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The interior of each equipment shall be clearly marked to show the phases and for this

 purpose either colored plastic disc screwed to fixed components or colors PVC sleeveshall be utilized.

Each service shall be labelled as detailed on the drawings. Labels shall be of clear‘Perspex’, reverse engraved and flush filled with red filling. Labels shall be attached bymeans of machine screws and nuts or machine screws driven into drilled tapped holes.

All L.V. switchboards and equipment shall be suitable for a symmetrical fault rating of

31 MVA or 43kA at 415V, 3 phase, 50Hz for one second. All equipment shall be typetested by an approved short circuit testing authority. Type test certificates for the

equipment shall be forwarded to the Consulting Engineers.

3. AIR CIRCUIT BREAKER  

Air Circuit Breakers shall be of metal cladded, flush mounted, horizontal draw out

isolation. They shall fully comply with BS4752 and certified accordingly by ASTA orother recognized short circuit testing authority.

Air Circuit Breakers shall be equipped with independent manual closing devices. Manual

charging of the ratchet spring mechanism shall be accomplished by a handle and aninterlock shall be incorporated such that closing of the breaker shall only be possible

when the spring is fully charged. The status of the spring mechanism shall also be

indicated. Normal opening of the breaker shall be accomplished by tripping coils, butnormal opening shall also be possible by insertion of the removal draw out handle into

 position. The tripping mechanism must be stable and will not be activated by shocks or

vibration. The trip coil shall be designed such that the trip plunger be operated

instantaneously without delay due to gradual building up of coil flux to maximum value.

The contacts shall be designed to operate efficiently under all conditions of service with

minimum deterioration under fault interruption. Devices should also be incorporated tocontrol the arc during opening and the contacts and shall be arranged to give a double

 break in each pole. All contacts shall be replaceable.

Individual arc chutes shall be provided on each pole of the breaker. They shall be so

designed that any arcing due to opening of the breaker during a maximum fault condition

shall be completely contained with no possibility of a flashover between phases, any

 phase to neutral or to earthed metal.

The breaker’s operating mechanism and the carriage on hinged panel shall be interlocked

so that it is not possible to withdraw the circuit breaker while it is in the closed while it is

at any position between the service and isolated position. Provisions shall be made sothat it is possible to operate the breaker’s mechanism if   required for inspection and

testing purposed when the breaker is in the isolated position.

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Auxiliary switches, relays, contactors, trip coils, electrical and mechanical interlocks,

alarm indication and operation status indication shall be provided to ensure the proper

operation of the circuit breaker. In addition to those required for the functions covered inthis specification, a reasonable number of auxiliary switches shall be provided to cover

 possibility of future alarm or signaling circuit requirements. All auxiliary switches shall

 be robust, double break design, easily accessible for maintenance and replaceable.

4. SWITCHGEAR  

All switchgear shall be of the approved type and comply with BS 5419. Where items ofswitchgear are to be mounted near to one another, they are to be selected from a

manufacturer’s standard range. All TPN fuse switches and switch fuses shall have a

 parallel motion quick make and slow break spring loaded operating mechanism. Positive

interlock shall be incorporated to ensure that the cover can only be opened when theswitch is in the ‘OFF’ position and fuse links isolated. Flag ON-OFF indication shall be

 provided to indicate the status of operation. All switchgear shall be complete with HRC

cartridge fuse link to BS 88 and bolted type neutral links. For all motor circuits, motorrated HRC fuse links shall be provided with ratings as specified.

5. INSTALLATION OF WALL MOUNTED PANELS

Panels shall be installed on walls at the locations indicated on the layout drawings. The

locations shown thereon are approximate only; therefore the Contractor shall liase with

the Supervising Engineer with respect to the exact positions and heights of the panels, prior to commencing wiring installation works.

The panels shall be held in position on walls by means of expansion bolts of sufficient

length and gauge to withstand the weights of the boards and cables connected to the boards. The fixing holes for the panels shall be internal of the board.

Where the panels are to be installed on steel columns or framework, purpose made m.s.clamps of robust construction shall be used for holding the boards in positions. Drilling

of holes in steel the columns or steel structured work for the installation of boards shall

not be permitted, except with the prior approval of the Architect.

If it is not possible for a panel to be installed in either manner stipulated above, then such

 panels shall be installed on a floor mounted m.s. pedestal and placed against the wall or

column as the case may be.

6. BUSBARS

Busbars shall be of hard drawn high conductivity copper to B.S. 159. All joints in busbars shall be bolted or clamped, with contact surfaces suitably prepared.

Busbars shall be painted with colors red, yellow, blue and black at appropriate points todistinguish the phases and neutral.

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The design should preferably be such that the main busbars are arranged in a horizontal

 plane, and in the order red, yellow, blue and neutral from back to front. On each panelconnections should be red, yellow, blue and neutral from left to right, viewed from the

front of the panel.

An earthing busbar, of appropriate cross section, shall run the full length of mainswitchboards preferably at the base of the switchboards.

The busbars shall be air insulated and rigidly supported so as to withstand anymechanical force to which they may be subjected under the maximum fault conditions.

Adequate connectors, droppers and links shall be fitted to serve circuit breaker panels.

 Non hydroscopic non tracking supporting insulators shall be used and spaced to

withstand the stresses due to the maximum fault current.

Full-neutral and earth busbars shall be provided with terminals, lugs and bolts with nuts

and washers to suit requirements. Each outgoing shall be provided with separateterminals.

The SESCO metering CT's and sealing chambers shall be mounted in the rear section of

the switchboard and shall be segregated from the busbar etc by insulating panels.

Connections from busbars to circuit breakers, fuse switches shall be by means of copper

 bars securely clamped to the busbars and identified by means of colored plastic sleeve toindicate the phase color. Drilling of busbars shall not be permitted without written

consent of the Engineer.

7. INTERNAL WIRING

The internal wiring for various instruments etc. shall be of minimum size 1.5mm2. But

for current transformer circuits, a minimum size of 2.5mm2  conductor shall be used.These cables shall be laid inside G.I. conduits which shall be neatly arranged with bends

set at 90o and securely held in position with suitable cleats.

External wiring shall be terminated on din rail mounted polyamide tunnel type terminal

 blocks within the switchboard before any internal wiring is carried out. Insulating bushes

of PVC or other approved materials shall be used where necessary. Power carrying

circuits shall be segregated from control wiring.

Identification ferrules of white insulating material with permanently marked black

characters and numerals having a glossy surface shall be fitted to each end of all internal

wiring.

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8. FUSES AND LINKS

Fuses shall be of the interchangeable cartridge type having a rupturing capacity of not

less than 31 MVA at 380 volts to B.S. 88 for AC 46 Category of duty and Class 1 fusing

factor.

Ratings shall be as indicated with 2A units being used for the protection of instrument

and control circuits.

Fuse carriers, links, link carriers and bases shall also comply with the requirements of

B.S. 88.

9. MINIATURE AND MOULDED CASE CIRCUIT BREAKERS 

The breakers shall be suitable for use on a system voltage of 415/240 volts, three or

single phase, 50Hz and shall comply with BS 3871 and BS 4752. The breakers shall beof quick make and slow break type with toggle operating mechanism. The breakers shall

 be provided with overload and overcurrent protection by means of thermal magnetic

tripping element and arc extinguishing devices. The tripping mechanism shall be ‘trip

free’ from the handle so that it cannot be closed onto a fault. Multi-pole breakers shallhave a common trip mechanism so that in the event of a fault on any one pole of the

 breaker, all poles will trip simultaneously. All breakers shall be to the appropriate ratings

as indicated in the drawings. Breakers located at the main switchboard shall be fittedwith external interlocking handles. Positive interlock shall be incorporated to ensure that

the cover can only be opened when the switch is in the ‘OFF’ position. 

10. MINIATURE CIRCUIT BREAKERS (MCB)

Miniature over current circuit breakers shall comply with the requirements of B.S. 3871

and be of the hermetically hydraulic type with ratings M6 at 380 volts A.C.

Discrimination shall be inherently provided with HRC fuses to B.S. 88 (e.g. Class Q1

type as manufactured by M/s GEC - English Electric) protecting the distribution boardsuch that except under extreme overloads, the miniature circuit breakers will discriminate

with the fuses. The required measure of discrimination is that the fuse curve crosses the

miniature circuit breaker curves only once and at a time not exceeding 20ms.

11. DISTRIBUTION BOARDS 

Distribution boards shall be fabricated from sheet steel, rustproofed and finished stove

enamel inside and outside. Doors shall be fitted with gaskets and circuit schedule and bemade removable to facilitate wiring. The free end of the door shall be secured by captive

knurled thumb screws. All distribution boards shall comply with BS 214.

