ADDITIONAL BLOCKS

TO

EXISTING PREMISES FOR

ESCOURT SCHOOL

SELECTED SUB-CONTRACT

ELECTRICAL INSTALLATION

SECTION 1

INDEX

PART 2 : GENERAL PROVISIONS FOR INSTALLATION WORK 2.1 INSTALLATION, TESTING AND COMMISSIONING OF MEDIUM VOLTAGE AND LOW

VOLTAGE CABLES ................................................................................................. 1/2/1 2.1.1 General......................................................................................................... 1/2/1 2.1.2 Standards ..................................................................................................... 1/2/1 2.1.3 Excavations and Backfilling ......................................................................... 1/2/1 2.1.4 Installation of Underground Cables ............................................................. 1/2/8 2.1.5 Sleeves......................................................................................................... 1/2/9 2.1.6 Identification of Cables................................................................................. 1/2/9 2.1.7 Cable Jointing ............................................................................................ 1/2/10

2.1.7.1 General........................................................................................... 1/2/10 2.1.7.2 M.V. Joint on Paper Insulated Cables ........................................... 1/2/10 2.1.7.3 M.V. Joint on XLPE Insulated Cables ............................................ 1/2/11 2.1.7.4 L.V. PVC cable joints ..................................................................... 1/2/12

2.1.8 Termination of Cables ................................................................................ 1/2/13 2.1.8.1 General........................................................................................... 1/2/13 2.1.8.2 Termination of paper-insulated 11 kV cables ................................ 1/2/14 2.1.8.3 Termination of XLPE Insulated Cables .......................................... 1/2/14 2.1.8.4 Termination of PVC Cables ........................................................... 1/2/15

2.1.9 Cable End Boxes and Glands .................................................................... 1/2/16 2.1.9.1 Cable end boxes for paper cables ................................................. 1/2/16 2.1.9.2 Cable end boxes for XLPE Cables ................................................ 1/2/17 2.1.9.3 Glands for PVC insulated Cables .................................................. 1/2/17

2.1.10 Testing of Cables ........................................................................................ 1/2/18 2.1.10.1 General............................................................................... 1/2/18 2.1.10.2 Paper Insulated Cables...................................................... 1/2/18 2.1.10.3 XLPE Insulated Cables ...................................................... 1/2/19 2.1.10.4 PVC Insulated Cables ........................................................ 1/2/19

2.1.11 Cable Markers ............................................................................................. 1/2/19 2.1.12 Crossing of Existing/Other Services ........................................................... 1/2/20 2.1.13 "As Built" Drawings of Cable Routes .......................................................... 1/2/20

2.2 INSTALLATION AND TERMINATION OF CONDUIT AND CONDUIT ACCESSORIES

................................................................................................................................ 4/2/21 2.2.1 General....................................................................................................... 4/2/21

2.2.1.1 Scope ………………………………………………………………… 4/2/21 2.2.2 Screwed Metallic Conduit .......................................................................... 4/2/21

2.2.2.1 Installation conditions ..................................................................... 4/2/21 2.2.2.2 Galvanised conduit ........................................................................ 1/2/21 2.2.2.3 Terminations .................................................................................. 1/2/22 2.2.2.4 Continuity ....................................................................................... 1/2/22

2.2.3 Plain end Metallic Conduit ......................................................................... 1/2/22 2.2.4 Non-metallic conduit .................................................................................. 1/2/22 2.2.5 Flexible Conduit ......................................................................................... 1/2/23 2.2.6 Installation requirements ............................................................................ 1/2/23

2.2.6.1 General........................................................................................... 1/2/23 2.2.6.2 Position of Outlets .......................................................................... 1/2/23 2.2.6.3 Draw wires ...................................................................................... 1/2/24 2.2.6.4 Flush mounted outlet boxes ........................................................... 1/2/24

2.2.7 Installation in concrete ............................................................................... 1/2/24 2.2.7.1 Timeous installation ....................................................................... 1/2/24 2.2.7.2 Draw boxes .................................................................................... 1/2/24 2.2.7.3 Elbows …………………………………………………………………..1/2/24 2.2.7.4 Cover Plates ................................................................................... 1/2/24 2.2.7.5 Neutral Axis .................................................................................... 1/2/24 2.2.7.6 Fixing to the Shuttering .................................................................. 1/2/25 2.2.7.7 Expansion Joints ............................................................................ 1/2/25 2.2.7.8 Screeds .......................................................................................... 1/2/26 2.2.7.9 Inspection ....................................................................................... 1/2/26

2.2.8 Installation in roof spaces .......................................................................... 1/2/26 2.2.8.1 Appearance .................................................................................... 1/2/26 2.2.8.2 Saddles .......................................................................................... 1/2/27 2.2.8.3 Fixing to Walls ................................................................................ 1/2/27

2.2.9 Chases and Builder's Work ....................................................................... 1/2/27 2.2.10 Surface Mounted Conduit ........................................................................... 1/2/28

2.3 WIRING .................................................................................................................. 1/2/28

2.3.1 General....................................................................................................... 1/2/28 2.4 MOUNTING HEIGHT OF DISTRIBUTION BOARDS, SWITCHES AND SOCKET

OUTLETS ............................................................................................................... 1/2/29 2.5 POSITION OF OUTLETS, EQUIPMENT AND CONDUIT .................................... 1/2/29 2.6 MOUNTING OF LIGHT FITTINGS ........................................................................ 1/2/30 2.7 CONNECTIONS .................................................................................................... 1/2/30

2.7.1 Outlets ........................................................................................................ 1/2/30 2.7.2 Electric Hot Water Geysers ....................................................................... 1/2/30 2.7.3 Electric Stoves ........................................................................................... 1/2/30 2.7.4 Incinerators ................................................................................................ 1/2/30 2.7.5 Panel Heaters ............................................................................................ 1/2/30

