Module 2

DESIGN OF ILLUMINATION SYSTEMS

BASIC DEFINITIONS
 Light : That part of radiant energy from a hot body which
produce visual sensation on human eye
 Luminous intensity (I) :The power or strength of the source of
light is known as luminous intensity (I) and is measured in
Candela(SI unit).
 Luminous Flux (L) : From the light source, energy is radiated in
the form of light waves. This flow of light from the source is
known as Luminous Flux (L) and unit is lumen(SI unit)
 Lumen (FPS unit) : One lumen is the luminous flux emitted per
unit solid angle from a point source of one candle power
 BASIC DEFINITIONS
 Illuminance (E) : When the light emitted by a
source falls on a surface, it is illuminated.
Illuminance (E) is the amount of light falling
on a surface measured in lux.
 1lux=lumen/area= 1lumen/m2
 Luminaire ( light fitting ): It is the apparatus
which distributes, filters or transforms the light
given by a lamp. It includes all the items
necessary for fixing and protecting the
lamps and for connecting them to the
supply circuit.
 Candle power(FPS unit): Number of lumens
given out by a source per unit solid angle in
a given direction is called candle power
BASIC DEFINITIONS

 Luminance is a photometric measure of the luminous intensity per

unit area of light travelling in a given direction. The SI unit for
luminance is candela per square metre (cd/m2).
 The luminance indicates how much luminous power will be detected by
an eye looking at the surface from a particular angle of view.
Luminance is thus an indicator of how bright the surface will appear.
 FPS & SI units of illumination

Sr. NO Quantity FPS UNIT SI Unit

1 Luminance candle- power candela
Intensity
2 Luminance Flux lumen lumen
3 Illuminance Foot-candle lux

Foot-candle=lumen/sq-ft
LAWS OF ILLUMINATION

 INVERSE SQURAE LAW:

 States that the illumination (E) of a surface is directly proportional to
the luminous intensity and inversely proportional the square of the
distance between the source and the illuminated surface, as long as
the source remains the same.
 E = I/r2
 I= luminous intensity
 E- illumination of the surface
 r- distance between the source and surface to be illuminated
 This is true only when the surface to be illuminated is placed normal
to the direction of the light beam.
LAWS OF ILLUMINATION
LAWS OF ILLUMINATION

 COSINE LAW
 When the plane to be illuminated may not be normal to the
direction of luminous flux, and is inclined by an angle θ, where θ is
the angle between the line of flux and the normal to the illuminated
plane.
 The law states that the illumination on a surface is proportional to
the cosine of the angle between the normal to the surface and the
line of flux and also to the luminous intensity. E is inversely
proportional to r2.
 E = I cos θ/r2
 These laws are applicable only to point sources( no reflecting
surfaces)
Qualities of good lighting scheme
 Sufficient illumination level.
 Uniformity of illumination
 Contrast with surroundings and sunlight
 Correct colour effect
 Freedom from glare
 Aesthetic appearance
 Economical
 No hazard of fire and accidents
 Free from pollution and corrosion
 No ageing and deterioration
 Modular in construction and replacement
 Free from noise and humming and no magnetic radiations
Types of Lighting Schemes
There are different types of lighting arrangements which can be
classified according to the proportion of light directing upward or
downward from the fittings.

 Direct lighting – In a direct lighting , light in a room

is produced by fittings that do not let any of the
light fall on the ceiling and walls , instead throw all
the light on the area to be lighted.

Advantages and disadvantages –

Most efficient, but causes shadows and glare. Mainly
used for industrial and general outdoor lighting.
 Types of Lighting Schemes

 Indirect lighting –
In this scheme, light is produced by fittings that
throw all the light on the ceiling from where it is
reflected to the area to be lighted , the method is
called indirect lighting

Advantages and disadvantages-

Glare is minimum, illumination is softer and
appearance of the room is much improved.
Types of Lighting Schemes

 Semi direct lighting – In semi direct lighting ,

most of the light produced by the fittings is
directed downwards and a certain amount of
light is directed upwards .

 Best suited for rooms with high ceilings where

a high level of uniformly distributed illumination
is desirable.
Types of Lighting Schemes

 Semi indirect lighting – In semi indirect

lighting , most of the light produced by the
fittings is directed upwards and a certain
amount of light is directed downwards.

