Chapter 5 ELECTRICAL POWER SUPPLIES
Chapter 5
ELECTRICAL POWER SUPPLIES
5.1
INSTALLATION
5.1.1
The installation, control and distribution of wiring of electrical
equipment in buildings shall be in accordance with SS CP 5
Code of Practice for Wiring of Electrical Equipment of Buildings
and SS CP 16 Code of Practice for Earthing.
5.2
PRIMARY AND SECONDARY SUPPLIES
5.2.1
Where any of the following installations is required by this Code
or other Codes/Regulations, its primary and secondary source of
power supplies shall comply with the corresponding Code of
Practice stated therein:
Apart from the supply from normal mains, a secondary source of
power supply shall be provided to serve all essential services in
the building when there is a power failure from normal mains.
Secondary source of power supply would come from standby
generator set, which would automatically start, when there is
power failure in the building.
(a)
Where electrical passenger or goods lift is required, its
electrical installations, inclusive of battery and other form
of secondary power supply, shall comply with SS CP 2
Code of Practice for Installation, Operation and
Maintenance of Electric Passenger and Goods Lifts. Where
the provision of fire lift is required by this Code, installation
of the primary and secondary supplies shall also comply
with the above mentioned Code of Practice.
(No illustration)
Atrium smoke control system is required if any building under Purpose
Group IV, V and VII is designed to incorporate an atrium under cl.7.5 of
Chapter 7. Large basement occupancy other than car park usage
shall be provided with engineered smoke control system, if the gross
floor area exceeds 1900 sq m under cl.7.4 of Chapter 7. All smoke
control systems shall be connected to secondary power supply.
Lifts that are commonly found in buildings under purpose IV, V and VII
are electrical passenger lifts, fire lifts and goods lifts.
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Although the current SS CP 2 does not specifically require the
installation of generator set to provide secondary power supply to the
above lifts, however in the case of multi-storey office, shops and
places of public resorts under Cl. 6.6.2(b) and (c), generator set is
required to be provided to operate the lifts during emergency.
Where emergency generator is provided, the lifts would be designed
to home to the designated floor under generator power upon loss of
normal power supply.
(b)
Where electrical fire alarm system is required, its primary
power supply as well as type and capacity of battery shall
comply with SS CP 10 Code of Practice for the Installation
and Servicing of Electrical Fire Alarm Systems.
(No illustration)
Electrical fire alarm system(manual or automatic fire alarm system) is
required in most buildings under purpose group IV, V and VII. The
electrical fire alarm system shall be provided with emergency battery
supply to the requirement of SS CP 10.
(c)
Where exit or emergency lighting system is required, its
electrical wiring, type and capacity of battery or other
form of secondary power supply shall comply with SS CP 19
Code of Practice for the Installation and Maintenance of
Emergency Evacuation Lighting and Power Supply Systems
in Buildings.
(No illustration)
Emergency lighting in exit staircases, escape routes and other
common area leading to the exit are to be provided with either selfcontained battery or connected to secondary power supply.
(d)
Where an emergency voice communication system is
required, its electrical wiring shall be fire rated or otherwise
fire protected in accordance with SS CP 25 Code of
Practice for Emergency Voice Communication System in
Buildings. Appropriate type and capacity of secondary
source of supply shall also be provided accordingly.
(No illustration)
The current Fire Code 2002 requires emergency voice communication
system to be provided in buildings under Cl. 8.2.1(a)(i) Purpose group
IV, V and VII.
The type and extent of the emergency voice communication shall be
in accordance with cl.8.2 of the Fire Code 2002. Technical
requirements such as fire rated cables, routing and emergency power
supply shall comply with SS CP 25.
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(e)
Where a wet rising main system is required, the relevant
electrical supply shall be installed in accordance with SS
CP 29 Code of Practice for Fire Hydrant Systems and Hose
Reels. A secondary source of power supply with capacity
stipulated in SS CP 29 shall be provided for the wet rising
main pumps.
(No illustration)
Where a building under purpose group IV, V and VII exceeds 60m in
habitable height, wet rising main system shall be provided. The wet
riser pump including any transfer pumps shall be connected to
secondary power supply. If electrical generator is available, the
electrical pumps shall be connected to this source of supply. In the
absence of electrical generator set, the duplicate wet riser pump or
transfer pump shall be diesel engine-driven and shall start
automatically when there is demand on the riser main system to
supply water. This is to ensure that the wet riser main system would
remain operational during failure of normal power supply.
(f)
Installation of electrical supply for sprinkler system shall
comply with SS CP 52 Code of Practice for Automatic Fire
Sprinkler System. Capacity of secondary source of supply,
where required, shall satisfy the operation requirements
under the respective hazard category.
(No illustration)
Buildings under purpose group IV, V and VII exceeding 24m in
habitable height, larger than the permitted compartmentation size
and containing the respective hazard category (high risk) shall be
provided with automatic fire sprinkler system complying with SS CP 52.
The sprinkler pump including any transfer pumps shall be connected to
secondary power supply. If electrical generator set is available, the
electrical pumps shall be connected to this source of supply. In the
absence of electrical generator set, the duplicate sprinkler pump or
transfer pump shall be diesel engine-driven and shall start
automatically when there is demand on the sprinkler system to supply
water. This is to ensure that the sprinkler system would remain
operational during failure of normal power supply.
(g)
Mechanical ventilation where required for the following
rooms or spaces shall be provided with secondary source
of supply in accordance with SS CP 13 Code of Practice
for Mechanical Ventilation and Air-conditioning in
Buildings:
(i)
exit staircases and exit passageways;
(ii)
smoke-stop and fire fighting lobbies;
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(iii)
areas of refuge within the same building;
(iv)
basement car parks;
(v)
fire command centres;
(vi)
flammable liquid/gas storage rooms.
(No illustration)
Standby source of power supply may be in the form of emergency
generator or uninterruptable power supply. This is to ensure that the
mechanical ventilation system provided to these rooms or spaces
would not be affected during power failure.
(h)
Where mechanical ventilation is installed to provide air for
the operation of the following equipment, secondary
source of supply shall be provided:
(i)
emergency generator;
(ii)
engine driven fire pump.
(No illustration)
If the emergency generator or engine driven fire pump rooms are
provided with mechanical ventilation, the mechanical ventilation
system should continue to function under secondary source of power
supply.
5.2.2
The following systems shall be provided with secondary source of
supply:
(a)
Atrium smoke control system, including associated AHU's
forming part of the system.
(b)
All smoke control systems where required by this Code.
(No illustration)
5.2.3
Where emergency generators are provided as a secondary
source of supply, they shall comply with SS CP 31 Code of
Practice for Installation, Operation, Maintenance, Performance
and Constructional Requirements of Mains Failure Standby
Generating Systems.
(No illustration)
Emergency generator shall start automatically upon simulation of power
failure and shall be sufficiently sized to supply power to fire safety systems
such as essential fans, fire pumps & lift system.
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