2.8 TELEPHONE OUTLETS ....................................................................................... 1/2/31 2.9 SOLDER, INSULATION TAPE, ETC. .................................................................... 1/2/31 2.10 EARTHING ............................................................................................................. 1/2/31

2.10.1 General ....................................................................................................... 1/2/31 2.10.2 Earthing of Sub-stations ............................................................................. 1/2/31

2.10.2.1 Main Earth Bar ................................................................... 1/2/31

2.10.2.2 Earth Rods ......................................................................... 1/2/32 2.10.3 Miniature Substation Earthing..................................................................... 1/2/32 2.10.4 Switch Room ............................................................................................... 1/2/32 2.10.5 Outdoor Equipment ..................................................................................... 1/2/32 2.10.6 L.T. System ................................................................................................. 1/2/33 2.10.7 Buildings...................................................................................................... 1/2/33 2.10.8 Sub-distribution boards ............................................................................... 1/2/33 2.10.9 Sub-circuits ................................................................................................. 1/2/34 2.10.10 Ring Mains ................................................................................................ 1/2/34 2.10.11 Non Metallic Conduit ................................................................................. 1/2/34 2.10.12 Flexible Conduit ........................................................................................ 1/2/34 2.10.13 Connections .............................................................................................. 1/2/34

2.11 SUB-STATION ACCESSORIES ........................................................................... 1/2/34

ADDITIONAL BLOCKS

TO

EXISTING PREMISES FOR

ESCOURT SCHOOL

SELECTED SUB-CONTRACT

ELECTRICAL INSTALLATION

SECTION 1

SPECIFICATION FOR ELECTRICAL WORK

PART 2 : GENERAL PROVISION FOR INSTALLATION WORK 2.1 INSTALLATION, TESTING AND COMMISSIONING OF MEDIUM VOLTAGE

AND LOW VOLTAGE CABLES 2.1.1 General

This section covers the installation, testing and commissioning of the medium voltage and low voltage cabling.

The Electrical Contractor must allow for the quantities relating to excavations and cable lengths as scheduled in the Bill of Quantities. During the course of the work actual quantities will be measured on site and adjustments made according to the unit rates quoted in the priced schedule and in terms of the Conditions set out in the preamble to the Bills of Quantities.

The Electrical Contractor is advised to check the exact lengths of cable prior to placing the order for cable as under no circumstances shall he be reimbursed for excess cable on site. All excess cable shall be removed from site by the Electrical Contractor on completion of the contract at his own expense.

The storage, transportation, handling and laying of the underground cables shall be according to first class practice, and the Electrical Contractor shall have adequate and suitable equipment and labour to ensure that no damage is done to the cable during operations. It is further a specific requirement that only personnel adequately trained in, and fully conversant with the cable manufacturers recommended procedures for cable jointing and terminating shall be employed by the Electrical Contractor on this project.

2.1.2 Standards

British Standards (BS) 6480. S.A. Bureau of Standards (SABS) 1500.

2.1.3 Excavations and Backfilling

The Electrical Contractor shall be solely responsible for all trenching excavations.

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The Electrical Contractor shall, before trenching commences, familiarise himself with the routes and site conditions and the procedure, and the order of doing the work shall be planned in conjunction with the general construction programme for other services and building requirements.

Trenching shall be programmed in advance and the approved programme shall not be departed from except with the consent of the Engineer.

Trenches shall be as straight as possible and shall be excavated to the dimensions indicated in this specification.

Where necessary the Electrical Contractor shall provide water-pump and associated equipment necessary to remove water from the cable trenches. Any water pumped from the cable trenches shall be disposed of in such a manner that no danger is caused to other services/personnel.

The costs for providing the above shall be incorporated in the excavation rates and no extra shall be allowed for.

The Electrical Contractor shall take all the necessary precautions and provide the necessary warning signs and/or lights to ensure that the public and/or employees on site are not endangered.

The Electrical Contractor shall ensure that the excavations will not endanger existing structures, roads, railways, other site constructions or other property.

The Electrical Contractor shall base his costs for trenching in ground, soft rock and hard rock on the quantities indicated in the Bills. The actual quantities of excavations shall be determined on site at the end of the contract and the cost thereof shall be determined at the scheduled rates quoted by the Electrical Contractor. Payment will be made for volumetric excavation which shall be calculated on the basis of specified maximum trench dimensions or the actual trench dimensions whichever is the smallest.

The Electrical Contractor shall base his price for trenching on the definitions of the various types of ground in section 8 - Standard Preamble to all trades:

No guarantee is given or implied that blasting shall not be required.

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Should blasting be necessary and approved by the Engineer, the Electrical Contractor shall obtain the necessary authority from the relevant Government Departments and Local Authorities. The Electrical Contractor shall take full responsibility and observe all conditions and regulations set forth by the above authorities.

Where trenching is in the vicinity of existing underground services power driven mechanical excavators may not be used for trenching operations.

The cable trenches shall be excavated to a minimum depth of 750 mm below finished ground level for LV cables and 1000 mm below finished ground level for 11kV cables, and shall not be more than 450 mm wide for one or two cables, and shall not be less than 300 mm wide. This dimension shall be valid for the total trench depth.

The width shall be increased where more than two cables are laid together so that the cables may be placed at least 150 mm apart throughout the run, or as specified in Section 2.3.4.

The bottom of the trench shall be level and clear and the bottom and sides free from rocks or stones liable to cause damage to the cable. Payment for cable trenching having greater volume than that specified for the purpose will not be considered except where extra excavations are necessary to by-pass obstacles such as water pipes, drains, large boulders etc. In all such instances the amount of the extra excavations must be agreed upon on site between the Engineer and the Electrical Contractor prior to backfilling and shall be approved in writing by the Engineer.

