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PART 3 SECTION5 REQUIREMENTS FOR SPECIAL INSTALLATIONS OR

LOCATIONS —
CONSTRUCTION AND DEMOLITION SITE INSTALLATIONS

1 SCOPE
The following are the requirements:
1.1 The special requirements of this part apply to temporary installations for
construction and demolition sites during the period of the construction or demolition
work, including for example the following:
a) construction work of new buildings;
b) repair, alteration, extension, demolition of existing buildings or parts of existing
buildings;
c) engineering works;
d) earthworks; and
e) work of similar nature.
The requirements apply to fixed or moveable installations.
1.2The rules do not apply to:
a) Installations where equipment of a similar nature to that used in surface mining
applications is involved; and
b) Installations in administrative locations of construction sites (offices,
cloakrooms, meeting rooms, canteens, restaurants, dormitories, toilets, etc.)
where the general rules of Clause 1 to 6 of IEC 732 apply.
NOTE — For special situations, more severe requirements apply, for example, Part 3/Section 6 of this code for
conductive locations with restricted movement.

2 REFERENCES
The Indian Standards given below contain provisions which through reference in this text, constitute
provision of this standard. At the time of publication, the editions indicated were valid. All standards
are subject to revision, and parties to agreements based on this standard are encouraged to investigate
the possibility of applying the most recent editions of the standards.

IS/IEC/ISO Number Title

IS 732: 2019 Code of practice for electrical wiring installations (fourth

revision)

IS/IEC 61439-4: Low-voltage switchgear and controlgear assemblies: Part 4

2012 Particular requirements for assemblies for construction sites
(ACS)
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IS/IEC 60309-2: Plugs, socket-outlets and couplers for industrial purposes:

2002 Part 2 Dimensional interchangeability requirements for pin
and contact-tube accessories (first revision)

IS/IEC 60309-1: Plugs, socket-outlets and couplers for industrial purposes: Part
2002 1 General requirements (first revision)

IEC 60245-4: 2011 Rubber insulated cables — Rated voltages upto and including
450/750 V — Part 4: Cords and flexible cables

3 ASSESSMENT OF GENERAL CHARACTERISTICS

For assessment of general characteristics, please refer 4.1 of IS732 for relevant items given
under this clause. Additional requirements have been mentioned against each sub -clause below.

3.1 Supplies
3.1.1 General
3.1.1.1 The following characteristics of the supply or supplies, from whatever source,
and the normal range of those characteristics where appropriate, shall be determined by
calculation, measurement, enquiry or inspection:
a) the nominal voltage(s);
b) the nature of the current and frequency;
c) the prospective short-circuit current at the origin of the installation;
d) the earth fault loop impedance of that part of the system external to the installation;
e) the suitability for the requirements of the installation, including the maximum
demand; and
f) the type and rating of the overcurrent protective device acting at the origin of the
installation.
These characteristics shall be ascertained for an external supply and shall be determined
for a private source. These requirements are equally applicable to main supplies and to
safety services and standby supplies.
3.1.1.2 Supplies for safety services and standby systems
Where the provision of safety services is required, for example, by the authoritie s
concerned with fire precautions and other conditions for emergency evacuation of the
premises, and/or where the provision of standby supplies is required by the person
specifying the installation, the characteristics of the sources of supply for safety s ervices
and/or standby systems shall be separately assessed. Such supplies shall have adequate
capacity, reliability and rating and appropriate change-over time for the operation
specified.
For further requirements for supplies for safety services, see 4.1.5.14 of IS 732 hereafter
and 5.6 of IS 732. For standby systems, there are no particular requirements in this
standard.
NOTE — A single construction site may be served by several sources of supply, including generating sets; see 5.5.2 of
IS 732.
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4 PROTECTION FOR SAFETY