 General diffusing lighting – In general lighting

, the light produced is equally distributed
upwards and downwards
 Types of Lighting Schemes

Type of illumination Percentage distribution Percentage distribution

upwards downwards

Direct 1-10 90-100

Semi- Direct 10-40 60-90
General diffusion 40-60 40-60
Semi-indirect 60-90 10-40
Indirect 90-100 1-10
Design considerations of a good
lighting scheme
In designing good lighting scheme , we have to consider mainly

 Intensity of illumination
 Selection of required lamp and fitting
 Size of the room

 Mounting heights and spacing of fittings

 Conditions under which the illumination is used
 Intensity of illumination
 Intensity of illumination required for different types of work
differ. Table shows the recommended intensity of
illumination for different types of work.
Selection of required lamp and fitting

 A luminaire is the apparatus which distributes, filters, transforms

the light given by a lamp. It includes all the items necessary for
fixing and protecting these lamps and for connecting them to
the supply circuit. The choice of lamps for different types of
occupancies differ.
 For small premises tubular fluorescent lamps or tungsten
filament lamps can be used .
 In large premises , lighting can be carried out by using high
intensity sources such as mercury or sodium discharge lamps.
Depending on the type of illumination required, (direct ,
indirect etc ) reflector types can be selected
 Size of the room
 The lumen output of the source or lamp is not fully utilized at the work place
 A part of the light is lost in the fittings and some part is directed to the walls
and ceilings where a part will be absorbed and a part will be reflected
 This is taken into account by a factor known as Coefficient of Utilization
(CU).
 The ratio of lumens reaching the working plane to the total lumens given out by
the lamps is known as CU or Utilization factor.
 CU depends on the following factors
 Lumen output of the fitting
 Shape of the room
 Reflection factors of walls and ceilings
 Height of the ceiling
 Arrangement of the fittings etc
Mounting height and spacing of fitting

 Governed by the type of the building and the type of

lighting scheme employed.

 The distance of the light source from the wall should be

equal to half of the distance between the two adjacent light
sources. Also distance between lighting fitting should not
exceed 1.5 times the mounting height
Conditions under which the illumination
is used
 For different types of buildings, the condition of use of light varies.

 Dust and dirt particles of the surroundings get deposited on the light
fitting and hence deteriorate the lamp efficiency.

 If regular periodic cleaning is adopted and assuming good

atmospheric condition, the maintenance factor (MF) is taken as 0.8
, but for dirty and dusty atmosphere, the MF is taken as 0.4.

 Depreciation factor (DF) =1/Maintenance Factor

SELECTION OF LIGHT SOURCES
 The choice of source for public lighting is guided by the following
considerations
 Luminous flux
 Economy
 Dimensions of the light sources
 Colour characteristics
 The sources normally used in public lighting are
 Incandescent lamps
 Fluorescent lamp
 High Intensity Discharge lamp
 Mercury vapour lamps

 Metal halide lamps Discharge Lamps

 High pressure sodium vapour lamps
 Low pressure sodium vapour lamps
 Incandescent lamps

 Produce light by heating tungsten filament

 Lowest efficacy (lumens/watt)
 Shortest life
 Limited in practice
 Used for residential streets
 Initial cost is low
 Most common types are Pear shaped, reflector type
and tungsten halogen lamp (quartz)
 Incandescent lamps

 Energy saving incandescent lamps

 Krypton filled lamps
 Use Krypton instead of Argon inside the bulb
 Consume 5-10% less wattage compared to normal
incandescent lamps
 Available in the range 36-143W
 Ellipsoidal reflector lamps
 Works on the principle of elliptical reflector such
that when a point source is placed at first focal
point of an elliptical reflector, all reflected lights
emerge through the second focal point
 Reduces wastage of light
 Fluorescent lamps

 Produce light by creating an arc between

two electrodes in atmosphere of low pressure
mercury vapour and some inert gas in a
glass tube
 Requires a ballast to initiate an arc in the
tube
 Efficient than incandescent lamps (50-70
lumens/watt)
 Energy efficient fluorescent lamps are CFL
 CFL- A 9W CFL can replace 60W incandescent
lamp saving 80% of energy
 Life of CFL- 7500 hrs
 Small luminaire, compact and preferred for
domestic applications
 High Intensity Discharge Lamps (HID)

 Used to designate 3 distinct type of lamp-

mercury vapour, metal halide and high
pressure sodium
 Produce light by establishing an arc
between two electrodes, the electrodes
being few centimeters apart enclosed in a
transparent arc tube
 Arc tube is then enclosed in an outer bulb
that is filled with nitrogen and an inert gas
 Mercury vapour lamps (MV)

