SECTION 5 - GENERAL ELECTRICAL SPECIFICATION TABLE OF …fastracktenders.com/wp-content/.../2013/02/tm06-Phase...Specificati… · the Specification, shall be new and the best of

LYONSDOWN SCHOOL PHASE 1

LS19561 1

SECTION 5 - GENERAL ELECTRICAL SPECIFICATION TABLE OF CONTENTS

SECTION 5 - GENERAL ELECTRICAL SPECIFICATION TABLE OF CONTENTS ................ 1

5.00 GENERAL ELECTRICAL SPECIFICATION.............................................. 3

5.01 Scope ....................................................................................................... 3

5.02 Main Switchgear and Distribution Equipment ........................................ 3

5.03 Bus Bar Chambers .................................................................................. 7

5.04 Fuse Switchgear and Isolators ................................................................ 7

5.05 Fuses ....................................................................................................... 8

5.06 Circuit Breakers ....................................................................................... 8

5.07 Distribution Boards .................................................................................. 9

5.08 Cabling ................................................................................................... 10

5.08.01 General................................................................................................... 10

5.08.02 Cables in Conduit and Trunking ............................................................ 11

5.08.03 LSF Insulated and Sheathed Cables and Installations .......................... 11

5.08.04 Flexible Cords/Cables ............................................................................ 13

5.08.05 Mineral Insulated Cable ......................................................................... 13

5.08.06 Pirelli General FP 200 Cable/Delta Fire Tuff/Radox Cable Soft Skin Type

Cable ...................................................................................................... 14

5.08.07 Low Voltage Power Cables .................................................................... 15

5.08.08 Cable Installation Accessories............................................................... 16

5.08.09 Cable Tray and Rack System ................................................................ 17

5.08.10 Cable Trunking ....................................................................................... 18

5.08.11 Conduit................................................................................................... 19

Steel Conduit ......................................................................................... 19

PVC Conduit .......................................................................................... 23

Flexible Conduit ..................................................................................... 24

5.08.12 High Voltage Cables .............................................................................. 24

5.08.13 Cable Testing ......................................................................................... 25

5.08.14 Segregation of Wiring Systems .............................................................. 25

5.09 Lighting Installation ................................................................................ 26

5.010 Emergency Lighting .............................................................................. 31

5.011 General Power ....................................................................................... 32

5.012 Earthing and Bonding ........................................................................... 34

5.013 Fire Alarm System ................................................................................. 36

5.014 Installation of Electrical Equipment in Hazardous Areas ..................... 38

5.015 Tests on Installation ............................................................................... 39


LS19561 2

5.016 Labels .................................................................................................... 39

5.017 Circuit Schedules .................................................................................. 40

5.018 Schematic Diagram of Distribution and Electric Shock Notice ............ 41

5.019 Mounting Heights .................................................................................. 41

5.020 Selection of Runs................................................................................... 42

5.021 Rubber Mats .......................................................................................... 42

5.022 Specialist Tools ..................................................................................... 42


LS19561 3

5.00 GENERAL ELECTRICAL SPECIFICATION

5.01 Scope

This section of the Specification details the standards of workmanship relating to the

installation of equipment and the quality of the equipment supplied. Generally,

materials used in fulfilling the installation, including those not described in detail within

the Specification, shall be new and the best of their respective kinds. All equipment

and materials used shall comply with the latest issue, including amendments, of the

relevant British Standard Specification.

Every care has been taken, at the time of preparing this Specification, to ensure the

availability of materials specified. The prevailing situation regarding the availability of

the materials and equipment specified shall be ascertained at the Contract

commencement and in the event of any specified items of equipment having a

prolonged delivery period; the Consultant Building Services Engineer shall be offered

suitable and equal alternatives for his consideration.

Good workmanship is an essential part of the contract, particularly the appearance of

all surface work, which shall be neat, compact and as unobtrusive as possible. The

Consultant Building Services Engineer retains the right to reject any work which does

not conform to good current practice and the above conditions.

This section of the Specification shall be read in conjunction with the Particular

Electrical Specification, and any other documents specifically referred to therein. The

clauses of this General Electrical Specification shall be deemed to apply unless stated

otherwise within this Specification or on the drawings.

Where British Standards and Codes of Practice have been updated from the details

shown in this specification, the current standards shall apply.

5.02 Main Switchgear and Distribution Equipment

Switchboards shall comply with IEC439-1, BS 5486: Part 1 and comprise equipment

complying with the appropriate clauses of this Specification.

Cubicle type switchboards shall be of the totally enclosed, free-standing type. They

shall be arranged for front or rear access as detailed in other parts of this

Specification. The switchboard shall comprise bus bar chambers, switchgear,

distribution boards, meters instruments, indication lamps and, where appropriate,

accommodation and fixing for the supply company’s service cut-outs, test blocks,

current transformers and meters.

Unless otherwise specified the switchboard shall be constructed to BS 5486, Form 4

requirements. The busbars shall be fitted with phase colour indication at various

locations and be contained within a segregated steel compartment. All outgoing

terminations including the neutral shall be made off within the protective device.

Common neutral terminations shall not be used.

The switchboard shall be robustly constructed of pressed and folded Zintec sheet

steel panels of not less than 2.64mm (12 SWG) thickness, strengthened and braced

as necessary with rolled steel channel or angle sections to form a rigid self-supporting

unit. All joints between steel panels and between panels and rolled steel sections shall

be continuously welded or bolted.


LS19561 4

All the fuse switches, circuit breakers and distribution boards shall be adequately

supported on rolled steel angle formed channel sections, or fabricated angle or

sections, to give a rigid structure. All doors and access covers incorporated within the

switchboard shall be constructed of Zintec sheet steel, having a minimum thickness of

2mm (14 SWG). All doors or cover plates of the front of the switchboard shall be of the

dished type.

The switchboard shall be built to IEC 529, BS 5420 rating IP31 for general purpose

unless otherwise stated in this Specification. In certain instances the switchboard shall

have a dual IP rating, where particularly susceptible items of equipment are mounted

and require protection against the ingress of excessive dust and moisture. In the

event of no definitive IP rating detailed elsewhere within this Specification, the

switchboard shall be manufactured to a minimum of IP31 and all control or

instrumentation sections shall be manufactured to a minimum rating of IP54.

The switchboard shall be constructed in sections so as to facilitate easy transportation

and erection on site. Each section of the switchboard shall be provided with four lifting

eye bolts in accordance with BS 4278. The switchboard shall be provided with a

minimum of 4 No. 12mm diameter ground fixing holes for each section, positioned to

facilitate the easy use of a 60mm long fixing bolt.

Each section of the switchboard shall be bolted to its adjacent sections with sufficient

number of set screws to ensure rigid structure, particularly in the event of a fault

condition.

All set screws and other fixing devices used within the manufacture of the switchboard

steelwork shall be stainless steel, cadmium passivated, zinc passivated or chromium

plated to prevent corrosion. Set screws used within the fabrication of bus bar

chambers and other conductive parts shall be manufactured from brass or zinc

passivated steel. In certain specified areas the use of high tensile set screws shall be

permitted in the construction of the bus bar chambers, particularly where a high fault

rating is required. Particular attention shall be paid to the correct torque settings on

bus bar connections, especially where connections between individual sections are

made on site. The Consultant Building Services Engineer shall at his discretion require

witnessed tests to be carried out on the torque settings of all set screws within a

switchboard.

Unless otherwise stated, the switchboard shall be constructed to withstand a fault

condition of 50kA for 1 second.

The switchboard shall be designed for top, bottom or top and bottom cable entry, as

detailed elsewhere in within this Specification or on the drawings. The gland plates

provided shall be Zintec sheet steel, brass or SRBP as required, depending upon the

cable type to be terminated. The gland plates shall be of a minimum thickness of

3.25mm (10 SWG) and shall be suitably drilled and slotted as required. In the event of

a top entry only switchboard, non-combustible barriers shall be incorporated into the

base of the switchboard to prevent the ingress of vermin.

Care shall be taken to ensure that adequate space is available for the easy

termination of outgoing cables onto the switches. All front access only switchboards

shall have suitably sized horizontal and vertical cableways to allow for easy

connection. Front access only switchboards shall have a terminal marshalling

compartment at top or bottom, depending on the cable entry mode or in the case of

larger outgoing ways, terminals or copper tags located within a vertical cableway.

All rear access switchboards shall have cable tray incorporated within the structure of

the switchboard to enable the neat and safe support of all outgoing cables.


LS19561 5

The switchboard shall have a continuous earth conductor suitably sized in compliance

with the IEE Wiring Regulations to accommodate the fault rating of the switchboard.

Each section of the switchboard, each gland plate and all items of equipment shall be

bonded to the main earth conductor. Where the main earth conductor passes from

one section of the switchboard to another, the cross sectional area of copper

conductor shall remain constant, using either a suitably sized copper link or a suitable

number of brass bolts.

All electrical connections and wiring within the switchboard shall be carried out using

copper conductors. Cables, unless otherwise stated, shall be PVC insulated 600/1000

volt rated. The colour coding for the PVC insulation shall be in accordance with the

current regulations, i.e., red, yellow or blue for phase conductors, black for neutral,

green and yellow for earth, unless otherwise stated.

Open frame type switchboards shall be suitable for wall and/or floor mounting as

shown on the drawings or as otherwise specified. The main frame and support

members of the switchboard shall be fabricated from a minimum of 50mm x 50mm x

6mm rolled steel angle section, welded or bolted together and suitably braced with

fillet pieces to form a rigid structure.

A wall mounted switchboard shall be provided with 4 No. 75mm x 75mm x 6mm mild

steel tabs, welded to the main upright steel sections. The steel tabs shall be suitably

drilled to facilitate fixing the structure by means of 10mm bolts.

A floor and wall mounted switchboard shall be provided with 2 No. wall fixing lugs as

detailed above and 2 No. floor fixing straps welded to the base of the main upright

sections.

A free standing framework shall be provided with support stanchions, both front and

back, with a suitable channel base section welded to the bottom of the main upright

angle sections.

A consumer’s earthing terminal shall be provided on the framework adjacent to the

main incoming cable. The earth terminal shall comprise a 50mm x 10mm brass set

screw tapped into the frame and should be provided with a nut and two additional

free running brass locknuts and washers. Care should be taken to remove the paint

from beneath the head of the bolt and locknut and suitable protective measures shall

be taken to prevent subsequent corrosion of the steel framework. A suitably sized

copper earth bonding tape shall be provided throughout the length of the framework

and shall interconnect all items of equipment including fuse switches, bus bar

chambers, cable sealing chambers and the framework and shall terminate securely to

the consumer’s earthing terminal.

The switchboard shall comprise bus bar chambers, fuse switches, switch fuses,

distribution boards, meters and where appropriate accommodation and fixings for the

Supply Company’s service head cut-outs, current transformers and meters, as

required. All items of switchgear shall be securely fixed to the framework using

appropriately sized zinc passivated or cadmium passivated steel set screws, nuts and

shakeproof washers.

Steel trunking, as detailed elsewhere within this Specification, shall be incorporated on

the framework to provide a pathway for cables interconnecting items of equipment. All

trunking utilised on the switchboard shall be securely fixed to the framework by means

of round head set screws, nuts and washers. Earthing straps shall be provided on all

joints within the trunking to ensure a continuous earth path and trunking runs shall be

correctly sealed at all open ends.


LS19561 6

All interconnecting cabling between items of equipment shall be PVC insulated

600/1000 volt grade and shall be totally enclosed in steel trunking. All cables entering

or leaving items of equipment shall do so through suitably sized bushed holes or slots

and care shall be taken to prevent excessive strain damaging cable insulation. All

circuits shall be routed through trunking and under no circumstances shall the bus

bar chambers, fuse switch enclosure or other unrelated enclosures be used as a

wiring compartment for circuitry.

