roof, and is built upon the car platform.

CAR DOOR ELECTRIC An electric device, the function of which is to prevent

CONTACT operation of the driving machine by the normal operating
device unless the car door is in the closed position.

CAR FRAME The supporting frame to which the platform of the lift
car, its safety gear, guide shoes and suspension ropes are
attached.
CAR PLATFORM The part of the lift car which forms the floor and directly
supports the load.

CAR SPEED See RATED SPEED (LIFT).

COMB PLATE A pronged plate that forms part of an escalator (or
moving walk) landing and engages with the Cleats of the
steps (or tread way) at the limits of travel.

CONTROL SYSTEM The system of equipment by means of which starting,

stopping, direction of motion, speed, acceleration, and
retardation of the moving member are controlled.

CONTROL, SINGLE- A control for a driving machine induction motor which is

SPEED ALTERNATING arranged to run at a single-speed.
CURRENT

CONTROL, TWO- A control for a two-speed driving machine induction

SPEED ALTERNATING motor which is arranged to run at two different
CURRENT synchronous speeds either by pole changing of a single
motor or by two different armatures.

CONTROL, A system of control which is accomplished by varying

RHEOSTATIC resistance or reactance or both in the armature or field
circuit or both, of the driving machine motor.

CONTROL,VARIABLE A system of control which is accomplished by the use of

VOLTAGE MOTOR an individual generator for each lift wherein the voltage
(GENERATOR FIELD applied to the driving machine motor is adjusted by
CONTROL) varying the strength and direction of the generator field.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4751

CONTROL, A system of control which is accomplished by the use of

ELECTRONIC DEVICES electronic devices for driving the lift motor at variable
speed.

CONTROL, A system of speed control which is accomplished by

ALTERNATING varying the driving and braking torque by way of voltage
CURRENT VARIABLE variation of the power supply to the driving machine
VOLTAGE (ACW) induction motor.

CONTROL, A system of speed control which is accomplished by

ALTERNATING varying the voltage and frequency of the power supply to
CURRENT VARIABLE the driving machine induction motor.
VOLTAGE VARIABLE
FREQUENCY
(ACVVVF)

CONTROL, SOLID- A solid-state system of speed control which is

STATE D.C. VARIABLE accomplished by varying the voltage and direction of the
VOLTAGE power supply to the armature of driving machine D.C.
motor.
COUNTER WEIGHT A weight or combination of weights to counterbalance
the weight of the car and part of the rated load.
DETERMINING The inside floor level at the entrance to the building.
ENTRANCE LEVEL
DEFLECTOR SHEAVE An idler pulley used to change the direction of a rope
lead.
DOOR, CENTRE A door which slides horizontally and consists of two
OPENING SLIDING panels which open from the centre and are so
interconnected that they move simultaneously.
DOOR, HINGED The hinged portion of the lift well enclosure which
closes the opening giving access to the landing.
DOOR, MID BAR A collapsible door with vertical bars mounted between
COLLAPSIBLE the normal vertical members.
DOOR, MULTI-PANEL A door arrangement whereby more than one panel is
used such that the panels are connected together and can
slide over one another by which means the clear opening
can be maximized for a given shaft width. Multi-panels
are used in centre opening and two speed sliding doors.
4752 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

DOOR, SINGLE SLIDE A single panel door which slides horizontally.

DOOR, TWO SPEED A two panel door which slides horizontally in the same
direction wherein each panel has different operating
speed and reaches the ends simultaneously.

DOOR, VERTICAL BI- A door or shutter which slides vertically and consists of
PARTING two panels or sets of panels that move away from each
other to open and are so interconnected that they move
simultaneously.

DOOR, VERTICAL A single panel door, which slides in the same plane
LIFTING vertically up to open.

DOOR, SWING A swinging type single panel door which is opened

manually and closed by means of a door closer when
released.

DOOR CLOSE A device which automatically closes a manually opened

door.

DOOR OPERATOR A power-operated device for opening and closing doors.

DRIVING MACHINERY The motorized power unit for driving the lift, escalator or
moving walks.

DUMBWAITER A small lift with a car which moves in guides in a

substantially vertical direction and has a net floor area,
total inside height and capacity not exceeding 0.9 m2,
1.25 m and 225 kg respectively, and is exclusively used
for carrying materials and no person. It may or may not
be provided with fixed or removable shelves.

ELECTRICAL AND A device provided to prevent simultaneous operation of

MECHANICAL both up and down relays.
INTERLOCK

ELECTRO- A device which combines in one unit, electrical contact

MECHANICAL LOCK and a mechanical lock jointly used for the landing and/or
car doors.

EMERGENCY STOP A push button or switch provided inside the car designed
PUSH OR SWITCH to open the control circuit to cause the lift car to stop
during emergency.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4753

ENCLOSED WELL The lift well having enclosure walls of continuous

construction without openings except for doors at
landings.

ESCALATOR A power driven, inclined, continuously moving stairway

used for carrying passengers from one level to another.

ESCALATOR LANDING The portion of the building or structure which is used to

receive or discharge passengers into or from an escalator.

ESCALATOR LANDING A space extending from a horizontal plane 40 cm below

ZONE a landing to a plane 40 cm above the landing.

ESCALATOR The mechanism and other equipment in connection

MACHINE therewith used for moving the escalator
FLOOR The lower surface in a storey on which one normally
walks in a building. The general term 'floor', unless
otherwise specifically mentioned shall not refer to a
'mezzanine floor'.

FLOOR LEVELING A switch for bringing the car to level at slow speed in
SWITCH case of double speed or variable speed machines.

FLOOR SELECTOR A mechanism forming a part of the control equipment, in

certain automatic lifts, designed to operate controls
which cause the lift car to stop at the required landings.

FLOOR STOPPING A switch or combination of switches arranged to bring

SWITCH the car to rest automatically at or near any pre-selected
landing.

GEARED MACHINE A machine in which the power is transmitted to the

sheave through a worm or, worm and spur reduction
gearing.

GEARLESS MACHINE A lift machine in which the motive power is transmitted

to the driving sheave from the motor without
intermediate reduction gearing and has the brake drum
mounted directly on the motor shaft.

GOODS LIFT A lift designed primarily for the transport of goods, but
which may carry a lift attendant or other persons
necessary for the loading or unloading of goods.
4754 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

GOVERNOR A device which automatically actuates safety devices to

bring the lift car and/or counter weight to rest in the
event the speed of the equipment in the descending
direction exceeds a predetermined limit.

GUIDE RAILS The members used to guide the movement of a lift car or
counterweight in a vertical direction.

GUIDE RAILS FIXING The complete assy. comprising the guide rails bracket
and its fastenings.

GUIDE RAILS SHOE An attachment to the car frame or counterweight for the
purpose of guiding the lift car or counter weight frame.

HANDLING CAPACITY The capacity of the lift system to carry passengers during
a five minute peak period, expressed as the percentage of
the estimated total population handled.

HOISTING BEAM A beam, mounted immediately below the machine room

ceiling, to which lifting tackle can be fixed for raising or
lowering parts of the lift machine.

HOSPITAL LIFT A lift normally installed in a hospital, nursing home or

clinic and designed to accommodate one number
bed/stretcher along its depth, with sufficient space all
around to carry a minimum of three attendants in
addition to the lift operator.

HYDRAULIC LIFT A lift where the vertical movement of the lift car is done
by hydraulic force of a hydraulic fluid. In this type of lift
a plunger is attached to the bottom or top of the lift car
wherein the plunger moves inside a cylinder by hydraulic
force. The hydraulic lift may be direct-plunger-driven
type where the cylinder extends into the ground as deep
as the lift rises. Hydraulic lifts may also be roller-chain
type actuated by a sheave on a vertical hydraulic
cylinder, installed beside the lift shaft. Hydraulic lifts
may be used for passenger and freight services. The
speeds are between 0.125 mps and 1.0 mps. The load
capacities are between 1,000 kg and 50,000 kg.

INTERVAL Average time gap(s) between consecutive lifts leaving

the ground floor or passing any specific floor.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4755

LANDING That portion of a building or structure used for the

reception and discharge of passengers or goods or both
into and from a lift car, escalator or moving walk.
LANDING CALL PUSH A push button fitted at a lift landing, either for calling the
BUTTON (LIFT) lift car or for actuating the call indicator.
LANDING DOOR (LIFT) The hinged or sliding portion of a lift well enclosure,
controlling access to a lift car at a lift landing.
LANDING PLATE The portion of the landing immediately above the
mechanism at either end of escalator or moving walk
and constructed so as to give access to this mechanism in
these areas.
LANDING ZONE A space extending from a horizontal plane 400 mm
below a landing to a plane 400 mm above the landing.
LEVELING DEVICE, Any mechanism which either automatically or under the
LIFT CAR control of the operator, moves the car within the leveling
zone towards the landing only and automatically stops it
at the landing.
LEVELING DEVICE, A device which corrects the car level only in case of
ONE WAY under run of the car but will not maintain the level during
AUTOMATIC loading and unloading.
LEVELING DEVICE, A device which corrects the car level on both under run
TWO-WAY and over-run and maintains the level during loading and
AUTOMATIC unloading.
MAINTAINING
LEVELING DEVICE, A device which corrects the car level on both under run
TWO WAY and over run but will not maintain the level during
AUTOMATIC NON- loading and unloading.
MAINTAINING
LEVELING ZONE The limited distance above or below a lift landing within
which the leveling device may cause movement of the
car towards the landing.
LIFT A machine designed to transport persons or materials
between two or more levels in a vertical or substantially
vertical direction by means of a guided car or platform.
The lifting force is provided by electric motor or fluid
pressure. The word "elevator" is also synonymously used
for "lift".
4756 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

LIFT CAR The load carrying unit with its floor or platform, car
frame and enclosing bodywork.

LIFT LANDING That portion of a building or structure used for discharge

of passengers or goods or both into or from a lift car.

LIFT MACHINE The part of the lift equipment comprising of electric

motor(s) and control gear therewith, reduction gear (if
any), brake(s) and winding drum or sheave, by which the
lift car is raised or lowered.

LIFT PIT The space in the lift well below the level of the lowest
lift landing served.

LIFT SYSTEM One or more lift cars serving the same building.
LIFT WELL The unobstructed space within an enclosure provided for
the vertical movement of the lift car(s) and any counter
weight(s), including the lift pit and the space for top
clearance.

LIFT WELL Any structure which separates the lift well from its
ENCLOSURE surroundings.

LIFTING BEAM A beam, mounted immediately below the machine room

ceiling to which lifting tackle can be fixed for raising
parts of the lift machine.

MACHINE ROOM The compartment allocated to house the lift machine and
associated items.

MACHINERY SPACE The space occupied by the driving machine and control
gear of the lift, escalator or moving walk.

MEZZANINE An intermediate floor between two floors above ground

level.

MOVING WALK A power driven, horizontal or inclined, continuously

moving conveyor used for carrying passengers,
horizontally or at an incline up to a maximum of 15
degree.

