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SECTION H - ELECTRICAL INSTALLATION

1.0 System Requirements

The following are the electrical system characteristics for which the equipment is to be designed and utilised:

Primary LV System : 415 V, 3 phase, 4 wire, 50 Hz

Power for space heater : 240 V, 1 phase, 2 wire,50 Hz Neutral solidlyearthed

Control voltage for : AC 110 Vswitchgear

Switchgear Current Rating : 150 Amps

2.0 Booster Station Accessories

The following accessories shall be provided for the booster station.

(a) A single line diagram framed in a glass panel.

(b) Rubber mats of approximately 1200mm wide and 10mm thick in continuous roll for the full lengths of the switchboards.

(c) A chart showing the first-aid procedures for electric shock.

(d) Danger sign boards of the format approved by TNB are fixed on all the doors.

(e) Booster station name signboard.

3.0 Underground Distribution Cables (Pvc/Swa/Pvc Type)

The underground distribution cables shall have conductors of annealed copper PVC insulated, steel wire armoured and PVC sheathed adequately sized to carry the total power output and lighting circuit required for the works and taking into consideration voltage drop in accordance with I.E.E. Regulations. PVC insulated armoured cables shall be manufactured in accordance with the current B.S. 6346.

The voltage rating (EO/E) for the cable shall be 600V/1000V. Cables unless otherwise specified shall be 4-core.

HLA96/BESUT/SPEC/SH-EI SH-1

Cables laid direct in the ground shall be laid in prepared trenches not less than 600mm deep for L.T. cables and of sufficient width to accommodate the number and size of cables required. There shall be a layer of compacted sand not less than 25mm thick as bedding. After the cables have been laid, sand shall be spread over the cables covering the entire length and width of the trench to a minimum thickness of 25mm above the largest cable and leveled. The sand used shall be fine river sand with no stones included. A layer of bricks shall be placed over the cables. Backfilling shall be made with first quality material and well compacted where cable trenches run across turfed area and roadways. The turfing and reinstatement of the road shall be properly carried out to the C&S Specification requirement. Wherever possible cables shall be laid in continuous unjointed lengths for the entire length of the cable route. Where joining of cable is unavoidable, this cost shall be deemed to have been included in the cabling cost. Cables shall be properly jointed to ensure full conductivity at rated current. The Project Director reserves the right to reject cables in short lengths below 27.5 metres.

4.0 P.V.C. Insulated Cables And Cable Runs

Cables used for indoor lighting shall be PVC insulated to B.S. 6004 run in heavily galvanised, rigid, steel conduit or in steel trunking. PVC/SWA/PVC cables run on steel cable trays shall be used for motors and power circuits. All the cables shall be adequately sized, taking into account of voltage drop, to carry the full load of the equipment.

Cables shall be delivered to the site in unbroken coils with the original wrapping intact. All wires or cables in which kinks or abrasions have occurred will be condemned and shall be replaced by the Contractor at his own expense.

All cables cores shall be distinguishing colours in accordance with local authority regulations.

Cables on walls shall run vertically or horizontally only. Vertical cable runs shall not be more than 300mm from ceiling level 150mm from the underside of beams. Cables running above ceilings shall be adequately supported in conduits and trunkings. There shall as far as possible be no joints in cables between termination. Where joints are required due to length exceeding 100m appropriate joint boxes specifically designed for this purpose shall be used.

5.0 Steel Conduit System

Steel conduits and fittings shall be manufactured in accordance with B.S. 31, heavy-gauge galvanised screwed type. Conduits shall be of adequately capacity for the sizes and number of cables to be contained therein.


Conduit systems shall be mechanically and electrically continuous and watertight throughout. They shall be provided with adequate inspection-type fittings, which shall be so installed that they remain accessible.All conduits shall terminate on proper conduit fittings and there shall be no unterminated conduit ends. All conduits shall be adequately supported.

6.0 Steel Trunking

Steel trunking shall be constructed of 16 SWG and cover plates of 14 SWG with flanged edges and of best quality mild steel sheet. The trunking shall be painted with a primer and two coats of semi-gloss gray or other approved colour. Removable covers shall be provided at suitable intervals to facilitate the drawing-in or removal of cables at any time. Steel hangers, brackets or other approved fixing media shall be provided at suitable intervals. If necessary, vertical trunkings shall be supplied in lengths to suit the installation. Joints and bends shall be so constructed that cables can be conveniently drawn through. Steel trunking where used on floor slab or to the damp environment shall be of weatherproof construction.