Prior to the assembly of the switchboard, the framework and switchgear enclosures

shall be painted to the following specification:

a) The metalwork shall be suitably descaled, degreased and finished where

necessary.

b) One coat of zinc rich etched stoving primer.

c) One coat of high build stove enamel filter primer.

d) One coat of high quality glossy finish stove enamel, the colour to be taken from

BS 4800, unless detailed elsewhere within this Specification.

Special care shall be taken on sharp edges, e.g., gland plates, to ensure that the

paint coverage is even.

All items of equipment and cover plates shall be suitably labelled, as described in

other parts of this Specification using white/black/white plastic lamination. All labels

shall be fixed to the switchboard using both adhesive and a minimum of 2 No. M3.5

chromium plated mushroom headed set screws.

Working drawings of each switchboard to a scale of not less than 1:10 shall be

submitted to the Consultant Building Services Engineer for approval four weeks

before manufacture is commenced. A schedule of label engravings shall likewise be

submitted to the Consultant Building Services Engineer for approval. The Consultant

Building Services Engineer reserves the right to inspect the switchboard at the time of

manufacture and testing, at the manufacturer’s works.

Switchboards shall be subjected to, as a minimum, the following tests and

inspections:

a) Visual inspection of all equipment.

b) Mechanical torque tests on all bus bar connections and other fixings.

c) Insulation resistance tests, phase to phase, phases to neutral, phases and

neutral to earth.

d) High voltage impulse tests, phase to phase, phases to neutral, phases and

neutral to earth, in compliance with British Standards.

e) Conductance tests.

f) Functional tests where applicable.

Care should be taken at the time of high voltage impulse testing and insulation

resistance testing to ensure that no items of equipment are damaged by the high

voltage. Any items of equipment susceptible to the high voltage shall be disconnected

prior to testing.


LS19561 7

A complete set of Test Certificates showing all readings shall be submitted to the

Consultant Building Services Engineer prior to dispatch, for record purposes. No

switchboard shall be energised prior to receipt of these Certificates.

The Consultant Building Services Engineer reserves the right to inspect the

switchboard on site prior to connection of supply. The switchboard and all

components thereof shall in any event comply with the requirements of all parts of this

Specification and the contract drawings.

All switchboards shall be complete with rubber matting to BS 921 sufficient to run the

whole length of the switchgear.

5.03 Bus Bar Chambers

All bus bars shall comply with BS 5486 and shall be constructed of heavy gauge

Zintec sheet steel of minimum thickness 2.64mm (12 SWG) with continuously welded

joints. The cover to the enclosure shall be secured by means of cadmium or zinc

passivated set screws. Where indicated on the drawings or in other parts of the

Specification, the cover to the enclosure shall be provided with a suitable gasket to

prevent the ingress of moisture or dust to the degree specified.

All bus bars shall be manufactured of hard drawn, high conductivity copper and shall

be sized to have a current density of not greater than 1.5 amperes per mm² of cross

section area. Bus bars shall be mounted within the enclosure on purpose made

insulated supports and in all instances the neutral bus bars shall be of equal cross

sectional area to that of the phase conductors. Where indicated on the drawings or

elsewhere within this Specification, the bus bars shall have removable links suitable

for the supply company’s current transformers. The cover fixings over the removable

links shall be drilled or other means provided to accept the supply company’s security

tags.

All bus bars and associated enclosures shall be constructed to withstand the fault

rating detailed elsewhere within this Specification.

Phase colour indications shall be provided at various locations throughout the bus bar

system.

5.04 Fuse Switchgear and Isolators

All switches, isolators, switch fuses, fuse switches and changeover switches, whether

mounted within switchboards or separately, shall be of the 500 volt mechanically

operated on load air break pattern shall be metal clad and shall conform with the

requirements of BS 5419 and BS 5420.

The mechanisms of all switches, isolators, fuse switches and switched fuses shall be

designed so that it will be impossible to gain access to the contacts, terminals or any

live part unless the equipment is first isolated. The operation shall be so interlocked

that it is impossible to close the switch when live contacts and/or connections are

exposed.

All electrical switchgear and equipment shall be installed strictly in accordance with

the manufacturer’s recommendation as to operating clearances and fixing methods.

No site alterations or modifications of switchgear and/or distribution equipment are to

be made without the written permission of the Consultant Building Services Engineer.


LS19561 8

The covers of each unit shall have solid hinges and shall be provided with a locking

device.

On/off indicators shall be fitted to all units which shall be lockable in the off position.

Fused switchgear shall have each pole fused and switched.

5.05 Fuses

Fuses for use with distribution equipment shall, unless otherwise specified, be of the

high rupturing capacity cartridge type and shall fully comply with the requirements of

BS 88. The marking on the cartridge showing its fuse rating shall, wherever possible,

be clearly visible when the cartridge is installed within its carrier under normal

operating conditions. Where switch and/or fusegear is de-rated in accordance with

the design, the ratings of all fuses shall be suitably displayed on the equipment

description label.

Spare fuses shall be provided as follows:

a) Up to 60A 10% of number installed of each type and rating. Minimum

of 3 each.

b) 60A and above Three fuses of each type and rating.

Fuse links for use in plug tops and spur units shall comply with BS 1362 and shall be

of the correct rating for the equipment connected or 13A where this is not known.

Fuse links for use in wiring accessories and equipment up to 5A rating shall comply

with BS 646 and shall be of the correct rating for the equipment connected.

5.06 Circuit Breakers

Circuit breakers shall fully comply with BS 4752: Part 1 or for miniature circuit breakers

BS 3871: Part 1.

Three pole type circuit breakers shall be so designed that the operation of the

protective device in any one phase shall cause the opening of all three phases.

The operating handle shall be trip free with a positive movement in both make and

break positions. Clear indication of the position of the handle shall be incorporated.

Each breaker shall be of the rating specified and have means to padlock in the off

position.

All air circuit breakers (ACB) shall be enclosed in a rigid sheet steel enclosure

comprising separate compartments for the bus bar, current transformers, breaker

mechanism and cable boxes.

Each ACB shall be complete with all ancillary protection circuits internal wiring, fuses,

links, auxiliary contacts, earthing connections and sundries to form a complete unit.

The breaker chamber shall be ventilated to allow gases to escape and to prevent

condensation.


LS19561 9

Efficient arc shutes and arc suppression equipment shall be incorporated. Contacts

shall be capable of carrying full load for an indefinite period and shall be readily

renewable.

Mechanical indication shall be provided to show the ACB is in the ‘on’, ‘off’ or

‘isolated’ position.

Each ACB shall be provided with a 3-phase isolating device suitably interlocked to

prevent isolation except when the circuit breaker is open. It shall not be possible to

withdraw the breaker or remove the front cover until the breaker is in the isolated

position.

When isolated, the bus bar and CT chamber orifices shall be guarded by automatic

covers.

Unless otherwise specified, each ACB shall be closed by mean of a trip-free handle

and the ACB shall be opened by means of a separate hand operated trip device. The

operating mechanism shall be accessible for inspection without withdrawing the

breaker.

All moulded case circuit breakers (MCCB) shall be enclosed in moulded plastic, with

tripping mechanism and arc chambers separated and sealed from the cable

terminations. Provision shall be made for accommodating auxiliary switches, shunt

trip and under voltage release equipment.

Where individually mounted, MCCBs shall be enclosed in heavy gauge steel surface

boxes or flush mounting cases with removable undrilled gland plates.

Where miniature circuit breakers (MCB) provide final circuit protection they shall be

grouped in metal enclosed distribution boards.

Each miniature circuit breaker shall carry its full rated current continuously, without

tripping, in the enclosure specified. The calibration of the magnetic hydraulic trip

mechanism shall not be affected by ambient temperature variations.

Residual current circuit breakers (RCD) shall comply with BS 4293 and shall be of the

rating specified.

Unless specified otherwise, RCDs shall have a sensitivity of 30mA with a tripping time

not exceeding 30ms. Features shall be incorporated to ensure that pulsating DC fault

currents and harmonics do not affect the operation of the unit.

5.07 Distribution Boards

Distribution boards shall comply with BS 5486 : Part 1 and with Part 11, 12 or 13 as

appropriate. Distribution boards shall be 500V grade, metal clad pattern, galvanised

sheet steel welded construction and shall be complete with lockable panel door,

phase barriers, masking plates, earth terminal bar, either MCBs or fuses as specified

and circuit charts.

External protection shall in excess of IP3X.

Each distribution board shall be complete with an incoming isolator unless otherwise

stated in this Specification or on the drawings.

All distribution boards shall be adequately marked using white plastic labels engraved

in black lettering to a minimum height of 6mm, stating its full description and/or areas


LS19561 10

served, the maximum voltage present and the fault level as so designed in

accordance with BS 5486.

Where neutral bus bars are installed, these shall be rated at the maximum current of

any phase conductor and where required these shall be suitably protected from other

live parts of the equipment. Reduced neutral bus bars shall not be installed. All neutral

connections shall be so designed as to incorporate full size neutral conductors using

mechanical clamp connections with suitably means of anchoring all cables for each

final sub-circuit installed. Bunching of neutral conductors except for ring main circuits

will not be permitted under any circumstances.

All distribution boards shall be fitted with earthing terminals, which shall consist of a

main copper bar allowing adequate termination facilities for the main earth continuity

conductor. Where cross bonding of earth connections is required within distribution

fuseboards, these shall be accessible and clearly visible from internal inspection.

Provision is to be made on the main earthing bus bar for adequate termination of all

circuit cables, allowing one mechanical clamp connection per circuit and with the

exception of ring main circuits, bunching of earthing cables will not be permitted.

All distribution boards shall have copper bus bars adequate for the full rating of the

distribution unit and shall not be less than the rating of any phase supply conductor.

Circuit schedules shall indicate phasing, connected load, circuit breaker or fuse rating

and final circuit cable size. Single phase boards shall include phase colour

identification discs.

5.08 Cabling

5.08.01 General

All cables shall comply with the appropriate British Standard and shall be BASEC

approved.

Cables shall be of the size and type as indicated on the drawings and in the

Specification. Generally all cables shall be low smoke and fume (LSF) or low smoke

zero halogen (LSZH or LS0H), unless specifically altered within the particular

specification.

Conductors shall comply with BS 6360 and shall be of plain annealed copper having

a conductivity of 100% International Standard. Aluminium conductors shall not be

used unless specified otherwise. Conductor size shall be a minimum of 1.5mm²

unless specified otherwise. Neutral conductors and, where separate, earth

conductors in multicore cables shall have the same cross sectional area as the phase

conductor(s).

Paper insulated cables shall not be used.

All necessary cable supports, clamps, cleats, suspension brackets, glands, shrouds,

sealing chambers and other accessories shall be included as required for the

complete installation.

The routing and arrangement of all cables, cable supports, trunking and conduit shall

be agreed with the Consultant Building Services Engineer prior to the installation

commencing.


LS19561 11

5.08.02 Cables in Conduit and Trunking

Generally, cables shall be single core. LSF insulated, copper conductors 450/750

Volt grade, in accordance with BS5467, BS6387, BS6724and BS7211. Colours shall

be as given in the 18th Edition of the IEE Wiring Regulations.

Where LSF cables are specified in plantrooms, they shall be of the high temperature

specification, tri-rated, for operating at temperatures up to 600C. Where higher heat

resisting grades of insulation are specified, silicone rubber insulated cables to BS

6007 shall be employed where the temperature will not exceed 150C. Such cables

shall be identified throughout their length. For higher temperatures, cables shall have

varnished glass-fibre insulation.

Cables smaller than 1.5mm2 shall not be used, and all cables shall be multi-strand

type.

During installation, the cables shall be combed to facilitate drawing in and future

replacement.

Inside trunking, cables forming final sub-circuits shall be tied together at 2m intervals,

to ease identification. The use of PVC self-adhesive insulating tape will not be

permitted for this purpose.

Cables shall be installed without joints.

Live conductors of lighting circuits shall be taken direct to switches, whilst associated

neutral conductors shall be looped at lighting points, unless 4 terminal ceiling roses

are specified in the detailed Technical Clauses of this Specification.