NEWEL An upright support of the handrail at the landing of

escalator/moving walk where the handrail reverses its
direction.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4757

OPEN TYPE WELL A lift well having enclosure walls of wire grille or
similar construction.
OPERATION The method of actuating the control and/or functioning
of any lift machine/equipment.
OPERATION, A method of operation in which by a momentary
AUTOMATIC pressure of a button the lift car is set in motion and
caused to stop automatically at any required lift landing.
OPERATION, NON- Automatic operation by means of one button in the car
SELECTIVE for each landing level served and one button at each
COLLECTIVE landing, wherein all stops registered by the momentary
AUTOMATIC actuation of landing or car buttons are made irrespective
of the number of buttons actuated or of the sequence in
which the buttons are actuated. With this type of
operation, the car stops at all landings for which buttons
have been actuated making the stops in the order in
which the landings are reached after the buttons have
been actuated but irrespective of its direction of travel.
OPERATION, Automatic operation by means of one button in the car
SELECTIVE for each landing level served and by up and down
COLLECTIVE buttons at the landings, wherein all stops registered by
AUTOMATIC the momentary actuation of the car made as defined
under non-selective collective automatic operation, but
wherein the stops registered by the momentary actuation
of the landing buttons are made in the order in which the
landings are reached in each direction of travel after the
buttons have been actuated. With this type of operation,
all 'up' landing calls are answered when the car is
travelling in upward direction and all ‘down' landing
calls are answered when the car is travelling in
downward direction, except in case of the uppermost or
lowermost calls which are answered as soon as they
reached irrespective of the direction of travel of the car.
OPERATION, SINGLE Automatic operation by means of one button in the car
AUTOMATIC for each landing level served and one button at each
landing so arranged that if any car or landing button has
been actuated, the actuation of any other car or landing
operation button will have no effect on the movement of
the car until the response to the first button has been
completed.
4758 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

OPERATION, GROUP Automatic operation of two or more non-attendant lifts

AUTOMATIC equipped with power-operated car and landing doors.
The operation of the cars is co-ordinated by a
supervisory operation system including automatic
dispatching means whereby selected cars at designated
dispatching points automatically close their doors and
proceed on their trips in a regulated manner.

Typically, it includes one button in each car for each

floor served and up and down buttons at each landing
(single buttons at terminal landings). The stops set up by
the momentary actuation of the car buttons are made
automatically in succession as a car reaches the
corresponding landings irrespective of its direction of
travel or the sequence in which the buttons are actuated.
The stops set up by the momentary actuation of the
landing buttons may be accomplished by any lift in the
group, and are made automatically by the first available
car that approaches the landing in the corresponding
direction.

OPERATION, CAR Method of operation by which the movement of lift car is

SWITCH directly under the operation of the attendant by means of
a handle.

OPERATION, SIGNAL Same as collective operation, except that the closing of

the door is initiated by the attendant.

OPERATION, DOUBLE Operation by means of buttons or switches in the car and

BUTTON at the landings any of which may be used to control the
(CONTINUOUS movement of the car as long as the button or switch is
PRESSURE) manually pressed in the actuating position.

OPERATING DEVICE A car switch, push button or other device employed to

actuate the control.

OVERHEAD BEAMS The members, usually of steel or reinforced concrete,

(LIFT) which immediately support the lift equipment at the top
of the lift well.

OVERHEAD PULLEY An idler pulley used to change the direction of rope.

PASSENGER LIFT A lift designed for the transport of passengers.

 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4759

POSITION AND/OR A device which indicates on the lift landing or in the lift
DIRECTION car or both, the position of the car in the lift well or the
INDICATOR direction or both in which the lift car is travelling.

POWER OPERATED A door operated automatically by a device initiated by a

DOOR momentary pressure on the push button or by operation
of the control system.

RATED LOAD The maximum load which the lift car, escalator or
moving walk is designed and installed to carry safely at
its rated speed.

RATED SPEED (LIFT) The speed attained by the lift in the up direction with
rated load in the lift car. Also known as CAR SPEED.
RATED SPEED The speed at which the escalator is designed to operate in
(ESCALATOR) the up direction. It is the rate of travel of the steps,
measured along the angle of inclination with rated load
on the steps or carriage.

RATED SPEED The speed at which the moving walk is designed to

(MOVING WALK) operate in the up direction. It is the rate of travel of the
tread way, measured along the angle of inclination with
rated load on the tread way.

RETIRING CAM A device which prevents the landing doors from being
unlocked by the lift car unless it stops at a landing.

ROPING MULTIPLE A system of roping where, in order to obtain a

multiplying the factor from the machine to the car,
multiple falls of rope are run around sheave on the car or
counterweight or both. It includes roping arrangement of
2 to 1, 3 to 1 etc.
SAFETY GEAR A mechanical device attached to the car frame or the
counter weight to stop and hold the car or counter weight
to the guides in the event of a free fall. Governor
operated safety gears are used to stop the car or
counterweight when it travels at a speed exceeding a
predetermined speed.

SERVICE LIFT A lift designed primarily for the transport of goods, but
which may carry a lift attendant or other persons
necessary for the loading and unloading of goods.
4760 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

SHEAVE A rope wheel, the rim of which is grooved to receive the

suspension ropes but to which the ropes are not rigidly
attached and by means of which power is transmitted
from the lift machine to the suspension ropes.
SLACK ROPE SWITCH Switch provided to open the control circuit in case of
slackening of rope(s)
STOREY The space between the surface of one floor and the
surface of the adjacent floor vertically above or below it.
The term 'Floor' shall include 'Roof' but will exclude
mezzanine floors.
STOREYS FOR Storeys which are named according to their functions
SPECIFIC USE and the specific uses they are put to. For example, a duct
storey is one through which service pipes and electrical
conduits may be taken.
SUBSIDIARY STOREY A storey which occurs below the determining entrance
level but above the basement storey.
SUSPENSION ROPES The ropes by which the car and counter-weight are
(LIFT) suspended.
TERMINAL SLOW A switch when actuated shall compulsorily cut off
DOWN SWITCH the high speed and switch on the circuitry to run the
lift in leveling speed before reaching on terminal
landings.
TERMINAL STOPPING Switch for cutting all the energizing current in case of
SWITCH NORMAL car travelling beyond the top bottom landing or a switch
cuts off the energizing current so as to bring the car to
stop at the top and bottom level.
TERMINAL STOPPING A device which automatically cause the power to be
DEVICE FINAL removed from an electric lift driving machine motor and
brake, independent of the functioning of the normal
terminal stopping device, the operating device or any
emergency terminal stopping device, after the car has
passed a terminal landing.
TOP CAR CLEARANCE The shortest vertical distance between the top of the car
crosshead, or between the top of the car where no
crosshead is provided, and the nearest part of the
overhead structure or any other obstruction when the car
floor is level with the top terminal landing.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4761

TOP COUNTERWEIGHT The shortest vertical distance between any part of the
CLEARANCE counterweight structure and the nearest part of the
overhead structure or any other obstruction when the car
floor is level with the bottom terminal landing.

TOTAL HEADROOM The vertical distance from the level of the top lift landing
to the floor of the machine room.

TRAVEL (LIFT) The vertical distance between the bottom and top lift
landings served by the equipment.

VENT An opening provided in the roof or the external wall of a

space for the purpose of ventilation.

4.1.4 Preliminary Design Particulars

4.1.4.1 All relevant aspects of lift, escalator or moving walk installations shall be
properly evaluated during the planning stage of the building in order to design the most
effective conveying system.
4.1.4.2 Appropriate steps shall be taken during the planning stage of the building to
determine particulars of lift, escalator or moving walk and the necessary provisions to be
kept in the building structure so as to meet the requirements of this Code. Discussion
shall be carried out, during planning stage, with all concerned parties, viz. building
owner, architect, consulting engineer and/or lift/escalator/moving walk manufacturer to
determine the extent of necessary provisions to be kept in the building.

4.1.4.3 Minimum amount of information to be collected for lifts during such meetings
shall be the following:

(a) Number, capacity, speed and disposition of the lifts necessary to give adequate
lift service in the building

(b) Layout and sizes of lift well

(c) Particulars of lift well enclosure, sizes of punches In the lift well enclosure

(d) Location of lift machine room (above or below), height of lift machine room

(e) Provision of adequate access to the lift machine room and size of machine room

(f) Total headroom clearance

(g) Provision of ventilation of the lift well

(h) Depth of lift pit

4762 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(i) Loads which the lift will impose on the building structure, and the holes to be
left in the machine room floor and cut-outs for wall boxes for push buttons and
signals

(j) Necessity for and type of insulation to minimize the transmission of vibration
and noise to other parts of the building

(k) Requirements for fixing guide brackets to the building structure, hoisting beam
for hoisting of lift machine

(l) Requirements and layout of electrical power feeders for the lift.

4.1.4.4 Minimum amount of information to be collected for the escalators shall be the
following :

(a) Number and size of each escalator

(b) Angle of escalator

(c) Arrangement and layout of escalators with dimensions of floor punches required

(d) Minimum floor to floor height requirement

(e) Dimensions of top and bottom escalator landings

4.1.4.5 Minimum amount of information to be collected for the moving walks shall be
the following:

(a) Number and size of each moving walk

(b) Angle of moving walk

(c) Arrangement and layout of moving walks with dimensions of floor punches
required

(d) Dimensions of top and bottom moving walk landings

4.1.4.6 For the safety considerations of lift installations and effective utilization of lift
installations, locations and arrangement of lifts shall be in accordance with Sec 4.3.3.

4.1.4.7 The building plan submitted with the application for seeking permission of
installation of lift, escalator or moving walk from the Authority shall include layout of
lift, escalator or moving walk properly identified in the drawing along with the detailed
particulars as per Appendix L.

4.1.4.8 Specifications for lifts, escalators and moving walks shall include detailed
particulars as per Appendix L.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4763

4.1.4.9 For the purpose of effective installation of lifts, escalators or moving walks,
working drawings showing the layout of lifts, escalators or moving walks properly
identified in the drawing, details of builders works, for example, holes and/or punches in
floors or, walls and supports for lifts, escalators or moving walks shall be prepared prior
to the finalization of building design drawings.

4.1.4.10 Necessary particulars of electrical requirements of lifts, escalators or moving

walks shall be determined early in the planning stage to include it in the electrical
provisions of the building.

4.2 Essential Requirements for Lifts

4.2.1 General
4.2.1.1 Lifts shall be provided in buildings more than six storeys or 20 m in height.
Installation of lifts shall be carried out in conformity with the "Lift Act" and rules there
under, wherever they are in force.
4.2.1.2 Stretcher Facility in Lifts

(a) When passenger lifts are installed in any building having more than ten
storeys or a height of more than 32 m, each floor served by these lifts must
have access to at least one lift with a stretcher facility in accordance with Sec
4.2.1.2(b).

(b) A lift required to have a stretcher facility by Sec 4.2.1.2(a) shall

accommodate a raised stretcher with a patient lying on it horizontally by
providing a minimum inside platform area 1275 mm wide x 2000 mm long
with a minimum clear opening width of 1050 mm, unless otherwise designed
to provide an equivalent facility, to allow the entrance and exit of an
ambulance stretcher (minimum size 600 mm wide x 2000 mm long) in its
horizontal position. These lifts shall be identified by the internationally
recognized symbol for emergency medical services.

(c) In any multi-storied hospital and health care building there shall be at least
one hospital lift having stretcher facility in accordance with Sec 4.2.1.2(a).

4.2.1.3 Standby power

(a) One or more lifts shall be provided with standby power in

(i) A building which has more than ten storeys or a height of more than 32 m,

(ii) Hospital and health care buildings.

4764 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(b) Standby power shall be provided by an approved self-contained generator set to

operate automatically whenever there is a disruption of electrical power supply
to the building.
(c) The operation of the standby power system shall be as follows:
(i) Where only one lift is installed, the lift shall transfer to standby power
within 60 seconds after failure of normal power.
(ii) Where two or more lifts are controlled by a common operating system, all
lifts may be transferred to standby power within 60 seconds after failure of
normal power, or if the standby power source is of insufficient capacity to
operate all lifts at the same time, all lifts shall be transferred to standby
power in sequence, shall return to the designated landing and discharge
their load. After all lifts have been returned to the designated landing, at
least one lift shall remain operable from the standby power.