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Each distribution board shall be complete with neutral bar for each single phase way on

the board. For conductors larger than 10mm² cross sectional area, cable sockets shall be

 provided. An earthing bar for protective (earth) conductor shall be provided and must beadequate to meet the number of circuits of the distribution board.

Fuse carriers and bases called for in the drawing shall be of the molded or porcelain typeand comply with B.S. 88. The current rating should be higher than or equivalent to therating of the fuse link it intends to carry. The terminations shall be suitable to accept the

size of cable it is intended to connect and reduction of cable strands is prohibited. The

molding material used shall be non-tracking and has good insulating properties. The baseand carrier contacts shall be non-slip during insertion or withdrawal to ensure proper

alignment and self-cleaning. It should not deform after repeated withdrawal and

continuous use.

The live busbars shall be shielded once wiring is completed by means of a fiber board.

Where indicated, an on-load isolator with quick make and slow break positive actingmechanism shall be incorporated with the distribution board. All the contacts shall be

shrouded.

Miniature and molded case circuit breakers called for in the drawing shall be of SP or TPwith breaking capacity of not less than 5 kA or as indicated in the circuit diagrams.

Distribution boards shall be wall mounted wherever practicable otherwise it shall bedesigned for floor mounting with the permission of the Consulting Engineer. A label of

engraved ‘Perspex’ shall be located in front of the panel to designate each distribution

 board in accordance to the drawings.

12. METERS AND RELAYS 

Meters and relays for external panel mounting shall be of the flush pattern, with squareescutcheon plates finished mat black and pressed steel cases. Indicating instruments shall

 be to B.S. 89 1st grade. Moving iron spring controlled with 4” diameter dials (240°

scale) with external zero adjustment and integrating meters shall be to B.S. 37 Part 1 and2 and Part 4. Cyclo-meter registers and protective relays shall be to B.S. 142.

Unless specified otherwise in the drawing or specification, all earth fault relays called for

shall be of the instantaneous operation type. The relay shall be provided with adjustable plug settings in seven equal steps ranging from 10% to 40%. A flag indicator with

external reset lever shall be provided with each relay.

In the event IDMT (Standard Inverse Definite Minimum Time) earth fault relays arecalled for, they shall have a definite minimum time variable from 0 to 2.2 seconds on a

time multiplier of 1.0. They shall have nominal current plug settings variable from 10%

to 40% in steps of 5%. Withdraw able type relays shall be provided with automaticmeans of short-circuiting the current transformer secondary circuits and capable of

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 breaking tripping circuits when the relay element is removed. Relays shall have a rated

current equal to secondary current of the current transformer. The relay shall be

complete with flag indicator and external reset lever.

Instruments, meters and relays located on the front of the switchboard shall be so

 positioned that as far as possible, each instrument, meter and relay is adjacent to the unitwith which it is associated. Other relays more suitable for mounting inside the cubiclesuch as those required for back indication and tripping etc. Shall be grouped conveniently

in dust-proof cases with removable covers to provide easy access for cleaning and

adjustment without dismantling. All relays shall be heavy duty pattern, unaffected byexternal vibration and capable of operation in any position. Meter panels shall be hinged

to provide ready access to all connections and all small wirings shall be enclosed in

flexible plastic conduit. All terminals shall be completely insulated and potential circuits

shall be suitably fused.

13. INDICATOR LAMPS 

Indicating lamps shall be adequately ventilated and easily removed or replaced from the

front of the panel without the use of extractors. Lamps shall be clear holders.

The color in colored lamp glasses shall be in the glass and not an applied coating.Transparent synthetic materials may, however be used instead of glass, provided no

discoloration or deformation takes place due to heat from the lamps.  

14. RESIDUAL CURRENT BREAKERS

Residual current breakers shall be fitted to the switchboards as indicated to detect earth

leakage currents of 300mA +10mA for 3 phase and 100mA +5mA for single phasecircuits except where indicated otherwise, residual current breakers shall trip within 20m

sec. A test button shall be provided for testing of operation.

Residual current units shall be of the core balance type complying with B.S. 4203 and

may be separate from or incorporated within a circuit breaker.

15. CONTACTORS

Contactors shall comply with the requirements of B.S. 5424 and 764 except where varied

in this document and supplied for the required applications which are: -

- disconnecting;

- bulk switching;

Of which are evident from the drawings.

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Each unit shall be suitable for AC3 utilization category with contacts suitable for the

required currents. (It shall be noted that the rating of the contacts for disconnection

duties shall be such as to avoid welding under fault conditions).

All units shall be suitable for uninterrupted duty, block type with contacts which may be

readily replaced and accommodated within the switchboard enclosure.

Auxiliary contacts of minimum 10A rating, of the quantity as indicated, together with at

least one set of normally open and one set of normally closed contacts shall be provided

which shall be wired to the terminal board. If it is impracticable to equip the contactorwith sufficient auxiliary contacts, auxiliary relays shall be installed. Contactors shall

have a making capacity of 10 times the rating and have at least 1 million operations life

span.

16. ISOLATORS

Isolators shall be provided at the incoming of all control panels. Isolators shall be of thedoor interlocked type to prevent opening the panel while the isolator is closed.

17. TERMINALS

Terminals shall have not more than two wires connected to one terminal, and shall be

mounted to allow ferrule numbers on the connecting wires to be readily discerned.

Terminals shall be fitted to accommodate cables as follows: -

(a) up to and including 6mm2 

- Tunnel type with brass screws, or clamp type

(b) Above 6mm2 

- stud type to accept cable lugs.

Terminals for all auxiliary contacts being provided, including those designated as spares,

shall be fitted, wired and clearly marked as such.

Cable Sockets

Cable lug sockets shall be of approved type with lug faces machined parallel and flat and

the sockets being drilled to suit the cable and tinned. Cable ends and sockets shall be

cleaned and soldered, using non-corrosive flux.

18. INSTRUMENTS

Instruments and like apparatus shall be provided where indicated, and shall comply withB.S. 89 and be capable of carrying continuously their full load current without undue

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heating and be of the flush mounted back connected type; square fronted meters 96 x

96mm with quadrant scale and means of adjusting zero without the need for dismantling.

Scales and figures shall be BLACK on a WHITE background.

Ammeters shall be dual movement type incorporating an instantaneous current valueindicator and a demand indicator with a 15 minute time constant period complete with ared maximum demand pointer having external reset.

Voltmeters shall be scaled 0/500 volts with a selection switch to provide phase to phaseindication and an OFF position.

KWH meters shall be suitable for measuring 3 phase unbalanced loads.

KWH and volt-meters shall be provided with 2A HRC potential fuses.

Power factor meters shall have a measuring range between 0.5 lead to 0.5 lag and besuitable for 3 phase 4 wire balanced load measurements.

19. CURRENT TRANSFORMERS

Current transformers necessary for protection, measuring and metering shall comply with

B.S. 3938, 1973 and shall have accuracies of Class `1.0' for measuring, Authority

requirement for metering, and Class 5P10 for protection.

All units shall be resin encapsulated type with 5A secondary winding and separate units

shall be provided for metering and protection functions (combined usage is not

acceptable).

The output of each unit shall be capable of operating the related protective equipment

connected with an additional allowance of 25%. However, all transformers forming athree phase group shall be identical.

20. SURGE SUPPRESSION

All equipment shall be capable of withstanding transient over voltages which may

develop.

M.I.C.C. cables, contactor coil circuits and all major runs of cables shall be equipped as

necessary with suitable non-linear resistors (surge diverters) to attenuate the effects of

over voltages caused by the equipment used or by lightning.

21. INDICATING LIGHTS

Indicating lights shall be of the encapsulated transformer type with 12 volts secondary incompliance with B.S. 1050 and be guaranteed for a burning life of 20,000 hours at

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operating voltage. The color of the lights shall be to B.S. 4099. Lenses shall be of the

25mm diameter type with 2 watts minimum lamps.

22. CONTROL RELAYS

Control relays shall be of the silver contacts type with minimum 5A, 220 volts 50Hzcontact rating. Time delay relays shall be of the electronic type. All relays shall be of the plug in type.

The base holder for the plug-in relays shall be 11 pin type and the connectors forterminating incoming cables to the base holders shall be of the screw type, accessible

from the front.

The plug-in type units shall be fully enclosed to prevent the ingress of dust or moisture.The enclosures shall be made from clear polyurethane or acrylic material and shall have

the connection diagram of the relay unit imprinted on the top.

23. CONTROL SWITCHES

All control switches shall be of the quick make and quick break type using double break

contacts operated by a common spindle.

The control switches shall be suitable for panel mounting and suitable for the load

carrying current of the circuit which the switch is controlling. Generally switches are to be used for controlling coils of starters and relays, etc., and the minimum rating of the

control switch shall be 16 amp, 220 volts, 50Hz.