The excavated material shall be placed adjacent to each trench in such a manner as to prevent nuisance, interference or damage to adjacent drains, gateways, trenches, water furrows, other works, properties or traffic. Where this is not possible the excavated materials shall be removed from site and returned for backfilling on completion of cable laying, at no extra cost.

Surplus material shall be removed from site and disposed of at the cost of the Electrical Contractor.

When laying cables in trenches excavated in soft or hard rock or containing sharp stones, rocks or other items likely to injure cables, the following precautions shall be taken:

Prior to cable laying the trench shall be inspected thoroughly and all objects likely to cause damage to the cables either during or after laying shall be removed.

Where ground conditions are likely to reduce maximum current carrying capacities of cables or where the cables are likely to be subjected to chemical or other damage or electrolytic action, the Engineer shall be notified before installing the cables.

The bottom of the trench shall be filled across the full width of 100 mm layer of suitable soil, sifted through a 6 mm mesh and levelled off.

Only sandy clay or loam soil with a satisfactory thermal resistivity (not exceeding 1,5 degree C m/W) may be used for this purpose. Sea or river sand, ash, chalk,

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peat, clinker or clayey soil shall not be used. The use of crusher sand is acceptable.

Where no suitable soil is available on site, the Electrical Contractor shall import fill from elsewhere and make all the necessary arrangements to do so. The cost of importing soil for bedding purposes shall be included in the unit rates for excavations.

After cable laying a further layer of bedding shall be provided to extend to 150 mm above the cables.

The Electrical Contractor shall not commence with the backfilling of trenches without prior notification to the Engineer so that the cable installation may be inspected. Should the Electrical Contractor fail to give a timeous notification, the trenches shall be re-opened at the Electrical Sub-contractor's cost. Such an inspection will not be unreasonably delayed.

A coloured plastic marking tape shall be installed above the cable across the entire trench width after the trench has been backfilled 500 mm. The tape shall be yellow, with a red skull and cross-bones with the words "ELECTRIC CABLE/ELEKTRIESE KABEL". These markings for the supply and installation of the marking tape shall be included for in the excavation rates.

Backfilling shall be undertaken with soil suitable to ensure settling without voids. The maximum allowable diameter of stones present in the backfill material is 75 mm.

The Electrical Contractor shall have allowed in his tender for the importation of suitable backfill material if required.

The backfill shall be compacted in layers of 150 mm and sufficient allowance shall be made for final settlement. The Electrical Contractor shall maintain the refilled trench at his expense for the duration of the contract. Surplus material shall be removed from site and suitably disposed. In all cases the compaction shall be to the original density of the surrounding material.

On completion, the surface shall be made good to match the surrounding area.

The Electrical Contractor must take all necessary precautions to safeguard all structures, roads, sewage works or other property on the site from any risk of subsidence and damage.

The Electrical Contractor will be held responsible for damage to any existing services brought to his attention (either on site or on a drawing) by the relevant authorities and shall be responsible for the cost of repairs.

Where the Electrical Contractor damages any existing services, or structures during excavations he shall immediately notify the Engineer in writing as to the extent of the damage and either effect repairs himself or arrange for the repairs to be carried out by a specialist contractor where he is not qualified to effect repairs.

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2.1.4 Installation of Underground Cables

The laying of cables shall not be commenced until the trenches have been inspected and approved by the Engineer

Except where ducts, tunnels or pipes are approved, cables shall be laid directly in the ground.

The cable shall be removed from the drum in such a manner that the cable is not subjected to twisting or tension exceeding that stipulated by the cable manufacturer.

Cable rollers shall be used as far as possible to run out cables. Rollers shall be spaced so that the length of cable in the trench will be totally suspended during the laying operation and sufficiently close to prevent undue sagging and the cable from touching the ground. Rollers shall also be placed in the trench in such a manner that they will not readily capsize. The spacing between rollers shall under no circumstances exceed 3 meters.

Cable rollers shall have no sharp projecting parts liable to damage the cables.

Where cables have to be drawn around corners, well-lubricated skid plates shall be used. The skid plates shall be securely fixed between rollers and shall constantly be examined during cable laying operations.

Where cables have to be drawn through pipes or ducts, a suitable cable sock shall be used and particular care shall be exercised to avoid abrasion, elongation or distortion of any kind. In the case of oil filled cables, a cable sock may never be used. Special eyes giving access to the interior of the cable, must be utilised.

The maximum allowable tension when pulling a cable is 70 N/cub.mm of conductor area, and the maximum speed at which cables shall be drawn must not exceed 10 meters/minute.

It will be assumed that the price or rates contained in the tender includes for the installation of cables in pipes and ducts or below existing or newly installed services.

Where cables are cut and not immediately made off, the ends are to be sealed without delay by means of an approved method.

Where cables are installed around corners the cables must be bent slowly and carefully and the minimum radius of curvature must not be less than "12d", where "d" is the overall diameter of the cable.

The separation between all cables shall be a minimum of 150 mm. Cables shall be installed at the following minimum depths below the final ground level :

Up to 11kV - 900 mm Up to 1 kV - 600 mm

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All cable depth measurement shall be made to the top of the cable when laid directly in ground or to the top of the duct or sleeve where these are provided.

The above depths shall apply to the top layer where cables are installed in layers.

Cables installed in the same trench shall be laid parallel to each other with the following spacings between cables (LV : up to 1kV; MV : 1 kV to 11 kV).

Control Cables - Adjacent to each other (touching) LV/LV - 2 cable diameters LV/MV - 300 mm minimum HV/MV - 500 mm minimum

Where MV and LV cables have to be installed in the same trench, the MV cable shall be laid on the one side of the trench at a depth of 900 mm and then covered with 300 mm of soil. The LV cable shall then be laid on the other side of the trench, ie., not above the MV cable, and then completely backfilled

All control cables or pilot cables shall be laid at least 300 mm from power cables.