4.2.1.4 ADA (American Disabilities Act) Approved Type Lift

(a) At least one of the lifts of any lift bank shall have features as per requirements of
ADA accessibility guidelines.
(b) Accessible lifts shall be on an accessible route and shall comply with the ASME
A17.1-1990, safety code for Elevators and Escalators.
(c) Lift operation shall be automatic. It shall have door safeties as per clause 4.2.3.9.
It shall have self-leveling feature as per clause 4.2.3.13.
(d) Hall call buttons in the lift lobbies and halls shall be centered at 1065 mm above
the floor. Such call buttons shall have visual signals to indicate when each call is
registered and each call is answered. Call buttons shall be a minimum 19 mm in
the smallest dimension. The button designating the up direction shall be on the
top.

(e) A visible and audible signal shall be provided at each hoist way entrance to
indicate which car is answering a call. Audible signal shall sound once for the
up direction and twice for the down direction or shall have verbal annunciators
that say “up” or “down”. visible signals shall have the following features:

(i) Hall lantern fixtures shall be mounted so that their centerline is at least 1830
mm above the lobby floor.
(ii) Visual elements shall be at least 64 mm in the smallest dimension.

(iii) Signals shall be visible from the vicinity of the hall call button. In-car
lanterns located in cars, visible from the vicinity of hall call buttons, and
conforming to the above requirements, shall be acceptable.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4765

(f) All lift hoistway entrance shall have raised and Braille floor designations
provided on both jambs. The centerline of the characters shall be 1525 mm
above finish floor. Such characters shall be 50 mm high. Permanently applied
plates are acceptable if they are permanently fixed to the jambs.

(g) Lift doors shall open and close automatically. They shall be provided with a
reopening device that will stop and reopen a car door and hoistway door
automatically if the door becomes obstructed by an object or person. The device
shall be capable of completing these operations without requiring contact for an
obstruction passing through the opening at heights of 125 mm and 735 mm
above finish floor. Door reopening devices shall remain effective for at least 20
seconds. After such an interval, doors may close in accordance with the
requirements of ASME 17.1.

(h) The minimum acceptable time from notification that a car is answering a call
until the doors of that car start to close shall be calculated from the following
equation:

T= D/(445 mm/s)
Where,

T = total time in seconds

D = distance in millimeters from a point in the lobby or corridor 1525 mm

directly in front of the farthest call button controlling that car to the
centerline of its hoistway door. For cars with in-car lanterns, T begins when
the lantern is visible from the vicinity of hall call buttons and an audible
signal is sounded. The minimum acceptable notification time shall be
5 seconds.

(i) The minimum time for lift doors to remain fully open in response to a car call
shall be 3 seconds.

(j) The floor area of lift cars shall provide space for wheel-chair users to enter the
car, maneuver within reach of controls, and exit from the car. The minimum
width and depth of the car shall be 2000 mm and 1291 mm. The clearance
between the car platform sill and the edge of any hoistway landing shall be no
greater than 32 mm.

(k) The level of illumination at the car controls, platform, and car threshold and
landing sill shall be at least 53.8 lux.
4766 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(l) Lift control panels shall have the following features:

(i) Buttons: All control buttons shall be at least 19 mm in their smallest

dimensions. They shall be raised or flush.

(ii) Tactile. Braille, and Visual Control Indicators: All control buttons shall be
designated by Braille and by raised standard alphabet characters for letters,
Arabic characters for numerals, or standard symbols, and as required in
ASME 17.1. The call button for the main entry floor shall be designated by
a raised star at left of the floor designation, and as required in ASME 17.1.
All raised designations for control buttons shall be placed immediately to
the left of the button to which they apply. Applied plates, permanently
attached, are an acceptable means to provide raised control designations.
Floor buttons shall be provided with visual indicators to show when each
call is registered. The visual indicators shall be extinguished when each call
is answered.

4.2.1.5 Responsibility of the owner

(a) It is the responsibility of the owner of the premises where the lift will be
installed, to obtain necessary permission from the Authority before the erection
of lifts(s) and for the subsequent commissioning and operation of lift (s).

(b) The owner shall conduct periodic inspection and maintain the installation in safe
working condition at all times.

(c) Conformity with the provisions of this Code does not relieve the owner of his
responsibility to satisfy the requirements of any other Act, Regulations or
Ordinances that may be in force from time to time.

4.2.1.6 Conformity with Bangladesh electricity act

All electrical work in connection with electrical lifts shall be carried out in accordance
with the provisions of the latest Bangladesh Electricity Act and the provisions of any of
its bye-laws and regulations, and shall also comply with the requirements of Chapter 1 of
Part 8 of this Code.

4.2.1.7 For detailed specifications of lifts, escalators and moving walks reference shall
be made to the latest edition of the ANSI/ASME A 17.1 code or the European EN81
code.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4767

4.2.2 Safety Considerations

4.2.2.1 Fire protection

(a) Necessary provisions shall be kept to prevent spread of fire through the lift well.
Adequate measures shall also be taken to reduce the possibility of spread of fire
from the machine room into the lift well.

(b) Lift well enclosures and machine room shall be constructed with fire resistant
materials. In case of fire, the lift well enclosure shall not give off harmful gas or
fumes.

(c) Where lift enclosures are fire rated, manually closing doors at the enclosure
well shall have a fire rating equal to that of the enclosure well and automatically
closing doors shall have a fire rating equal to one-half of that of the enclosure
well.

4.2.2.2 Fire switch

When required fire switch shall be provided, the function of which is to enable the fire
authority to take over complete control of one or more lifts in an installation by operating
with a fireman's key.

4.2.2.3 Fireman's lift

For buildings having height of 15 m or more at least one lift shall meet the requirements
of fireman's lift as described below:
(a) Lift car shall have floor area of not less than 1.44 m2. It shall also have a loading
capacity of not less than 544 kg (8 persons).
(b) Lift landing doors shall have minimum fire resistance of two hours.
(c) Doors shall be of automatic operation for car and landing.
(d) The lift speed shall be 1.0 m/s or more so as to reach the top floor from the
ground (or entrance) floor within 60 seconds.

4.2.2.4 Warning signs

Warning signs against use of the lifts during a fire shall be displayed near every call
button for a passenger lift in accordance with Sec 4.2.10.3.

4.2.2.5 Over speed safety

Efficient automatic devices shall be provided and maintained in each lift to stop the car
by suitable braking devices and to cutoff power from the motor whenever excessive
descending speed is attained.
4768 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

4.2.2.6 Over travel safety

Efficient automatic devices shall be provided and maintained in each lift to cut off power
from the motor if the car over travels either the top or bottom terminal landing.

4.2.2.7 Manual cranking system

There shall have standard cranking system operable from the lift machine room to move
the car manually, during a power failure, to the nearest higher or lower landing for
evacuation of passengers.

4.2.2.8 Emergency evacuation system

There shall have arrangement for emergency unlocking of the landing and lift door with a
special key from any landing for evacuation as well as for maintenance.

4.2.2.9 Protection of rope breakage

Necessary protection shall be taken against breaking of steel rope.

4.2.2.10 Safe working environment

In order to maintain a safe work environment, and to avoid potential hazards, the
following shall be provided:

(a) caution sign shall be installed in the areas listed below where potential hazard
exists:

(i) Trip hazard in machine room; and

(ii) Caution notice against unauthorized use of rescue devices (for example,
brake release device).

(b) Use of hard hats for entry in pit and car top during construction period.

(c) Warning sign shall be provided on the controller so also to eliminate the
possibility of contact with any exposed or concealed power circuit.

(d) Car top barricade system shall be provided as primary protection against fall,
on car top.

(e) Whenever work is carried out on the lift and lift is not required to be moved
on power, notice shall be put on electrical main switch indicating requirement
of de-energized condition.

(f) During lift installation/maintenance, protection against fall shall be provided

with suitable barricades for all open landing entrances.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4769
4.2.2.11 Car door safeties
Lift car doors and landing doors shall be provided with necessary safeties as per Sec
4.2.3.9.
4.2.3 Lift Cars
4.2.3.1 Lift cars shall have net maximum inside area for different loading
capacities as shown in Table 8. 4.1.
4.2.3.2 Lift car frame shall be of steel construction having sufficient strength to
support safely the rated load, the lift car and all requisite accessories.
4.2.3.3 There shall be provisions for elastic isolators between metal parts to ensure low
vibration and low noise during car travel.

Table 8.4.1: Maximum inside Net Platform Areas for Various Rated Loads
Rated Load Maximum Maximum Rated Load Maximum Maximum
(mass) Available Number of (mass) Available Number of
(kg) Car Passengers (kg) Car Passengers
Area (see Area (see
note) (m2) note) (m2)
100 0.40 1 975 2.35 14
180 0.50 2 1000 2.40 14
225 0.70 3 1050 2.50 15
300 0.90 4 1125 2.65 16
375 1.10 5 1200 2.80 17
400 1.17 5 1250 2.90 18
450 1.30 6 1275 2.95 18
525 1.45 7 1350 3.10 19
600 1.60 8 1425 3.25 20
630 1.66 9 1500 3.40 22
675 1.75 10 1600 3.56 23
750 1.90 11 1800 3.88 26
800 2.00 11 2100 4.36 30
825 2.05 12 2500 5.00 36
900 2.20 13

Note: (i) Beyond 2500 kg, add 0.16 m2 for each 100 kg extra
(ii) Maximum available car area = (W x D) + Available area near the car
door(s) inside the car.
Where, W = Car inside width in metre; D = Car inside depth in metre
4770 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

4.2.3.4 The car bodywork shall be of sufficient mechanical strength to resist accidental
impact by users or goods. The roof, solid or perforated, shall be capable of supporting
two persons or a minimum load of 150 kg. Perforations shall be sufficiently close in
mesh not exceeding 40 mm to provide reasonable protection against falling articles to
any person travelling in the car.
4.2.3.5 The floor shall be a smooth nonslip surface. If carpeting is used, it shall be
securely attached, heavy duty, with a tight weave and low profile, installed without
padding.
4.2.3.6 A handrail shall be provided on at least one wall of the car, preferably the rear.
The rails shall be smooth and the inside surface at least 38 mm clear of the walls at a
nominal height of 800 mm from the floor.
4.2.3.7 Height of the entrance to the lift car shall not be less than 2 m.
4.2.3.8 The lift car doors, shall be power operated horizontally sliding type (non-
collapsible), opened and closed by automatic means. However, if space is limited,
collapsible doors may be installed in case of buildings not exceeding 8 storeys or 26 m in
height, but they shall not be power operated. Sliding doors shall be guided at top and
bottom. Means shall be provided to prevent all sliding doors from jumping off the tracks
and suitable stops shall be provided to prevent the hanger carriage from leaving the end
of the track.
4.2.3.9 Lift door safeties
(a) Car and landing doors shall open and close in full synchronization being
mechanically connected to each other.
(b) Doors closed by automatic means shall be provided with door reopening
device(s) which will function to stop and reopen a car door and adjacent
landing door in case the car door is obstructed while closing. The reopening
device shall also be capable of sensing an object or person in the path of a
closing door without requiring contact for activation. Door reopening devices
shall remain effective for a period of not less than 20 seconds. The operating
mechanism of car door shall not exert a force more than 125 N.
(c) Car doors shall be equipped with efficient interlocking or other devices so
that the door cannot be opened except when the lift car is at the landing, and
that the lift car cannot be moved away from the landing until the leading edge
of the single slide or double speed door is within 50 mm of the nearest face of
the door jamb or the leading edges of the centre opening doors are within 50
mm of contact of each other.
4.2.3.10 Lift car doors, when closed, shall cover the opening fully except in the case of
vertical biparting car doors of goods lifts.
4.2.3.11 Where the lift car has solid enclosure and doors, provision shall be made for a
fan for adequate ventilation. To permit switching off the power supply to the lift without
switching off the fan and light, a separate switch shall be provided for fan and light.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4771
4.2.3.12 Any vision panel in a car door shall be fire resisting and shall be of safety wired
glass or similar material. The area between division bars or other supports shall not
exceed 0.1 m2. The bottom rail of a framed and glazed door shall be not less than 300
mm deep. Any projections on or recesses (including vision panels) in sliding car doors
shall be kept to a minimum in order to avoid finger trapping between sliding parts of the
door and any fixed part of the structure.
4.2.3.13 The lift car shall be provided with a self-leveling feature that will automatically
bring the car to the floor landing within a tolerance of + 13 mm under normal loading
and unloading conditions. This self-leveling shall, within its zone, be entirely automatic
and independent of the operating device and shall correct the over-travel or under-travel.
The car shall also be maintained approximately level with the landing, irrespective of
load. Where no self-leveling device is provided, the leveling difference between the car
and the landing shall be within + 40 mm.
4.2.3.14 Car operating panels shall be conveniently located on the side near the door so
that passengers can register calls as quickly as possible. The centre line of the alarm
button and emergency stop switch shall be at a nominal height of 890 mm, and the
highest floor button no higher than 1.37 m from the floor. Floor registration buttons,
exclusive of border, shall be a minimum of 18 mm in size, raised, flush or recessed.
Visual indication shall be provided to show each call registered and extinguished when
the call is answered. Depth of flush or recessed buttons when operated shall not exceed
10 mm. Markings shall be adjacent to the controls on a contrasting colour background to
the left of the controls; letters or numbers shall be a minimum of 15 mm high and raised
or recessed 0.75 mm. Sign plates permanently attached shall be acceptable. Emergency
controls shall be grouped together at the bottom of the panel.
4.2.3.15 A suitable battery operated alarm system shall be installed inside the lift car so
as to raise an alarm at a convenient place for getting assistance for passengers trapped
inside the lift car.
4.2.3.16 A car position indicator shall be provided above the car operating panel or over
the opening of each car to show the position of the car in the lift well by illuminated
visual indicator corresponding to the landing at which the car is stopped or through
which it is passing.
4.2.3.17 In addition, an audible signal shall preferably be installed which shall sound to
tell a passenger that the car is stopping at a floor served by the lift. A special button
located with emergency controls may be provided, operation of which shall activate an
audible signal only for the desired trip.
4.2.3.18 Each lift car shall be fitted with a light and the car shall be kept illuminated
during the whole period the lift is available for use.
4.2.3.19 In installations with more than two lifts in a bank, a telephone or other device
for two-way communication between each lift car and a convenient point outside the lift
well shall preferably be provided. Markings or the international symbol for telephones
shall be placed adjacent to the control on a contrasting colour background.
4772 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