For protection for safety, please refer to relevant items under4.2 of IS732. Additional requirements have
been mentioned against each sub-clause below.
4.1 Application of Measures of Protection Against Electric Shock
4.1.1General
In this standard the following specification of voltages is intended unless otherwise
stated:
a) a.c. voltages are r.m.s.; or
b) d.c. voltages are ripple-free.
Ripple-free is conventionally defined as an r.m.s. ripple voltage of not more than
10 percent of the d.c. component.
4.1.1.1 Circuits supplying socket-outlets with rated current up to and including 32 A and
other circuits supplying hand-held electrical equipment with rated current up to and
including 32 A shall be protected by:
a) residual current devices having a rated residual operating current not exceeding 30
mA (see 4.2.15.1.1 of IS 732),
b) be supplied by SELV or PELV (see4.2.14 of IS 732), or
c) have electrical separation of circuits (see4.2.13 of IS 732), each socket-outlet and
hand-held electrical equipment being supplied by an individual isolating transformer
or by separate windings of an isolating transformer.
4.1.2 In each part of an installation one or more protective measures shall be applied,
taking account of the conditions of external influence.
The following protective measures generally are permitted:
a) automatic disconnection of supply (4.2.11 of IS 732),
b) double or reinforced insulation (4.2.12 of IS 732),
c) electrical separation for the supply of one item of current -using equipment (4.2.13
of IS 732), and
d) extra-low-voltage (SELV and PELV) (4.2.14 of IS 732).
NOTE —If electrical separation is used special attention should be paid to the requirements of 4.2.13 of IS 732.

4.2 Requirements for Unearthed Circuits (SELV)

The following requirements are added to 4.2.14 of IS 732:
4.2.1 The requirement for protection against direct contact in accordance with 4.2.14.4
of IS 732 shall be provided, irrespective of the nominal voltage.

4.3 Requirements for Earthed Circuits (PELV)

The following requirements are addedto 4.2.14 of IS 732:
4.3.1 The requirement for protection against direct contact in accordance with 4.2.14.4
of IS 732 shall be provided, irrespective of the nominal voltage.

4.4 Protection Against Direct Contact

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4.4.1 Obstacles
The measure of protection by means of obstacles (clauseB-2 of Annex B, IS 732) is not
permitted.
4.4.2 Placing Out of Reach
The measure of protection by placing out of reach (clause B-3 of Annex B, IS 732) is
not permitted.

4.5 Disconnection of Supply

The following requirement is added to 4.2.11 of IS 732.
4.5.1 For circuits supplying socket-outlets with a rated current exceeding 32 A, residual
current operating devices having a rated residual operating current not exceeding 500
mA shall be used as disconnection devices.
5 SELECTION AND ERECTION OF EQUIPMENT
For selection and erection of electrical equipment, please refer relevant items under 5 of IS732.
Additional requirements have been mentioned against each item below.
5.1 Common Rules
The following requirement is added to 5.1 of IS 732:
5.1.1 All assemblies on construction and demolition sites (ACS) for the distribution of
electricity shall be in compliance with the requirements of IS/IEC 61439-4.
Plugs and socket-outlets with a rated current exceeding 16 A shall comply with the
requirements of IS/IEC 60309-2 or where interchangeability is not required,
IS/IEC 60309-1.
NOTE —Socket-outlets with a rated current not exceeding 16 A may be used according to relevant national standards.

5.2 Wiring Systems

The following requirement is added to 5.2 of IS 732:
5.2.1 To avoid damage, cables should not be run across site roads or walkways. Where
this is necessary, special protection against mechanical damage and contact with
construction plant shall be provided.
Particular attention shall be given to the protection of surface run and overhead cables
against mechanical damage given the environment and activities at the construction site.
Flexible cables that are subject to movement shall be IEC 60245-4 type 66 or equivalent,
resistant to abrasion and to water.

5.3 Switchgear and Controlgear

5.3.1 Devices for Isolation
5.3.1.1The devices for isolation shall effectively isolate all live supply conductors from the
circuit concerned, subject to the provisions of 5.3.1.2.
Equipment used for isolation shall comply with 5.3.1.2 to 5.3.1.8.
5.3.1.2 Devices for isolation shall comply with the following two conditions:
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a) withstand in the new, clean and dry condition, when in the open position, across the
terminals of each pole, the impulse voltage value given in Table 1 in relation to
the nominal voltage of the installation.
NOTE — Greater distances than those corresponding to the impulse-withstand voltages may be necessary from
consideration of aspects other than isolation.