LSF cables shall not be installed when the temperature is below 2ºC, and if the cables

have been exposed to such temperature, a warming time shall be allowed before the

cables are used, such that the temperature is 2ºC and rising.

Where cables are permitted to traverse channel ways or similar on continuously

mounted fluorescent luminaires. heat resistant cables shall be used throughout.

In addition to phase identification, the cores of cables connecting control gear,

thermostats, valves etc. shall be fitted with identification sleeves bearing the same

markings as the terminals of the apparatus to which they are connected.

5.08.03 LSF Insulated and Sheathed Cables and Installations

Cables shall be LSF insulated and sheathed, complying to BS5467 and BS7211, up to

and including 35mm2

.

No conductors less than 1.5mm' will be permitted. Cables shall have copper

conductors, twin core and combined circuit protective conductor (CPC) with white

LSF sheath. Conductors shall be multi-stranded for cable of 4mm size and above.

Care shall be exercised in selecting cable sizes to ensure that the cross sectional area

of the combined circuit protective conductor complies with the 18th Edition of the IEE

Wiring Regulations (see Section 17 "EARTHING").

Accessory boxes shall be provided for all accessories where used in concealed

installations, boxes shall be rustproof metallic boxes, with bushed cabled entry and

adjustable alignment lugs. Rubber grommets shall be acceptable.


LS19561 12

Where used in surface installations, boxes shall be of white coloured plastic to match

the accessory.

All boxes shall have fitted earth terminals, and shall be 25mm deep for lighting

accessories, and 35mm deep for socket outlets and fuse connectors. Boxes shall

comply generally with BS4662.

The installations shall be surface or concealed, as specified in the following section

and shall comply in all respects to the 18th Edition of the IEE Wiring Regulations.

All cables shall be adequately fixed as required, using PVC single pin or saddle clips.

The fixing of boxes shall be by steel screws, using proprietary fixing method.

All cable sheaths shall enter fully into the box via a rubber insert bush and web the

protective conductor shall have green/yellow sleeving where connecting to the

earthing terminal.

In Class 4 areas, packed glands with neoprene washers shall be used in lieu of the

rubber insert bushes.

Lighting circuits shall be wired on the three plate rose system and socket outlets/fuse

connectors on ring main systems, unless otherwise specified in the following section.

Where bolted connections are required, connection lugs shall be fitted by

compression using an automatic tool, which cannot be released until the correct

pressure and crimp depth is obtained.

LSF cables shall not be allowed to come into contact with any form of polystyrene.

Cables shall be installed as inconspicuously as possible, taking advantage of the

features of the building by fixing in corners, behind or along skirting boards,

mouldings etc. and behind fitments etc.

Where rising from the floor, the cables shall be protected by metal conduit or channel

to 300mm height, or in the case of areas where heavy equipment traffic is envisaged,

the protection height shall be increased by 2m.

Where wiring terminates at a luminaire other than a ceiling rose for a plain pendant,

the cores shall be sleeved with heat resistant sleeving, from the point of entry into the

luminaires and up to the terminals.

When under timber or chipboard floors, the joists shall not be notched, but drilled at

right-angles 50mm below the floor level to allow the passage of cables. Hole sizes

shall be kept to a minimum, but of sufficient size to avoid cold running. Where 50mm

depth cannot be achieved, then a short piece of conduit, 150mm long, shall be

employed, and slotted into the battens or bearers. Alternatively, the point at which the

holes are made shall be protected by the installation of a metallic BESA type box lid.

For cables in battened ceilings, the requirements for protection in 9.19 shall apply.

except where double battened ceiling bearers are used.

In hollow partitions, patent fixings will be permitted In metallic partitions, cables shall

be protected using LSF conduit.

All lighting points shall terminate in a plastic LSF ceiling rose box, mounted flush to

ceiling. The box shall be heavy gauge self-extinguishing LSF to BS4607. reinforced

with tapped metal inserts. A fixed terminal block shall be provided, and heat resisting

cables or sleeves used to connect the luminaires.

Direct wiring to ceiling rose will be permitted where pendants are specified. The box

shall be securely fixed to a joist or to timber noggins using 2 No. fixings.


LS19561 13

Cables in roof spaces shall be clipped to the sides of joists and, where traversing

joists the binder joists or suitable battens provided and fixed by the Installer shall be

used.

All cables shall be neatly installed, dressed to give a neat and workmanlike

installation.

5.08.04 Flexible Cords/Cables

Cords shall be to BS5467, BS6141, BS6360, BS7211 and BS7629, 300/300 Volt or

300/500 Volt insulated, and of conductor cross-section 0.5mm2 greater.

For connections to terminals of lampholders and heaters, cores shall be glass-fibre

insulated glass braid/varnish, sheathed for a service temperature of 1500C to BS6141

and BS6500

For applications where the temperature does not exceed 60ºC. Cords shall have LSF

insulation and sheath.

Final connections to water heaters and immersion heaters shall be effected with a

multi-core cable, with tinned copper multi-strand conductors, with rubber insulation

and sheathing to BS6007 and BS6883, with TQ reference.

5.08.05 Mineral Insulated Cable

Mineral insulated cables shall be 600 Volt grade to BS5372, BS6207, Part 1, 1991 and

BS6387, light or heavy duty metric grade, as appropriate for the circuit conditions.

Fixing centres for mineral insulated cable shall be 300mm horizontal and 450mm

vertical.

Terminations employing cold plastic compound seals shall be use unless otherwise

specified. Insulating sleeves shall be colour coded, in accordance with the IEE

Regulations.

When LSF covered cable is specified, LSF gland shrouds shall be fitted. All shrouds

and clips shall be of the same colour as the specified cable sheath. Generally, orange

LSF shall be used, except for fire alarms, where red LSF sheath shall be employed.

Other colours may be used as indicated later in this Specification.

No cable joints will be allowed.

Where cables pass through walls, floor, ceilings etc. they shall be protected by fibre or

LSF sleeves which shall be fire stopped after installation using proprietary foam.

When such cables are used to connect motors or equipment where vibration is likely

to occur, they shall be looped one complete turn.

Earthing pots shall be used for terminating all low voltage cables connected to the

mains supply.

Where cables are installed singularly in roof voids, ‘Hiat’ type clips may be used for

fixing to timber. In all other cases, LSF covered copper clips are to be employed. In

cases where two cables are to be clipped together, two hole fixing clips are to be

used.


LS19561 14

Multiple runs of Ml cables to be cleated to cable trays as previously mentioned. Fixing

to such trays shall be by means of LSF covered metal strip (colour to match sheath)

bolted to the tray with brass pins and nuts. Tie wraps shall not be used for this

purpose.

Where specified, the PVC sheath and associated components are to be of the LSF

(low smoke and fume) type, complying with the current British Standards.

MICC cable shall be protected to a height of 300mm by conduit or trunking when

rising on the surface from the floor. Wherever there is a possibility of heavy

equipment traffic, this protected height shall be increased to 2m.

Where MICC cables are to be concealed in walls, these shall be full protected by

means of galvanised metal capping., i.e.: ends connected to motors with star

connection, up to and including 2kW size and discharge lighting.

Surge suppressers shall be fitted to all cable ends connected to motors, with star

connection, up to and including 2kW size and discharge lighting.

5.08.06 Pirelli General FP 200 Cable/Delta Fire Tuff/Radox Cable Soft Skin Type Cable

Where specified fire resistant cables to IEC331 shall be employed, and shall meet the

requirements of BS6207 CWZ Condition, and BS6837.

They shall be installed in accordance with the manufacturer’s recommendations.

During installation the cables shall be drawn from the cable drums to prevent 'kinking'

and shall be dressed by hand only.

The radius of any bend measured to the inside of the cable shall not be less than six

times the overall diameter of the cable.

Cables shall be fixed using suitable single hole or universal fixing band finished in LSF

to match cable. Fixing centres shall be in accordance with the IEE Wiring Regulations

and manufacturer's recommendations where no regulation applies.

The cables shall be terminated in a suitable range of integrally glanded and shrouded

boxes for use with these cables, complete with seal, shroud and compression ring,

unless otherwise specified in the detailed sections of this Specification.

Insulating sleeves shall be colour coded in accordance with the IEE Wiring

Regulations.

No cable joints will be allowed

Where cables pass through walls, floors, ceilings etc. they shall be protected by fibre

or LSF sleeves, which shall be fire stopped after installation using proprietary foam.

Additional mechanical protection shall be provided for these cables where they are

run on the surface of a wall within 1 metre of the floor by means of a conduit or

capping as specified.

These cables shall not be used on circuits operating in excess of extra low voltage,

and shall only be employed where detailed in the Particular Clauses.


LS19561 15

5.08.07 Low Voltage Power Cables

Low voltage power cable shall generally be wire armoured to BS6346, 1989, BS5467,

BS6724 or BS6360, with XLPE compound insulation and/ or LSF bedding, as detailed

further in this Specification.

Cables shall be fixed to tray or direct to a surface using cable cleats. The intervals for

fixing shall be as stated in the IEE Regulations, or as stated by the cable manufacturer

where no regulation applies Where fixed to cable trays, power cables having an

overall diameter of 10mm or less may be strapped to the tray using PVC covered

metal strip of appropriate colour, fixed using brass pins and nuts. Cable routes shall

be so arranged that cables, hangers, cleats etc. do not come into contact with or in

close proximity to piped services.

At all terminations, the sheath and armour shall be secured by brass compression

glands, of a type suitable for both cable and location. The glands shall be complete

with both earthing tag and plastic shroud. Connections to the earthing tag shall be by

brass nuts and bolts. At the point of termination for SWA cables feeding any

equipotential zone, the cable shall terminate in a BICC type BW gland, with integral

earth and 481AA insulated adaptor.

Any underground jointing of LSF SWA cables required shall be achieved using

proprietary resin joint kits manufactured by Messrs. BICC Limited or AEI Limited.

Copper bonds shall be provided within the joint to maintain full earth continuity. The

resistance shall be no greater than that of the live conductors and the insulation

resistance between cores and between cores and earth shall be no less than that of

the original cable.

Cores shall be phased out. Either coloured core insulation or coloured sleeve

markers shall identify the phases. All cable colours will harmonise with BS7671.

Cables buried in the ground shall be in a trench with 100mm of sand laid in the

bottom, the cable laid on the sand then covered with 100mm of sand. Interlocked

arched based cable protection covers stamped 'Electric Cables' or high impact UPVC

polyethylene carpeting shall be placed over the full length of the route, then back-filled

with sifted earth, free from rocks and stones, well rammed and 200mm below finished

ground level, 100mm wide PVC tape with the letters ‘Electric Cables' stamped or

printed overall shall be laid the full length of the route, and the ground then reinstated

to existing ground level. Please refer to drawings for depth of trench.

NOTE: Where groups of cables are installed in a common trench, cable protection

covers are to be of sufficient width to cover all cables. This may be achieved by using

two or three rows of narrow tiles, if required.

Cables which follow the same route, and are laid in the ground, shall be horizontal

formation with spacing between cables, where possible of not less than 150mm. with

the exception of single core cables which shall be laid in trefoil formation and touching

along their entire length. Each group of cables shall be indicated by separate marker

tapes.

Earthenware type cable conduits or ribbed PVC ducting shall be installed under

roadways, crossing roadways and for building access, or wherever specified in the

following section. The provisions shall be as specified above, and the depths shall be

to the top of the conduit.

Earthenware type cable conduits ducts shall be smooth bore vitrified clay or heavy

duty plastic socket and spigot type. All ends of conduit shall be sealed around the


LS19561 16

cable with a waterproof and gas-proof seal of the self-extinguishing plastic foam type

approved by the Electricity Council.

Any spare earthenware type cable conduit shall have suitable end caps and shall be

complete with draw ropes.

Cable markers, concrete block type, with inset label stating size and type of cable(s)

and function(s) shall be placed in the route at a maximum of 50m apart, and at each

change of direction, with a minimum of two markers per route, and at entry to a

building a pillar type marker giving the same information. The markers shall be block

and pillar type 'Electric Cable' markers with 'Traffolyte'.