24. POWER CAPACITORS

The power capacitors shall conform to B.S. 1650. The impregnate and filling used in the

capacitors shall be non-flammable, non-explosive liquid, possessing excellent insulationand dielectric properties including high insulation resistance and high dielectric constant.

The material shall be chemically stable (i.e. it shall not oxidize or sludge under the most

severe conditions of operating temperature), and shall not be P.C.B. The electrodes shall be made of commercially pure aluminum foils free from all rolling lubricants.

A continuously rated, low loss discharge device shall be incorporated in all capacitors.

This shall ensure that the capacitor is discharged from peak alternating voltage to avoltage not exceeding 50 volts, measured at the capacitor terminals, one minute after

disconnection from the supply. Capacitors losses shall not exceed 3 watts per KVAR of

capacitor rating.

The containers of power capacitors shall be fabricated from heavy tinplate or stainless

steel and shall be hermetically sealed to prevent leakage of filling or ingress of moisture.

The containers shall be coated with a zinc chromate primer and a heavy coat of enamel

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 paint. The case temperature shall not rise more than 15 deg C when operated under rated

conditions.

25. RATING PLATES

Small rating plates giving serial numbers and data in accordance with the relevant BritishStandards are required on equipment supplied, namely:- Circuit Breakers, Fuse Switches,

Isolators, Current Transformers, etc.

26. PANEL IDENTIFICATION

Each switchgear panel shall be clearly identified and designated according to its function.

The labels shall be engraved and arranged as shown in the drawings submitted by theElectrical Contractor and approved by the Consulting Engineers.

27. TESTS

Type tests certificates issued by recognized testing authorities shall be submitted for all

switchgear to the Consulting Engineers.

Routine & Factory Tests

The Electrical Contractor shall submit certified test sheets showing details of all routinetests conducted during manufacture of switchboards and individual components thereof.

Delivery Test

After the equipment has been erected on site and before final connection to the supply,

the Electrical Contractor shall with his own instruments and expense carry out all tests

necessary to demonstrate that the equipment complies with the requirements of thisspecification and to the satisfaction of the Consulting Engineers.

The tests to be conducted shall be as follows: -

i) Demonstration that all equipment are installed and all wiring connected, so that

the switchboard functions as required.

ii) Insulation resistance between phases, between each phase and neutral, and

 between each phase, neutral and earth with the breaker open and all equipment

installed.

iii) Insulation resistance across breaks in all circuit breakers, with the breaker open

and all equipment installed.

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iv) Setting of overcurrent and earth fault protection relays on circuit breaker in

accordance with the requirements of the Electricity Supply Authority.

Copies of test sheets, showing the results of all tests carried out in accordance with this

section of the specification shall be submitted to the Consulting Engineers.

28. FLOOR MATS

The Electrical Contractor shall supply floor-mats of rubber material without perforation

of minimum 12mm thickness for each switchboard. These shall extend to the full lengthof the switchboard and shall be minimum 1.2m wide at the front and sides and 0.9m wide

at the rear of the switchboard.

29. METERING PANEL

The metering compartment shall be constructed with a removable hinged transparent

front cover to Authority's requirements. Facilities shall be provided on the panel formounting of Authority's meters and for wiring connections. Should multiple tenant

meters be provided, the electrical contractor should label the individual meters. This

meter panel shall be located as close as possible to the metering CT's, and must be

sealable.

A totally sealable C.T. chamber shall be provided at the incoming before the switchgear.

The protection voltage fuses for the kWh meter shall be located within the metercompartment itself.

30. SIGNS, CHARTS AND DIAGRAMS TO BE HUNG

Detailed single line and control wiring drawings mounted on a wooden frame with a

transparent polyethylene cover shall be hung in a conspicuous location and within the

cubicle covers for control panels and distribution boards.

A first aid chart shall be provided for electrical shock within all switchboard rooms. A

danger signs shall also be provided on entry doors to Switch rooms.

31. INTERLOCKS 

The breaker’s operating mechanism and the carriage on hinged panel shall be interlockedso that it is not possible to withdraw the circuit breaker while it is in the closed position.

It is also not possible for the breaker to be closed while it is at any position between the

service and isolated position. Provisions shall be made so that it is possible to operate the

 breaker’s mechanism if required for inspection and testing purposes when the breaker isin the isolated position.

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LIGHTING FITTINGS

1. GENERAL

The Electrical Contractor shall supply, deliver, install and connect the light fittings in the

location shown on the drawings. All trimming supports, etc. necessary for recessed,

surface and suspended mounting of the light fittings shall be supplied by the ElectricalContractor. The types of light fittings are as shown and specified in the drawings.

2. STANDARDS

The light fittings, together with lamps, lamp holders, auxiliary and other necessary

equipment shall conform to the latest British Standard Specifications in all respect with

regard to design, construction, performance and test as a minimum requirement.

3. LUMINARIES

Luminaries shall

- comply with B.S. 4533 unless otherwise specified or scheduled;

- luminaries shall be arranged such that control gear and auxiliary wiring is

separated from the lamp compartment by means of removable covers which

 prevent inadvertent contact during re-lamping operations; access between

compartments for wiring shall be through holes fitted with grommets. Each

luminaries shall be fitted with a fused terminal block and be suitable for 20mmconduit entry.

4. FINISHES

All equipment shall be protected to minimize the effects of corrosion and galvanic action.

All fixing onto painted surfaces shall have washers, felt or nylon washers and be of the

captive type.

For proprietary equipment, the manufacturer's standard finishes may be accepted

 provided they are, in the opinion of the Engineer, equal or superior to the standards of

finishes described.

All internal light reflecting surfaces shall be gloss white unless denoted otherwise by the

Catalogue No. or description (i.e., silver reflector down light).

All external surfaces shall be finished anodized, plated or enamel to color selected by the

Consulting Engineers or as denoted by Catalogue No. or description.

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 Non-Ferrous Metal

Aluminium surfaces shall be etched primed prior to the application of

anodized finishing coats.

 Non-ferrous parts shall be chromium plated or tinned. Nuts, bolts andthreads shall be chromium plated where mounted internally.

External bolt heads, nuts and screws should be positioned to be outsidenormal view but where this is impracticable, they shall be chromium

 plated.

Ferrous Metal

After fabrication all surfaces shall be thoroughly cleaned to remove

rust, and then using a suitable solvent, shall be degreased followed bythe removal of residual foreign materials.

Immediately prior to painting all dirt shall be removed from surfaces by

wiping. At no stage shall coatings be applied over rust, dirt, dust,moisture or any other foreign matter.

Ferrous metal shall be finished using one of the following approved systems:

- Phosphated Zinc Seal

Apply 2 coats of blue tone white baking enamel in accordance withthe paint manufacturer's recommended practice. After baking the

finished coating shall be 30 microns minimum dry film thickness.

- Zinc Anneal

Apply one coat of two pack vinyl butyl etch primer to produce 15microns maximum dry film thickness. Lightly scuff the surface with

400 grit emery paper to remove any nibs. Then continue as for

Phosphated Zinc above.

- Thermosetting Epoxy Powder

Apply one coat of white epoxy powder and cure in accordance

with manufacturer's recommended practice. After curing finishedcoating shall be 50 microns minimum film thickness.

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Irrespective of the coating medium, the finished coating shall be fully cured, hard,

coherent and free from sags, blistering, cracking, wrinkling, lack of bond or other defects

that may impair the appearance and/or performance of the coating.

5. WIRING WITHIN FITTINGS

Luminaries shall be supplied with all internal wiring colour coded and completed.

Wiring shall have Class 105oC PVC insulation except where internal temperatures are

likely to exceed the safe limits of such insulation, in which case roved (Class C)insulation shall be used. Conductors shall be of adequate size and rating for the

 particular duties and terminations.

Single strand conductors shall be used for clip connections and multi-strandedconductors for screw connections. Wiring shall be neatly arranged within the fittings and

clipped to the metal ware at intervals not exceeding 200mm.

Wires shall be kept clear of auxiliary components. The method of clipping shall be such

as to prevent damaged to the insulation. Adhesive tape shall not be used for clipping or

looming of wires.

A fixed two terminal fused connector block with an earth terminal adjacent or integral

shall be provided near the incoming cable entry of each fluorescent and discharge fitting.

The fuse shall comply with requirements of B.S. 88 and generally be of 2A rating.

6. VENTILATION

Luminaries shall be designed to promote cooling, ensuring that in service, temperaturesin excess of the thermal ratings of any of the components are not exceeded.

7. AUXILLIARIES AND CONTROL GEAR

7.1 BALLASTS

All ballasts shall be Electronic Ballasts.

7.2 POWER FACTOR CORRECTION

Discharge and fluorescent fittings shall be fitted with metalised

 polypropylene capacitors to correct power factor to 0.85 lagging. Capacitors shall

comply with B.S. 2135. Discharge resistors shall be provided on all capacitors.