Cables laid beneath road crossings shall be laid at a depth of 1200 mm measured to the top of the cable.

2.1.5 Sleeves

All cable sleeves shall be uPVC thick wall type to SABS 791. The following diameter and number of uPVC sleeves shall be provided for each road crossing.

1 x 11kV cable - 1 x 160 mm sleeve 1 or 2 LV cables - 1 x 160 mm sleeve 1 or 2 House connections - 1 x 100 mm sleeve

Only one 11kV cable may be laid in a sleeve. The Electrical Contractor shall ensure that all sleeves not containing cables are provided with galvanised steel draw wires and are sealed with a non-hardening watertight compound.

After the installation of cables in sleeves the Electrical Contractor shall ensure that the space between the cable and the sleeve is sealed with a non-hardening watertight compound.

Each sleeve shall extend at least 1500 mm on either side of the road.

2.1.6 Identification of Cables

All cables shall be fitted with identification labels. Identification labels shall be of flat lead with 9 mm punched characters as an identification code. (Cable sheath may be used for this purpose). The identification code shall not consist of more than 12 characters. Labels shall be fitted to cables at 6 m intervals.

Labels on different cables in the same trench shall be staggered by 3m.

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The use of PVC tape with punched characters is not acceptable.

The cost for the supply and installation of the cable identification labels shall be incorporated in the unit rate for the supply and installation of the appropriate cable.

2.1.7 Cable Jointing 2.1.7.1 General

Jointing of cables must be restricted to an absolute minimum and shall not be carried out during overcast/rainy conditions.

Jointing shall be carried out strictly in accordance with the manufacturer's instructions and by personnel competent in jointing the types of cables used.

When an outdoor cable joint is to be carried out, the contractor shall excavate a joint hole of sufficient dimensions to enable the cable jointer to work efficiently and unhindered.

During outdoor jointing operations, the joint bays shall be adequately covered by tents of waterproof material suitably supported. Where necessary a trench shall be excavated around the bay to prevent the ingress of moisture. The sides of the hole shall be draped with a small tarpaulin or plastic sheeting to prevent loose earth from falling in during jointing operations.

The joint shall not impair the anti-electrolysis characteristics of the cable.

At every M.V. cable joint the cable shall be looped in the ground to allow for future re-making of the joint should this become necessary. The minimum permissible bending radius of the cable must be adhered to when installing the cable loop in the horizontal plane. Unless otherwise specified one complete loop shall be provided.

The joint shall be covered with a layer of soil which shall not be less than 75 mm in final thickness. Concrete cable slabs shall then be laid over the joint and cables for a distance of 2 m either side of the joint to provide protection.

Sufficient length of cable shall be left if the joint cannot be completed.

The cable ends are to be capped, coiled and buried until the making-off of the joint can be completed.

The Electrical Contractor shall notify the Engineer timeously of the day on which jointing is to be carried out in order than an inspection may be arranged if so required. Any cable joint not inspected by the Engineer because of insufficient notice being given, shall be opened for inspection and redone at the discretion of the Engineer at the cost of the ElectricalSub-contractor.

2.1.7.2 M.V. Joint on Paper Insulated Cables

M.V. joints in paper insulated cables shall be of the compound type with lead sleeve and cast iron protection box. All compound used in joints shall comply with the Specification for "CABLE END BOX FILLING COMPOUND" as

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contained under "Terminations" below.

Cables shall be laid so that their ends overlap by at least 300 mm before jointing.

Lead sleeves shall not be split lengthwise.

Cable insulation papers shall be tested for freedom from moisture before jointing.

Copper conductors shall be jointed by means of soldered weak-back ferrules.

Exposed cable cores and insulation shall be basted with resin oil compound heated to 130 + 5 degree C before applying ferrule insulation.

All insulating papers and tapes shall be crackle tested in 130 + 5 degree C resin oil compound before application.

The completely insulated joint shall again be basted with 130 + 5 degree C resin oil compound before sliding over the lead sleeve.

The lead sleeve shall be filled with compound whilst it is still hot from wiping and topped up at intervals until is has completely cooled down.

Compounds and oils shall be heated over slow fires - no direct gas flames -to prevent carbonization and temperatures shall be determined by means of thermometers.

All 11kV joints for paper insulated cables shall be similar and equal to the "HENLEY" type.

2.1.7.3 M.V. Joint on XLPE Insulated Cables

The jointing of XLPE cables is to be carried out using 3M, Sigmaform or Raychem type jointing kits.

The procedure for preparing the two cable ends for jointing shall be carried out in accordance with the recommendations provided by the supplier of the jointing kit. Care must be taken when ring cutting to remove the inner jacket as damage to the copper shielding tapes could result in a failure of the joint.

From one end of the core measure half the length of the ferrule plus 10 mm and friction cut to the copper conductor. Pencil the insulation using a pencilling tool. A knife is not acceptable.

Sand the insulation of the pencil smooth and round. The insulation can then be sanded clean and wiped down with the cleaning pad.

Only aluminium oxide abrasive cloth shall be permitted for sanding procedures.

Special care shall be observed when preparing the ends of XLPE cables such that the underlying insulation does not become damaged when removing semi-conducting screens. A special rotating tool shall be used to remove semi-inductive layers.

The correct size ferrules must be used. A hexagonal crimping tool shall be used.

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All sharp edges shall be filed smooth.

From the edge of the ferrule build a taper of Scotch No. 13 type tape extending 2 mm onto the pencil. Cover the entire ferrule with a half lapped layer of No. 13 tape extending onto the tapers on both sides.

Apply highly stretched half lapped layers of No. 23 tape across the ferrule from side to side until the tape is built up into a cigar shape, with a maximum insulation thickness over the ferrule of 1,5 times original insulation thickness. Stop the No. 23 tape 5 mm short of the semi-conductive material on each core.