4.2.3.20 Lift well and lift well enclosures

The Lift well shall only be used for housing equipment forming part of the lift installation
or for its operation and maintenance. No other equipment or services shall be
accommodated therein. For this purpose, the main electric supply line for lift machine
shall be deemed to be part of the lift and the electric cable, if laid along the lift well shaft,
shall be properly clamped to the wall.
4.2.3.21 The lift well shall not form part of the ventilation system of the building.
4.2.3.22 In multi-story residential buildings, hotels and hospitals, lift well shall be
isolated from sleeping rooms (bed rooms) by lobbies or other spaces.
4.2.3.23 Lift well shall not be located above any room, passage or thoroughfare.
However, when absolutely necessary, this can only be permissible with the prior
approval of the competent authority and in such case the following provisions shall be
made:
(a) The pit shall be sufficiently strong to withstand the impact of the lift car with
the rated load or the impact of the counterweight when either of these is
descending at the rated speed or at governor tripping speed;
(b) Spring or oil buffers shall be provided for lift car and counterweight; and
(c) The car and counterweight shall be provided with a governor operated safety
gear.
4.2.3.24 When there are three or fewer lift cars in a building, they may be located within
the same lift well enclosure. When there are four lift cars, they shall be divided in such a
manner that at least two separate lift well enclosures are provided. When there are more
than four lifts, not more than four lift cars may be located within a single lift well
enclosure.
4.2.3.25 The lift car and its counterweight shall travel in juxtaposition to each other.
4.2.3.26 Totally enclosed wells
The enclosure of the totally enclosed wells shall be continuous and shall extend on all
sides from floor to floor or stair to stair. No openings except for doors at landings and
necessary access panels shall be provided. The enclosure shall be of sufficient
mechanical strength to support the lift guides at appropriate intervals and to support in
true alignment the landing doors with operating mechanisms and locking devices.
4.2.3.27 Open type wells
(a) When Lift well enclosures are constructed of wire grille or similar material,
the mesh opening shall not be greater than 30 mm (except for door at
landings). Such enclosures shall be of sufficient strength to resist accidental
impact by users of adjoining areas or by materials or vehicles being moved in
the vicinity.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4773

(b) Where the clearance between the inside of an open type lift well enclosure
and any moving or movable part of the lift equipment or apparatus is less
than 50 mm, the openings in the enclosure material shall not be more than
10 mm. Larger openings up to 30 mm shall be permissible provided it is
further protected by square mesh netting with aperture of not greater than 10
mm and wire not smaller than 1 mm in diameter.

4.2.3.28 There shall be no opening in the lift well enclosure for access to the lift well
through the space under the counterweight.

4.2.3.29 The inside surfaces of the lift well enclosures facing any car entrance shall
form a smooth continuous flush surface devoid of projections or recesses. Where
projections or recesses cannot be avoided, the underside of these projections/recesses
shall be beveled to an angle of 60 degrees from the horizontal by means of metal plates
or other fire resistive materials as shown in Figure 8.4.1.

Figure 8.4.1 Beveled projections/recesses

4.2.3.30 Sufficient clearance space shall be provided between the guides for the car and
the side walls of the lift well enclosure to allow safe and easy access to the parts of the
safety gears for their maintenance and repairs.
4774 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

4.2.3.31 Maximum clearance between the inner surface of well enclosure on the landing
door side and any part of car facing the surface shall be 150 mm except that 230 mm
and 200 mm clearance will be permissible when power operated vertically bi-parting
landing doors or two speed horizontally sliding doors are installed respectively.

4.2.3.32 Each lift well serving more than two floors shall have vent(s) properly located at
the top of the exterior wall. The vents shall be louvered with birds screens. If the well is
located in such a way that no exterior wall is available for louvers, vents with connecting
noncombustible ducts to an outside wall shall be provided. The area of vent shall not be
less than 3.5% of the area of the lift well, provided that a minimum of 0.3 m2 per lift is
provided. Of the total required vent area not less than one-third shall be permanently
open or automatically opened by a damper.

4.2.3.33 Bottom car clearance, passenger and service lift

When the car rests on its fully compressed buffer there shall be a vertical clearance of not
less than 600 mm between the pit floor and the buffer striker plate or the lowest structural
or mechanical part equipment or device installed. The clearance shall be available
beneath the whole area of the platform except for:

(a) Guide shoes or rollers, safety jaw blocks, platform aprons, guards of other
equipment located within 300 mm measured horizontally from the sides of the
car platform; and

(b) Compensating sheaves.

Provided that:
(i) In all the cases, including small cars, a minimum clearance of 600 mm is
available over a horizontal area of 800 mm x 500 mm.

(ii) In all the cases, when the car rests on its fully compressed buffers, there
shall be a vertical clearance of not less than 50 mm between any part of the
car and any obstruction of device mounted in the pit.

4.2.3.34 Top car clearance, passenger and service lift

The vertical clearance between the car cross-head and the nearest overhead obstruction
within 500 mm measured horizontally to the nearest part of the crosshead when the car
platform is level with the top landing, shall be not less than the sum of the following;

(a) The bottom counterweight runby

(b) The stroke of the counterweight buffer used.

 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4775

(c) One-half of the gravity stopping distance based on:

(i) 115 percent of the rated speed where oil buffers are used and no provision is
made to prevent the jump of the car at counterweight buffer engagement;
and
(ii) Governor tripping speed where spring buffers are used.
Note: The gravity stopping distance based on the gravity retardation from any
initial velocity may be calculated according to the following formula
S  51V 2
Where,
S = Free fall in mm (gravity stopping distance), and
V = Initial velocity in m/s
(d) 600 mm.
Where, there is a projection below the ceiling of the well and the projection is more than
500 mm, measured horizontally from the centre line of the cross-head but over the roof of
the car, a minimum vertical clearance not less than that calculated above shall also be
available between the roof of the car and the projection.
Provided that the vertical clearance between any equipment mounted on top of the car
and the nearest overhead obstruction shall be not less than the sum of the three items (a),
(b) and (c) as calculated above plus 150 mm

4.2.3.35 Bottom runby for cars and counterweights, passenger and service lift
The bottom runby of cars and counterweights shall be not less than the following:
(a) Where oil buffers are used 150 mm
(b) Where spring-buffers are used:
(i) 150 mm for variable voltage motor control, electronic devices, ACW
control, ACVVVF control and solid state DC variable voltage control as
defined in Sec 4.1.3
(ii) Not less than the following values for single-speed AC control, two-speed
AC control and rheostatic control as defined in Sec 4.1.3.
Rated speed (m/s) Runby (mm)
Up to 0.125 75
0.125 to 0.25 150
0.25 to 0.50 225
0.50 to 1.0 300
4776 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
4.2.3.36 Maximum bottom runby, passenger and service lift
In no case the maximum bottom runby shall exceed the following:
(i) 600 mm for cars
(ii) 900 mm for counterweights.

4.2.3.37 Top Counterweight Clearances, passenger and service lift

The top counterweight clearance shall be not less than the sum of the following four
items:
(a) the bottom car runby;
(b) the stroke of the car buffer used;
(c) 150 mm; and
(d) one-half the gravity stopping distance based on
(i) 115 percent of the rated speed where oil buffers are used and no provision is
made to prevent jump of the counterweight at car buffer engagement; and
(ii) Governor tripping speed where spring buffers are used.

4.2.3.38 Top car clearance, Goods lift

The top car clearance shall be sufficient to avoid any protruding part fixed on the top of
the car coming in direct contact with the ceiling or diverting sheave. The clearance shall
not be less than the sum of the following four items:
(a) The bottom counterweight runby,
(b) The stroke of the counterweight buffer used,
(c) The dimensions of the portion of the diverting sheave hanging underneath the
ceiling in the lift well
(d) 150 mm for compensating for gravity stopping distance and future repairs to the
rope connections at counter weight and at the car or at the suspension points.

4.2.3.39 Bottom car clearance, goods lift

The bottom car clearance shall be maintained in such a way that the counterweight shall
not come in contact with the ceiling or any part hanging underneath the ceiling, when the
car completely rests on fully compressed buffers, provided the buffers are spring type
mounted on solid concrete or steel bed.
In case of wooden buffers the bottom car clearance shall be maintained in such a way that
the total downward travel of the car from the service level of the immediate floor near the
pit, shall not be more than the top counterweight clearance, when the wooden buffers are
completely crushed.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4777

4.2.3.40 Top counterweight clearance, goods lift

The top clearance for the counterweight can be calculated taking into account the
following and shall not be less than the sum of the following three items:

(a) Car runby,

(b) Compression of the buffer spring or height of the wooden block used as buffer,
and

(c) 150 mm to compensate for gravity stopping distance for counterweight and any
future repairs to rope connections at the counterweight at the car ends or at the
suspension points.

4.2.3.41 Runby for cars and counterweights, goods lift

The bottom runby for cars and counterweights shall not be less than 150 mm
4.2.3.42 Maximum bottom runby, goods lift

In no case the maximum bottom runby shall exceed 300 mm.

4.2.3.43 Overhead Height

The overhead height shall not be less than as shown in Table 8.4.2

4.2.3.44 Lift well dimensions

Recommended dimensions of lift well and its entrances are provided in Tables 8.4.3 to
8.4.6. These dimensions are primarily for architects and building planners for planning of
lift well.