7.3 STARTER

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Where installed, starters must be compatible with, and in accordance with,

the ballast and lamp or tube manufacturer's recommendations.

Starter sockets shall have metal strip spring type contacts for connection

 by twist action. Housings shall be moulded plastic.

Thermoplastic materials used in the construction of starter switches andholders shall comply with B.S. 3772.

7.4 LAMP AND TUBES

Fluorescent tubes shall comply with B.S. 1853 and generally be of the

switch start type, similar to Philips T5 W, cool white type, 26mm diameter 86

lumen/w, colour rendering index 66, colour temperature (approx.) 4100K or otherequal manufacture. Lamps shall have a guaranteed life of 7500 hrs.

Rapid start tubes aged for 100 hours shall be used where fitted to circuitswhich are dimmed.

Discharge lamps shall be of the colour corrected type in compliance with

B.S. 3677 and 3767.

Incandescent lamps shall be in compliance with B.S. 161 and 555 and be

of the type and ratings indicated. Lamps shall be of the bayonet cap, frostedglass, coiled coil filament type with a nominal life of 1000 burning hours.

7.5 LAMP HOLDER

Lamp holders shall be constructed of nonflammable high impact resistant

materials which do not deteriorate under the temperatures encountered during

service (porcelain or brass type). Lamp holders shall be secured to the body ofthe luminaries such that they maintain their position and plane during lamp

replacement.

Lamp holders for fluorescent tubes shall comply with the requirements of

B.S. 1875 & B.S. 5042 Part 4 and be of the two pin retractable or counter twist

type with metal strip spring type contacts, designed to positively retain the lamps.

Lamp holders for incandescent lamps shall comply with the requirements

of B.S. 52 and B.S. 5042 for B22 bayonet cap for lamps up to 100 watts and

Edison screw types for lamping up to 300 watts.

Discharge lamps shall be of the Edison screw type up to 300 watts and of

the G.E.S. type above 300 watts in compliance with the requirements of B.S. 5042

Pt. 2.

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8. FIXINGS

Luminaries shall:

- be provided with standard means of achieving satisfactory fixings;

- in the case of pendant types, have 85oC suspension cords, and where thesuspension is metal or other arrangement with the cable inside, the cable shall be

glass or PTFE insulation;

- in the case of recessed or semi-recessed type, in addition, be provided with

concealed holes for side screw fixings into the ceiling aperture trimming;

- in the case of surface mounted type, be furnished with minimum of twofixing holes at the ends of the fitting. Fittings wider than 150mm shall be

 provided with 4 fixing holes.

All ceiling recessed fluorescent fittings wider than 150mm shall be individually secured

with 2mm dia. galvanised steel wire to the building structure.

Where chain suspensions are required they shall be of welded, twisted link pattern,minimum 18 gauge (1.20mm) diameter.

9. FINAL CONNECTIONS

All recessed luminaries shall be connected to the fixed wiring system by a length of

flexible steel conduit. The cables within the conduit shall be looped into and terminate

only in the luminaries. All fixed wiring within the luminaries shall be sleeved with glassroved high temperature insulation.

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CABLING AND WIRING

1.  GENERAL 

The type of cables used and the method of wiring shall be as described in the `scope ofworks' and as detailed below.

All cables shall be installed in one continuous length between the points of connectionand no straight through joints of any description, other than those required for terminating

the cables, will be allowed.

Cables shall be delivered to the site in unbroken coils with the original wrapping intact.Cables shall be of distinct colours: - Red, yellow, blue as applicable for phase conductors,

 black for neutral and green for insulated earth conductor.

All joint boxes and termination accessories shall comply with the cable manufacturer’s 

standard design.

Where single core cables are used, they shall be installed in a flat formation for sizes upto and including 120mm2 and in a trefoil configuration for larger sizes: conductor shall be

installed such that proximity effect in adjacent ferrous metals are minimized.

Where conduits, trunking, or ducting cross expansion and settlement joints in the building

structure, purpose made expansion coupling shall be used to allow for movement of the

structure. Adequate slack shall be allowed in the cables to take up the movement.

The Electrical Contractor shall provide all compound and other jointing materials to

complete the cable terminations to switchgears to which the cables are run. Cutting of

apertures for cable entry shall be done by the supplier of the control panel/switchboards.

Hydraulic compressible crimped (i.e. non compound-filled) type of cable lugs shall be

used at all times.

Wiring throughout shall be on the `looping-in' method and no `tee' or other joints will beused. Wiring shall not be looped through the bodies of luminaries unless specified

otherwise.

Bending radius of cables shall be in accordance to the cable manufacturer’s 

recommendations and in any case not less than 6 times the cable diameter. Cable shall be

run in a straight line vertically and perpendicularly to building lines wherever possible.All cables, busbars shall be marked with permanent identification tags bearing the

appropriate cable number as indicated on drawings. Tags shall be located at intervals not

exceeding 20 meters, at all points where cables leave a group and in all the risers. Cablemarkers marked `L.T. cable' shall be installed at every 150' along the underground cable

route, draw pits, and at any change in direction whichever is applicable.

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2. PVC CABLES

PVC cables shall be manufactured in accordance with the requirements of B.S. 6004 and be rated at 600/1000 volts conductor shall be of stranded copper.

3. PVC/SWA/PVC CABLES

PVC armored cables (600/1000 volts) shall comprise of equal section of stranded

annealed copper lay up in sector shape, the cores being PVC insulated twisted, wormed

circular and further insulated with an overall PVC sheath, single wire armored and PVCsheathed overall.

The cables shall be rated at 600/1000 volts in accordance with B.S. 6346. Termination of

cables to panels shall be by means of compression glands, which enable effective bonding and termination of armor wires to the earth terminal.

4. M.I.C.C. CABLES

Mineral insulated copper conductors, copper sheathed cables shall be of 1000V grade and

manufactured in accordance with B.S. 6207 with terminations and glands manufactured

to B.S. 6081.

The cables shall be installed on cable trays without through-joints except where the

 particular route exceeds the maximum length of cable manufactured. In thesecircumstances joints shall be made by the cable manufacturer.

Bends shall be formed by tools designed by the cable manufacturer. Saddle spacing shall

 be not less than 60 times of the cable diameter and not greater than 750mm whichever isthe lesser.

Insulation tests shall be carried out before the cables are installed. Readings shall betaken with a 1000V bridge megger. Readings less than 100 Mega-ohms will not

acceptable.

Blow lamps may be used for drying out cut cable ends if it is impracticable to cut to

waste.

M.I.C.C. cables shall be equipped with terminations suitable for the intended duties and prevailing conditions in which they will be installed by using pot seals filled with cold

setting for multi-core cables and the heat shrink technique for single core cables, with the

tails enclosed within color coded poly-chloroprene. Seals shall have a temperature rating

of 185°C.

M.I.C.C. cables shall have tails entering equipment not exceeding 450mm in length. In

switchboards and like enclosures, where the distance between the point of entry to theequipment and to the terminals to which it is to be connected may otherwise exceed

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450mm, the cable shall enter the enclosure through a hole equipped with a gland to

maintain the security of the circuit and be terminated in pot seal at the termination

 position.

The cables shall be looped twice through 360° to form helices at positions where they

terminate at equipment which may be periodically moved and for vibrating machinery.

5. PAPER INSULATED CABLES

Paper insulated cables shall be copper conductor mas impregnated non-draining (MIND)type, lead sheathed and armored double steel tape or armored steel wire complete with

serving inhibited with anti-termite treatment and manufactured to B.S. 6480. All cores

shall be marked numerically to identification i.e., 1, 2 and 3 for phases and 0 for neutral

conductors.

Cable jointing shall be started and finished on the same day and wherever cables are to be

 jointed in the open during wet weather, suitable precautions shall be taken to preventingress of moisture into the dielectric.

Wherever a cable is cut, the open ends shall be sealed immediately, unless jointing is to

follow. A lead cap shall be wiped to the sheath forming an air tight seal.

Sealing end boxes shall be of the split type with effective sealed joint surfaces and

manufactured from high quality cast iron and of such design as to permit continuousfilling of compound in one operation. Boxes shall be completed with brass cone shaped

cable gland and protective earth conductor bond across the box from armor clamp to

switchboard or equipment frame. Joint and sealing boxes shall be thoroughly flame

warmed before pouring of compound. Checks shall be made periodically to ensure thatthe filling compound is not overheated.

Paper insulated cables should be tested for moisture before commencement of jointing.Samples of paper both from the layer nearest to and farthest from the conductor shall be

obtained.

The lead sheath shall be securely bonded to the armor at all joints and terminations.Where straight through joints occur, efficient bonding of the armor across the joint shall

 be provided.