7.0 Steel Cable Tray

Cable trays shall be of the perforated type and constructed of minimum 16 gauge galvanised mild steel. The trays shall be supported at 1 metre intervals by mild steel hangers of adequate strength fixed to walls or ceiling slabs in an approved manner. The width of the cable trays shall be sufficient to allow the numbers of cable to be run, evenly spaced without overlapping and with spare room to accommodate 10% future increase in number of cables. Spacing between cables shall be half the diameter of the largest adjacent cable. Cable clamps shall be provided at 2 metres centres on horizontal run and 1 metre centres for vertical run.

All cable trays shall be effectively bonded to earth with suitable earth continuity conductors.

8.0 Wiring System Of Final Circuits

All wiring shall be executed in accordance with the design drawings of the Engineer.

The loop-in wiring system shall be used.

Cable sizes for final sub-circuits shall be adequate to carry the loads required and shall be in accordance with the I.E.E. requirements.


Each motor/control circuit or group motor/control circuit shall be fed from the M.C.C. through switchgear. The connections between the motors and starters shall include a bend to allow for any vibration or realigning of the motor.

9.0 Motor Starters

Starters for motors shall be in accordance with B.S. 587 and as a guide shall be as follows: -

Type Motor

Direct-on-line 0 to 7.5kW squirrel cage

Star-delta or auto-transformer Over 7.5 to 25kW squirrel cage

Electronic soft-starter Over 25 to 110kW squirrel cage

Stator-Rotor resistance Over 110kW slip-ring

All starters shall be of the contactor type suitable for remote control with no-volt releases and thermal or magnetic overload relays in each phase and is suitable for fully automatic operation in tropical conditions.

Star delta starters shall have air break triple pole electromagnetic “Line” contactor fitted with the necessary auxiliary contacts, closing-holding coil, adjustable thermal overload relay per phase with resetting device which shall be accessible from the outside, airbreak triple pole ‘STAR’ and ‘DELTA’ contacts fitted with the necessary auxiliary contacts. The star and delta contactors are to be electrically and mechanically interlocked. Overload relays are to be connected in the delta position to give inherent single-phase protection.

Stator rotor resistance starters shall have multiple contactors which accelerate the rotor by shorting out sections of the starting resistor under the control of time delay relays and consist of a starter resistor, contact unit, air interlocking contact, a thermal contact and a temperature fuse, The starter resistor shall be air-cooled and consist of rustless unbreakable resistor grids mounted between sheet steel and frames. The interlocking contact shall prevent the motor from being started up unless all resistance or reactance are in circuit. The thermal contact shall open the under-voltage trip circuit when the temperature exceeds 90 oC. Overload relays shall be wired to give inherent single-phase protection. Suitable earth leakage circuit breakers shall also be provided.

Each starter shall be equipped with auxiliary contacts for wiring to a green pilot light to indicate the live condition of the out-going circuit and a red pilot when the motor is tripped due to overload, push buttons and hand-auto-off selector switch and wired to remote control console.


Each starter shall be entirely suitable for frequent starting of up to 15 starts per hour. Each starter shall incorporate a H.R.C. fuse and fitted with an isolating switch in the distribution fuse board.

All contactors, starters, relays and controllers for the motors shall be grouped together in the control consoles.All incoming and outgoing circuits and wiring shall be brought to the contactors, starters, relays and controllers via. insulated terminal strips mounted within the consoles and all wiring between terminal strips and electrical equipment inside the consoles shall be neatly run and taped .

10.0 Contactors

Contactors where specified shall be totally enclosed, quick action type and of robust construction. They shall be adequately rated to take the full load current of the circuit.

11.0 Time Switches

Time switches shall be of the electricity wound type Venner or other approved makes with a 24 hours dial provided with setting adjustment. Time switch shall be enclosed in metal casing fitted with a removable panel with viewing glass and complete with by-pass switch suitable for the full load current of the circuits.

12.0 Automatic Power Factor Correction Panel

The capacitor banks and control equipments shall be housed in a floor standing steel cabinet connected to main switchboard. The capacitor banks shall be totally enclosed with dust-tight and hose-proof terminal boxes. Construction and finishes of the panel shall be identical to that for switchboards. The panel shall be adequately ventilated. The power factor correction board shall either be an integral part of the main switchboard or be separate cubicle boards as stated on the relevant Schematic Diagrams.