The Electrical Contractor shall provide all covers, markers, tapes etc. The laying of

sand, covers, tapes, concrete and markers shall be by the Main Contractor, but the

Electrical Contractor shall ensure and be responsible for the compliance with

requirements. Where a direct contract exists, the Electrical Contractor shall be

responsible for all provision and installation.

Prior to the cable(s) being laid, the Engineer shall be informed and arrangements

made for an inspection to be made at each stage.

Where cables are to be buried in water logged ground, or have to cross streams, then

cables with a polyethylene sheath shall be employed. The extent of any such cabling

is detailed elsewhere in this Specification, or on the associated drawings.

Where multi-core cables are employed, each core shall be numbered and numbered

markers at each end shall identify the terminal number of the equipment to which the

core is to be connected.

Below the armour clamp of all terminations, a noncorrosive identification band shall

be fitted giving details of the type and size of cable in 5mm stamped letters and

figures.

Where power cables pass through walls or floors, they shall pass through properly

formed openings, which shall be fire stopped after installation using proprietary foam.

Where power cables are laid in a common trench with other services, particularly

communication cables, there shall be a minimum separation of at least 300mm

between these services.

5.08.08 Cable Installation Accessories

Cable cleats shall be manufactured from die cast aluminium alloy to BS 1490 or

reinforced glass filled nylon. Die cast aluminium alloy cleats shall consist of two

identical half racks fixed by two bolts and shall be used on all cables of 50mm overall

diameter and above. Reinforced glass filled nylon cleats shall be of the hook type,

with locating pins to prevent rotation of the claws, fixed by means of a single bolt and

shall be used on cables up to 50mm overall diameter.

Cleats shall be fixed on metal back straps using galvanised bolts or stud where

installed in tiers. Where cleats are mounted in tiers, a manufacturers packing piece

shall be provided between cleats. The correct size of cleat shall be used to avoid

deformation of the cable sheath. The studs shall extend beyond the tightened nut by

about 13mm.


LS19561 17

Plastic cable clips shall be used for the surface fixing of PVC/PVC cables, shall be

manufactured from white polypropylene and shall be complete with a hardened steel

fixing nail.

Cable ties shall be of the self-locking releasable type and shall be manufactured from

nylon. Cable ties may be used for securing cables to cable trays where the ambient

temperature is between -15°C and 60°C and when the cables are located above and

supported by the cable tray. Cable ties shall not be used to support cable. Surplus

ends of the ties shall be cropped.

Grommets and grommet strip shall be manufactured from PVC and shall comply with

BS 1767.

Cable tape shall be of yellow rot resistant polythene with black wording ‘CAUTION

ELECTRIC CABLES BELOW’.

5.08.09 Cable Tray and Rack System

Cable tray and rack system shall be installed generally as indicated on the drawings.

Cable trays shall be perforated sheet steel to BS1449, hot dip galvanised to BSEN

ISO1461, BSEN10142, BSEN10143, BSEN10147 and formed with returned flange.

Thickness of tray shall not be less than:

(i) 0.9mm for up to 100mm width.

(ii) 1.6mm from 101 mm up to 300mm width.

(iii) 2.0mm from 301 mm to 600mm width.

(iv) 2.5mm for all exterior applications.

Cable tray shall generally be hot dipped galvanised or PVC coated where indicated.

Full use shall be made of standard auxiliary components of bends, junctions,

reducers and sets purpose made by the manufacturer and of a similar construction

and finish to the cable tray. Where this is not possible these units may be made up on

site only with prior agreement of the Consultant Building Services Engineer. All flat

bends shall have 45° gussets.

Cable trays shall only be cut along a line of plain metal and not through perforations.

All sharp edges and burrs shall be removed and any exposed steel shall be treated

with zinc rich paint.

The routing and method of installation of cable trays and rack shall be agreed with the

Consultant Building Services Engineer prior to the installation commencing. The trays

and rack shall be arranged in a neat manner and generally installed parallel to the

building structure with the width in the horizontal position and the flanges on the upper

side.

Cable trays and racks shall be supported by mild steel galvanised brackets or

channels at regular intervals of about 1.5m for tray and 3m for rack and at not more

than 300mm from a bend or junction.

The trays and rack shall be coupled by means of rigid edge bars, fish plates or

channel couplers securely fixed to each section by at least two fixings comprising

mushroom headed steel bolts, locking washers and nuts. Fixings shall be installed

with the head on the inside of the tray or rack clear of any cables. Effective earth

continuity between sections shall be ensured using separate copper bonding strips

bolted across each coupling point. The contact surfaces shall be thoroughly cleaned

prior to bonding. The tray and rack systems shall be mechanically and electrically


LS19561 18

continuous throughout but shall not be used on the earth return path for any electrical

system.

Cable tray and rack shall be installed to provide a minimum clearance between the

structure and the underside of the tray or rack of 25mm for tray or rack up to 300mm

width, and 40mm for larger sizes and to provide at least 150mm between the upper

side of the tray or rack and the structure or other services.

Cables shall be secured to the cable trays and rack using cable cleats, cable ties or

PVC covered copper saddles or metal strip of the two screw fixing type.

Where the size is not indicated, the tray or rack shall be sized to suit the installation

and allow approximately 25% spare capacity for future use.

Cable rack shall be manufactured from mild steel of a minimum thickness to

BS 1449 and shall comprise two side channels with cross channels or rungs at

300mm intervals.

The rungs shall have performed holes suitable in shape and size for the type of cable

fixings to be used. Site drilling of rungs or side channels will not be permitted.

All bends, junctions, reducers and sets shall be of the same finish and manufacture

as the rack and bends shall be radiused to suit the bend radius of the largest cables

to be installed. Site formed bends, etc., will not be permitted.

5.08.10 Cable Trunking

Cable trunking shall be manufactured from steel except where specified otherwise.

Where the trunking sizes are not specified they shall be determined in accordance

with the IEE Wiring Regulations with spare capacity of 20%. Steel trunking shall be

manufactured from zinc coated sheet steel and shall comply with BS 4678 and BS

2989. The steel thickness shall be at least 1.2mm for trunking sizes up to and

including 150mm x 150mm and at least 1.6mm for larger sizes except for underfloor

trunking which shall be of 1.6mm thickness for all sizes. The trunking shall have a

removable cover throughout its length fixed by screws at no more than 900mm

centres.

PVC trunking shall be manufactured from high impact PVC and shall comply with BS

4678 : Part 4. Trunking lids shall be of the internal ‘snap-on’ type.

As far as possible, all bends, junctions, reducers and other accessories shall be

made by the manufacturer and of similar construction and finish to the main trunking.

Wherever possible all bends, junctions and reducers shall be provided with gussets.

Trunking runs shall be arranged so that the lid or cover plate is on the top or side.

Where trunking lids are installed on the side or, where agreed with the Consultant

Building Services Engineer, on the underside of the trunking, cable retaining straps

shall be provided at not more than 900mm intervals to ensure that cables are not

damaged when the lid is secured.

Trunking shall be fixed to the structure or supported from substantial brackets at

intervals not exceeding those detailed in the IEE Wiring Regulations. Suspensions or

fixings shall, as far as possible, not intrude into the internal space. Where cutting or

slotting of trunking is carried out, all sharp edges and burrs shall be removed and

bare steel shall be treated with zinc rich paint. Where conductors pass through slots

or holes in steel trunking, the perimeter of the slot shall be shrouded within continuous

PVC sleeving, grommet or other means to prevent mechanical damage to cables.


LS19561 19

In vertical runs, cable support pins shall be installed at intervals not exceeding 5

metres and all cables shall be bound to the pins.

Where trunking passes through walls, floor, ceilings or partitions, the trunking lids

shall terminate 50mm either side of the division. Between the removable sections of

lid, a fixed section of lid shall be installed through the division.

Where trunking passes through a fire division, an internal fire barrier shall be provided

within the trunking.

Trunking shall terminate with end flanges bolted direct to the equipment. Where the

trunking does not terminate into equipment, the open end shall be blanked off using

end cap securely fixed in position.

Where conduits connect to multi compartment trunking and the appropriate

compartment is not accessible from the side, they shall be provided with skeleton

type ‘stop-end’ boxes securely fixed onto a short length of fixed lid, positioned so that

direct wiring is possible.

Lengths of steel trunking shall be connected by internally fixed rectangular coupling

units of sufficient length and rigidity to prevent any sagging. The lengths of lids shall

be arranged such that the joints coincide with the centre of the coupling units. At each

joint in the trunking a copper bonding strip shall be connected across the joint to

maintain earth continuity. The contact surfaces on the trunking shall be thoroughly

cleaned and the bonding strips fixed by M4 round head screws, nuts and locking

washers.

The trunking shall be thoroughly cleaned to remove all steel, brass and other particles

prior to the installation of any cables.

PVC trunking shall be installed in accordance with the manufacturer’s instructions and

recommendations. Earth continuity conductors shall be provided for all PVC trunking

runs. Joints in the trunking lid shall be arranged not to coincide with joints in the

trunking. Trunking shall employ purpose made accessories as a standard

requirement. In exceptional circumstances Trunking may be cut to length and mitred

using a fire tooth tenon saw and a mitre block.

5.08.11 Conduit

Steel Conduit

Except where otherwise specified the whole of the installation shall be carried out

using steel conduit. No conduit less than 20mm diameter will be permitted.

Where not specified conduit sizes shall be determined in accordance with IEE Wiring

Regulations with approximately 20% spare capacity.

Steel conduits shall be of the heavy gauge welded type and shall be fully in

accordance with BS 4568 and BS 6053. Conduits shall be finished in stove enamelled

black to provide a minimum of class 2 protection or hot dip zinc coated to provide a

minimum of class 4 protection. Class 4 conduit shall be used for installations within

the following areas:

a) Mechanical plant rooms.

b) Water storage and pump rooms.

c) Lift machine rooms and shafts.

d) Switchrooms and transformer chambers.


LS19561 20

e) External areas.

f) Areas exposed to dampness.

Conduit accessories, including saddle fixings, shall be finished to the same degree of

protection as the particular conduit being used.

Conduit boxes shall be of the standard circular type manufactured from malleable

cast iron with steel cover lids secured by means of brass roundhead screws. Conduit

boxes shall be provided with tapped spouted entries and shall be complete with a

brass earthing terminal.

Where more than three conduits are required to terminate in one box this shall be

facilitated using an adaptable box.

Adaptable boxes shall be manufactured from sheet steel and shall be of minimum

size 100mm x 100mm x 50mm. Boxes shall be provided with steel overlapping covers

secured by means of brass roundhead screws.

Where boxes are mounted externally or in damp areas they shall be of a weatherproof

pattern and be provided with a rubber gasket.

Surface mounted conduit shall be fixed by steel spacer bar saddles installed at

centres not exceeding 1.2m and within 300mm of a bend, box or other equipment.

Flush mounted conduit shall be installed in chases of adequate depth to provide a

minimum of 12mm cover to the finished surface using pipe hooks or crampets.

Where multiple parallel conduit runs would otherwise occur, use may be made of

cable trunking subject to the provisions of this Specification.

All conduits shall be installed generally to be parallel to the structure. Where bends or

sets occur in multiple runs they shall be arranged symmetrically to present a uniform

and neat arrangement.

All bends and sets in conduit shall be made on site using a proprietary bending

machine to suit the conditions ensuring that all bends and sets are neatly made

without change of section or restriction of bore. Badly marked conduit or poorly made

sets or bends will not be accepted.

The bending radius of all conduits shall be determined in accordance with the IEE

Wiring Regulations. Solid or inspection pattern bends, tees and elbows shall not be

used.

Long straight runs of conduit shall have draw boxes installed at intervals of not more

than eight metres and not more than two right angle bends, as defined in the IEE

Wiring Regulations, shall be permitted between any two access or outlet boxes.

In flush installations, conduit shall be arranged such that separate draw in points are

not necessary. Cables shall be drawn in from lighting points, switches or other outlets.