4.2.4 Landing Doors

4.2.4.1 Every landing, where there is access from the landing to the lift car, shall be
fitted with a landing door. Such door shall be fitted with efficient interlocking or other
devices so as to ensure that the door cannot be opened except when the lift car is at the
landing and that the lift car cannot be moved away from the landing until the door is
closed and locked. Where mid bar collapsible doors are used for landing entrance, they
shall not be power operated.

4.2.4.2 Where landing doors are manually operated and no indicators are provided,
vision panels of similar construction as in Sec 4.2.3.12 shall be provided.

4.2.4.3 No automatic fire door or shutter which operates by means of a fusible link or
otherwise due to the action of heat shall be allowed in any landing opening or lift way
enclosure of any lift, if such opening gives access to any exit from the building.
4778 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

4.2.4.4 In case of passenger lifts, solid sliding doors shall preferably be provided for
buildings above 6 storeys or 20 m in height. Solid swing doors may also be used where
sliding space is not available parallel to the entrance door. Collapsible doors shall not be
provided in case of buildings above 8 storeys or 26 m in height.
Table 8.4.2: Minimum Pit Depths, Overhead Heights and Machine Room sizes for
Traction Lifts - Overhead Machines

Speed (m/s) Up to >0.70 >1.00 >1.50 >1.75 >2.00 >2.50 >3.00

0.70 ≤1.00 ≤1.50 ≤1.75 ≤2.00 ≤2.50 ≤3.00 ≤4.00

(i) Pit Depth, mm 1500 1500 1600 2150 2200 2500 3000 3200
(ii) Overhead 4200 4250 4800 4800 5200 5400 - -
Height, mm
(iii) Machine Room D+ D+ D+ D+ D+ D+ D+ D+
Depth, mm 2000 2000 2000 2500 2500 2500 3000 3000
(iv) Machine Room C+ C+ C+ C+ C+ C+ C+ C+
Width, mm 1000 1000 1200 1200 1500 1500 1800 1800
Notes:
1. C is lift well depth (mm) and D is lift well width (mm).
2. The total overhead height has been calculated on the basis of car height of
2300mm.
3. Dimensions of pit depth and overhead height may differ in practice as per
individual manufacturer's design depending upon load, speed and drive. However,
the pit depth and overhead height shall be such as to conform to the requirements
of bottom clearance and top clearance In accordance with the accepted standard.

Table 8.4.3: Recommended Dimensions of Passenger & Service Lifts and Lift Wells
Capacity Car Dimensions Lift Well Entrance
(mm) Dimensions (mm) Size (mm)
Persons Kg Width Depth Width Depth

4 272 1100 700 1900 1300 700 (Min)

6 408 1100 1000 1900 1700 700 (Min)
8 544 1300 1100 1900 1900 800
10 680 1300 1350 1900 2100 800
13 884 2000 1100 2500 1900 900
16 1088 2000 1300 2500 2100 1000
20 1360 2000 1500 2500 2400 1000
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Notes :
1. In case of manually operated doors, clear entrance will be reduced by the amount of
projection of handle on the landing.
2. All dimensions given above for lifts having centre opening power operated doors
with counterweight at rear, are recommended dimensions primarily for architects and
building planners. Any variations, mutually agreed between the manufacturer and
purchaser, are permitted. However variation in:
(i) Car inside dimensions shall be within the maximum area limits specified in
accordance with Table 8.4.1
(ii) Entrance width on the higher side is permitted.
(iii) Entrance width may be reduced up to a maximum of 100 mm subject to a
minimum of 700 mm.

Table 8.4.4: Recommended Dimensions of Goods Lifts and Lift Wells

Load (Kg) Car Dimensions (mm) Lift Well Dimensions Entrance
(mm) Size (mm)
Width Depth Width Depth
500 1100 1200 1900 1500 1100
1000 1400 1800 2300 2100 1400
1500 1700 2000 2600 2300 1700
2000 1700 2500 2600 2800 1700
2500 2000 2500 2900 2800 2000
3000 2000 3000 2900 3300 2000
4000 2500 3000 3400 3300 2500
5000 2500 3600 3400 3900 2500
Notes :
(i) The width of lift machine room shall be equal to be lift well width subject to a
minimum of 2500 mm.
(ii) Clear entrance width is based on vertical lifting car door and vertical bi-parting
landing doors. For collapsible mid-bar doors the clear entrance width will be
reduced by 200 mm (maximum 1800 mm).
(iii) All dimensions given above are recommended dimensions primarily for
architects and building planners. Any variations mutually agreed between the
manufacturer and the purchaser are permitted. However, variation in car inside
dimensions shall be within the maximum area limits in accordance with
Table 8.4.1.
(iv) For dimensions of pit depth and overhead height, consider data shown in
Table 8.4.2.
4780 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
Table 8.4.5: Recommended Dimensions of Hospital Lifts and Lift Wells
Capacity Car Dimensions Lift Well Entrance
(mm) Dimensions (mm) Size (mm)
Persons Kg Width Depth Width Depth

12 1020 1000 2400 1800 3000 800

20 1360 1300 2400 2200 3000 1200
26 1768 1600 2400 2400 3000 1200

Notes :
(i) In the case of manually operated doors, clear entrance will be reduced by the
amount of projection of handle on the landing door.
(ii) Although 15 persons capacity lift is not standard one, this is included to cover
lifts of smaller capacity which can be used in small hospitals.
(iii) All dimensions given above are recommended dimensions primarily for
architects and building planners. Any variations mutually agreed between the
manufacturer and the purchaser are permitted. However, variation in car inside
dimensions shall be within the maximum area limits in accordance with Table
8.4.1.
(iv) For dimensions of pit depth and overhead height, consider data shown in Table
8.4.2.

Table 8.4.6: Recommended Dimensions of Dumb Waiter and Lift Wells (for speeds
up to 0.5 m/s)
Load Car Inside Dimensions (mm) Lift Well Dimensions Entrance
(Kg) (mm) Size
Width Depth Height Width Depth (mm)

100 700 700 800 1200 900 700

150 800 800 900 1300 1000 800

200 900 900 1000 1400 1100 900

250 1000 1000 1200 1500 1200 1000

Notes: Entrance width is based on assumption of provision of vertical bi-parting doors

(no car door is normally provided).
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4781

4.2.5 Guide Rails

4.2.5.1 Guide rails shall be made of high quality steel, straight and of proper thickness.
Where the nature of processes carried on in the building gives rise to acid fumes or
corrosive substances the steel rails shall be treated for corrosion resistance.
4.2.5.2 Lift car and counterweight guide rails shall be continuous throughout the entire
length right from the bottom of the pit floor to the top most floor served plus additional
length as may be required for operation of safety against over run. They shall be
provided with adequate brackets or equivalent fixing devices of such design and spacing
that the rails shall not deflect more than 4 mm under normal operations
4.2.5.3 For passenger and goods lifts having a rated speed of 0.5 m/s or more, the car
guide rails shall have working surfaces machined and smooth.
4.2.6 Lift Pits
4.2.6.1 A lift pit shall be provided at the bottom of every lift well. The minimum depth
of lift pit shall be as shown in Table 8.4.2.
4.2.6.2 Lift pits shall be of sound construction and shall be maintained in dry and clean
condition. Where necessary, provision shall be made for permanent drainage.

4.2.6.3 Lift pits having depth more than 1.6 m shall be provided with a suitable
descending arrangement to reach the lift pit.

4.2.6.4 Light points shall be provided in all lift pits for facility of repair and
maintenance works.

4.2.6.5 In case of a group of two or more lift wells, arrangements shall be provided to
allow inspection of a lift pit through the adjoining one.

4.2.7 Buffers

4.2.7.1 Buffers of spring or oil shall be used for safety. Buffers shall be fitted under the
lift car and counterweight directly or on the pit floor with suitable concrete or steel
foundation. Oil resistant rubber buffers may be used with lifts having a rated speed not
exceeding 0.25 m/s. Lifts having rated speed in excess of 0.25 m/s and up to and
including 1.0 m/s, spring or oil buffers shall be used. For lifts having rated speed more
than 1.0 m/s, only oil buffers shall be used. Wooden blocks suitably treated may also be
used for service lifts for speeds up to 0.5 m/s. Buffers shall be located symmetrically
with reference to the vertical centre line of the car/counterweight with a tolerance of 50
mm.

4.2.7.2 The minimum stroke of oil buffers shall be such that the car or the
counterweight on striking the buffers at 115 percent of rated speed shall be brought to
rest with an average retardation of not more than 10 m/s2.
4782 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

4.2.7.3 When buffers are struck with an initial speed of less than 115 percent of the
rated speed, the peak retardation shall not exceed 25 m/s2 for a duration of more than
0.04 second, with any load in the car ranging from 75 kg to the rated load.

4.2.8 Machine Room and Overhead Structures

4.2.8.1 The lift machine room shall only be used for housing lift machinery, controller
and other associated apparatus and equipment. No other services or equipment shall be
accommodated therein. If motor-generators for controlling speed of multi-voltage or
variable voltage machines, secondary sheaves, pulleys, governors, floor selecting
equipment and other associated equipment are installed in an adjoining room, this room
shall also be reserved for exclusive use of lift equipment.

4.2.8.2 Lift machine room and other associated equipment rooms shall be fire proof,
weather proof and adequately lighted. Means to prevent spread of fire or smoke from
machine room into lift well shall be provided. Machine room shall have permanent
ventilation opening direct to the open air having a free area not less than 0.1 m2 per lift.
Ambient temperature of machine room shall be maintained between +5oC and +40oC

4.2.8.3 The height of the machine room shall not be less than 2.30 m throughout under
the lifting beam (trolley beam) to allow any portion of equipment to be accessible and
removable for repair and replacement. An overhead trolley beam of steel construction of
adequate strength shall be provided in the machine room, for movement of equipment
during installation.

4.2.8.4 The machine room shall be adequately sized and shall have sufficient floor area
required for easy access to all parts of the machines and equipment located therein for
purposes of inspection, maintenance or repair. Clearance space of 1 m shall be provided
on those sides of control panels where maintenance is required to be carried out while the
panel is energized, otherwise 0.5 m clearance space may be provided. For planning
purposes the lift machine room size can be as shown In Table 8.4.2

4.2.8.5 The room shall be kept closed, except to those who are concerned with the
operation and maintenance of the equipment. When the electrical voltage exceeds
220/230 V dc, a danger notice plate shall be displayed permanently on the outside of the
door and on or near the machinery.

4.2.8.6 Machine room floor shall not have holes/punches in it except for necessary
small openings for passage of ropes cables etc. If any machine room floor or platform
does not extend to the enclosing walls the open sides shall be provided with hand rails or
otherwise suitably guarded.

4.2.8.7 All machines, pulleys, over speed governors and similar units shall be securely
fixed on the machine room floor.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4783

4.2.8.8 Adequate artificial light shall be provided in the machine room. A 15 amps 3
pin power outlet for hand operated tools and a 5 amps 2 pin electrical outlet for portable
hand lamp set shall be provided in the machine room.

4.2.8.9 Access to Machine Room

(a) The machine room shall be provided with a direct, independent and
convenient access. Access to a machine room above a lift well may be either
from the roof or by an internal staircase.

(b) Machine room floor may be provided with a trap door. When access to the
machine room is provided through the trap door, the size of the trap door
shall not be less than 1.0 m x 1.0 m otherwise it may be 0.5 m x 0.5 m. Trap
doors shall be hinged, opening into the machine room, of sound construction,
balanced and tightly secured to minimize noise travel. Hand rails shall be
provided around trap door opening.

(c) Where a machine room entrance is less than 1.5 m above or below the
adjacent floor or roof surface, a substantial permanently attached ladder may
be used.

(d) Where the machine room entrance is 1.5 m or more above or below the
adjacent floor or roof surface, access shall be provided by means of standard
stairs.