Table 1Impulse-withstand Voltage as a Function of the Nominal Voltage

(Clause 5.3.1.2)
Nominal Voltage of the
Required Impulse Withstand Voltage for
Installation a
kV c
V
Appliances
Equipment at Equipment of Specially
and Current-
Single-phase the Origin of Distribution and Protected
Three-phase using
Systems with the Installation Final Circuits Equipment
Systems b Equipment
Middle Point (Overvoltage (Overvoltage (Overvoltage
(Overvoltage
Category IV) Category III) Category I)
Category II)
– 120-240 4 2.5 1.5 0.8
230/400b
– 6 4 2.5 1.5
277/480b
400/690 – 8 6 4 2.5
1 000 – 12 8 6 4
a According to IEC 60038.
b, c This impulse withstand voltage is applied between live conductors and PE.

b) have a leakage current across open poles not exceeding:

1) 0.5 mA per pole in the new, clean and dry condition, and
2) 6 mA per pole at the end of the conventional service life of the device as
determined in the relevant standard,
when tested, across the terminals of each pole, with a voltage value equal to 110
percent of the phase to neutral value corresponding to the nominal voltage of the
installation. In the case of d.c. testing, the value of the d.c. voltage shall be the same
as the r.m.s. value of the a.c. test voltage.
5.3.1.3 The isolating distance between open contacts of the device shall be visible or
be clearly and reliably indicated by "off" or "open" marking. Such indication shall onl y
occur when the isolating distance between open contacts on each pole of the device has
been attained.
NOTE — The marking required by this subclause may be achieved by the use of the symbols "O" and "I" to indicate
the open and closed positions respectively.

5.3.1.4Semiconductor devices shall not be used as isolating devices.

5.3.1.5Devices for isolation shall be designed and/or installed so as to prevent
unintentional closure.
NOTE — Such closure might be caused for example by shocks and vibrati ons.

5.3.1.6Provision shall be made for securing off-load isolating devices against

inadvertent and unauthorized opening.
NOTE— This may be achieved by locating the device in a lockable space or enclosure or by padlocking. Alternatively,
the off-load device may be interlocked with a load-breaking one.
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5.3.1.7 Means of isolation shall preferably be provided by a multipole switching device

which disconnects all poles of the relevant supply but single-pole devices situated
adjacent to each other are not excluded.
NOTE — Isolation may be achieved, for example, by the following means:
a) disconnectors (isolators), switch-disconnectors, multipole or single-pole;
b) plugs and socket outlets;
c) fuse-links;
d) fuses; and
e) special terminals which do not require the removal of a wire.

5.3.1.8 All devices used for isolation shall be clearly identified, for example by
marking, to indicate the circuit which they isolate.
5.3.1.9Each assembly for construction sites (ACS) shall incorporate devices for
switching and isolating the incoming supply.
Devices for isolating the incoming supply shall be suitable for securing in the off
position (see5.3.7.3.1.3 of IS 732) (for example, a padlock or location inside a lockable
enclosure).
Current-using equipment shall be supplied by ACSs, each ACS comprising:
a) overcurrent protective devices;
b) devices affording protection against indirect contact; and
c) socket-outlets, if required.
Safety and standby supplies shall be connected by means of devices arranged to prevent
interconnection of the different supplies.

5.4 Safety Services

The following note is added:
NOTE — Site conditions may require the provision of safety services, for example, escape lighting.

5.5 Verification
Site work is in a constant state of change and, therefore, the associated electrical
installation is subject to risk of damage or misuse. Therefore, in addition to initial and
periodic verification, the installation shall be inspected frequently, for example daily,
weekly, or monthly, as appropriate. Examples of some items to be inspected include:
a) the adequacy of connections and the condition of the protective conductors;
b) the condition of flexible conductors and their connections to portable equipment and
hand-held equipment;
c) the rating and condition of fuses and the setting of the circuit-breakers to ensure that
they are not unduly altered; and
d) the functioning of residual current devices.