Each power factor correction board shall generally comprise the following components: -

a) A suitable, T.P & N fuse-switch unit, or ACB or MCCB for controlling the incoming supply or busbar connection to the board. Where power factor correction boards are mounted externally of switchboards, then an incoming-supply controlling isolator shall be fixed on the power factor correction board with a suitable fuse-switch unit or ACB or MCCB mounted on the switchboard controlling the outgoing supply to the power factor correction board.


b) A flush-mounted type, automatic power factor regulator unit of approved type, complete with a current transformer of suitable burden, ratio and class, for installation on the busbars of the circuit which requires power factor correction. The regulator shall be fitted with 6 or 12 switching steps as the case may be, to cater for switching in the number of capacitor units in the capacitor bank.

c) The required number of capacitor units to form the capacitor bank shall be built-in with the cubicle. Each capacitor unit shall be manufactured in accordance with BS 1650 and housed in its own steel container comprising a vertically - arranged stack of flattened roll capacitor elements of high purity aluminium foil, separated with multiple layers of high-grade dielectric tissue. The steel container shall be internally lined with a high grade insulating board. Each capacitor unit is to be fitted with a built-in discharge in not more than a minute after the electricity supply is switched-off. The terminals of each capacitor unit shall be glazed ceramic or other approved insulating materials. The impregnant which shall be non-flammable and the whole shall be hermetically sealed within the container.

If it is stated on the Schematic Diagrams that capacitor units are to be added to the bank in the future to cater for increased load, then sufficient space shall be allocated in the cubicle to allow for the future installation of such capacitors units. All capacitor units shall have appropriate voltage and frequency ratings to suit the voltage and frequency of the supply to which they are connected.

13.0 Exterior Lighting

Exterior lighting will be required for the mixing chamber, flocculation channels, sedimentation tanks, filters, roadways car park and site. The types and positions of the lighting fittings shall be suitable and adequate for the functions.

All exterior lighting shall be controlled by time switches with contactors and manual overriding by-pass switches. the underground cables shall be PVC-insulated, steel wire armouring and P.V.C. served with annealed copper conductors (PVC/SWA/PVC). Where underground cables terminate in a column, the loop-in and out system shall be adopted.

Steel poles for outdoor lighting shall generally conform to B.S. 5649 and shall have adequate strength to carry the designed load with a safety factor of 2.5 when subject to a wind velocity of 96 km.p.h. at right angles to the poles.

All poles shall be provided with square base plates measuring not less than 1 1/2 times the largest diameter of the poles. Weather proof compartments and access door covers shall be provided to house the control gear and looping boxes. In soft or unstable ground, the bottom of excavation shall be provided with precast or cast-in-to concrete slabs of adequate dimensions to spread the pole load. Steel


poles at a depth of 600mm below ground level. The steel poles shall be of minimum height 9.15M with 1.5M buried in ground. Access for cable entry shall be provided in the steel poles at a depth of 600mm below ground level. The steel poles shall be complete with outdoor lighting fittings, lamps, control gear, H.R.C. fuses and fuse holders, switch fuses, looping boxes, wiring base plates, etc. The steel poles shall be hot dipped galvanised internally and externally in accordance to B.S. 729.

14.0 Lighting Fittings

Lighting fittings shall generally be in accordance with the types and sizes as given hereof. All fittings shall be supplied and installed complete with fluorescent tubes and necessary accessories, readily detachable and accessible for cleaning, maintenance and replacement.

The types and numbers or lighting fittings and power socket-outlets for the various locations are shown in the drawings.

15.0 Switches

Switches shall be to B.S. 3676 rated at 5 amps or 15 amps as appropriate for the respective circuit. All sub-circuit switches shall be of the quick make and break type.

Generally all switches for lighting circuits shall be flush mounting for concealed wiring and surface-mounting for surface wiring. Flush switch cover plates shall be of approved white coloured moulded plastic of the break resistant material such as polycarbonate.

Adjacent switches shall be grouped under one cover plate and the switch boxes shall be suitable for the number of switches required.

Mounting height for lighting switches shall be 1,350mm above finished floor level.

16.0 Power Switch Socket-Outlets

Where the wiring is concealed, switch socket-outlets and wiring accessories shall be of the flush-mounting type.

Switch socket-outlets and plugs located inside the buildings shall be of the 13 amps 3 pin shuttered and switched type sockets with metal plates either of brass or anodised aluminium complete with fused unbreakable plugs with an efficient cable grip.