 Outer tube is filled with nitrogen and inner

tube contains mercury and argon gas
 Consists of starting electrode and main
electrode
 When voltage is applied to starting
electrode, an argon arc is produced by
main electrodes adjacent to it which heats
up and vaporises mercury
 These ionised mercury atoms decrease the
resistance between the main electrodes
and produces arc to strike
 Available from 40-1000W
 Metal Halide lamps (MH)
 Similar to Mercury Vapour Lamp in operating principle
 Contains metallic additives in addition to argon and
mercury in the arc tube which produces different colour
rendering in the overall light output
 Higher efficacy (66-100 lumens/watt) than metal vapour
lamps
 Combinations of metal additives used in metal halide
lamps are
 Sodium iodide and scandium iodide
 Sodium iodide, thallium iodide and indium iodide.
 Of the different metal additives the sodium, thallium and
indium are the principal producers of dominant colour
spectra, while others produce multiple spectra across
the full visible region.
 These lamps provide energy at all wavelengths across
the visible spectrum, creating a well balanced colour
rendering.
High pressure sodium vapour lamps
(HPS)
 The arc tube is made of a ceramic translucent
aluminium oxide, which can withstand temperature as
high as 1300 °C. The outer envelope is made of a
borosilicate glass that can withstand as high as 400 °C.
 Produce energy in all wavelengths - the major portion of
energy is concentrated in the Yellow Orange part of the
spectrum. Because of this, the light produced by this
lamp is a golden white colour.
 Has highest efficacy of all lamps (60-127 lumens/watt)
 Available in 35-1000W size
 Life is 24000 hours
 Best energy savers in HID lamps
High pressure sodium vapour lamps
(HPS)
 The HPS lamps do not have a starting electrode. The
starting is done with the help of a special circuitry in
the ballast.
 A high voltage with high frequency pulse is used to
ionise the xenon starting gas. As the lamp warms up,
it goes through different colour radiation stages.
 At first when xenon and mercury are ionised, a
bluish white glow takes place, next comes the
monochromatic yellow of the sodium at low
pressure.
 Finally a broad spectrum appears to its fullest
brightness.
Low pressure sodium vapour lamps
 The Low Pressure Sodium Lamp is the most efficient light source presently
available providing up to 183 lumens per watt.
 The light producing element in an LPS is a U-shaped arc tube containing
sodium vapour.
 The outer jacket is made of borate glass.
 The use of these lamps indoors is severely restricted, because, it has a
monochromatic (yellow) light output. Consequently, most colour
illuminated by this source appears as tones of grey.
 Long and reliable life of 18000 hours, 18 W- 180 W available
 Used in street lighting and outdoor area & security lighting
 Light Emitting Diodes (LED)
 Light Emitting Diodes or LEDs are among the most widely used of all the
different types of semiconductor diodes available today.
 They are the most visible type of diodes that emit a fairly narrow bandwidth
of either visible light at different coloured wavelengths, invisible infra-red
light for remote control applications or laser type light when a forward
current is passed through them.
 LED as it is more commonly called, is basically just a specialized type of PN
junction diode, made from a very thin layer of fairly heavily doped
semiconductor material.
 When the diode is forward biased, electrons from the semiconductors
conduction band recombine with holes from the valence band releasing
sufficient energy to produce photons which emit a monochromatic (single
colour) of light.
 Thus, we can say that when operated in a forward biased direction Light
Emitting Diodes are semiconductor devices that convert electrical energy
into light energy.
 LIGHTING CALCULATIONS
Lighting design is the process of selecting right kind of luminaires to
produce light of required quantity and quality at right locations. All
light designs are related to two major considerations.
 Quantity of Lighting
 Quality of Lighting
While the quantity requirement is an unavoidable one, quality also
plays an equally important role.
There are 2 methods for calculating quantity.
 Average lumen or light flux method
 Point to point method or inverse square law method
Average lumen method

 Simplified way of calculating an average uniform illuminance level

on a plane in interiors
 Takes into account the effects of surface reflectance
 Simplified and accurate method of quantity evaluation for interiors
 This method is developed from the basic definition of lux, which
states that one lux is the illuminance on a surface of one square
metre having a light flux of one lumen
 Illuminance E= L/A where L = lumens produced by all the luminaires
in room and A= area in sq.m.
Average lumen method

 In reality, all the luminous flux generated by the lamps will not fall on
the work plane
 Factors like luminaire candle power distribution, efficiency, room
size and shape and luminaire height, will affect the total number of
lumens reaching the work plane
 The formula is multiplied by a coefficient of utilization (CU) to take
into consideration all above factors. Therefore,
E=(L*CU)/A
Average lumen method

 The luminaire, lamp and even the surface will accumulate dust over
a period of time and the lamp lumen output will depreciate with
time
 To obtain the maintained illuminance level, the formula now must
be multiplied by a light loss factor(LLF) to account for the
depreciation in light output
E=(L*CU*LLF)/A
Average lumen method