Apply a half layer of No. 13 tape starting 15 mm on the semi-conductive core screen across the joint finishing 15 mm onto the semi-conductive core screen on the other side.

An approved method shall be used to ensure that adequate clearance exists between the armour bridge conductor and the conductor screens so that the original insulation levels are restored. The testing procedures detailed in Section 3.1.10 shall be applied to check the integrity of the cable after insulation.

To replace the shielding on individually screened cables, the tapes that were folded back from each core should be smoothed out with a hammer handle or such implement and wound helically across the core to the original position. Apply a layer of no. 23 shielding tape half lapped across the core from crutch to crutch. Secure the copper tapes in position with a roll spring. This procedure is to be carried out on each core.

The armour continuity sock bridging the armouring at the joint shall be adequate to carry the fault current and shall not be less than 70 mm2 cross-section.

One constant force roll spring shall be used at either end of the joint to ensure uniform contact pressure between the earth sock and the armouring.

Set the joint in the final installation position, place the mould over the joint and ensure that the armouring sock is formed uniformly inside the mould and not touching the mould.

Apply layers of No. 23 Tape from the mould taper onto the outer jacket of the cable to form a seal between the mould and the jacket.

Pour the resin into the mould, and allow to set properly before backfilling commences. DO NOT MOVE JOINT BEFORE RESIN HAS PROPERLY SET.

2.1.7.4 L.V. PVC cable joints

Low voltage PVC cable joints shall be of the cast resin type. Joints shall be large enough so that the cable armouring as well as the PVC serving is well covered by the resin in order to avoid corrosion of the armouring. Cores shall be jointed with ferrules and shall be individually insulated with PVC tape or sleeves before casting the resin. Core joints in pilot cables shall be staggered.

Armouring shall be jointed through inside the mould such that its current carrying capacity is not impaired and that it is protected by a sufficiently thick resin layer to

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prevent electrolytic corrosion.

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2.1.8 Termination of Cables 2.1.8.1 General

Cable ends shall be terminated with glands or in cable boxes with the associated accessories such as clamps, shrouds, etc in a manner recommended by the cable gland manufacturer and approved by the Engineer.

The termination of cables shall not be carried out during overcast/ rainy conditions.

At every M.V. cable termination the cable shall be looped in the ground to allow for future re-making of the termination should this become necessary. The minimum permissible bending radius of the cable must be adhered to when installing the cable loop in the horizontal plane.

The termination of both L.V. and M.V. cables shall be carried out strictly in accordance with the manufacturers instructions, SABS Code of Practice and performed by personnel competent in terminating the cable types specified.

Connection of cables to switchgear shall always be effected in such a way that the various phases, seen from the front of the switchgear will be in the following positions :

No. 1 Conductor : Left (red) (A) No. 2 Conductor : Centre (white) (B) No. 3 Conductor : Right (blue) (C)

Exposed armouring shall be covered with bitumen-base paint.

All cable ends shall be supplied with the necessary earth connection.

A P4000 "SANKEYSTRUT" channel or other approved means of support shall be provided to remove mechanical stress from the glands.

Cable cores shall be marked with heat-shrunk sleeves where necessary to identify the phases. Refer to paragraph 5.2.1(d) of SABS 0142. Split ferrules or sticky tape type numbers are not acceptable.

The current-carrying capacity and breakdown voltage of the cable end shall be the same as for the complete cable. Suitable lugs shall be used, solidly sweated to the cable conductor ends. Lugs may be crimped, using mechanical or pneumatic tools designed for this purpose. A hexagonal crimp must be used on L.V. and M.V. terminations, and then all the sharp edges filed off.

Contact surfaces shall be thoroughly cleaned and smoothed and fixing bolts shall match the hole size of the lug. Cables that are connected to clamp type terminals where the clamping screws are not in direct contact with the conductor, need not be lugged but the correct terminal size shall be used.

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Ferrules shall be used as far as possible where cable conductors are connected directly to equipment with screws against the conductor strands.

When cutting away insulation from cable conductors to fit into lugs, care shall be taken that no strands are left exposed. Under no circumstances may any of the conductor strands be cut away to fit into lugs.

2.1.8.2 Termination of paper-insulated 11 kV cables

For paper insulated cables moisture tests shall be done as for through joints and the standard of workmanship shall be the same.

Compound filled type boxes (cast iron or steel) shall be used for terminating.

With indoor end boxes without bushing stems insulated tails shall be jointed to the cable ends by means of solid centre ferrules under the compound level in order to create moisture stops.

The armouring shall be bonded to the main earth bar of the switchgear or transformer, but the bond shall be easily removable for testing purposes.

The lead sheath shall be wiped against the conical wiping gland.

All cut cable ends which will be exposed to the atmosphere for more than two hours shall be sealed and wiped to prevent penetration of moisture.

Out doors paper insulated cables are to be terminated in a suitable inverted type compound box which must comply with the section covering Cable End Boxes and Glands.

2.1.8.3 Termination of XLPE Insulated Cables

XLPE cable terminations shall be carried out using 3M, Sigmaform, Raychem, or pre-stressed sleeves of the 3M type. Sheds shall be used on outdoor terminations.

The procedure, dimensions and method of preparing and terminating an XLPE cable end shall be in accordance with the suppliers recommendations of the termination kit chosen.

The same precautions shall be taken when preparing the cable ends as in XLPE cable jointing.

A copper earth braid is to be connected to each copper screen and to the armour using steel constant force roll-strips to ensure uniform contact pressure between the earth braid and screen. The screen and armouring braids shall be bonded to the main earth bar of the transformer, but the bond shall be easily removable for testing purposes. The manufacturers insulation clearances between the copper screens and armouring shall be adhered to, so that the testing procedures detailed in Section 3.1.10 can be applied.