Any draw in boxes or other boxes in conduit runs shall be made permanently

accessible.

Where the finish of the conduit is damaged or suffering from the effect of corrosion,

the surface shall be wire brushed and painted with rust inhibiting paint to the same

standard as the normal surface. Exposed threads shall be similarly treated to prevent

corrosion.


LS19561 21

Where conduit risers are installed, a substantial right angle shall be interposed at

every ten metres to ensure adequate support of the installed cabling.

Where conduits turn through walls, back outlet boxes shall be provided. Conduit sets

through a wall will not be permitted.

Conduit boxes and adaptable boxes shall be fixed to the structure independent of the

conduit using countersunk wood screws of appropriate size.

Steel conduits shall be cut square to the required lengths and threaded by means of

good quality dies. The conduit shall be well reamed, free from burrs and other defects

and cleaned out. Adequate precautions shall be taken to prevent the ingress of silt or

moisture into the conduit system. If this should occur the affected conduits shall be

swabbed clean before cables are installed.

Cables shall not be drawn into conduit until the conduit system is complete, accepted

by the Consultant Building Services Engineer and all associated concreting and

plastering works completed. The separate conductors of the same circuit shall be

drawn in at the same time. Cables forming circuits connected to different distribution

boards shall not be drawn into the same conduit.

The conduit system shall be mechanically and electrically continuous throughout.

Earth wires shall be installed externally across any expansion joints to facilitate this.

Draw in wires shall be provided in all conduits which are installed but not used.

Where conduits terminate in accessories, trunking or equipment having untapped

entries, the conduit shall be threaded to the required length and terminated using a

coupler backed by a lock nut and a smooth bore brass bush.

Unused spouts on conduit boxes and holes in adaptable boxes, switchgear, etc.,

shall be blanked off by means of brass stopping plugs.

Running couplings shall be kept to a minimum but where they are used they shall be

fitted with milled circular lock nuts at each end of the coupling, firmly tightened, when

erecting the conduit. Care shall be taken to ensure that the nuts seat firmly and evenly

onto the mating faces. On vertical conduit runs the running thread shall be above the

coupling. All running joints shall be painted immediately after erection.

Deep boxes or extension rings on standard circular boxes shall be used where

necessary in order to bring the front of each box flush with the surface of the ceiling or

wall. Where conduits are laid direct on the shuttering of the reinforced slab

construction, conduit extension rings or deep boxes shall be used to raise the run of

conduit to between the top and bottom reinforcing. PVC tape shall be installed around

butt joints on extension rings to prevent the ingress of wet concrete. Conduit boxes

cast into concrete walls or floors shall be held in place in an approved manner so that

they are absolutely rigid until and while the concrete is poured and/or vibrated.

Where conduits are laid in slab floors, etc., a competent person shall be in attendance

whilst the concrete pouring or screeding operation is being carried out, in order to

avoid damage being caused to the conduits and also to ensure that the conduit work

is in sound condition and properly and efficiently maintained during this installation

period.

Particular care shall be taken when setting out conduit runs to outlet points where are

to be fitted to furniture, kitchen fittings, etc. The exact details of furniture and fittings

constructions shall be ascertained in order that all conduit work shall wherever

possible be concealed.


LS19561 22

The routes of conduits shall be arranged such that it is impossible for water from

condensation or other sources to collect at any point. Where this is not practical, 3mm

diameter drain holes shall be drilled at the lowest points in the conduit runs or boxes

and at any other points necessary.

In positions where the appearance of the conduit run is likely to be improved by the

introduction of dummy lengths of conduit and where a more secure fixing for the

suspension of fittings would be obtained, such dummy conduits and continuations

shall be provided.

Where a conduit terminates at a main switch, distribution board sub-switch or other

metal clad accessory, a screwed socket shall be employed and so arranged as to be

in good mechanical and electrical contact with the metal case with a brass male bush

screwed into the sockets from inside the case and the two locked together with a

compression washer between. For boxes with tapped entries, and where internal

space permits, a ring bush shall be used as a lock nut. Where there is no room, a

knurled lock nut shall be used on the outside of the box.

For surface work where conduits pass directly through concrete, terrazzo or similar

floors and where washing down is likely to occur the conduits shall be ‘sleeved’. The

sleeve shall be flush with the underside of the floor, extend 75mm above the top

surface of the floor and be secured to the wall by means of a heavy gauge saddle.

Conduits in ceiling cavities shall be supported independent of the suspended ceilings.

Concealed conduits shall be securely fixed to prevent movements during building

operations. Fixing shall be by means of purpose made clips or other approved means

so as to ensure that there will be no conduit deformation.

Where conduits are installed in ducts or voids, fixing shall be in the manner specified

for surface conduits.

A surface installation is defined as one where the conduit is installed on a surface of

the building finishes and is normally visible. All other installations are described as

flush or concealed.

Where a conduit run passes from a concealed area to a surface area, the whole of

that conduit run shall be carried out using galvanised conduit.

Conduits installed in chases of walls and floors shall be firmly secured by wrought iron

pipe hooks or crampets and these fixings shall in themselves be sufficient to hold the

conduits in place. Conduits installed in chases shall be painted with one coat of rust

inhibiting paint before erection and a further coat shall be applied to all accessible

surfaces including the hooks and crampets after erection.

Where a conduit is exposed to different temperatures (either by surrounding air

conditions or by virtue of the surrounding medium with which it is in contact) at any

particular time, the section of the conduit at the higher temperature shall be isolated

from the section at the lower temperature by means of a conduit box filled with an

approved permanently plastic compound after completion and testing of all wiring.

Such a condition would arise if a conduit running in a warmed building is run to

exterior points.

Conduit buried in the ground shall be wrapped with PVC self-adhesive tape half

lapped. The taping shall extend for a distance of 150mm beyond the point where the

conduit emerges from the ground. Joints in galvanised conduit systems shall be

made watertight using lead, aluminium paint and hemp and/or gaskets. The joints


LS19561 23

shall be partially screwed up before the paint and hemp are applied to maintain

continuity.

PVC Conduit

Generally, the requirements for the installation of steel conduit shall apply also to PVC

conduits. The minimum diameter of any conduits shall be 20mm unless otherwise

specified. PVC conduit shall be high impact heavy gauge and comply with BS 4607 :

Part 1, BS 6053 and BS 6099.

Conduit boxes shall be standard small circular pattern, shall be constructed of PVC,

shall be provided with brass earthing terminal and shall be fitted with PVC covers

secured by means of brass screws.

Where PVC boxes are to be used with luminaires they shall have rigid metal fixing lugs

so designed as to remain effective even if the PVC box or extension ring softens due

to high working temperatures. PVC conduits shall not be used where the ambient

temperature is below -5°C or above 60°C.

Inspection bends, solid bends, elbows, tees or normal bends shall not be installed

unless agreed in writing by the Consultant Building Services Engineer. Agreement will

be given only in exceptional circumstances.

All conduit boxes, couplers, etc., shall be provided with slip type couplings with

socket ends and be of the same manufacture and colour as the conduit.

Where boxes form part of an external installation, circular rubber gaskets shall be

provided between the cover lid and box.

PVC conduits shall be installed in a similar manner as specified for steel conduits and

in accordance with the manufacturer’s recommendations.

The conduit system shall be mechanically continuous throughout so that the cables

are fully protected. Conduits shall be cut to the required length and jointed to fittings

using a permanent solvent. At expansion joints semi-permanent mastic shall be used.

It shall be ensured that all loose PVC is removed from the conduit ends and that

conduit ends butt up to internal sockets prior to jointing.

All purpose made bends shall be formed in a manner recommended by the

manufacturer of the conduit.

PVC conduits shall not be installed when the ambient temperature is below 0°C.

Where a conduit terminates at a main switch, distribution board, sub-switch or other

metal clad accessories a half screwed socket shall be employed and so arranged as

to be in good mechanical contact with the metal case with an internal bush screwed

into the socket from inside the case and the two locked together.

Conduits shall be fixed to the structure of the building by means of spacer bar

saddles to BS 4607 : Part 5 within 300mm of each box or fitting and at intervals not

greater than 500mm on horizontal runs and 1200mm for vertical runs.

Earth continuity through PVC conduit shall be maintained by means of a PVC

insulated earth continuity conductor. Earth facilities shall be provided at all terminal

points.


LS19561 24

Conduit bending springs shall be of the correct diameter for the size of conduit and

be free from damage or kinks which may cause damage to conduits.

Conduits that are kinked, fractured, heat damaged or have internal projections shall

be removed from site.

Conduits shall be provided with expansion couplings in surface straight runs in excess

of 5 metres and at building expansion joints.

Conduit boxes shall only be used to support luminaires, etc., up to 3kg in weight.

Masses above 3kg shall be provided with independent suspensions and fixings.

All unused spouts on conduit, etc., shall be provided with polythene conduit plugs.

Flexible Conduit

Flexible conduits shall be steel unless specified otherwise.

Flexible connections shall only be used on items of equipment that are withdrawable

or subject to vibration or adjustment.

Flexible steel conduits shall have a galvanised steel core twine packed with black PVC

covering and shall comply with BS 731 : Part 1, LS1 PVC.

Flexible PVC conduits shall be formed of self-extinguishing corrugated PVC and shall

comply with BS 4607 : Part 3, classification type ‘A’. Earth continuity shall be

maintained in a similar fashion to that employed for rigid PVC conduit.

Electrical continuity shall be maintained by an independent protective conductor

selected in accordance with the IEE Wiring Regulations unless specified otherwise.

Where protective conductors are run external to the flexible conduit, they shall have a

minimum csa of 4.0mm², be taped at intervals or wrapped round the conduit and

securely bonded at each end using earthing couplers.

The interior surface of the flexible conduit shall be free from burrs and sharp edges

and each length of flexible conduit shall be provided with a proprietary type of

screwed brass male adaptor at each end.

5.08.12 High Voltage Cables

High voltage cables shall be suitable for use with an 11kV 50Hz 3-wire system.

HV cables shall be 6350/11000V rated and shall have stranded copper conductors

with semi-conductor screening. Conductors shall be insulated using cross linked

polyethylene with semi-conductor and copper screens overall. The cores shall be laid

up, filled to circular and PVC sheathed. A single layer of galvanised steel wire armour

shall be applied with a red PVC sheath overall.

Cable glanding shall be carried out using compression type terminations. The cable

glands shall be fully weatherproof and shall be suitable for steel wire armour. Cable

terminations shall be complete with heat shrink outer sleeve and earth tag.

Copies of the jointing and terminating instructions for each type of cable shall be

submitted to the Consultant Building Services Engineer prior to any work


LS19561 25

commencing. Cable jointing and terminating shall only be carried out by competent

tradesmen qualified and experienced in the jointing of 11kV cables.

5.08.13 Cable Testing

Every cable shall be tested prior to its connection to site voltages in the following

manner.

All sub-main cables shall be tested using a dc voltage injection equipment and digital

voltmeter. The tests shall follow the following procedure:

a) Insulation Resistance Test (at 1000V).

b) Apply test voltage for 2 minutes on each of the following:

Phase to phase

Phases to neutral

All conductors to earth

All conductors not under test shall be bonded to earth. The Contractor shall

record the leakage current at the time of all tests.

c) Insulation Resistance Test at 1000V.

d) Apply a reduced AC voltage at 50Hz and record the charging current.

All final connections and small wiring shall be tested using a 1000V insulation tester

and each reading tabulated and submitted to the Consultant Building Services

Engineer.

The test voltage shall be dc 2E+2kV where ‘E’ equals the line (phase to phase)

voltage that the cable will see in normal operation. It will be acceptable to test LV

cables while connected to their source, if the source may be readily isolated.

MICS cable shall be tested at 1000V only.

HV cables shall be tested with their ends segregated and adequately shielded.

When testing cables at test voltages exceeding 50V, adequate barriers and signs shall

be provided to prevent inadvertent contact by personnel and responsible personnel

shall be positioned at either end of the cable being tested.