(e) Access to a machine room in a basement may be provided from a corridor.

(f) Access to a machine room via the lift well shall be prohibited.

(g) Emergency exit shall be provided in case of large machine room having four
or more lifts.

4.2.8.10 The space at secondary level in which the overhead pulleys, overspeed
governors and similar machinery are housed shall have a clear height of at least 1.2 m.
Where practicable, it shall have a substantial platform or floor and be provided with
permanent and adequate artificial illumination. Safe and convenient access to secondary
level shall be provided. Means of access between a secondary floor and machine room
may be a ladder. Hand rails shall be provided at platform and access to floor.
4.2.9 Hall Buttons, Hall Lanterns and Special Signs

4.2.9.1 Hall buttons

(a) Each landing shall have hall call buttons to register call for lift service for
upward or downward movements. The centre line of the hall call buttons
shall be at a nominal height of 1 m above the floor.
4784 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

(b) Direction buttons, exclusive of borders, shall be a minimum of 18 mm in

size, raised, flush or recessed. Visual indication shall be provided to show
each call registered and extinguished when the call is answered. Depth of
flush or recessed button when operated shall not exceed 10 mm.

4.2.9.2 Hall lantern

(a) Where lifts are installed in totally enclosed wells, a visual signal shall be
provided at each lift well entrance indicating to the prospective passenger the
car answering the call and its direction of travel. An audible signal may also
be included.

(b) The visual signal may be in the form of digital lift position indicator or
directional indicator. The visual signal for each direction/lift position shall be
a minimum of 62 mm in size and visible from the proximity of the hall call
buttons.

(c) The centre line of the fixture shall be located at a minimum of 1.8 m from the
floor.

4.2.9.3 Special signs

(a) Door Jamb Marking: The floor designation shall be provided at each lift well
entrance on both sides of jamb visible from within the car and the lift lobby at
a height of 1.5 m above the floor. Designations shall be on a contrasting
background 50 mm high and raised 0.75 mm.
(b) Applied plates permanently attached shall be acceptable. In case of a
completely enclosed lift well a notice with the word 'Lift' shall be placed
outside of each landing door. Electric light shall be provided such that this
sign remains visible even if the surroundings are dark.
(c) A permanent warning sign shall be installed immediately above each hall
push button station on each floor reading: IN FIRE EMERGENCY, DO NOT
USE LIFT. USE EXIT STAIRS. This sign shall be in letters not less than 12
mm high.
The warning sign may consist of incised, inlaid or embossed letters on a metal, wood,
plastic or similar plate securely and permanently attached to the wall, or letters incised or
inlaid directly into the surface of the material forming the wall.
4.2.10 Electrical Wiring and Apparatus
4.2.10.1 Construction, installation and maintenance of all electrical supply lines and
apparatus in connection with lift installation shall be done with proper protection so that
there may be no danger to persons there from. No bare conductor shall be used in any lift
car. Installation of electrical wiring shall conform to the provisions of Chapter 1.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4785

4.2.10.2 Electrical circuits for lights and ventilation fans, and supply to 3 pin and 2 pin
socket outlets shall be controlled by a separate main switch or circuit breaker, and shall
be independent of machinery power supply such that lighting circuits remain alive when
power to machinery is interrupted.

4.2.10.3 Suitable cautionary notice shall be affixed near every motor or other apparatus
in which energy used is at a voltage exceeding 220 volts.

4.2.10.4 Travelling cable

(a) Circuits which supply current to the motor shall not be included in any twin
or multi-core travelling cable used in connection with the control and safety
devices.

(b) For building 10 storeys (33 m) or less in height, a travelling cable which
incorporates conductors for the control circuits shall be separate and distinct
from that of lighting and signaling circuits. In case of buildings more than 10
storeys or 33 m in height or where high speed (1.50 m/s or more) lifts are
employed, a single travelling cable for lighting and control circuits may be
permitted, provided that all conductors are insulated for the maximum
voltage in the cables.

4.2.10.5 Supply cables and switches

(a) Each lift shall be provided with a main switch or circuit breaker of a capacity
determined by the lift manufacturer and the incoming supply cable shall
terminate in this switch. For a single lift, this switch shall be fixed adjacent to
the machine room entrance. In a machine room common to more than one
lift, each main switch shall be conveniently situated with respect to the lift it
controls. Switches and fuses (which may form part of a distribution switch
board) shall be provided for isolating the supply power to machine room.
(b) Where a supply cable serves more than one lift, a diversity factor may be
used for the determination of conductor size. The actual diversity factor to be
adopted shall be decided by the lift manufacturer.
4.2.10.6 Earthing
All electrical machinery/equipment viz. electric motor, winding machine, control panel
etc. which normally carry mains current shall be properly connected to the earthing
system. Similarly all metallic cases, covers of door interlocks, door contacts, call and
control buttons, stop buttons, car switches, limit switches, junction boxes and similar
electrical fittings which normally carry only the control current shall also be properly
connected to the earthing system. All earthing terminal and earthing conductors in this
regard shall conform to the requirements of Chapter 1 Part 8.
4786 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

4.3 Design Considerations

4.3.1 Number of Lifts and Capacity

4.3.1.1 The number of lifts, car capacity and speed of the lift shall be selected to have
the most effective lift system. The lift system shall be able to handle adequate number of
passengers during peak hours and at the same time Interval and Travel Time shall be
within reasonable limits.
4.3.1.2 Average Interval shall not be more than shown in Table 8.4.7. Travel time shall
not exceed 150 seconds.
4.3.1.3 The passenger handling capacity (H) of a lift system for different occupancies in
terms of the number of passengers to be handled in the building in a five minute peak
period shall not be less than that indicated in Table 8.4.7.
4.3.1.4 For the purpose of population estimation, the density of people shall be based
on the actual number of occupants, but in no case less than those specified in Table 8.4.8.
The occupant load of a mezzanine floor shall be taken into account for working out the
population for a particular floor to which the mezzanine floor discharges its loads.
4.3.1.5 Car speed and acceleration
The car speed for the different types of lifts in different occupancies shall normally be as
given in Table 8.4.9. A higher or lower speed lift may be used in special cases when
conditions warrant use of such lifts. The car acceleration or deceleration shall not be
more than 1.2 m/s2.
Table 8.4.7: Recommended Interval and 5-minute Handling Capacity for Different
Occupancy
Type of Occupancy Interval 5-min. Handling Type of Occupancy Interval 5-min. Handling
(Sec) Capacity (H) % (Sec) Capacity (H) %

Office Apartments (contd.)

Diversified Tenancy Middle Income Apartments 60-80 6-8
High Quality 15-29 12 Low Income Apartments 80-120 10-11
Standard Quality 30-39 14 Dormitories, Halls of Residence 60-80 10-11
Single Tenancy Hospitals
High Quality 15-24 14 Private Hospital 50-60 12
Standard Quality 25-35 16 General Hospital 60-70 14
Hotels and Motels Long term Nursing Facilities 60-70 8
High Quality 30-50 12-15 Educational Institutions 40-50 25
Standard Quality 50-70 10-12 Buildings with Assembly Facilities 40-50 15
Apartments Shops and stores 40-50 5
High Cost Apartments 50-70 5-7
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4787

Table 8.4.8: Occupant Load for Estimation of Population

Type of Occupancy Population Factor Type of Occupancy Population Factor

Office Apartments (contd.)

Diversified Tenancy Middle Income Apartments 2 people per bedroom

High Quality 14-23 m2 net usable area per Low Income Apartments 2.5-3 people per bedroom
persona

Standard Quality 10-12 m2 net usable area per Dormitories, Halls of 20 m2 net usable area per
person Residence person

Single Tenancy Hospitals

High Quality 12-19 m2 net usable area per Private Hospital 3 people per bed
person

Standard Quality 8-10 m2 net usable area per General Hospital 3-4 people per bed
person

Hotels and Motels Long term Nursing Facilities 1.75 people per bed

High Quality 1.3 people per room Educational Institutions 4 m2 per student

Standard Quality 1.7 people per bedroom Buildings with Assembly

Facilities

Conventions 1.9 people per bedroom With fixed or movable seats 0.60 m2 per personb
and dance floor

Apartments Without seating facilities 1.5 m2 per personb

including dining rooms

High Cost Apartments 1.5 people per bedroom Shops and stores 2 m2 of net selling areac

Notes :

(i) Net usable area = gross area less lift shaft and lobby space, mechanical space,
columns, toilets, corridor around core, air-conditioning machinery space.

(ii) Population estimation shall be based on gross area (plinth area or covered area).
The gross area shall include, in addition to the main assembly room or space, any
occupied connecting room or space in the same storeys or in the storey above and
below, where entrance is common to such rooms and spaces and they are
available for use by the occupants of the assembly place. No deductions shall be
made in the gross area for corridors, closets or other subdivisions, the area shall
include all space serving the particular assembly occupancy.
(iii) Net selling area is area open to the public.
4788 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Table 8.4.9: Car Speed for Lift in Different Kinds of Usage

Building Type Rise (m) Minimum Building Type Rise (m) Minimum
Car Speed Car Speed
(m/s) (m/s)

Office Building 0 to 40 2.0 Hospital (contd.) 31 to 40 1.6

41 to 70 2.5 41 to 55 2.0
71 to 85 3.6 56 to 75 2.5
86 to 115 4.0 Above 75 3.6
Above 115 5.0 Apartments 0 to 25 0.63
Hotels 0 to 40 2.0 26 to 40 1.0
41 to 70 2.5 41 to 60 1.6
71 to 85 3.6 Above 60 2.0
86 to 115 4.0 Stores 0 to 30 1.0
Above 115 5.0 31 to 45 1.6
Hospital 0 to 20 0.63 46 to 60 2.0
21 to 30 1.0 Above 60 2.5

4.3.1.6 Handling capacity and interval

(a) The handling capacity, for incoming/up-peak passenger, shall be calculated by
the following formula:
300 Q  N 100
H
P T

Where,
H = passenger handling capacity of the lift system during five minute peak
period, expressed as the percentage of the estimated total population
handled.
Q = average number of passengers carried in each car per trip,
N = number of lifts in the system,
P = total population to be handled during peak period (it is related to the
area for which a particular bank of lift serves)
T = average round trip time in seconds, that is, the average time required
by each lift in taking one full load of passengers from ground floor
discharging them in various upper floors and coming back to ground
floor for taking fresh passengers for the next trip;
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4789
The value of Q depends on the dimension of the car. It may be noted that the car
is not loaded always to its maximum capacity during each trip and therefore, for
calculating T and H the value of Q shall be taken as 80 percent of the maximum
capacity of the car.
T is the sum of the time in seconds required in the following process:
(i) Time for entry of passengers on the ground floor or lowest lift lobby;
(ii) Time for exit of the passengers on each floor of discharge;
(iii) Door operation time (opening and closing) and car start time on each
floor the lift stops, including ground floor;
(iv) Acceleration and deceleration periods;
(v) Stopping and leveling periods;
(vi) Periods of full rated speeds between stops going up and
(vii) Periods of full rated speeds between stops going down.
(a) The average Interval shall be calculated by the following formula:
T
I 
N

Where, = Interval of availability of lifts on the lowest lift lobby.