The braid cross-sectional area must be sized for the earth fault current with a minimum cross-sectional area of 50 mm2 or two Scotch No. 25 braids being used

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on the armouring. The armour braid is then insulated using Scotch No. 23 tape. The screen braids shall have a minimum cross-sectional area of 25 mm2, as in one Scotch No. 25 braid.

The connection of the braids to the armouring shall be by means of a steel roll spring. The braid shall be interleaved at least twice at right angles through the spring.

Bare the armour bedding just above the armouring, the conductor screens are then wound around the conductor so that four turns are made around the core. One Scotch No. 25 braid is then laid between the copper screen and the steel roll spring. One and a half revolutions of the roll spring are made and then the braid is bent at right angles out of the screen towards the end. The roll spring is then rolled over the braid again and twisted to ensure tightness.

Six (6) half lap layers of Scotch No. 23 tape shall then be applied to cover the roll spring, screen and bedding. A pre-stressed control cone is then installed following the manufacturer's instructions.

A pre-stressed sheath seal shall also be used to seal the crutch of the termination.

Correctly sized lugs shall then be crimped onto the ends of the cable using the correctly sized hexagonal crimping tool. All sharp edges shall be filed off. The space between the lug and the insulation shall be filled with semi-conducting tape and any holes in the lug filled with Scotchfill Putty.

A pre-stretched tube or heat shrink tube shall then be placed over the end lug and switchgear spout to completely insulate the termination. Taping of the end lug shall not be allowed.

2.1.8.4 Termination of PVC Cables

In the case of PVC cables, the cable is to be terminated in either a suitable moisture proof enclosure, equal or similar to 3M type terminations, or by means of a heat shrink terminating system, equal or similar to RAYCHEM or SIGMAFORM terminations.

To prevent water from entering in between the conductor strands in the case of PVC terminations, the tails are to be curved between the connecting point and termination so that the lowest point of the cure is below the termination. The PVC insulation is to be removed from the conductors for a width of approximately 5 mm at the lowest point of the curve in order to form a moisture gap.

On all gland plates or boxes made to accept glands, PVC cables shall be terminated with compression glands complete with neoprene shrouds.

The ends of cable cores, which form current paths in accordance with circuit diagrams, shall be fitted with ferrules which give the current path number. Split ferrules or sticky tape type numbers shall not be acceptable and they shall be held captive on the end by a suitable lug.

When multi-core PVC insulated cables are terminated within miniature sub-stations, cable clamps similar and equal to the "K" series of O-Line clamps

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shall be used to secure the cable to the cable support channel.

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2.1.9 Cable End Boxes and Glands

2.1.9.1 Cable end boxes for paper cables

Cable end boxes for copper insulated medium voltage cable shall be equal and similar to "Martes", "AEI-Henley", "Raychem" or "Scotchcast" manufacture, of the shallow type, filled with grade 621 bitumen compound.

Cable end boxes shall be suitable to accept PLSTS, PLSTC, PESTS and PESTC cables.

The cable end boxes shall be of the metal clad type suitable for indoor or outdoor uses as required for the specific application. Only inverted type boxes shall be supplied for outdoor use. The insulators of the inverted type boxes are angled downwards.

The boxes shall be equipped with armour clamps and brass or gunmetal conical wiping glands.

All cable end boxes shall comply with BS 542.

The cable boxes shall be suitable for filling with bituminous, cold filling compound or resin oil semi-fluid compound.

The cable boxes for resin oil semi-fluid compound shall be equipped with a sight glass for compound level indication.

Bituminous Compound

Compound shall be suitable for filling metal clad cable end boxes.

Compound shall comply with BS 1858, shall be non-hygroscopic and shall have a high dielectric strength and insulation resistance.

The compound shall have good adhesive properties and shall not be susceptible to cracking.

The compound shall be suitable for use in high ambient temperatures and system voltages of up to 11kV nominal.

Catalysed cold filling compound

The compound shall be suitable for filling metal clad cable end boxes.

The compound shall consist of two components, a base compound and a hardening agent, supplied in separate containers in the correct proportions ready for mixing.

Additional heat shall not be required and the compound shall be suitable for use at atmospheric pressure.

The compound shall be non-hygroscopic and shall have a high dielectric strength

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and insulation resistance.

Shrinkage shall be limited so that topping up of the boxes is not necessary.

Resin oil semi-fluid compound

The compound shall be suitable for filling metal clad cable end boxes with level indicators.

This compound shall have a pouring temperature above 100 degree C.

The compound shall be non-hygroscopic and shall have a high dielectric strength and insulation resistance.

The compound shall have minimal contraction when cooling.

The compound shall be of the HENLEY COMPOUND NO. 57018, INSULOL DG or equivalent.

2.1.9.2 Cable end boxes for XLPE Cables

The cable end boxes shall be purely to prevent mechanical damage or access to the terminals and/or bushings.

The end boxes shall not be filled with any type of filling compound.

The dimensions of the cable end box shall be such that the crutch of the termination shall fall inside the box.

The cable shall be clamped outside the cable end box using suitable wooden clamps approved by the Engineer.

Where it is not possible to provide a cable end box, a suitable bracket or other approved means of support shall be provided to remove mechanical stress from the cable termination and crutch.

2.1.9.3 Glands for PVC insulated Cables

Glands to be used for terminating PVC/PVC/SWA/PVC cables shall be of the adjustable type, similar and equal to PRATLEY.

Glands shall be suitable for general purpose 600/1000V grade cable with steel armouring.

The glands shall be made of heavily nickel-plated bronze or brass.

The glands shall consist of a barrel carrying a cone bush screwed into one end and a nickel-plated brass nipple carrying a nickel-plated brass of a heavy galvanised steel locknut screwed into the other end. The galvanising shall comply with SABS 763.