5.08.14 Segregation of Wiring Systems

Wiring systems shall be independent and contained in separate conduit and trunking

installations for the following:

Band 1

Extra low voltage systems e.g. bell and call systems

Radio and television systems

British Telecom systems

Private telecommunication systems

Intruder alarm system

Impulse clock wiring


LS19561 26

Any Category 2 specialist system, e.g. data transmissions, BMS/EMS Cable

systems

DC systems (excluding Category 3 circuits)

Band 2

Low voltage lighting and power systems including 100V AC systems and 'Mains'

mechanical plant wiring not exceeding 1000 volts ac

Band 3

Fire alarm circuits

Emergency lighting installation (central battery systems)

5.09 Lighting Installation

All luminaires, including all circuits and necessary materials, shall be supplied,

installed, and connected in accordance with this Specification and schedule of

luminaires and as shown on the drawings.

Luminaires shall comply with BS 4533 : Part 1.

All diffusers shall, unless otherwise specified, be manufactured from acrylic material,

satisfy BS 2782 and be in accordance with the requirements of the Local Fire Officer.

Conduit or chain suspensions as specified, shall be provided for all pendant fittings.

The stems of conduit suspensions shall be screwed to ball and socket type dome lids

with positive earth connection.

The lighting installation shall be wired in single core PVC insulated cable except where

otherwise specified.

Luminaires in suspended ceilings shall be connected using flexible cables from plug

in type ceiling roses. Flexible cables shall be of a minimum length to facilitate the

disconnection of the respective luminaire and in any event shall not be more than 2m

in length.

Metallic louvres shall be provided with an equipotential bonding conductor between

the main body of the luminaire and louvre.

Within plant rooms, luminaires shall be complete with chain suspensions of adequate

length to provide suitable illumination when all plant is erected. The final locations of

luminaires within plant rooms shall be agreed on site with the Consultant Building

Services Engineer to suit the arrangement of plant.

White break joint rings or pattresses shall be provided wherever necessary.

Circuit cables shall not be routed through bulkhead or other fittings where the cables

would be liable to undue temperature rise, but shall terminate in a fixed base

connector in a conduit box mounted behind or adjacent to the fitting.

Luminaires intended for external use shall be a minimum of IP23 classification.

Steel conduit terminations to all aluminium fittings shall be fitted with brass bushes to

prevent corrosive action between the steel and aluminium components.

Lamp holders with the exception of hand lamps and fluorescent bi-pin units shall be

of the non-ferrous metal type. Lamp holders types ES and GES shall be so connected

that the screw portion is in the neutral conductor.


LS19561 27

All luminaires shall be cleaned using an anti-static cleaning fluid prior to final

handover.

Any modifications to the manufacturer’s standard luminaires to comply with the

requirements relative to mounting height shall be included within this Contract. In the

event of extra-long suspensions being required, these shall be ordered concurrent

with the luminaires.

Where lamp holders are not supplied with the luminaires, they shall be provided,

within this contract and be of an approved type and make.

All fittings shall be suspended from, or fixed to, a small BSS conduit box, except

where specified otherwise. Every lighting point shall be suitable for supporting

luminaires as detailed. Fluorescent luminaires shall be supported from two separate

fixing points. The fixing centres of these luminaires shall be as detailed by the

appropriate luminaire manufacturer.

All luminaires shall be provided with power factor correction to at least 0.9 by means

of capacitors complying with BS 4017 unless otherwise stated.

Wherever lighting track is required for flexible display lighting or simple stage lighting it

shall be complete with power supply box, connectors, fixing clamps, end plugs and

spot-light adaptors.

Where circuiting has not been detailed, proposals shall be submitted to the

Consultant Building Services Engineer for his approval, before any work is put in

hand, a table showing the proposed arrangement of lighting circuits and the size of

cables to be used. When preparing this table, loading of the circuits shall be limited to

50% of the circuit protective device rating. Attention is also directed to compliance

with the appropriate clause of the IEE Wiring Regulations.

Unless otherwise specified elsewhere in this Specification, the installation shall be

wired on the ‘looping-in’ system. The ‘looping-in’ of live conductors shall be effected

at the switch positions and the neutral conductors at the lighting points.

Unless otherwise specified and except for direct connections to the terminals of

ceiling roses and fluorescent luminaires, final connections shall be by means of heat

resisting flexible cord sized to suit the circuit protective device.

Ceiling roses for pendant luminaires shall be white plastic and comply with

BS 67 having substantial terminals including an earth connection and a completely

shrouded looping terminal and an effective cable anchoring device. They shall have

an enclosed integral pattress incorporating knockouts and a screw on cover which

shall conceal the fixing screws. All terminals shall be of the pinching screw type. The

base shall be suitable for direct mounting on to a conduit box.

Pendant lamp holders shall be white plastic, bayonet socket, short sleeve shade

carrier pattern with an effective cable anchoring device, have non-rising terminal posts

and be so designed that the dome of the lamp holder cannot become detached by

the action of removing the lamp or shade carrier sleeve. The whole shall comply with

BS 5042.

Batten lamp holders shall be of white plastic and comply with BS 5042, have

substantial terminals including an earth connection and a completely shrouded

looping terminal and shall permit intermediate connection between the terminals and

circuit wiring with heat resisting flexible cable. They shall have an enclosed integral


LS19561 28

pattress incorporating knockouts and the lamp holder attachment shall be

independently secured to the base and shall conceal the fixing screws.

The lamp holder shall have non-rising terminal posts and an adequately ventilated

Home Office skirt. All terminals shall be of the pinching screw type.

Extra Low Voltage Lighting transformers shall be safety isolating type to IEC72 BS

3535, Class II with voltage regulation of 5% or better and suitable for dimming. The

transformers shall be enclosed in a steel casing and fused protection shall be

provided to the primary of each transformer. Secondary terminals shall be sized to

accommodate the required number of outgoing cables. Terminals shall be labelled

with either 240 volts or the appropriate low voltage output.

Where transformers are used to feed a number of luminaires each luminaire shall be

fed with a separate cable from the transformer secondary terminals. Cabling between

transformers and luminaires shall be carried out using high temperature PVC/PVC

85°C flexible cord 300/500 volt grade to BS 6500. Secondary cable runs shall not

exceed the lengths given in the following table:


LS19561 29

Lamp Cable Size

Watts 1.5mm² 2.5mm² 4.0mm² 6.0mm²

20 8.6m 14.1m 21.8m 33.8m

50 3.4m 5.7m 8.7m 13.5m

75 2.3m 3.8m 5.8m 9.0m

100 1.7m 2.8m 4.4m 6.8m

After installation the voltage at each lamp shall be measured and the results shall be

submitted to the Consultant Building Services Engineer.

All discharge and fluorescent luminaires shall be complete with control gear, power

factor capacitors and lamps. The metalwork of all fittings and starting equipment shall

be effectively earthed to the installation. Fittings without a shunt connected PF

capacitor shall incorporate a voltage dependent resistor to counteract surge voltages.

Shunt capacitors shall not incorporate any integral fusible element.

The control gear shall comply with the relevant BS Specifications where indicated and

be marked with the Kite mark. A separate set of control gear shall generally be

provided for each lamp.

All unless otherwise specified the control gear for fluorescent luminaires shall be

electronic. All components (excluding the fuse and starter) shall be guaranteed for at

least three years under the conditions of assembly and use.

A suitably rated cartridge fuse and terminal block shall be mounted in an approved

manner adjacent to the cable entry.

Where luminaires have spines that are narrower than a standard besa box, cover

plates shall be provided to obscure each box. Plates shall be coloured to suit the

ceiling finish.

If the control gear is switched on without a lamp in circuit the temperature rise in any

of the windings shall not exceed acceptable limits and none of the components shall

suffer deterioration due to excess surface temperature or otherwise.

The approved method of fixing components shall not require access to the top of the

spine of the fitting whether it is direct ceiling mounted or not.

Lamps shall be made by a manufacturer holding a British Standards Institution licence

for electric lamps and shall be of the correct rated voltage.

Each luminaire shall be complete with a lamp for each lamp way. Tungsten lamps

shall be clear type where enclosed and opal type where exposed. Fluorescent lamps

shall be of appropriate size and ratings and of the bi-pin pattern. All lamps of each

type (tungsten, fluorescent) shall be supplied by the same manufacturer.

Fluorescent lamps shall be of the high efficiency, low energy type with a colour

temperature of 3600 deg. K unless otherwise specified. They shall be compatible with

the control gear supplied with the fluorescent lighting fitting.

Losses shall not exceed the following:


LS19561 30

Lamp Max. Losses

TC lamps 7/9/11/36 W 5.5 W hot

TC lamp 13W 4.5 W hot

TC lamps 18/24 W 6.0 W hot

T8 lamps 18/36 W 5.5 W hot



T12 lamp 30 W 8.5 W hot

Ballasts shall be selected after a life cost study of the available types.

All lighting switches shall be supplied and installed in accordance with the types and

ratings specified elsewhere in this Specification. The position of all lighting switches

shown on the drawings shall be checked prior to installation to ensure, where

appropriate, that the switches are located on the handle side of the door opening.

Local switches controlling lighting and equipment shall comply with BS 3676 and shall

be of the finish and type specified.

Switches shall be of the slow break ‘AC only’ pattern in which the successful operation

of the switches does not wholly depend upon the action of a spring and the operating

mechanism is insulated from all parts. The switches shall be 15A minimum rating (5A

for all insulated plate switches) and suitable for inductive operation at their rated

capacity.

Where more than one phase occurs in one switchbox, phase barriers shall be

installed to segregate the circuits on different phases. In addition a label engraved

“Danger 415 Volts”, shall be attached to or engraved upon the front grid plate.

Where metal or metalclad switches are utilised, a 1.5mm² earth continuity conductor

shall be installed between a metalclad switch and its associated metal box.

All boxes used for fixing switches shall be supplied with an earth terminal or screw in

the base of the box.

Every switch controlling an appliance not visible from the switching position shall be

engraved with the name of the appliance it controls, and where called for shall be

fitted with 0.5 watt neon indicating lamp.

Switches shall be of one of the types detailed below and shall be selected to suit the

finishes schedule.

a) All Insulated Plate Switches

Switches shall be rocker type mounted on an all insulated front plate.

The switches shall be mounted on boxes not less than 25mm deep of metal or

white PVC depending on the type of construction with cable or conduit entries.

Where switches are mounted in PVC boxes these shall have accessory fixing

lugs/columns with brass fixing screw inserts.

The front plate shall overlap the box on all sides.

b) Grid Switches

The switch shall be fixed in a grid with adjustable fixings, and an earth terminal.


LS19561 31

The switch and grid shall be mounted in a sheet steel box not less than 40mm

deep.

For surface units the cover plate shall be steel and shall fit flush with the edge

of the box and be of matching colour.

For flush units the cover plate shall be metal or PVC and of the specified finish.

Boxes for surface installations shall not have knockouts but be drilled on site as

necessary.

c) Weatherproof Switches

Weatherproof switches shall be mounted in heavy galvanised cast iron boxes

having dome covers with waterproof machine joints, neoprene seals and

external fixing lugs.

The switches shall be operated by a rotating knurled knob, the stem of which

shall pass through a packed gland.

The switches shall be a minimum classification of IP54.

d) Ceiling Switches

Ceiling switches shall be of the 15A or where specified 45A all while insulated

pattern cord operated type, with a positive action capable of being operated

when the cord is 30 degrees from the vertical. 45A switches shall include a

mechanical on/off indicator and shall comply with the requirements of the IEE

Wiring Regulations.

The switch shall be of the pattern that the cord can be replaced without

removal of the cover.

The switch shall be suitable for mounting upon a circular conduit box or a

purpose made pattress.

e) Dimmer Switches

Dimmer switches shall be of the plate switch pattern, suitable for operation at

250 volts and be rated to the circuit load shown on the drawings.

Each plate shall have either a dimmer control on its own or a dimmer control

and switch.

The dimmer control shall be of the solid state type and the variation in

illumination level shall be carried out by either thyristor or triac control.