4.3.2 Shape and Size of Lifts
4.3.2.1 Careful analysis shall be performed during selection of shape and size of lifts so
as to get full advantage of its shape for the most effective use of lifts and building space.
4.3.2.2 The dimensions of the car platform shall be such that the car will not exceed its
rated load when packed full. Net inside area of the lift car shall be as per Sec 4.2.3.1.
For the same platform area, a lift having higher width to depth ratio can accommodate
more passengers and takes less time for passenger transfer. The width of the car is
determined by the width of the entrance and the depth of the car is regulated by the
loading.
4.3.3 Location and Arrangement of Lifts
4.3.3.1 A thorough investigation shall be carried out for assessing the most suitable
location for lift(s) while planning the building. It shall take into account future
expansions, if any.
4.3.3.2 The lifts shall be easily accessible from all entrances to the building. For
maximum efficiency, they shall be grouped near the centre of the building. Walking
distance from the lift to the farthest office or suite shall not exceed 60 m.
4.3.3.3 Arrangement of lifts
(a) When more than one lifts are installed in a group, they shall be arranged side
by side or in two rows facing each other. Separation of lifts in the group shall
be avoided.
4790 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
(b) The lift lobby in front of lifts shall be wide enough to allow sufficient space
for waiting passengers and proper vision of hall button and hall lanterns.
Figures 8.4.2 to 8.4.6 give acceptable arrangements of lifts in a group with
acceptable space for waiting passengers. More space shall be allowed in front
of the lifts in the main floor than in the upper floors.
(c) It is preferable that the lift lobby is not used as a thoroughfare, but when
absolutely needed the lift lobby shall be wider enough to take into account of
the space for people who are moving.
4.3.4 Location of Machine Room
4.3.4.1 The machine room shall, as far as practicable, be placed immediately above the
lift well.

Figure 8.4.2 Two car arrangement

Figure 8.4.3 Three car arrangement

evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4791

Figure 8.4.4 Four car arrangement

4792 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

Figure 8.4.5 Six car arrangement

 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4793

Figure 8.4.6 Eight car arrangement

4.3.4.2 If a machine room on the lift well is impracticable for architectural or other
reasons, the machine room may be placed below the lift well or in the basement, keeping
adequate safety provisions. If the lift machine room is located in the basement, it shall be
separated from the lift well by a separation wall. Alternatively, machine room less lift
can be considered for installation.
4.3.4.3 High speed lifts with gearless machine shall, in all cases, have machine room
above the lift well.
4.3.4.4 Machine room shall not be located adjacent to or above sleeping rooms (bed
rooms) in residential and hotel buildings; and patients' rooms, intensive care rooms and
operation theatres of hospital/health care buildings.
4.3.5 Structural Considerations
4.3.5.1 Lift well enclosures, lift pits, machine rooms and machine supports, besides
conforming to the essential requirements in Sec 4.2, shall form part of the building
construction and comply with the lift manufacturer's drawings.
4.3.5.2 Machine room
Machine room floor shall be strong enough to support the heaviest component of lift
machinery and shall be designed to carry a load of not less than 500 kg/m2 over the
whole area and also any load which may be imposed thereon by the equipment used in
the machine room or by any reaction from any such equipment during periods of both
normal operation and repair.
4794 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
4.3.5.3 The total load on overhead beams and their supporting structural members shall
be assumed to be equal to the dead load of slabs including load of all equipment resting
on the beams plus twice the minimum load suspended from the beams.
4.3.5.4 The deflection of the overhead beams under the minimum static load calculated
1
in accordance with Sec 4.3.5.3 shall not exceed 1500 of the span.
4.3.5.5 Beams at all other floor slabs which correspond to the beam at machine room
floor shall also be made stronger to take the reaction from the guides when the lift is
made to stop consequent to the breaking of the wire ropes or the application of the safety
device.
4.3.5.6 Suitable lifting beams may be provided immediately below the machine room
ceiling for carrying the tackle to facilitate lifting of any heavy part of a heavy lift. For
lower capacity lifts, suitable suspension hooks may be provided.
4.3.5.7 The roof of the machine room shall be strong enough to take up the pulley
which could be used for lifting up parts of the lift machinery for inspection and repair.
4.3.5.8 The equivalent dead loads imposed upon the building by the lift installations
shall be shown on the lift manufacturer's drawing so that the architect/engineer may
make provisions accordingly.
4.3.6 Control System
4.3.6.1 The control of operation of the lift system, leveling, door opening and closing,
response to hall calls etc. shall be fully automatic. All control equipment shall be
efficient and fail-safe.
4.3.6.2 The control system shall be capable of accelerating the car smoothly to full
running speed and stopping the lift with smooth retardation.
4.3.6.3 Variation in speed of the lift between no load and full load conditions shall not
be more than plus or minus five percent. The control system shall be capable of
correcting any tendency to over speed or under speed. The control system shall have
safety device(s) to stop the lift car if its running speed exceeds its rated speed by ten
percent.
4.3.6.4 It shall have facility to level or re-level the lift car within  13 mm. The leveling
system shall be fully automatic and shall correct for over travel or under travel and rope
stretch. The car stopping and leveling system shall be unaffected by external influences
like variation in load, temperature, rope elongation etc.
4.3.6.5 Closing and opening of car doors and landing doors shall be fully automatic and
shall operate in full synchronization with one another. Door opening and closing
operations shall be so controlled as to ensure proper safety of passengers.
4.3.6.6 Door opening and closing time and door hold open time shall be automatically
controlled to get minimum transfer time in any landing. For larger installations, transfer
times shall be independently adjustable to suit the requirements of the building as well as
the characteristics of the traffic.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4795
4.3.6.7 Independent door closing push button shall be provided in the lift car to allow
instant door closing. Similarly door opening push button shall be provided in the lift car
to reverse the closing motion of the doors or hold them open.
4.3.6.8 When there are conditions that particularly affect the safety of passengers, the
closing of doors shall only be effective by the continuous pressure of push buttons in the
lift car or landings.
4.3.6.9 Each lift shall have key operated switch to transfer from normal passenger
control to a car preference control. During car preference control the operation of the lift
shall be from the car only and the doors shall remain open until a car call is registered for
a floor designation. All landing calls shall be bypassed and car position indicators on the
landings for this lift shall not be illuminated.
4.3.6.10 Provisions shall be made in the control system to take any car out of service
still maintaining the controlled operation of the remaining cars of a group of cars
required for passenger traffic. It is essential that such provision shall not stop the
fireman's control from being operative in the event of the lift being designated as a
fireman's lift.
4.3.6.11 When required, fire switch shall be provided in the control system as per
Sec 4.2.2.2.

4.4 Escalators
4.4.1 General
4.4.1.1 Escalators shall be located in the main line of circulation and in such a way that
most persons entering the building can see it. Care shall be taken to eliminate
interference to the traffic movement.
4.4.1.2 Escalators shall discharge into an open area with no turns or choice of direction
necessary. Ample space for people must be provided at the entry and exit landings of an
escalator, space between the newel and the nearest obstruction in front of the escalator
shall be a minimum of 3 m.
4.4.1.3 If an unloading area is restricted, such restrictions as doors or gates shall be
interlocked with the escalator to insure that the restriction is removed before the escalator
can be run.
4.4.1.4 The escalator shall have provision to run in both upward and downward
directions. However it shall not run in one direction for one trip and reversed for the
next. Starting, stopping or reversal shall be controlled only by an attendant and with the
assurance that no passenger is riding at that time.
4.4.1.5 Minimum head room above the escalator (minimum vertical clearance between
the line of step nosing and lowest edge of ceiling opening) shall not be less than 2.3 m.
4.4.1.6 Near the place of escalator installation, one lift with wheel chair facility shall be
installed to facilitate vertical movement of disabled persons.
4796 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

4.4.2 Essential Requirements

4.4.2.1 Angle of incline of the escalator shall not be more than 30⁰∞ from the
horizontal. In particular cases, an angle of incline up to 35⁰ may be permitted for
escalators having a vertical rise not more than 6 m.
4.4.2.2 The speed of the escalator, measured along the incline shall not be more than
0.63 m/s for 30⁰ angle of incline and 0.50 m/s for 35⁰ angle of incline.
4.4.2.3 Balustrades
(a) Escalators shall be provided on each side with solid balustrades. On the step
side (interior panel), the balustrades shall be smooth and substantially flush
except for protective molding parallel to the run of the steps. Vertical
moldings that cover joints of panels shall be properly beveled and shall not
project more than 6.5 mm. Gaps between interior panels of the balustrade
shall not be wider than 4mm.
(b) The width between balustrades, measured on the incline up to a point 680
mm vertically above the nose line of the steps, shall not be less than the width
of the step. It shall not exceed the width of the step by more than 330 mm
with a maximum of 165 mm on either side of the escalator.
(c) There shall be no abrupt changes in the width between the balustrades on the
two sides of the escalator. Where a change in width is unavoidable, such
change shall not exceed 8 percent of the greater width. In changing the
direction of the balustrades resulting from a reduction in width the maximum
allowable angle of change in balustrades shall not exceed 15 degrees from the
line of the escalator travel.
(d) The balustrade interior paneling shall have adequate mechanical strength and
rigidity. When a force of 500 N is applied at an angles on gap greater than 4
mm and no permanent deformation.
(e) The use of glass for balustrade interior panelling is permitted, provided it is
splinter free one layer safety (tempered) glass and has sufficient mechanical
strength and rigidity. The thickness of the glass shall not be less than 6 mm.
4.4.2.4 The clearance on either side of the steps between the steps and the adjacent skirt
guard shall not be more than 5 mm and the sum of the clearances on both sides shall not
be more than 6 mm.
4.4.2.5 Where the intersection of the outside balustrade (deck board) and the ceiling or
soffit is less than 600 mm from the centre line of the handrail, a solid guard shall be
provided in the intersecting angle of the outside balustrade (deck board) and the ceiling
or soffit. The vertical face of the guard shall project at least 360 mm horizontally from
the apex of the angle.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4797

4.4.2.6 Handrails
(a) Each balustrade shall be provided with a handrail moving in the same
direction and at the same speed as the steps.
(b) Each moving handrail shall extend at normal handrail height not less than
300 mm beyond the line of points of comb plate teeth at the upper and lower
landings.
(c) Hand or finger guards shall be provided at points where the handrails enter
the balustrade.
(d) The horizontal distance between the centre lines of two handrails, measured
on the incline, shall not exceed the width between the balustrades by more
than 150 mm, with a maximum of 75 mm on either side of the escalator.
4.4.2.7 Step treads
(a) The depth of any step tread in the direction of travel shall not be less than 400
mm and the rise between treads shall not be more than 220 mm.
(b) The maximum clearance between step treads on the horizontal run shall be 4
mm.
(c) The tread surface of each step shall be slotted in a direction parallel to the
travel of the steps. Each slot shall not be more than 6.5 mm wide and not be
less than 9.5 mm deep; and the distance from centre to centre of adjoining
slots shall not be more than 9.5 mm.
(d) Safety provision shall be installed in the system to stop the escalator when
anything is stuck in the clearance between the step tread and the skirting.
4.4.2.8 Landings
Landings shall be made of anti-slip material.
4.4.2.9 Comb plates

There shall be comb plates at the upper and lower landings of every escalator. The comb
plate teeth shall be meshed with and set into the slots of the tread surface. Comb plates
shall be adjustable vertically. Safety provision shall be installed in the comb plate
assembly so that the safety contact stops the escalator when anything is caught between
the comb plate and the step.

4.4.2.10 Trusses

The truss shall be designed to sustain the dead and live loads of the steps and running
gear in operation safely. In the event of failure of the track system it shall retain the
running gear in its guides.
4798 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

4.4.2.11 Step wheel tracks

These shall be designed to prevent displacement of steps and running gear if a step chain
breaks.

4.4.2.12 Rated load

The escalator shall be selected in such a way that it does not exceed its rated load during
operation. The rated load in kilogram on an escalator shall be computed by the following
formula:
Rated load 0 .27WA kg

Where,

= width between the balustrades, mm ; and

= horizontal distance between the upper and lower comb plate teeth , (m).