The shrouds shall be made of non-deteriorating neoprene or other synthetic rubber, and shall be resistant to water, oil and sunlight. The shrouds shall fit

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tightly around the glands and cable.

Glands shall be provided with ISO threads and shall be suitable for the specified cable sizes.

Flame-proof glands shall comply with SABS 808, Groups 1, 2a and 2b.

Suitable accessories shall be provided with glands to be used on EEC armoured cables to facilitate a bolted lug connection of the earth continuity conductors. Grooves cut into the barrel or cone bush to accommodate the earth continuity conductors are not acceptable.

For unarmoured cables the cone and compression ring of the glands shall be replaced with a synthetic rubber compression bush and ring to provide the required grip on the outer sheath of the cable.

2.1.10 Testing of Cables

2.1.10.1 General

Each cable shall be tested after installation in accordance with SABS 150 (up to 1kV), SABS 97 for Impregnated-paper insulated cables (up to 11kV) and SABS 1339 for Cross-linked polyethylene (XLPE) insulated cables. The requirements of the Local Supply Authorities shall also be adhered to when testing cables.

MV Cables shall be pressure tested in accordance with the tables below and the exact leakage current shall be tabulated and certified.

The Electrical Contractor shall notify the Engineer timeously so that a representative of the Engineer may witness the tests.

On completion of the tests on any cable, the Electrical Contractor shall without delay, submit three copies of the certified Test Reports to the Engineer.

2.1.10.2 Paper Insulated Cables

Cable Rating

(kV)

Test Voltage

(Applied for 15 minutes) (kV)

Between Conductors

Conductors to Sheath

AC (rms)

DC

AC (rms)

DC

3,6/6,6 6,35/11

12 20

18 30

12 20

18 30

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2.1.10.3 XLPE Insulated Cables

Cable Rating

(Volts)

Test Voltage

(Volts)

Conductors to

Screen/binder/armour (applied for 15 minutes)

Between overall

copper screen and armour (applied for

1 minute)

DC

DC

3,6/6,6 6,35/11

11 18

4 4

2.1.10.4 PVC Insulated Cables

Cable Rating

(Volts)

Test Voltage

(Volts)

Phase to Phase

(Applied for 1 minute)

Phase to Earth

(Applied for 1 minute)

DC

DC

220/380

1000

500

L.V. cables shall be tested by means of a suitable meggar at 1kV and the insulation resistance shall be tabulated and certified.

2.1.11 Cable Markers

The cable markers shall consist of a concrete block in the shape of a truncated pyramid approximately 300 mm deep x 150 mm x 150 mm at the top and 230 mm x 230 mm at the bottom. An aluminium or brass indicator plate shall be either cast onto the top of the marker or secured in such a manner that it is impossible to price loose and it shall have the following stamped inscriptions

"CABLE/CABLE SLEEVES" "INDICATE NUMBER AND SIZE"

Cable joint markers shall be constructed exactly the same as the above markers but shall have the following stamped inscription on the indicator plate :

"CABLE JOINT NO. ......"

Markers shall be placed at regular intervals along cable routes, approximately 50 meters apart and also at all changes in direction with arrows indicating route of cable either :

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or

A sample of the proposed markers shall be submitted to the Engineer for approval before they are manufactured.

The Electrical Contractor must base his tender price on the quantities as given in the price schedule. During the course of the work the actual quantities will be measured and the cost adjusted in accordance with the unit prices quoted.

The position of cable markers shall be indicated on the "as built" drawings.

2.1.12 Crossing of Existing/Other Services

The Electrical Contractor must acquaint himself with all services that are existing and to be maintained or are being installed concurrently or subsequently to his operations to ensure that any excavations he may undertake will not damage or hinder such services or expose his work to possible damage by others.

The Electrical Contractor will be held responsible for damage to any existing, or concurrently installed service, which might be brought to his attention by the relevant authority and shall be responsible for the cost of any repairs.

Wherever it might so happen that there is a clash between the electrical and other services, due to oversight or miscalculation, the Engineer shall be consulted for solution or to advise the relevant design team.

At all positions where LV cables cross MV cables, approved concrete slabs shall be placed over the MV cables and shall extend for a distance of 2 meters on either side of the crossing.

In all instances where electrical cables cross telephone cables the electrical cable shall be installed at least 300 mm below the telephone cable. A concrete block shall then be installed 75 mm above the electrical cable extending at least 2 meters on either side of the crossing. A cable marker shall be provided to indicate that an electrical and telephone cable intersect.

In all cases where MV cables cross sewage pipes, water pipes and fuel lines a similar procedure to that as described for the LV cable crossing shall be adopted.

2.1.13 "As Built" Drawings of Cable Routes

After all the cables have been laid, the Electrical Contractor must provide a final "As Laid" drawing showing all the cable routes.

The drawing shall also show all M.V. cable joints, sleeves, point of entry into each site of the house connection cable (including dimensions) and all labelling as required.

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2.2 INSTALLATION AND TERMINATION OF CONDUIT AND CONDUIT

ACCESSORIES 2.2.1 General 2.2.1.1 Scope

This section covers the installation of conduits and conduit accessories in buildings and allows for the following types of conduit installations.

i) Screwed metallic conduit - black enamelled and galvanised. (to SABS

162)

ii) Plain-end metallic conduit - black enamelled and galvanised. (to SABS 1007)

iii) Non-metallic conduit (to SABS 950)

iv) Flexible conduit.

Outlets on a common circuit shall be wired through conduit which shall be looped from one outlet to the other.

The conduit and conduit accessories shall comply fully with the applicable SABS specifications, and the conduit shall bear the mark of approval of the South African Bureau of Standards.