6. DUCTS

Ducts shall be installed in places where indicated and also in all situations (including

future areas) where cables pass under roads, pathways and other hard standings, together

with all places where cables enter or leave buildings. Ducts shall be extended a minimumof 900mm on either side of such hard standing and 2m from any building. Ducts shall be

encased in concrete where indicated on the drawings.

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Where cables leave trenches or ducts to rise up the walls and where they are not

otherwise encased, they shall be protected by a suitable length of galvanized steel pipe

solidly fixed or concealed in the walls. In the event of several cables following the sameroute, a galvanized metal trunking can be used to accommodate all cables in place of

individual pipe for each cable. The piping or trunking shall be securely fixed and where

necessary be made watertight by cementing into position.

7. UNDERGROUND CABLES

General

The Electrical Contractor shall before the commencement of excavation, prepare and

agree with the Supervising Officer a record of the state of the surface with particular

reference to any features that may require special care and reinstatement.

A sufficient number of pumps in good working order shall be kept on site to ensure that

any water entering an excavation can immediately be removed.Underground cables shall be installed at a minimum depth of 750mm.

Cable stockings/pulling eyes shall be used to draw cables with due care taken to avoid

damage from applying too much stress, abrasion and bending too tightly.

Trenching 

Trenching shall be excavated in the areas where defined on the drawings using approved

machinery and methods. It shall be done such that disruption to the normal operation of

the site is minimal.

The excavation so formed shall be reasonably level from side to side. The trench bottom

shall be cleared of projections such as rock, stones, trees, etc. Any holes so formed shall

 be filled and consolidated with selected material.

 No length of trench excavation shall be started until the cables/pipes to be laid in that

length are available.

Laying/Protection 

The method of laying and protecting the cables/pipes shall be as follows: -

- Supply, lay and compact a bed of 75mm deep sandy material at the bottom of

the trench

- Lay the cable/pipe on the bed. Care shall be taken such that the cable/pipe is

supported evenly along its whole length. If there is more than one cable in the

trench, the necessary separation between cables shall be maintained. Sufficientslack shall be allowed in cables to take up settling of the ground

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- In the case of pipes: -

Side support material shall be placed and compacted in 150mm thick layers on both sides

of the pipe. Care shall be taken to preserve its alignment and grade while carying out the

compaction. With full support all round the pipe or fitting, the overlay material shall be placed and compacted in two 150mm thick layers over the pipe and across the full widthof the trench.

- In the case of cables: -

Further sandy material shall be placed and compacted to provide a total layer of sand

75mm deep over the top surface of the cable. The cables shall then be protected

throughout their length with bricks or concrete slabs butted end to end with a minimumside overhang of 150mm each side measured from the centre line of the cable (or the

centre line of the outer cables in the case of multiple cable installation).

Backfill

Trenches shall be backfilled with soil and shall be consolidated after every 150mm of

 backfill using hand held compaction equipment. Hand held compaction equipment shall be used for compaction up to 450mm above the tops of pipes/cables.

Wet clay and wet sand should not be returned to the trench but otherwise the materialshould be returned in the reverse order from excavation.

Reinstatement and Surfacing

In general, backfill and surfacing of excavated and other areas shall restore the ground

and the surface to a condition not inferior to that which existed before excavation.

8. UNDERGROUND CABLE ENTRY INTO BUILDING

Where cables enter buildings below ground level they shall pass through cast iron orequal and approved conduits that shall form runs laid to fall under the surrounding paths,

etc. The cast iron pipes shall be complete with suitable puddle flanges and after the

installation of the cables the conduits shall be plugged to ensure that a complete

watertight seal is provided around and within the conduit. This contract shall include forthe provision of the necessary detail and liaison attendance.

9. SURFACE-RUN CONDUIT WIRING

Surface-run conduit wiring with PVC cables, wherever indicated on the Drawings, shall

 be run on walls, steel structural work as the case may be.

Other details of conduits shall be as in the section titled "Conduits and Fittings".

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Where conduits are installed directly on walls and concrete works, they shall be fastened

 by means of galvanized, heavy gauge spacer-bar saddles and Rawl plugs at maximumintervals of 1.2 meters for straight runs and at all bends. Rawl plugs shall be drilled into

walls and concrete work. Spacer-bar saddles shall be fastened by means of round head,

 brass screws and washers. All conduits shall be painted orange in color, unless otherwisespecified.

10. CONCEALED CONDUIT INSTALLATION

Where conduits are to be concealed in the plasterwork of walls, the Electrical contractor

is required to cut the necessary chases in the walls for the installation of the conduits.

Initial plastering of chases shall be undertaken by the Electrical Contractor after conduits

have been erected in position, but the final plastering of chases shall be undertaken by theBuilding Contractor. Conduits buried in the slab shall have a minimum cover of 15mm

while those in the wall shall have a minimum cover of 5mm.

Conduit buried in concrete shall have the threads coated with an approved jointing

compound during assembly. Wherever the exposed galvanized surface has been cut or

otherwise damaged, a layer of rust inhibiting paint shall be painted over. Conduits shall

 be securely fixed to prevent movement and all joint boxes and ends to be effective plugged to prevent the ingress of water and dirt during pouring of concrete.

Outlet boxes, switch boxes, etc shall be installed with the face of the box flush with thefinished surface. Where necessary extension boxes shall be provided.

11. CONDUITS AND FITTINGS

Galvanized steel conduits and fittings shall be used. They shall be of Class B and

manufactured in accordance with B.S. 31.

The minimum diameter of conduits used shall be not less than 20mm. In no

circumstances, the number of cables drawn into one conduit shall not exceed the space

factors as stated in the latest Edition of the I.E.E. Regulations.

The ends of conduit shall be cut square, filed and reamed out after threading. Care

should be exercised to ensure removal of cutting oil and swarf. The finished end shall be

free from sharp corners which will damage the cable insulation when it is drawn in.Conduit terminations at switchboards, distribution boards, trunking, switch and socket

outlet boxes are to be properly secured with an adaptor and brass bush. Conduit and

terminations to apparatus subject to vibration movement shall be in flexible metallic

conduit with adaptors for connection to the rigid conduit system at each end. The flexiblemetallic conduit shall be to B.S. 731. For outdoor application, the flexible metallic

conduits provided shall be complete with extruded thermoplastic cover similar to

"Anaconda Metal Hose".

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Where long runs of conduits are unavoidable, junction boxes shall be provided at a

maximum interval of 10 meters on straight runs, and 300mm from bends for ease of

drawing in of cables. Draw wires shall be provided inside each spare conduit to facilitatedrawing in of cables. Where moisture is likely to collect, drainage outlets shall be

 provided such that it is drained off without entry into the terminations.

Inspecting-type conduit fittings such as inspection boxes, draw boxes, bends, elbows andtees shall be so installed that they can remain accessible for such purposes as the

withdrawal of existing cables or the installation of additional cables. All these

accessories shall be indecently fixed to the fabric of the building.

The inner radius for bending a conduit shall not be less than 2.5 times the outside

diameter of the conduit.

The use of the conduit system as a sole means of earthing is not permitted. A separate

 protective conductor (earth conductor) for each circuit shall be used and run inside the

conduit. The entire conduit system shall be effectively earthed.

In areas where a ceiling is provided, spare conduits shall be provided for the distribution

 box to the ceiling space. The number of conduits provided should be adequate to

accommodate the circuits which would be connected to the spare ways provided in thedistribution bends.

12. CABLE-TRAYS

Cable trays shall be fabricated from perforated mild steel with 12mm return edges at each

side, and sized in accordance with the numbers of cables they are required to support. In

this regard, cables shall be installed in a single layer formation, with the exception ofsingle core cables required to be installed in a trefoil configuration, with adequate space

allowed for air circulation.

Cables laid horizontally in the tray shall be secured with cable ties spaced at a interval of

600mm and at all bends. Cables installed in the vertical plane shall be supported by at 1

meter interval by cable cleats or cable saddles and clips for MICC cables.

Cable trays shall be manufactured from steel 1.6mm in thickness for those not exceeding

300mm in width, 2mm where wider sections up to 600mm are required, finished using a

hot dip galvanizing or approved equivalent process, and provided with factory made sets, bend and intersection pieces as required, the finishes of any cut sections being made good

with the same type of paint. Where cable trays wider than 600mm are required multiple

cable trays of maximum 600mm dimension are to be used.

Cable trays shall be supported using purpose made brackets or proprietary accessories

fixed such that there is an air space of 75mm minimum to the structure to which they are

secured, and installed in straight runs, true, horizontal or perpendicular to building line in

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a manner such as to reduce the number of bends and sets to a minimum. The spacing

 between jackets shall be 1 meter on straight runs and additional brackets at bends.