 The formula can be modified as

 E=(Ln*N*CU*LLF)/A where Ln, = Initial lumen output per luminaire
and N= total number of luminaires
 N=(A*E)/(Ln*CU*LLF)
 From the above, it is obvious that for a given level of illuminance
and area, the only means or reducing the number of luminaires is
by using the highest values of Ln, CU and LLF
 The lower the number of luminaires, the less the power consumption.
LIGHT LOSS FACTOR (LLF)

 Periodic schedule and appropriate maintenance is very essential in

maintaining the initial lighting level
 An LLF would not be required if light output remains constant
throughout the useful life.
 Inherent light loss characteristics of the luminaire and unfavourable
ambient conditions will force the net output to deteriorate with time
 An LLF is introduced in lighting calculations to make up for expected
loss of light in the lighting system
LIGHT LOSS FACTOR (LLF)
 The various factors that
contribute to light loss are of
two types.
 Non-Recoverable factors
 Recoverable
 Luminaire ambient temperature
 Non-recoverable. (LAT)

 The recoverable factors  Voltage variation (VV)

include:  Ballast factor (BF)
 Luminaire dirt depreciation  Luminaire surface depreciation
(LDD) (LSD)

 Room surface dirt  These factors present those

depreciation (RSDD) conditions of a lighting system
that reduce the light output,
 Lamp lumen depreciation where nothing in terms of periodic
(LLD) and maintenance can recover the
 Lamp burn out (LBO) losses
Luminaire dirt depreciation (LDD)

 The greatest loss of light output is due to the dirt accumulation on

lamps and luminaire reflecting surface
 Proper selection of maintenance is essential
 Air-conditioned spaces - Once in two years
 Non A/C offices, School, etc - Once in a year
 Industrial areas- 3-6 times a year
 Food preparation area - every week
Room surface dirt depreciation (RSDD)

 This factor takes into account the dirt or dust accumulation on

surfaces
 A proper schedule for cleaning the reflecting surface must be
followed to maintain the reflectance
Lamp lumen depreciation and lamp
burn out (LLD and LBO)
 Lamp lumen depreciation is an inherent characteristic of all lamps.
 Two types
 Spot re-lamping
 Group re-lamping.
 Spot re-lamping refers to changing of lamps as and when a lamp
burns out
 Group re-lamping is the process of replacing all the lamps in an
installation after the useful life period of the lamps irrespective of the
fact whether the lamps are in working condition or not
Non-Recoverable factors

 Luminaire ambient temperature (LAT)

 A variation in the ambient temperature does not have much effect on
the incandescent and HID lamps
 Fluorescents are affected by a change in ambient temperature
 Fluorescent produces a peak output at about 25 °C
 Voltage variation factor (VV)
 For incandescent lamps a variation of 1% voltage may cause as much
as 3% variation in light output
 For HID and fluorescents also variation in voltage affects their output
Non-Recoverable factors

 Ballast Factor (BF)

 Ratio of light output by a commercial ballast to that by reference
ballast
 Luminaire surface depreciation factor (LSD)
 Changes in the various components used in the manufacture of
luminaires can cause reduction in the light output
 Due to aging, polished surface will have reduced reflectance
 All four non-recoverable factors will depreciate the output permanently
and nothing can be done to recover them
 Calculations

Given: Area of room =15*9=135m^2

E=200lux
CU=0.75
MF=0.8
Ln=3000 lumens
E=(Ln*N*CU*MF)/A
N=(E*A)/(Ln*CU*MF)
N=(200*135)/(3000*0.75*0.8)
N=15 lamps
An office 30 m x 15 m is illuminated by 40 W fluorescent lamps of
lumen output 2700 lumens. The average illumination required at the
work place is 200 lux. Calculate the number of lamps required to be
fitted in the office.
Assume coefficient of utilisation to be 0.6 and depredation factor
1.25.
An illumination of 50 lux is to be produced on the floor of a
room 12 m x 9 m. 36 lamps are required to produce this
illumination in the room, if 50% of the emitted light falls on the
floor. What is the power of the lamp in candela?
Let us consider a point source which emits light energy in all
directions located at the centre of a sphere of radius 1 m. If the
power of the source is 1 candela, then the luminous flux emitted
from the point source within a unit solid angle is 1 lumen.
Point to point method or inverse square
law method
 This method permits determination of illumination level due to one
or more source upon a specific point within an area.
 Here inverse square law is made use of in this.
 E=I/r^2
 When light arrives at the point on horizontal surface at an angle
 E=I cosθ /r^2
Point to point method or inverse square
law method
 The method is simple but no of assumptions made in calculations
limits its application.
 Formula only true for point source
 For luminaires with asymmetrical candle-power distribution the CP
distribution curve of the required vertical angle must be used
 Application with rows of fluorescent lamps will be unsuitable
 This method does not take into action surface inter reflectance
Calculation
Calculation
calculations
An office 30 m x 15 m is illuminated by twin 40 W fluorescent luminaires
of lumen output 5600 lumens. The lamps being mounted at a height
of 3 m from the work place, the average illumination required is 240
lux. Calculate the number of lamps required to be fitted in the office,
assuming the coefficient of utilisation to be 0.6 and maintenance
factor to be 0.8. Assume the height of the building as 5 m.
EXTERIOR LIGHTING