Switches socket-outlets and plugs located outside the buildings shall be of the 15 amps 3 pin metal-clad watertight switched type sockets complete with plugs having an adjustable cable grip and packed gland capable of taking a flexible heavy workshop cable.

Mounting heights of switch socket-outlets shall be as specified.

17.0 Item no not used.

18.0 Telephone Installation

18.1 General

The Contractor must be registered with Telekom Malaysia Berhad (TMB) and shall supply, deliver, install and connect a complete key telephone system c/w telephone distribution boxes, trunking, conduit, telephone socket outlets, manholes and cabling to TMB Standards and requirements. The equipment capacity is 8 exchange lines and 20 extensions..

18.2 Telephone Distribution Boxes

The Contractor shall be responsible for the supply and installation of telephone distribution boxes and trunking as shown on the drawings strictly in accordance with the relevant TMB specification and instructions.

All distribution boxes shall be provided with earth connection by means of having a separate terminal. Wiring termination blocks shall be the jack in type.

The earth connection should be extended to the MDF. The telephone distribution boxes shall be located at a height 625mm above floor level or as required by TMB.

18.3 Earthing Of Telephone System

The Contractor shall be responsible to provide a separate earthing system for the entire telephone installation. This earth system shall consist of concrete earth electrode pit c/w earth electrodes. The earth resistance value measured at the DF earthing bar shall be less than 3 ohm or to TMB requirement.

18.4 Internal Telephone Trunking And WiringHLA96/BESUT/SPEC/SH-EI SH-8

There shall be a comprehensive system of internal telephone trunking and wiring in the buildings as detailed in the drawings.

All work shall be to the requirements and approval of TMB.

Internal MS trunking and G.I. conduit shall be completed with draw wire. The sizes and thickness of these items shall be to TMB’s requirement. The junction boxes and telephone socket outlets shall be fabricated from mild steel and hot dipped galvanised to B.S. 729.

Internal telephone wiring shall be 10 lbs multi pairs pvc insulated type. Each cable shall have minimum 3 pairs.

The Contractor shall be responsible for all the necessary wiring of telephone cables from the distribution frame to the distribution boxes and from the distribution boxes to the various telephone socket outlets.

The type of distribution boxes is different at localities as shown in the drawings.

All telephone wiring points shall terminate at TMB approved sockets outlets.

18.5 External Underground Telephone Ductings, Junction Pits, Manholes And Cabling

The Contractor shall be responsible for the supply and installation of all the telephone cables from the cabinet to distribution boxes in different localities as detailed in the drawings. The Contractor shall also the responsible for the excavation, backfilling and reinstatement of all the trenches for the telephone underground ducts from nearest TMB manhole to equipment room.

The Contractor must obtain the approval of the local Authorities before any excavation of the public road. He shall be fully responsible for the control of traffic, road safety and signages. The work may be required to be carried out on Sunday or after mid-night in order not to disrupt traffic. Compaction of backfilling must in layers of not more than 150mm and subsidence of reinstatement is not permitted. The whole works must be completed within 24 hours. Manholes shall consist of R2A, JC9C and JC9 types to TMB Specifications.

External telephone cables shall be 10 lbs multi-pairs pvc insulated, fully filled and lead sheathed type.


18.6 Telephone Socket Outlet

Telephone socket outlet shall be of the flush type, single outlet housed in flush mounting metal box c/w conduit knockouts. The telephone plate shall be of impact resistance polycarbonate complete with 1 gang 6 pin connector. Telephone plate for public telephone point shall be of impact resistance polycarbonate with cord grip.

The whole of the telephone trunking, conduit system and telephone socket outletsshall meet the requirements of TMB.

18.7 Test

Before test of any materials or equipment are undertaken, the Contractor shall submit to the Project Director for approval a detailed inspection schedule covering all aspects of inspection, works and site testing.

During the progress of the work and prior to Commissioning the Contractor shall carry out all test required by TMB and the Engineer. He shall provide test certificate and Certificate of Fitness for all equipment as may required by the Local Authorities or the Project Director and shall provide all necessary tools, instrument and equipment for conducting site tests. All fees imposed by the Authorities for such tests shall be borne by the Contractor.

In general the Contractor shall be responsible for the testing of all equipment and certifying that such equipment is safe before commissioning and that all the equipment complies with the requirements of the Specification.


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