The contractor shall be responsible for checking the size and routes of all cable trays

where indicated on the drawings to determine that they are adequate for the cables to be

installed and that the routes are fully co-ordinated with all other trades. Should the sizeof any cable tray require resizing, this shall be advised to the Consulting Engineers priorto ordering and/or installation.

13. CABLE TRUNKING

Cable trunking shall be manufactured from galvanized mild steel sheets of not less than

1.2mm for trunking up to 100mm and 1.6mm minimum for larger sizes. The trunking

shall be filled with cables to not more that 45% of it usable capacity. Trunking lids shall be removable and secured at centers not exceeding 600mm by cadmium plated

mushroom head screws. The screws shall seat into bushes on the trunking return edges.

Cable trunking shall be employed to replace multiple runs of conduit in addition to the

instances where specifically indicated, and provided with removable cable retaining

straps installed at a maximum interval of 600mm along the length to permit covers being

removed and replaced without impedance from the cables enclosed.

Cables in steel trunking shall be supported by means of hardwood clamps spaced at

600mm centers. Fire barriers shall be provided where trunking pass throughcompartment slabs. The rating of the fire barriers shall be the same as that of the

compartment.

Internal fish plate couplings of 2.5mm thickness c/w tinned copper bonding links shall beinstalled between adjacent lengths to facilitate electrical conductivity and mechanical

union. Each side of the couplings shall be secured by means of 4 mushroom head screws

with the nuts installed external to the trunking. Integral partitions shall be providedthroughout the length of ducting where it is necessary to accommodate services of

different voltages and frequencies within a common trunking run. Each service shall be

mutually segregated and completely surrounded by earthed metal.

Cable trunking shall be installed complete with all requisite accessories in straight runs

true, horizontal or perpendicular to building lines to reduce the number of bends and sets

to a minimum, where necessary factory made bends, sets, end sections and intersection pieces shall be used. The spacing between support brackets shall be 1 meter on straight

runs and additional brackets at bends.

Where multiple circuits are installed in the same trunking each circuit shall be groupedtogether by cable tie at 2m intervals and distinguished by identification label at 20m

intervals.

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Cable trunkings shall be installed such that there is a minimum clearance of 10mm to the

structure to which they are secured. Trunking covers shall be installed either above or

sideways and not at the bottom.

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ACCESSORIES

1. SWITCHES

Lighting switches shall be 5A for circuits rated up to and including 5A, and 15Afor circuits rated above 5A but not exceeding 15A ratings. All switches for

internal wiring of lighting points shall be rocker operated type, grid pattern, single

 pole, one way or two ways or intermediate as required on the layout drawings.The lighting switches shall also be of the quick make and slow break, silent

switch action type with solid silver alloy contacts. Switches shall be in accordance

to B.S. 3676.

All switches at switch centers indicated in the drawings shall be arranged in an

orderly sequence to the satisfaction of the Consulting Engineers. A grid switch

system of modular design shall be used.

Switches shall be suitable for flush or surface mounting, as required, and be

complete with pressed steel box, adjustable grid plate, switch interior and cover

 plate. A minimum clearance of 9mm shall be provided between the back of theswitch and the back of the conduit box.

Pull cord operated switches shall be fixed to white moulded plastic mounting blocks which in turn shall be fixed to a circular conduit box. Pull cords shall be

white or natural colour and the lower end shall terminate in a moulding of rubber

or plastic material.

The switches of each phase shall be grouped in row(s) and adequate insulationshall be provided between the phases. A warning sign "DANGER 415 VOLTS"

shall be placed near switch centre where different phases are grouped together.

2. SWITCH SOCKET OUTLETS

Switch socket outlets shall be of the three rectangular pins (i.e. 2 poles and earth),shuttered type conforming to B.S. 1363.

The switch shall be of the quick make, slow break, type with silent, totally

enclosed, switch action.

In cases where the socket outlets cannot be flush mounted, switch socket outlets

of the metal clad type shall be used. Knock outs for conduits entry shall also be provided on the steel boxes. The cover plate shall also be of steel.

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EMERGENCY SUPPLY SYSTEM

1. GENERAL

A standby generator set complete with automatic mains failure controlpanel shall be provided to supply power to the main switch board (existing)as shown in the drawing.

2. MODE OF OPERATION

a)  Mains Failure

The operation of the Generator set Installation shall be such that under

normal condition, the essential loads shall be supplied via the mainscontractor/MCCB by the generator supply. Upon power supply failureon any one phase or any phase voltage drops below 70% of its ratedvoltage, the main contact/MCCB opens and an under voltage sensingdevice operates to signal the standby generator to start.

The mains contractor/MCCB and emergency contractor/ACB shall bemechanically and electrically interlocked to prevent parallel operation. Itshall be positively interlocked mechanically in either the normal oremergency position. The contractors shall be provided with a short timedelay device to ensure a clean break between opening of one and closingof the other.

b)  Transient Disturbance

To guard against unnecessary operation on transient disturbances, anadjustable time delay shall be provided after which the engine start/runcircuit shall be energized (0-60 seconds).

c)  Run Up Period

Provided the mains supply is still unavailable when the correct voltageand frequency is obtained, then the emergency load shall be transferredto the other generator via the changeover contractor/MCCB. The timelag between starting of emergency set and closing of emergencycontractor shall be adjustable between 3 to 60 seconds.

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Should the main supply be once again available during the engine ‘Run-up’ period, the automatic changeover switching shall abort. However,the genset shall run up, ready to assume load for the present Run-onPeriod and be available during this period for essential load supply. Onexpiry of the Run-on period the shutdown sequence shall commence.

d)  Mains Return

When the normal supply is restored i.e. all phase voltages return to 90%of its rated value, the Genset shall continue to run on load for anadjustable period (normally 0-60 sec) after which the load shallautomatically switch over to the mains supply. The Genset shall thencommence the shutdown sequence.

e)  Shutdown Sequence (Run-On Period)

The shutdown sequence shall incorporate a time-delay to allow theengine to run in loaded for a short period before stopping the engine (1-10 mins). All settings must then return to the normal position forautomatic operation.

If the main fails during the shutdown sequence when the genset isrunning unloaded, then the genset shall (after a predetermined period(0-60 sec) to guard against operation on transient disturbance of mainssupply) take on the load.

3. DIESEL ENGINE

a)  General

The engine shall be of multi-cylinder, naturally aspirated or pressurecharge, water cooled, direct injection, compression ignition type, capableof cold starting and complying with B.S. 5514 Class A1 (as minimum) forcontinuous running at a speed of 1500 RPM. The engine shall be suitablefor running on class ‘A’ fuel oil comply with B.S 2869.

b) 

Safety Controls

Safety Circuits shall be arranged: -

- For 24V dc operation;

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-  For “fail safe” operation such that a fault, high jacket watertemperature or low lubricating oil pressure, etc. results in energizingof solenoid to prevent fuel entering the engine. The solenoid shall bede-energized after the engine has stopped;

- 

Such that following a failure, the system requires to be resetmanually at the control panel.

Control settings shall be those recommended by the enginemanufacturer.

c)  Starting Controls

Each set shall be equipped with starting controls as follows;

- The engine shall start automatically on signal from the control panel;

-  An overriding manual start/stop control shall be provided andmounted on the control panel;

-  The starter motor shall be isolated on engine firing and re-engagement shall be prevented until the engine is at rest.

-  Manual cranking.

4. ALTERNATOR

The alternator shall be of the flange mounted, forced ventilated, drip proofscreen protected, two bearing type, revolving field, salient pole type withdamper windings, minimum Class E insulation, in accordance to B.S 500Part 99, of the brushless self-regulating type, with inline exciter and controlsystem capable of maintaining voltage constant within +2% at all loads andpower factors between 0.8 lagging and unity.

5. GENERATING SET

The diesel engine and alternator shall be mounted upon a fabricated steelunder-frame by means of steel spring isolators so that the entire unit can bebolted to a solid concrete floor without transmitting vibrations to adjacentapparatus or to any part of the building. All services shall be provided withflexible connections as necessary.

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A complete set of all necessary hold down bolts, washers, nuts, shims, etc.,shall be included.

A drip tray of 2mm galvanized sheet steel with minimum 12mm high sidesshall be provided where drips are likely to occur, as an integral part of the

set and shall be provided with a readily accessible drain cock.

Suitable guards shall be provided on all exposed moving parts.

A label ‘Danger – keep clean of this set. It is remotely controlled and maystart at any time’ shall be provided. 

6. PERFORMANCE

Each genset shall:-

-  have a continuous site rating of the sizes shown (KVA) at 0.8 laggingpower factor with capacity for operating at a 10% overload for anyone hour during a period of 12 hours continuous running at full load.