 Lighting design for exterior application will have to consider the

following aspects:-
 Functional lighting-Road lighting, yard lighting (area lighting), flood
lighting
 Decorative lighting- Monumental lighting, façade lighting and
special lighting for festivals
General consideration

 Primary aim of exterior lighting :- Safety and Security

 Luminaires used for exterior lighting can be classified into :-
 Static luminaries-Luminaries fixed on top of a pole, to produce light in a
predetermined manner.
 Adjustable luminaries - Luminaries mounted with adjustable brackets
are referred to as adjustable luminaries. Mostly used for flood lighting
and area lighting
Terminologies
 Origin - The point on the road directly under the luminaire.
 Longitudinal Road Line (LRL) - Imaginary line running parallel to the
curb (a concrete margin along edge of a road) expressed as a
multiple of mounting height (MH).
 Transverse road Line (TRL) - Imaginary lines perpendicular to the
curb or LRL, expressed in terms of MH.
 Reference Line (0MH LRL and 0 MH TRL) - Reference line passing
through the origin.
 Street Side (SS) – The space located on the street side of 0 MH LRL.
 Longitudinal Distance (LD) - A distance measured between two TRL
in a direction parallel to the curb.
 Transverse Distance (TD) - A distance measured between two LRL in
a direction perpendicular to the curb
Photometric Report(refer mk giridharan
text chp:7)
 Luminaries used for external lighting are always supplied with a
photometric report by the manufactures.
 The most important features are:-
 Luminaire identification and depreciation
 Luminaires Classification
 Utilization Curve
 Iso-Lux curve
 Luminous flux distribution
Luminaire Classification

 According to their light distribution luminaries used for exterior

lighting are classified into

 Vertical light distribution or spread.

 Lateral light distribution.
 Control of light distribution at high angles.
ROAD LIGHTING

 Main requirement is to provide driver of a moving vehicle the exact

information continuously and accurately from the road
 Objects should be present with clear contrasts with their
surroundings
 Dangerous objects shall be seen and recognized in time
 The scene should have adequate brightness, at the same time it
should not appear to be so bright to cause discomfort or disability
 The patterns created by the road lights shall not be confusing to the
driver
Selection of light sources for street
lighting
 Over the past century ,complete range of light sources available
from incandescent lamps to high intensity lamps are used. Now
incandescent lamps are not used due to its low efficacy and shorter
span.
 Fluorescent lamps have better efficiency but drawbacks are
difficulty in light control, relatively large size and sensitive to
temperature. For external use ,these lights should be enclosed in
sealed housing.
 Mercury vapour lamps are used because of its longer life. But their
efficacy and light quality are not so good compared to HID( High
Intensity Discharge) lamps.
 Metal halide lamps offer good color quality and efficacy. But they
have lower life span than HPS (High Pressure Sodium ) lamp.
Selection of light sources for street lighting

 HPS lamp offer maximum efficacy and have extremely long life.
Their colour rendering is termed as golden white and is acceptable
for most of the exterior applications.
 LPS(Low Pressure Sodium) lamps have the highest efficacy, but their
biggest disadvantage is its colour which is monochromatic yellow,
under which all colours other than yellow look gray, brown or black.
 All roadway lightings are done using MH (metal hallide) ,HPS and
LPS sources.
 Where colour rendering and energy saving are important, MH is the
only solution.
 If colour rendering is not important , but energy saving and long life
are the main concern , the choice is limited to HPS or LPS.
 Power LED lights are considered for exterior lighting because of their
inherent qualities like very long life and low power consumption.
Classification of roads

 Classified based on the volume of traffic, speed and composition of

the traffic
 For roads with width ranging from 6-9m, lamp posts are arranged on
side of the roads
 For roads with width 9-12m, zig zag spacing is recommended
 For roads with width 12-20m, face to face spacing of lamp posts on
both sides of the road becomes necessary
 For multi-lane roads, spacing of lamp posts on the median or on the
median plus the curbs on both sides may have to be chosen
depending upon the number of the lanes of traffic, planned on the
road
Classification of road according to NEC 2011
Design considerations

 Initial lumen Ln = (E*A)/(LLF*CU*N)