The finish of the plate and switches shall be as specified for other switches in

the same room, as particularly specified or detailed on the drawing.

5.010 Emergency Lighting

The emergency lighting system shall be installed in accordance with the

recommendations of BS 5266 and to the complete satisfaction of the Fire Officer. The

system shall provide emergency illumination for a period of three hours to selected

luminaires as shown on the drawings and indicated in the schedule of luminaires.


LS19561 32

The complete system including all batteries, lamps, luminaires, chargers, invertor

units, enclosures and wiring shall be supplied, installed, tested and commissioned.

Conversion packs shall be contained within the spine of the luminaire wherever

possible or in a purpose made enclosure fixed to the back of the luminaire or to the

wall or ceiling soffit in a concealed or inconspicuous position. Conversion units shall

wherever possible be factory fitted under strict quality control conditions.

All invertor modules and self-contained non-maintained emergency luminaires shall

be ICEL approved. All battery packs shall be vented high temperature nickel cadmium

types. Invertor modules and chargers shall be entirely solid state. Charging indication

shall be provided by a red monitoring LED located to be normally visible.

Individual self-contained emergency lighting units and those contained within the

normal lighting luminaires shall be connected direct to the mains supply and in the

event of a failure the unit shall automatically connect to the battery housed within the

unit. On restoration of the permanent supply the unit shall revert to mains operation.

All units shall be supplied complete with rechargeable battery, changeover relay and

silicone rubber covered cable interconnections.

Each unit shall include solid state switching and the re-charge equipment shall enable

a fully discharged battery to be fully re-charged within 14 hours. Facilities shall be

included to prevent reverse polarity at low battery voltage.

Each unit shall derive its supply from an unswitched circuit connected directly to the

MCB or fuse serving the normal local mains lighting such that the battery is on

automatic charge when the mains are healthy. A key switch shall be included in the

live connection to the unit so that simulation of power failure can be achieved without

intercepting the supply to the normal lighting. The switch shall be engraved

“Emergency lighting test switch”.

Emergency lighting systems connected from central batteries shall be connected

direct from the battery cubicle or associated double pole distribution board. No

intermediate switches shall be included in the circuits. Where switches are shown on

the drawings, they shall apply to the standard AC lighting points forming an integral

part of the same lighting fittings.

5.011 General Power

Socket outlets, fused connection units, isolating switches and other accessories

together with the associated wiring shall be supplied, installed and connected in

accordance with this Specification and the drawings.

The positions, finishes and method of mounting of all outlets shall be checked with

the Consultant Building Services Engineer prior to the installation commencing. The

finishes and manufacture of the outlets shall be as scheduled elsewhere in this

Specification except as otherwise agreed with the Consultant Building Services

Engineer.

Unless otherwise specified, 13 ampere switched socket outlets complying with BS

1363 shall be used and shall be wired as ring circuits having conductors no less than

2.5mm². Socket outlets shall not be spurred from the ring circuit nor connected as a

radial circuit unless specified or authorised by the Consultant Building Services

Engineer. Circuits shall be as indicated on the drawings. Where the circuits have not

been detailed the number of outlets per circuit shall be limited to a maximum of 9.


LS19561 33

Socket outlets shall generally be of the flush pattern with all insulated or metal front

plate of the finish and colour specified, mounted in metal or PVC boxes, according to

the system of installation, not less than 35mm deep with cable or conduit entries as

appropriate. PVC boxes shall have accessory fixing lugs with brass screw inserts.

Each socket outlet shall have a separate earth continuity conductor, minimum size 2.5

sq. mm connected to an earth terminal on the box.

Where high integrity earthing is provided within ring circuits, double socket outlets with

dual earth terminals shall be used and compliance with BS 7671 section 607 shall be

assured.

13 ampere fused plugs complying with BS 1363 shall be provided where specified.

Fuses shall be supplied separately for each plug in the ratio of 2:1 for 13A and 3A.

Plugs shall be of moulded all insulated white material with safety sleeving on the live

and neutral pins.

5A socket outlets and plugs shall be generally as specified for 13A outlets and plugs.

Socket outlets shall be of the shuttered type and the plugs shall be unfused. Each

socket outlet shall be provided with one plug.

Socket outlets mounted externally shall be galvanised water resistant pattern with

gasket, screwed cover plate, securing chain and screwed plug top. Three phase

outlets shall be four pole with earth connection and interlocked switch. Each socket

outlet shall be provided with a water resistant plug.

Fused connection units shall comply with BS 3676 and shall be so designed that

withdrawal of the fuse holder does not expose any live parts or permit any extraneous

connection to the contacts. The units shall contain a fuse of the appropriate rating for

the appliance served or 13A where the rating is not known.

Where the purpose of the unit is not obvious, the name of the appliance served shall

be engraved onto the unit.

Very particular attention shall be paid to the method of fixing of outlet boxes so that

they shall, when completed, be level and in an exact position relative to the finished

surrounding surface to permit the cover plate to be fixed accurately.

Where conduit work is to be concealed the alignment of outlet boxes make allowance

for the thickness of walls, depths of finished plaster and final finishes of all relevant

surfaces.

Outlet boxes shall be secured with countersunk screws with screw heads suitably

countersunk, otherwise round head screws shall be used.

All accessories shall be co-ordinated with final finishes (particularly wall tiling) to the

satisfaction of the Consultant Building Services Engineer.

Contactors shall comply with BS 5424 : Part 1 and shall be rated in accordance with

‘uninterrupted duty’ and utilisation category AC1 unless otherwise specified.

Contactors shall be metal clad of the continuously rated pattern, as required by the

particular duty and the number of operations per hour. Each contactor shall be fitted

with a minimum of one normally open and one normally closed auxiliary contact

unless otherwise specified or required by the duty.

Unless specified otherwise, all contactor coils shall be wound for single phase 240V

AC supply and shall be protected by a suitable fuse link or MCB. The coils shall be AC

or rectified (one rectifier per coil) DC operated.


LS19561 34

Where small contactors are incorporated in composite panels the wiring shall be

brought to terminal blocks adjacent so that each complete unit can be easily removed

and replaced. Such contactors (together with any associated relays) shall be housed

in a separate compartment with its own hinged lid.

Time switches shall be self-contained units, 7 day, 24 hour dial, solar dial or digital

type as specified, suitable for operation on the local low voltage AC supply. The

switches shall include a self-starting synchronous motor with a 36 hours spring

reserve or quartz movement with 100 hour reserve.

The solar dial shall be capable of switching ‘ON’ at sunset and ‘OFF’ at sunrise

through the year by control of a secondary calendar dial with month and day settings,

and automatic switch time shall be adjustable up to one hour.

Facilities shall include for day omission and separate motor connections protected by

a suitable fuse link or MCB.

Each time switch shall be encased in a dust-tight metal or plastic casing having a

front cover with a clear Perspex window. Metallic casings shall be effectively earthed.

The time switches shall be provided complete with metal conduit box to facilitate

trunking/conduit connections or otherwise fixed into a suitable box.

5.012 Earthing and Bonding

Earthing and bonding shall be provided as detailed in this specification or shown on

the drawings and in accordance with the IEE Wiring Regulations, British Standard BS

7430 and the local supply company requirements.

A main earth tag shall be provided adjacent to the incoming supply position and shall

be drilled to accept the main incoming earth conductor. The size of the earth

conductor termination shall be ascertained and the size of the tag shall be adjusted

accordingly.

Except as otherwise specified the exposed metalwork in the electrical system shall be

connected to earth via one or more of the following methods:

1 The metallic sheath or armouring of the supply cables.

2 An earth continuity conductor carried within a cable.

3 Metallic conduit or trunking containing wiring.

4 A separate earth wire enclosed in conduit or trunking.

5 A special earth conductor.

Every earthing or bonding conductor, other than copper tape or where contained in a

composite cable, shall be protected by PVC, or where necessary, heat resisting,

insulation identified by the colours green and yellow.

Bonding conductors shall be concealed and provided with mechanical protection as

far as practical.

The incoming gas and water services shall be bonded to the main earth terminal.

Connections to these services shall be as near as practicable to the points of entry

into the building and on the building side of any meter.


LS19561 35

All bond connections shall be made with the appropriate pipe clamps and shall be

complete with a metal label embossed with the words “SAFETY ELECTRICAL EARTH

- DO NOT REMOVE” in capital letters not less than 5mm high.

The earth continuity of metal conduits, metal trunking, and metal sheathing and/or

armouring of cables shall be maintained by efficient bonding between the conduit,

trunking, cable sheath, armouring and gland and the metal case of the switch,

distribution board, or other metal clad accessory or appliance at which they terminate.

All metal clad fittings, accessories and enclosures shall be efficiently earthed.

Where required, a dedicated earth rod shall be provided for the telephone equipment

room with a resistance to earth no greater than 7 ohms. The earth rod shall be

connected using a copper conductor of at least 25mm² to a copper earth bar at least

300mm long x 50mm wide x 6mm deep located in the telephone equipment room.

An earth bar shall be provided within each low voltage switchroom. The earth bar shall

be 50mm wide, 6mm deep and at least 300mm long and shall be mounted on the

wall using insulated supports. The earth bar shall have sufficient connection bolt holes

at no less than 50mm between centres to enable all the earth conductors to be

connected separately and have two spare holes.

The electrical continuity of the mechanical services ductwork, pipework and plant is

required to be provided by others. Under this Specification the bonding to each

isolated system of pipework or ductwork or plant shall be completed to ensure the

mechanical services installation is effectively connected to earth.

The following extraneous conductive parts shall, as a minimum, be bonded to earth.

1) Ductwork

2) Insulation metal facing

3) Pipework

4) Hot and cold water systems

5) Metallic sinks and sink services

6) Gas and water incoming services

7) Suspended ceiling support system

8) Raised floor metallic support system

9) Dry riser, hydrant and other fire protection pipework

Earth electrodes shall consist of minimum 12mm diameter rods of copper molecularly

bonded to a steel core with a roll formed thread at both ends. The rods shall be driven

in the positions shown on the drawings and shall be located in a purpose made

concrete inspection pit with cover.

After installation of the electrodes, tests shall be carried out to ascertain the resistance

to earth. If necessary additional rods shall be installed to achieve the required

resistance.

The whole earthing system shall be tested and test certificates shall be issued to the

Consultant Building Services Engineer within 10 working days following completion of

the tests.

The tests shall include but not be limited to:

1) Measurements of earth electrode resistance.

2) Measurements of earth continuity conductors resistance.

3) Measurements of earth loop impedance.

4) Test for continuity of protective conductors and equipotential bonding.


LS19561 36

The tests shall be carried out upon completion of the works. A minimum of 10 working

days notice shall be given to the Consultant Building Services Engineer of his intention

to carry out these tests and allow the Consultant Building Services Engineer to witness

the tests.

5.013 Fire Alarm System

A complete fire detection and alarm system shall be supplied, installed, connected,

tested and commissioned generally as indicated on the drawings and detailed in this

Specification. The system shall be fully in accordance with BS 5839.

The system shall be of the microprocessor based addressable conventional type, and

shall incorporate the following components:

1) System main control and operating panel.

2) Power supply unit with standby batteries.

3) Automatic fire detection devices.

4) Manual alarm breakglass units.

5) Fire alarm sounder units.

The system shall be of modular design incorporating standard hardware and software

packages only, and shall be arranged such that expansion and modification of the

system is possible at a future date, with minimal change to existing system modules.

The system shall be compatible with the currently installed system.

All basic equipment utilised within the system shall be designed and manufactured by

the same manufacturer.

The main control and operating panel and alarm annunciation terminals shall be

contained within the same wall mounted enclosure.

The central data processing unit (CPU) shall be of the multiprocessor type, and of

modular design to enable future expansion of the alarm system.

The CPU shall incorporate random access memory (RAM) data logic for the system

main operating programme and configuration data, which shall be permanently

monitored to detect malfunction and give alarm to the main control terminal prior to

the system operation being affected.