-  have a full load output voltage of 380/220 volts, 3 phase, 50hZ., 4

wire star connected system with neutral solidly earthed.

-  Be capable of assuming full load within not than 10 seconds of signalto start.

-  Exhibit the following characteristics at load power factor of 0.8lagging.

(a)  Steady state, load change

0 – 100% F.L.

Voltage - +2.5%

Frequency - +0.8%

(b)  Transient load change of 60%

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Voltage - the initial voltage transient shall belimited to +20% of rated voltage,recovering to at least 97% of ratedvoltage in less than 0.5 sec.

Frequency - +6% to +8% returning to steady statewithin 5 seconds.

-  generate a waveform with deviations from a sine wave not exceeding5% as defined in B.S. 5000 Part 99.

7. STARTING SYSTEM

The engine electric starting system shall be provided complete with enginemounted starter motor and contractor, 24 volts heavy duty nickel-cadmium

battery of ample rating to start up the engine after six consecutive cycles of15 seconds cranking with 6 seconds rest. The control shall be such that thefail to start alarm and indication shall be given after 3 attempts. Crankingand rest period shall however carry on for the remaining 3 cycles.

Cranking and rest period shall be manually adjustable.Each Set of batteries shall:

-  Be mounted in a suitable wooden rack located adjacent to the Genset.

- 

Comprise nickel-cadmium cells preferably in translucent containersto facilitate determination of electrolyte level;

-  Have a nominal output voltage of 24V;

-  Include a cell nut spanner and a distilled water dispenser;

8. OPERATION CONTROL SYSTEM

A panel consisting of various control and protection features, including thefollowing shall be provided for each generator set:-

a)  Automatic shut down, audible alarm and indication lights for overspeed, low oil pressure and high jacket water temperature.

b)  Earth fault shut down alarm and indication light.

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c)  Fail to start alarm and indicating light after 3 attempts. However,should the genset start in the subsequent 3 attempts, then the fail tostart alarm and indication light shall extinguish

d)  Audible alarm and indicating lights for;

i)  Low fuel level – the warning should be given in due time beforethe tank becomes empty.

ii)  Battery charge failure

iii) Low battery voltage

iv) High battery voltage

v) 

Low electrolyte level

vi) Overload.

Occurrence of one or more of the conditions mentioned above shallresult in a condition ‘GENSET ABNORMAL’. A pair of wires toindicate this condition shall be provided from the AMF Board to theFire Alarm Panel.

e)  Mains “ON’ and generator ‘ON’ indication lights shall be provided. 

f)  Auto/Manual/Test-duty selector switch.g)  Non-automatic indicator. This shall be lit when the duty selector switch

is any position except automatic. This shall be treated as a condition of‘GENSET NON-AUTOMATIC’. 

h)  Manual start push button.

i)  Alarm cancel push button.

 j)  Reset push button

k)  Emergency stop push button

l)  Test Start/Load Transfer/Break Load-test selector switch

m) Remote indication of ‘GENSET ON’, GENSET FAIL TO START’,GENSET NON AUTOMATIC’ and ‘GENSET ABNORMAL’, shall be

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provided at the Fire Alarm Panel. This shall the wiring between theA.M.F. Board and Fire Alarm Panel by the Electrical Contractor. The‘Genset ON’ shall be indicative of the genset supply power to theswitchboard.

n) 

A pair of wires to indicate Mains Failures shall be provided from theAMF Board to the Fire Alarm Panel and the Lift Control Panel in the liftmotor by the Electrical Contractor.

9. GENERATOR SET TESTING FACILITIES

When the duty selector switch and the Test Start/Load Transfer/ BreakLoad switch (test selector switch) are both in the test position the generatorset shall start irrespective of the mains supply.

The load Transfer switch shall enable the generator set to be loaded undertest conditions. When the test Selector switch is moved to the Load Transferposition a time lag adjustable between 3 to 60 sec. shall be available beforethe mains contractor opens and the generator contractor is closed. Transferof load back to the mains supply shall be achieved by the Break Loadswitch, which shall open the generator contactor and close the mainscontactor.

10. BATTERY CHARGER UNIT

The Battery Charger Unit shall be of the solid state type capacle ofmaintaining the batteries in a charged condition for optimum fullyautomatic operation. The charge unit shall incorporate a 2-stage chargeselector switch. The charger stages being a) Automatic and B) High BoostRate.

For automatic charging the charge shall have constant voltage chargingcharacteristics with a stability of +2%. Under automatic operation thecharger shall provide automatic boost and float/trickle charging tomaintain the battery bank in a fully charge state. Under the automatic modeof operation the charge shall be capable of charging the battery bank from a

fully discharge condition to a fully charged condition within a maximumperiod of 24 hours.

The charger output voltage shall be adjustable between 1.35 and 1.7 voltsper cell. The charger shall maintain any set voltage between +2% withcharge input AC voltage fluctuation of +10%, AC supply frequencyfluctuation of +5%, and output load variations between 0 and 100%.

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For manual High Boost Rate charging the charge unit shall have constantcurrent characteristics and the minimum output current shall not be lessthan C/20.

Under High Boost Rate the battery bank shall be charged at constant currentof C/10 amps.

The charger unit shall be provided with an output voltmeter, chargingammeters, D.C. fuses, off/Auto/High Boost Rate charge selector switch,switches and relays.

The voltmeter shall monitor continuously the charge voltage and shall havea scale that reads within 0.5 volt. The charge voltage of the battery shall bemarked in red on the inside of the instrument faceplate.

The ammeter shall be connected in the battery supply circuit to measure thecharge and discharge of the battery. The ammeter shall be provided with arange switch, which shall be non-locking in the low current range tofacilitate reading of the battery charging current within 20mA? If oneinstrument is unable to provide the above facilities, the more instrumentsshall be provided as required. The normal float charge and high boost ratecurrent for the battery shall be marked as specified for the voltmeter.

The charge unit shall be provided with overload and short-circuit

protection. Current limiting devices shall be provided to limit short-circuitcurrent to 120% of full load current.

11. COOLING SYSTEM

The radiator shall be cooled by a double belt driven fan. The discharge shallbe ducted away through a wall louver duct. The fan shall be capable ofdeveloping the required static pressure to achieve the necessary airflow forcooling. The generator room supply fans shall be interlocked to operatewith the generator.

12. EXHAUST SYSTEM

The exhaust piping and fittings shall be suitably sized with as short a lengthand as few bends as possible to ensure that measured exhaust back pressuredoes not exceed the maximum limitations specified by the generator setmanufacturer. The piping and fittings shall have a minimum thickness of3.2mm and shall be suitably protected from corrosion.

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The exhaust system shall incorporate a residential type silencer of the heavyduty baffle and absorption type which shall be installed inside the roomwherever possible. The whole system shall be properly supported to relievethe engine of all weight.

The silencer and all exhaust piping within the building shall be properlyinsulated with 50mm thick calcium silicate. The sheathing shall be of 24gauge (0.6mm) thickness, aluminums sheet for interior sections andstainless steel sheet for exterior sections. The insulation shall be installed sothat it does not interfere with the functioning of the flexible exhaust fitting.The exhaust system shall comply with critical level sound attenuation asspecified by relevant authorities.

Suitable condensate removable plugs or cooks shall be provided at the

lowest point in the system.

13. EARTHING

The neutral point of the generator shall be earthed and the tank piping andall other metalwork associated with the installation must be electricallycontinuous with the metalwork of the engine. A suitable connection in theform of a brass stud shall be provided in the control panel for connectingthe alternator star point to a local earth electrode network.

14. A.M.F./GENERATOR SET CUBICAL

The A.M.F./Generator Set cubical shall be of the floor standing type whichhave a construction similar to that of the main switchboard. A lockablecompartment for Tools/Spares shall be provided in the cubical.

The A.M.F./Generator Set cubical shall incorporate the following:-

a) Voltmeters and Ammeters c/w selector switches.

b)  Kilowatt hour meter

c)  Hour run meter

d)  Power factor meter

e)  Frequency meter ( Electromagnetic direct reading type)

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f)  Earth fault relay

g)  All indicator lights, alarms, control relays, selector switches, stop/startpushbuttons etc. as specified.

15. FUEL SYSTEM

A services tank of sufficient capacity for at least 24 hours continuousoperation of the generator set(s) at rated conditions shall be installed atclose proximity to the set(s). The tank shall comply with B.S. 799 Part 5.

The tank shall be constructed from minimum 1.6mm thick mild steel. Itshall be fitted with a tight fitting bolted cover, which can be easily removedfor maintenance. The tank shall be painted inside and outside with oilresistant primer and externally finished with an undercoat and topcoat of

good quality aluminium paint.

A float operated dial type fuel level indicator, associated level control andalarm switches shall also be incorporated.