 Area of the road = Width* Spacing between lamp poles
 LLF= LLD* LDD
 LLD- lamp lumen depreciation
 LDD- lamp dirt depreciation
 Spacing = (Ln*N*LLF*CU)/(E*W)
Design considerations

 It is necessary that the illuminance directly under the luminaire be

the same as the midway between the poles
 The ratio of average to minimum illuminance should not than 3
 For residential areas the ratio can be as high as 6
 Three popular models of the pole placement along the roadway
are:
 Spaced continuously on the road side with a spacing of S meter (least
expensive and less wiring)
 Staggered spacing on both sides of the road with spacing of S meters
between consecutive poles
 Spacing on opposite sides of the road with a spacing of 2S meter
between two consecutive poles on the same side
Design considerations

 Of the three arrangements, item 1 is the least expensive since it

involves less wiring and trenching.
 As a general rule for the purpose of energy saving, economy and
uniformity of illumination, the ratio of spacing to mounting height
should not be less than 3 or larger than 5.
 Closer spacing means higher cost and power consumption,
whereas with larger spacing it is impossible to obtain the specified
ratio of average to minimum illumination of 3:1.
problem
solution

purpose of energy saving,

economy and uniformity of
illumination, the ratio of spacing to
mounting height should not be less
than 3 or larger than 5.

Therefore calculate for other

lamps from the input table
AREA LIGHTING
 Illumination of large area with average level of lighting
 Examples are airport parking space, railway yards, vehicle parking
space etc
 All luminaires used for road lighting can be used for area lighting
 Limiting factors for area lighting are
 Mounting height
 Colour rendering property of light source
 Spacing limitations
 Spacing between poles shall not be more than 4.5 times the height
of the poles
 Spacing between the edges of the area and the nearest pole shall
not be greater than 2.25 times the mounting height
 A minimum of two lights per pole shall be employed for even
distribution of lighting
Problems
Spacing between poles shall not be
more than 4.5 times the height of the
poles
Spacing between the edges of the
area and the nearest pole shall not
be greater than 2.25 times the
mounting height
Electrical Installations In High
Rise Buildings
 Buildings of height 15m and above are treated as high rise buildings
 Transformer Installations in high rise buildings
 If the building is a residential one, dry type transformers shall be installed
inside the building (indoor substation) at ground level itself
 In corporation areas, outdoor transformer with overhead lines is not
allowed
 There should not be any inflammable materials stored in the transformer
room
 The walls, ceilings and other fittings shall be fire resistant
 The transformer shall be installed in clean and dry locations
 Air Break SFU or VCB is used depending on the capacity of the
transformer. Oil filled switch gears shall be avoided.
Installation of Standby Generator

 The minimum rating of the generator selected should be able to

feed at least 20 % of the total connected load
 The following points shall also be noted
 A generator shall be installed at the periphery of the building
 Fuel tank of the generator shall be kept outside the building
 Sufficient clearances and ventilations shall be provided with respect to
walls and ceilings
 Exhaust pipe of DG sets shall be brought above roof top for venting out
smoke
 Sound proof arrangements shall be provided to DG sets
Recreational/ Assembly
Buildings
 Recreational/ Assembly buildings are those which are used for
recreational, amusement, social or religious activities.
 It also includes cinema hall, theatre, auditorium, etc.
 Control of Circuits
 Power Load - Stage machinery, Ventilation and air conditioning
installation, lifts, etc.
 Lighting Loads - General lighting of outdoor, corridors and stairs and
auditorium and in the rear of the assembly hall for stage, workplace,
dressing rooms, workshops and store houses
 Emergency supply - cabin, passageways, stairways, ‘EXITS’ and parts of
the building open to the public
Recreational/ Assembly
Buildings
 Substation Facility
 The assembly building must have its own electrical substation. The
location of substation is decided based on the following aspects.
 The substation should be located away from the area
 The substation should not be in the way of people and fire fighting
vehicles and personnel
 It is desirable that the transformer which contains a large quantity of oil
is not located in the basement as there is risk of fire
Miscellaneous Provisions
 Emergency Supply
 Standby supply either from generator or battery system shall be installed
or the generator set shall be installed in the ground floor.
 Stage lighting
 The stage may require a number of spot lights, border lights, projectors,
etc. for illumination
 Sufficient number of lights and power sockets shall be fitted in the stage
to feed such loads.
 Group control
 Group control facility inside auditorium
 Good view of the stage in order to follow the performance inside stage
 Audio visual system
 Provision for the installation of amplifying and sound distribution systems
shall be provided in the stage and these equipments must be earthed
independently
Refer textbook problems and notes