The CPU shall also incorporate a separate disk unit which shall provide programme

back-up for the entire RAM operating and configuration data, and which is capable of

expansion at a future data.

The CPU shall incorporate all necessary software packages to operate the complete

fire alarm system generally as indicated in this Specification.

The software packages shall be modular in organisation and shall enable the

following facilities:

i) System data base and operating programme

ii) System monitoring and control

iii) Event and command priority control

iv) Output message generation

v) Text and graphics editing

vi) Service assistance

vii) Diagnostic facility

viii) System peripheral drives


LS19561 37

ix) Auxiliary facility programme

The CPU shall incorporate access protection to system operating functions such that

access to the system for editing, priority changes, etc., is only possible via entry of a

pre-selected pass code.

The main control and indication panel shall provide the alarm system main indication

and operating functions.

The panel shall incorporate facilities for connection and indication of a minimum of 8

No. addressable alarm loops, to give 40 zones of alarm indication and individual

addressing of all fire detection devices.

The general arrangement of alarm zones for fire detection devices and sounders is

detailed in this Specification or on the drawings.

Indication of fire and fault zone alarms shall be by means of LEDs contained on the

fascia of the indication panel, and additionally the panel shall contain an LED or LCD

alpha numeric display which shall give indication of the device operating under alarm

or fault conditions.

The panel shall incorporate a numeric function keypad which shall provide operation

of the alarm system control facilities, and allow interrogation of the system status.

The panel shall provide the following system facilities, initiated via coded inputs on the

function keypad:

1. Two-stage operation (Plus day/night mode)

2. Alarm accept

3. Alarm cancel - (reset)

4. Alarm sound - alert (intermittent sounder operation)

5. Alarm sound - evacuate (continuous sounder operation)

6. Isolate remote transmission

In addition, the panel shall incorporate LED indication for the following system

functions:

1. Mains supply failure

2. DC supply failure

3. System in day mode operation

4. System in night mode operation

5. Remote transmission isolated

The panel shall incorporate 6no. sets of auxiliary voltage free changeover contacts,

The installation shall incorporate detection loop mounted programmable fire interface

devices capable of fire and fault indication in and out and or auxiliary voltage free

changeover contacts, which shall operate signalling to mechanical plant installations

and ancillary building services systems.

A separate power supply unit, comprising sealed lead acid batteries and charger unit,

shall be provided for the fire alarm main control and indication panel.

The power supply unit shall be suitable for operation from a 240 volt 50Hz AC supply,

and shall incorporate standby supply batteries of nominal 24 volt DC output.

The power supply unit shall be provided with sufficient battery capacity to maintain the

system in an operational condition for a minimum of 24 hours in the event of a mains


LS19561 38

supply failure and shall have sufficient capacity remaining to operate all alarm

sounders for a minimum period of 30 minutes.

Each power supply unit shall be fully monitored to indicate its operational status and

failure of either AC of DC supplies shall initiate a fault alarm on the alarm indication

panel.

Automatic fire detectors shall be provided as indicated on the drawings and shall be

either of the photo-optical (scattered light) or ionisation pattern smoke detection type,

or rate-of-rise pattern heat detection type, as shown.

Each detector shall incorporate an individually addressable module for connection

onto the addressable detection loops provided from the main alarm control panel.

Each detector shall be provided with a separate plug-in type base connection unit

housing the addressable module, and detector types shall be interchangeable

between bases without further modification to system configuration.

Each detector base shall incorporate an LED indicator to denote operation of a

detector and, where shown on the drawings, extended indication facilities shall be

provided remote from the detector base.

Manual alarm call points shall be provided generally as indicated on the drawings,

and shall comprise semi-recessed units incorporating a baseplate, alarm module and

cover.

The alarm call points shall incorporate a suitable activation device such that the

breaking of the glass (or Perspex) cover shall immediately indicate an alarm signal.

Additionally, each unit shall be provided with facilities to test the operation of the unit

without destroying the glass cover or removing the cover frame.

All manual alarm call points shall be individually addressable and compatible with

automatic detection devices for connection to the addressable alarm loops provided

from the main alarm control panel. Spare glass shall be provided for 10% of the

manual alarm call points with a minimum of 10.

Alarm sounders shall be provided as indicated on the drawings and shall comprise

high output electronic pattern devices giving a nominal sound power level of 110 dB

at 1 metre at 1.2 kHz. Sounders shall be capable of producing separate sounds to

indicate first and second stage alarm condition.

Alarm sounders shall generally be surface mounted units suitable for fixing direct to

standard flush mounted BESA conduit boxes, and shall be connected on zones as

detailed in this Specification.

Fire zones shall be allocated on the central control panel for the air sampling systems

each of which has four sampling tube circuits.

5.014 Installation of Electrical Equipment in Hazardous Areas

Any areas of the site which are, or will become, ‘Hazardous’ as defined by BS 5501

and BS 5345, are detailed elsewhere in this Specification or shown on the drawings.

Due note shall be taken of any hazardous nature of the environment where work is

being carried out.


LS19561 39

The installation work carried out in areas which will become hazardous shall be fully in

accordance with all sections of BS 5501 and BS 5345.

All operators carrying out installation work in compliance with BS 5501 and

BS 5345 shall be fully trained in the type of work and shall be aware of the normal

practice and standards of the industry. The Consultant Building Services Engineer

reserves the right to reject an operator who does not meet the requirements outlined

above.

5.015 Tests on Installation

On completion, and again on the expiry of a period specified elsewhere in this

Specification and/or contractual document, the whole of the work specified shall be

tested in accordance with the IEE Wiring Regulations.

Interim tests will be required for any section of the installation which is required to be

handed over or occupied prior to completion of the contract.

Appropriate completion and inspection certificates as called for in the IEE Wiring

Regulations duly signed by the appropriate personnel shall be submitted immediately

following testing.

A Test Certificate shall be provided to the Electrical Supply Authority if this is a

condition of accepting the installation or part thereof for final connection of the supply.

If such a certificate is required. Sufficient copies of the type of certificate shall be

provided to satisfy the Authority’s requirements.

All instruments and labour for the tests shall be provided.

The Consultant Building Services Engineer shall be given three working days notice

prior to the commencement of any test and the Consultant Building Services Engineer

reserves the right to witness all or any of the prescribed tests.

Upon completion of the electrical services installation, functional and operational tests

shall be conducted with as many items of plant and equipment connected, in order to

demonstrate to the Consultant Building Services Engineer that the installations

operate in accordance with the design.

Where solid state controls or electronic devices are installed, these shall be electrically

disconnected before any testing commences. Final connection of electronic

equipment shall not be made until permission is received from the Consultant Building

Services Engineer.

All solid state controls and devices shall be effectively isolated before the appropriate

tests are carried out.

All figures taken are to be tabulated and submitted to the Consultant Building Services

Engineer.

5.016 Labels

Non-inflammable white labels, engraved with 6mm black lettering adequately

describing the function, shall be fixed to the outside of each isolator, switch-fuse,


LS19561 40

fused switch, distribution panels. For meters, they shall be fixed at adjacent approved

positions.

Any sub-circuit switch or fused connection unit that is located out of sight from the

apparatus it controls shall have a plate immediately above the dolly, engraved with

3mm high black lettering stating its function.

Abbreviations of lettering will not be permitted - unless specifically agreed by the

Consultant Building Services Engineer.

Labels shall be fixed by round head or mushroom head screws, nuts and washers or

rivets.

Fuse switches and switch fuses shall be labelled as generally indicated below (10mm

black lettering).

Lift No. 7

200A fused switch

Fused at 160A

70mm² 4C XLPE/SWA/PVC cable

Three phase and three phase and neutral switch and/or fuse gear shall be fitted with a

white Traffolyte label engraved with 15mm high red letters to read ‘DANGER 415

VOLTS’.

‘DANGER 415 VOLTS’ labels shall be installed, where appropriate, to all items of

switchgear.

Upon completion of the works, an A3 non-fading print, enclosed within plastic and

framed shall be installed at each distribution board or control centre, fixed to the wall

or door where appropriate, detailing the circuits that are controlled from that point.

Where no indication is given of the particular item of plant controlled by a specific item

of switchgear or starter, etc., a suitable white Traffolyte label engraved with black

letters to indicate the plant controlled shall be provided. Each label shall be secured

by means of suitably sized brass nuts and bolts.

Prior to ordering of labels, a schedule of all labels, detailing wording and size of

characters to be utilised shall be submitted to the Consultant Building Services

Engineer.

In all main intake rooms, switchrooms, plant rooms, boiler rooms and kitchens, a

plastic notice containing instructions and illustration of the correct procedure to be

followed when dealing with cases of electric shock shall be provided.

5.017 Circuit Schedules

Circuit schedules typed on A4 size sheets shall be supplied and enclosed in

transparent plastic and framed and fixed adjacent to the distribution boards.

Circuit schedules shall incorporate full description of each circuit, circuit load, breaker

rating, breaker type, rating of RCBO, cable size, cable type, method of installation,

phase and way of circuit.

Draft circuit schedules based on the final allocation of the circuits, etc., together with a

sample frame, shall be submitted to the Consultant Building Services Engineer for his

approval before the final copies are prepared.


LS19561 41

5.018 Schematic Diagram of Distribution and Electric Shock Notice

A framed, glass fronted Schematic Diagram of Distribution together with an approved

durable notice of Treatment for Electric Shock shall be provided in a clearly visible

position adjacent to all main LV switchgear.

5.019 Mounting Heights

The approximate position of main switchgear, control equipment, distribution boards,

luminaires and accessories are indicated on the drawings and are intended to

indicate the general arrangement of the works under this contract. Actual positions

shall be determined on site before the work commences.

The right is reserved prior to the work commencing to make minor alterations to

accessory positions of up to one metre in either direction, without incurring any cost

variation to the Contract.

Unless indicated elsewhere in the Specification or on relevant drawings or as directed

by the Architect the following mounting heights of all accessories between finished

floor level and centre line shall be adhered to:

Lighting switches 1000mm

Socket outlets 600mm

Fire alarm call points 1200mm

Fire alarm sounders 200mm below ceiling/slab level or 2100mm above floor

level whichever is the lower

Wall lighting point 2000mm

Connection units 1350mm

Distribution boards 1800mm to upper edges

All groups of accessories shall be in line either vertically or horizontally or as detailed

on the drawings.

Where groups of distribution fuse gear, switches, contactors, etc., are to be installed

in the same location shall be submitted a detailed drawing of the proposed

arrangement for approval prior to work commencing.

No operating handle, fuse or other protective device shall be located more than

2000mm or less than 300mm above finished floor level.

THE WHOLE WORKS SHALL BE SET OUT IN RELATION TO THE WORK OF OTHER

TRADES. If during the progress of the work any error shall appear or arise in the

positions, levels or dimensions of the several works, these shall, if required, be altered

and/or disconnected at no cost to the contract and to the satisfaction of the Architect

and Consultant Building Services Engineer.

All equipment shall be located and positioned such that routine maintenance can be

readily carried out in the future.


LS19561 42

5.020 Selection of Runs

The routing of all conduits, cables and trunking and the positions of all equipment,

luminaires, accessories and switchgear shall be fully co-ordinated and approved by

the Consultant Building Services Engineer before any work is put in hand.

No additional claims will be considered if the Consultant Building Services Engineer

selects and approves different routes from those envisaged in order to avoid other

services. Should the actual measured length of a cable route exceed that shown on

the drawings or in the schedules by more than 10%, the Consultant Building Services

Engineer shall be informed and his confirmation of cable size obtained prior to the

cable being ordered.

5.021 Rubber Mats

The Installer shall install rubber mats, in accordance with BS921, as necessary in each

switch room.

The mat(s) shall be at least 600mm wide, and the length not less than that of each

switchboard, and laid on the floors in front of all switchboards.

5.022 Specialist Tools

Any tools which are required of a special nature for any equipment etc. installed by

the Installer, shall be handed to the Engineer at the handover meeting, in a purpose

designed box or receptacle.

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