The tank shall be provided with filling, supply and return fuel lines to andfrom the engine, drain and vent pipes, Isolating gate valves shall beprovided for the filling and supply pipes.

All fuel piping from fuel tank to engine shall be of copper tubing. The

connection to the engine shall be by means of flexible fuel lines.

A rotary hand pump of cast iron construction shall be provided andmounted in the wall of the gen-set room by means of suitable bracketing.Adequate length of oil resistant flexible hose for transfer of oil from thedrum to tank shall be provided. The hand pump shall be capable oftransferring oil at a rate of 20 times the maximum consumption of theengine.

A full tank of fuel shall be left at the time of handing over of the installationto the clients.

16. INDICATIONS

Indication lamps on each control panel shall comply with B.S. 1050, besuitable for 24 dc operation and have a minimum guaranteed burning life of20,000 hours at operating voltage. Lenses shall be of 25mm diameter type.

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Indication lights with colors with B.S. 4099 shall be provided. A bulb testswitch shall be incorporated.

17. TOOLS

A complete set of maintenance tools shall be provided as standard. All toolsprovided shall be listed in the “Schedule of Tools”. A toolbox shall also beincluded.

18. SPARES

The following minimum amount of spares shall be supplied:

a)  Two sets of fuel filters, air filters and seals.b)  Two sets of lubricating oil filter, elements and seals.

c) 

Two sets of injector nozzles and renewable parts.d)  Two sets of belts.e)  One no. oil pressure switch.f)  One no. water temperature thermostat.g)  One complete set of engine joints, gaskets and hosesh)  One unit automatic voltage regulator.

All spares provided shall be listed in the “Schedule of Spares”. 

19. TESTING

a) 

General

The Electrical Sub-Contractor shall provide test certificates for fuelconsumption, water temperature, exhaust temperature, lubricates oilpressure and efficiency at various loads, speed variation on load throwand any other test carried out by the manufacturer as a standard.These certificates are to be related to the particular engine supplies ortheir batch as conducted by the manufacturer.

Prior to the test, the Electrical Sub-Contractor shall submit a complete

and detailed schedule of the tests to be carried out to the ConsultingEngineers for approval and the Consulting Engineers shall make suchalterations and addition as deemed necessary.

b)  Tests At Suppliers Workshop

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The following tests shall be carried out at the generator set suppliersworkshop as a minimum requirement;

b.i Load Test

The generator set shall be load tested as follows:-

i) 25% Load for one hourii) 50% Load for one houriii)  75% Load for one houriv)  100% Load for one hourv)  110% Load for one hour

During the test period the following data shall be logged at 15minutes intervals.

- Alternator current in each phase- Alternator voltage in each phase- Frequency- Lubricating oil pressure- Jacket water temperature- Exhaust gas temperature

b.2 Fuel Consumption Test

The fuel consumption of the Generator Set at 50%, 75%, 100% and110% full load shall be tested.

b.3 Frequency Variation Test

The frequency variation, response time of the Generator Set upon‘Disconnection’ and Connection’ of 60% full load shall be tested. 

b.4 Operation Of Engine Automatic Protection Devices

The operation of the engine overspeed trip, low oil pressureshutdown and high jacket water temperature shut down devicesshall be tested.

b.5 Engine Settings

The following settings shall be carried out:-

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i) The engine speed shall be set so that the alternator outputfrequency is at 50Hz at full load.

ii)  The exciter voltage shall be set so that the alternator outputis 380 volts phase to phase at full load.

b.6 Noise levels shall be measured 15 meters from the exhaust andcooling air discharges with plant idle and running. Levels shall beneasured in eight octave bands from 63.5 to 8000Hz at a timewhen the background sound level is at least 7 db below the levelwhen the plant is running.

c)  Tests At Site

Upon completion of the Generator Set Installation the following tests

shall be carried out.c.1 Load Test

The Generator Set shall be run at various loads, up to themaximum connected load available and be allowed to run for atotal period of 12 hours. The engine performance under theseconditions shall be measured.

c.2 Automatic Operation

A mains failure situation shall be simulated and the automaticoperation of the generator set shall be tested with all load on thegenerator set switched ‘ON’. A minimum of three (3) automaticstartup and shutdown operations shall be carried out.

c.3 Starting Battery Test

The fuel valve of the engine shall be closed and the engine shallthen be subjected to six (6) consecutive cycles of 15 secondscranking and 6 seconds rest. At the end of the six (6) attemptedstarting cycles, the engine fuel valve shall be opened and theengine started.

c.4 Operation of Protective Devices and Indicators

The operation of all controls, alarms, warning signals etc. listedunder the heading ‘Operation Control System’ shall be fullytested.

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c.5 Temperature rise in accordance to B.S. 5000.

20. CONTROL SWITCHES

All control switches shall be of the quick make and quick break type usingdouble break contacts operated by a common spindle.

The control switches shall be suitable for panel mounting and suitable forthe load carrying current of the circuit which the switch is controlling.Generally switches are to be used for controlling coils of starters and relays,etc., and the minimum rating of the control switch shall be 16 amp, 220volts, 50Hz.

21. RATING PLATES

Small rating plates giving serial numbers and data in accordance with therelevant British Standards are required on equipment supplied, namely:-Circuit Breakers, Fuse Switches, Isolators, Current Transformers, etc.

22. PANEL IDENTIFICATION

Each switchgear panel shall be clearly identified and designated accordingto its function. The labels shall be engraved and arranged as shown in thedrawings submitted by the Electrical Contractor and approved by theConsulting Engineers.

23. TESTS

Type tests certificates issued by recognized testing authorities shall besubmitted for all switchgear to the Consulting Engineers.

a) Routine & Factory Tests

The Electrical Contractor shall submit certified test sheets showingdetails of all routine tests conducted during manufacture ofswitchboards and individual components thereof.

b) Delivery Test

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After the equipment has been erected on site and before finalconnection to the supply, the Electrical Contractor shall with his owninstruments and expense carry out all tests necessary to demonstratethat the equipment complies with the requirements of thisspecification and to the satisfaction of the Consulting Engineers.

The tests to be conducted shall be as follows:-

i) Demonstration that all equipment are installed and all wiringconnected, so that the switchboard functions as required.

ii) Insulation resistance between phases, between each phase andneutral, and between each phase, neutral and earth with thebreaker open and all equipment installed.

iii) Insulation resistance across breaks in all circuit breakers, with thebreaker open and all equipment installed.

iv) Setting of over current and earth fault protection relays on circuitbreaker in accordance with the requirements of the ElectricitySupply Authority.

Copies of test sheets, showing the results of test carried out inaccordance with this section of the specification shall be submitted tothe Consulting Engineers.

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EARTHING

The complete installation shall be earthed and tested in accordance with the IEE Regulations.

The earth termination network shall comprise of a system of earth electrodes of 4.8m deep x 16mdiameter copper-weld rods of 1.2m sections driven into the ground. 25mm x 3mm copper tapes

 buried at 1m below ground and protected by a layer of bricks shall be used for interconnection

 between earth electrodes. The copper tapes shall be secured to the electrodes by means of brasclamps.

The earth electrode lead shall be located not less than 500mm below the ground level and shall

 be kept free of earth.

A precast concrete earth chamber complete with cover shall be used to protect each earth

electrode, and for future inspection and testing. The connection to the earth electrode must beclearly and permanently labeled ‘MAIN EARTH –  DO NOT DISCONNECT’. Where earthinginspection chambers are located on access roads a heavy duty cover shall be provided.

Sufficient earth electrodes shall be provided to meet the general earth resistance stipulated by thelocal supply authorities. Claims for supplementary earthing will not be accepted.

All metals, sinks, tanks, exposed pipework etc., shall be supplementary bonded under thiscontract to the earth terminal of socket outlets or power circuits using green PVC insulated

cables.

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INSPECTION, TESTING AND COMMISSIONING

1. GENERAL

The Consulting Engineers shall be allowed to inspect the installation works at anytime and if required, the Electrical Contractor shall be present at such an

inspection.

The Consulting Engineers shall be given adequate notice of completion of works

to be covered. No work shall be covered without the prior approval of the

Consulting Engineers. The Consulting Engineers shall be given 7 days advanced

notice of works to be tested.

The Contractor shall supply all labor, materials, equipment, tools, and instruments

which shall be certified as to their accuracies, dates when calibrated, by whomand of types approved by the Consulting Engineers. The Contractor shall be

responsible for all electrical tests at the site and shall be represented by a capable

Charge-man or Engineer during the whole of the period required for the tests.

The Contractor shall arrange for factory tests to be performed on all items of

equipment supplied under this contract and shall advise the Consulting Engineers,

the times at which the equipment will be available for testing in order that theymay witness any tests. The expenses involved by the Consulting Engineer and

client's representatives for the witness te