 MK giridharan
 Chapter 3
 Chapter 7
 SK bhattacharya
 Chapter 8
Design aspects of Vertical
Transportation
 Lifts and escalators form the major means of vertical transportation
 Following aspects to be taken into account while -
 Number of lifts, its size or passenger carrying capacity and location in
the building
 Number of floors served by the lifts
 Height between floors
 Location of the machine room
 Provision for lighting and ventilation
 Location where electric supply is required and in what quantity
 Quantity of electric supply
 Occupant load factor
 Control systems used
 Operation and maintenance
Definition & Types of Lift/Elevator
 A vertical transport equipment that efficiently moves people
between floors (levels, decks) of a building ,vessel or any other
structure.
 Generally, powered by a electric motor that drive by a traction
cable and counterweight systems like a hoist or hydraulic pump.
 Types of Lifts(on basis of USE)
 Trade Lift- used in offices, buildings, hotels, etc.
 Hospital Lift- used in hospitals and treatment centers.
 Car Lifts- used to lift car in multi-storey car parks.
 High Residential Lift- used in flats and other high-rise buildings for
efficient transportation of people.
 Fire Lift-This lift controls a system back in emergency.
Types of Lifts(on basis of function)

 Electric Lift- It is basically electro-mechanical enabled gearless traction

electric technology to send people to higher floors.
 Hydraulic Lift-These are powered by piston that travels inside a cylinder. An
electric motor pumps hydraulic oil into the cylinder to move the piston. The
piston smoothly lifts the cabin.
 Pneumatic Lift- The principle operation of the lift is based on the ascending
push generated by difference in the atmospheric pressure on the top of
car and under the car. The vacuum required is achieved by turbines
operating as exhaust fans, located at the top of the elevator.
 Paternoster Lift- It is a passenger elevator which consists of chain of open
compartments that move slowly in a loop up and down inside a building
without stopping. Passenger can step on or off at any floor they like.
 Components of Lifts
 Lift Car- It is vertically moving chamber in which passenger or goods are transported. It is mainly
constructed of steel or iron attached with steel frame. It is provided with door, floor panel
indication, emergency button, phone, lightning and many emergency supplies.
 Lift Door- The utilization of centre opening door is recommended as they reduce the round trip time
and help in improving the efficiency of lift.
 Governor- It is a mechanical device used to control the speed of lift on the basis of load in the lift
chamber. It is usually placed at top of list shaft in a room equipped with electric motor, safety gear,
etc.
 Lift Shaft- It is also called lift hoist. It is constructed with RCC to accommodate the loading and fire
resistance. The size is decided on the basis of no. of users. It is pathway of lift.
 Guard Rail- It is track laid on both the sides of the lift shaft to keep the car and counterweight in
balance. It also act as a safety device to hold the lift from crashing down if the rope breaks
 Counterweight- It is connected with a rope of elevator car to support the load carried by
generator. Its main function is to grip the lift car and reduce the power of generator.
 Buffer- It is group of springs placed in vertical direction to absorb the impact of lift car when it falls. It
is placed in lift pit.
Factors affecting Selection of Lift
 Utility- The function must be identified whether lift is for residential,
commercial, or hospital etc.
 Capacity- This depends on type of building and frequency of access to lift.
 Speed- This depends on no. of stops and users.

Design of Lift{lS14665(part 2)}

 There are 3 major factors which contribute in design of lift mainly
 Population or the no. of people who require lift service.
 Handling Capacity or the maximum flow rate required by these people.
 Quality of Service Required or interval.
 Population
 Exact population calculations are rarely available so the calculation of this
factor is made on the basis of type of building, No. of floors, net area
available. Average population density can vary from one person per (4-20)
sq. metre. If no indication possible population of 5 sq. metre is generally
assumed.

Quantity of Service
 The quantity of service is measure of passenger handling capacity. It is
Quality of Remarks measured in terms of total no.of passengers handled during each 5 min
Service
peak period of the day.
20-25 Seconds Excellent
 NOTE- The passenger handling capacity should be approx 10-15% of
estimated population that has to be handled during peak time for office
30-35 Seconds Good
building, 7-5% for residential building.
34-40 Seconds Fair
Quantity of Service
45 Seconds Poor  It is measured by the passenger waiting time at various floors. The following
Over 45 Unsatisfactory is guiding factor for this aspect
Seconds
Design Specifications of Lifts

 Capacity- The minimum size car recommended for single purpose buildings
is one suitable for a duty load of 884kg. For office buildings cars with
capacities up to 2040kg are recommended as per requirement.
 Speed- It depends upon quality and quantity of service desired. There are
no set formulas. General Recommendations are

No. of Floors Speed

4-5 0.5-0.75m/s
6-12 0.75-1.5m/s
13-20 Above 1.5m/s
 Layout- The width of car is determined by the width of entrance gate and the depth of
car is regulated by loading per sq. metre permissible. Centre opening door are the most
efficient for passenger lifts. Handling Capacity- It is calculated by formula-