4.4.2.13 Design factor of safety

The factor of safety based on static load shall be at least the following:

(i) Trusses and all structural members including tracks 5

(ii) Driving machine parts:

Made of steel or bronze 8

Made of cast iron and other materials 10

(iii) Power-transmission members 10

(iv) Step chain composed of cast-steel links thoroughly annealed 20

4.4.2.14 Driving machine, motor and brake

(a) The driving machine shall be connected to main drive shaft by toothed
gearing, a coupling, or a chain.

(b) An electric motor shall not drive more than one escalator.

(c) Each escalator shall be provided with an electrically released, mechanically

applied brake capable of stopping the up or down travelling escalator with
any load up to the rated load. The brake shall be located either on the driving
machine or on the main drive shaft. Where a chain is used to connect the
driving machine to the main drive shaft, a brake shall be provided on this
shaft. It is not required that this brake be of the electrically released type if an
electrically released brake is provided on the driving machine.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4799

(d) The braking system shall have provision to bring the escalator automatically
to a smooth stop in the event of failure of electrical power or mechanical
parts.
(e) Speed Governor: A speed governor shall be provided, the operation of which
shall automatically shut down the escalator in case of over speed or under
speed, and prevent reversal of direction (up or down).
(f) Adequate illumination shall be provided at all landings, at the comb plates
and completely down all stair ways.
(g) An emergency stop switch shall be located near the comb plate or in some
obtrusive location.
(h) All machinery spaces shall have access doors or panels for inspection and
maintenance. These panels shall remain locked to prevent unauthorized
access.
(i) Reasonable ventilation shall be provided in machinery spaces.

4.4.2.15 Escalator capacity

(a) For normal peak period, the recommended handling capacity for design
purposes shall be taken as 3200 to 6400 persons per hour depending upon the
width of the escalator.
(b) The number of persons that may be theoretically carried by the escalator in 1
hour can be calculated as follows :
(i) For determination of theoretical capacity it Is assumed that one step with an
average depth of 0.4 m can carry 1 person for step width of 0.6 m, 1.5 persons
for a step width of 0.8 m and two persons for step width of 1 m.
(ii) The theoretical capacity = 3600 × ( v × k)/0.4

Where,
v = rated speed of escalator in m/s
k = 1, 1.5 or 2 for step width of 0.6 m, 0.8 m and 1 m respectively.

4.5 Moving Walks

4.5.1 Essential Requirements

4.5.1.1 Angle of incline of moving walks shall be no more than 15o. A moving walk
may have sloping entrance and exit or level entrance and exit.
4800 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

4.5.1.2 The operating speeds of moving walk at different inclinations and different
entrance and exit conditions shall not be more than those given in Table 8.4.10
Table 8.4.10: Operating Speeds of Moving Walk (Based on 1000 mm Nominal Tread
Width)*

Incline of Ramp on Slope Maximum Speed with Maximum Speed with

Level Entrance and Exit Sloping Entrance and Exit
(m/s) (m/s)

0 to 3⁰ 0.9 0.9
Over 3 to 5⁰ 0.9 0.8
Over 5 to 8⁰ 0.9 0.7
Over 8 to 12⁰ 0.7 0.65
Over 12 to 15⁰ 0.7 0.63
* Higher tread width may be allowable on horizontal runs.

4.5.2 Balustrades
(a) Moving walks shall be provided on each side with solid balustrades. On the
tread way side the balustrades shall be smooth and substantially flush.
(b) The width between balustrades, measured up to a point 680 mm vertically above
the tread way, shall not be less than the width of the tread way. It shall not
exceed the width of the tread way by more than 330 mm with a maximum of
165 mm on either side of the moving walk.
(c) There shall be no abrupt changes in width between the balustrades on the two
sides of the moving walk. Where a change in width is unavoidable, such change
shall not exceed 8 percent of the greater width. In changing the direction of the
balustrades resulting from a reduction in width the maximum allowable angle of
change in balustrades shall not exceed 15o from line of moving walk travel.
4.5.3 Handrails
4.5.3.1 Each balustrade shall be provided with a handrail moving in the same direction
and at the same speed as the tread way. Only one handrail may be allowed in a moving
walk when the slope of the walkway does not exceed 3⁰, operating speed is less than 0.35
m/s or the width is no more than 530 mm.
4.5.3.2 Each moving handrail shall extend at normal handrail height not less than 300
mm beyond the line of points of comb plate teeth at the upper and lower landings.
4.5.3.3 Hand or finger guards shall be provided at the point where the handrails enter
the balustrade.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4801
4.5.3.4 The horizontal distance between the centre lines of two handrails shall not
exceed the width between the balustrades by more than 150 mm with a maximum of 75
mm on either side of the moving walk.
4.5.4 Tread Way
4.5.4.1 The tread surface of the tread way shall be slotted in a direction parallel to the
direction of travel.
4.5.4.2 The clearance on either side of the tread way between the tread way and the
adjacent skirt guard shall not be more than 5 mm and the sum of the clearances on both
sides shall not be more than 6 mm. Safety provisions shall be kept in the system to stop
the moving walk when anything is stuck in the clearance between the tread way and the
adjacent skirt guard.
4.5.5 Landings
Landings shall be made of anti-slip material.
4.5.6 Comb Plates
4.5.6.1 There shall be comb plates at the entrance and exit of each moving walk. The
comb plate teeth shall be meshed with and set into the slots in the tread surface. Safety
provision shall be installed in the comb plate assembly so that the safety contact stops the
moving walk when anything is caught between the comb plate and the tread.
4.5.6.2 An emergency stop switch shall be located near the comb plate or at some
obtrusive location.
4.5.6.3 Adequate illumination shall be provided at comb plates.

4.6 Energy Conservation

4.6.1 General
Lifts, escalators and moving walks shall be designed and installed for efficient use of
energy herein provided.
4.6.2 Equipment and Controls
4.6.2.1 Lift
All lifts shall be equipped with necessary sensors and controls to reduce energy usage.
For this purpose following features shall be included in the lift system:
(a) AC Variable-Voltage and Variable-Frequency (ACVVVF) drives for the car and
door shall be used.
(b) Energy efficient lamps shall be used inside the car and for displays.
(c) The lifts shall operate in standby mode during off-peak periods.
(d) The power side of the lift controller and other operating equipment such as car
lights, display lights and ventilation fans shall be switched off when the lift has
been inactive for more than five minutes.
4802 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021
4.6.2.2 Escalator
All Escalators shall be equipped with necessary sensors and controls to reduce energy
usage. For this purpose following features shall be included in the lift system:
(a) The escalator shall reduce speed and operate at lower speed when there is no
passenger on the escalator for a period of a maximum of three (03) minutes.
(b) The escalator shall shut down when no activity has been detected for a period of
a maximum of fifteen (15) minutes.

4.7 Inspection and Certification

4.7.1 All new lifts, escalators and moving walks, after installation, shall be inspected
and tested by the Authority before these are put into normal services. These shall not be
brought into use unless the Authority is satisfied that the installations have been carried
out as per provisions of this Code and tests indicate that all the safety devices operate
satisfactorily. It shall be unlawful to operate any lift, escalator or moving walk without a
current certificate of inspection issued by the Authority. Certificates shall not be issued
when the conveyance is posted as unsafe pursuant to Sec 4.7.7.
4.7.2 All electrical lines, control lines and earthings of lift, escalator and moving walk
systems shall be tested to determine whether these have been installed properly to meet
the requirements of the machine and as per provisions of Chapter 1.
4.7.3 Testing: Tests shall be carried out to determine the operational and safety
conditions of lifts, escalators and moving walks in accordance with the provisions of the
sections as under:
4.7.3.1 Lift
Tests shall be conducted to ascertain that
(a) the motor, brake control equipment and car leveling mechanism function
properly,
(b) the door operation is proper and door locking devices function properly,
(c) the car raises and lowers rated load,
(d) the car achieves at least the rated speed,
(e) the lift motor can be overloaded up to a minimum of 10% above the rated
capacity,
(f) the safety gear stops the car with the rated load in case of over speed and/or over
travel etc.,
(g) the buffers function properly, and
(h) the safety gear operate and keeps operation of the lift suspended in case of the
lift car is loaded above its maximum capacity.
 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021 4803
4.7.3.2 Escalator and moving walk
Tests on escalators and moving walks shall be conducted to ascertain that
(a) the automatic control device functions properly and brings the escalator to a
smooth stop in case of failure of any mechanical parts or electrical power,
(b) the automatic safety protection for over speed, under speed and direction
reversal functions properly
(c) safety devices function properly and stops the escalator or moving walk when
anything is caught between the comb plate and the treads or the skirting and the
treads.
(d) the handrail and steps or tread way travel at exactly the same speed.
4.7.4 A lift, escalator or moving walk, in which repair and/or maintenance work has
been carried out shall also be put to the relevant tests as provided for in Sec 4.7.3.
4.7.5 After proper testing, the Authority shall issue certificate regarding suitability of
the lift, escalator or moving walk for normal or regular service. A lift, escalator or
moving walk shall be allowed to work only on issuance of this certificate.
4.7.6 The lift, escalator or moving walk shall be inspected periodically to ensure
safety.
4.7.7 When an inspection reveals an unsafe condition and the Authority finds that the
unsafe condition endangers human life, the Authority shall cause to be placed on such
lift, escalator or moving walk, in a conspicuous place, a notice stating that such
conveyance is unsafe. The owner shall see to it that such notice of unsafe condition is
legibly maintained where placed by the Authority. The Authority shall also issue an
order in writing to the owner requiring repairs or alterations to be made to such
conveyance necessary to render it safe and may order the operation thereof discontinued
until the repairs or alterations are made or the unsafe conditions are removed. A posted
notice of unsafe conditions shall be removed only by the Authority and when satisfied
that the unsafe conditions have been corrected.

4.8 Operation and Maintenance

4.8.1 The owner shall be responsible for the safe operation and maintenance of each
lift, escalator or moving walk installation and shall cause periodic inspections, tests and
maintenance to be made on such conveyances as required in this Section.
4.8.2 The lift, escalator or moving walk shall receive regular cleaning and lubrication
of relevant parts, and adjustment and adequate servicing by authorized competent
persons at such intervals as the type of equipment and frequency of service demand. In
order that the lift, escalator or moving walk installation is maintained at all times in a
safe condition, a proper maintenance schedule shall be drawn up in consultation with the
machine manufacturer which shall be strictly followed.
4804 evsjv‡`k †M‡RU, AwZwi³, †deªæqvwi 11, 2021

4.8.3 In case of lift, periodic examination of wire ropes, components of landing and
car doors, door interlocking mechanism, brakes, gears, components of safety gears,
guides, rollers, channels etc. shall be carried out as recommended by the manufacturer. In
no case shall the interval between such inspections exceed six months.

4.8.4 Grooves of drums, sheaves and pulleys of lifts shall also be examined when
rope replacement is made. If necessary, the drums, sheaves or pulleys shall be properly
re-machined.

4.8.5 In case of escalators and moving walks, periodic examination of balustrades,

handrail, tread way, tread way interconnection, comb plates speed governor, drives,
chains, non-reversal device, brakes, gears etc. shall be carried out as recommended by
the manufacturer, but in no case the interval shall exceed six months.

4.8.6 Sundry Precautions

4.8.6.1 Adequate precaution shall be taken to guard against any possibility of a lift
being operated by unauthorized persons. Precautions shall also be taken to prevent a lift
from being operated by any person when it is not intended for use.

4.8.6.2 No person shall remain in the pit while the lift is working. Adequate precautions
shall be taken to protect persons working in the pit from accidental contact with the
counter weight.

4.8.6.3 While the lift is under examination or repairs, suitable steps shall be taken to
ensure that the lift is not operated inadvertently by a person in such a manner as may
endanger the safety of persons working in the lift.

4.8.6.4 No such explosive or other inflammable material shall be carried in the lift car
as may endanger the safety of persons and property.

4.9 Related Appendix

Appendix L Format for Particulars of Lifts, Escalators and Moving Walks.