 Where, H= handling capacity as % of peak population,

 Q= average no. of persons carried in a car,
 T=waiting interval, and
 P=total population to be handled during peak period. P is calculated assuming
population density and net area landing area available for use.
 Q is taken as 80% of max. carrying capacity of car.
 T is calculated as- T=RTT/N; N= no. of Lifts, RTT= round trip time.
 RTT is taken as sum of-
 Entry and exit of passenger on each floor.
 Door Opening and Closing time at each time.
 Acceleration Periods, Stopping and Levelling Periods.
 Periods of full rated speeds between stops going up &down.
 Note- RTT is inversely proportional to Handling Capacity, so to decrease RTT entry and
exit time of lift car should be adjusted. It has been found that most suitable door width is
1000 mm and car width is 2000 mm. The utilization of centre opening doors favours the
door opening and closing periods.
Definition of Escalators
 Escalators are moving stairs-a conveyor transport device where the treads
moves on a track at an incline or decline to transport people from one floor
to another. These may not be used as a means of egress. The typical speed
of an escalator is 100 feet per minute.

Types of Escalators
 Parallel Type- These are escalators which are constructed side by side or
with some distance between them. These are usually at metro stations.
 Multi-Parallel Type- These are the two or more escalators constructed of
same nature in parallel.
 Criss-Cross Type- These are escalators which are constructed keeping the
same nature of escalators on one side.
Design Requirements(lS4591:1968)
 Angle of Inclination- It shall not be degree from horizontal for
vertical transportation up to 6m. Permitted up to 35 degree in
extreme case.
 Balustrade- Escalators shall be provided on each side with
solid balustrades. Glass balustrading can be used considering
IS2553:1964. The width between balustrades shall be
measured on the incline at a point 68.5cm vertically above
the nose of steps and shall not be less than width of step. It
shall not be more than33cm with 16.5cm on each side. There
should be no abrupt change in the width on the other side.
 Handrails- Each balustrade should be provided with a
handrail moving in the same direction at same speed as that
of steps. These handrails should be extended beyond comb
plate and the height at the normal should not be less than
30cm. The distance between the handrails should not exceed
the distance between balustrade by more than
15cm,provided 7-5cm on both the sides.
 Treads/Steps- The depth of any step tread in the direction of travel shall
not be less than 40cm and the rise should not be more than 22cm. The
width should not be less than 40cm and not more than 102cm.
Maximum clearance between the steps should be 4mm. Each tread
step should be slotted and slotting should not be more than 6.5mm wide
and 9-5mm deep. The distance between adjoining slotting should not
be more than 9-5mm.
 Landings- Landings of RCC concrete may be provided conforming to
secure foothold. No clear specifications are provided so design should
be done taking care of rated load.
 Combplates- There should be combplate at entrance and exit of every
escalator. These should be meshed up with tread surface and should be
adjustable.
 Trusses/ Girders- Truss is hollow metal structure that bridges the lower and
upper landings. Its ends are attached to upper and lower landings. It is
composed of two sections joined together with cross braces across the
bottom and just below the top.
 Tracks System- This is embedded inside the truss and these are
connected by chain or belt. There are two tracks which move relatively
such that a stair comes out at combplate called as step-wheel track
and trailer-wheel track. It is mainly provided to prevent the displacement
of steps if the chain breaks.
 Rated Load- It is computed by formula-
Rated Load-2.7xWxA
 W= width in cm b/w balustrade
 A= horizontal teeth between upper and lower teeth of combplate.
 The Rated speed should m=not be more than 38m/min.

Advantages of Escalator
 It has more loading capacity and allows large no of people to move from one
place to another at the same time.
 It is more efficient as people don't have to wait as incase of elevator.
 Its speed can be adjusted as per crowd management and can be turned off
when not in use.
Design and layout of cinema theatres
 Auditorium-
 one celing fan for 50 seats
 One exhaust fan for every 50 m^2
 Security room-
 One celling fan , one lamp
 Projector room
 Lamp 2, fan 2 , projector 7.5 kVA
 Rewinding motor – 200 W
 Recorder – 100 W
 Power amplifier – 1000 W
 AC
 2 compressor each of 50 hp
 2 air handling unit – blower – 2HP
 MCCB
Question
 Design and prepare the schematic diagram of electrification of a cinema
hall having seating capacity of 800 people .also prepare the estimate
materials required

Solution
Assumptions
1. Centralised AC is used
2. Standby generator can supply the entire essential load except AC load
3. 11 kv supply is made available through UG cables
4. Indoor substation is preffered