Unless specified to the contrary in Part 5, DETAIL SPECIFICATION SPECIAL PROVISIONS, the conduit and accessories shall be of the screwed metallic type.

In order to ensure that maximum mechanical and electrical continuity is maintained throughout the installation, only one manufacture of conduit and conduit accessories will be permitted throughout the installation.

2.2.2 Screwed Metallic Conduit 2.2.2.1 Installation conditions

In general screwed steel conduit shall be used in the wiring of buildings.

Conduit accessories used for flame-proof or explosion proof installations and for the suspension of luminaires as well as all load bearing conduit shall in all instances be of the metallic screwed type.

The installation shall conform to par. 5.4 of SABS 0142.

All joints in conduit tubing shall be red leaded to prevent rust.

2.2.2.2 Galvanised conduit

Galvanised conduit and accessories shall be used in the following circumstances and normally be electro-galvanised or cadmium plated.

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i) In damp areas. ii) In areas exposed to the weather. iii) For all installations within 50 km of the coast. (These conduits and

accessories shall be hot-dip galvanised to SABS 763). iv) In plenum chambers containing humidifying equipment. v) For surface mounted conduit installations in kitchens and boiler rooms.

vi) In screeds resting directly on soil.

vii) For connection points to future installations.

viii) For underground conduit containing earthing conductors.

ix) In buildings where animals are housed such as cattle, sheep, dogs, etc.

2.2.2.3 Terminations

Conduits shall be terminated by means of a brass female bush and two locknuts in pressed steel switchboards and distribution boxes, cable ducts, power skirting, etc. The conduit end shall only project far enough through the hole to accommodate the bush and locknut. A female bush and two locknuts shall be used to terminate conduits at draw boxes and outlet boxes without spouts should there be sufficient room in the box. Where there is insufficient room, a coupling, brass male bush and locknut may be used with sufficient allowance for the reduction of the internal diameter by the male bush.

2.2.2.4 Continuity

Mechanical and electrical continuity shall be maintained throughout the conduit installation. The resistance of a completed joint shall not exceed 0,2 ohm

Under no circumstances shall conduit be relied on for earth continuity.

2.2.3 Plain end Metallic Conduit

As an alternative to the screwed conduit, plain-end conduit conforming to the Standard Specification for 'CONDUITS AND CONDUIT ACCESSORIES', may be installed under the following conditions :

i) Bending and setting of plain-end conduit must be done with special

benders and apparatus manufactured for this purpose. Damaged conduit resulting from the use of incorrect bending apparatus shall be completely removed and rectified at the electrical Contractor's expense.

ii) Plain-end conduit and associated accessories shall be manufactured of

mild steel having a minimum thickness of 0,9 mm and shall conform to SABS 1007.

2.2.4 Non-metallic conduit

Where specified for a particular service, non-metallic conduit may be installed under the following conditions :

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i) All non-metallic conduit shall comply fully with SABS 950 and shall be installed in accordance with Appendix C of the same specification.

ii) Insulated heat-resistant boxes shall be used for outlets of totally enclosed

luminaires and other fittings where excessive temperatures are likely to occur.

iii) Luminaires and other fittings shall not be supported by non-metallic

conduit or conduit boxes. These fittings shall be secured to the surrounding structure in an acceptable way.

2.2.5 Flexible Conduit

In installations where the equipment has to be moved frequently to enable adjustment during normal operation, for the connection of motors or any other vibrating equipment, for the connection of thermostats and sensors on equipment, for stove connections and where otherwise required, flexible conduit shall be used for the final connection to the equipment.

Flexible conduit shall be connected to the remainder of the installation by means of a draw box. The flexible conduit may be connected directly to the end of a conduit if an existing draw box is available within 2 m of the junction and if the flexible conduit can easily be rewired.

Flexible conduit shall consist of metal reinforced plastic conduit of PVC covered galvanised metal conduit with an internal diameter of at least 15 mm, unless approved to the contrary. In false ceiling voids, flexible conduit of galvanised steel construction may be used. Connectors for coupling to the flexible conduit shall be of the gland or screw-in type, manufactured of either brass or mild steel plated with either zinc or cadmium.

2.2.6 Installation requirements 2.2.6.1 General

Running joints in screwed conduit are to be avoided as far as possible and all conduit systems shall be set or bent to the required angles. The use of normal bends must be kept to a minimum with exception of larger diameter conduits where the use of such bends is essential.

Bending and setting of conduit must be done with special bending apparatus manufactured for the purpose and which are obtainable from the manufacturers of the conduit systems. Damage to conduit resulting from the use of incorrect bending apparatus or methods applied must on indication by the Engineer's inspectorate staff, be completely removed and rectified and any wiring already drawn into such damaged conduits must be completely renewed at the Electrical Contractor's expense.

2.2.6.2 Position of Outlets

All accessories such as boxes for socket outlets, switches, lights, etc., shall be accurately positioned. It is the responsibility of the Electrical Contractor to ensure that all accessories are installed level and square at the correct height from the floor, ceiling or roof level as specified. It shall be the responsibility of the

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Electrical Contractor to determine the correct final floor, ceiling and roof levels in conjunction with the Main Contractor.

Draw boxes shall not be installed in positions where they will be inaccessible after completion of the installation. Draw boxes shall be installed in inconspicuous positions to the approval of the Engineer's representative and shall be indicated on the "as built" drawings.

2.2.6.3 Draw wires

Galvanised steel draw wires shall be installed in all unwired conduit, e.g. conduits for future extensions, telephone installations and other services.

2.2.6.4 Flush mounted outlet boxes

The edges of flush mounted outlet boxes shall not be deeper than 10 mm from the final surface. Spacer springs shall be used under screws where necessary.

Oversize cover plates shall be provided on all flush mounted round conduit boxes, where required. Surface mounted boxes shall be provided with standard size cover plate.

2.2.7 Installation in concrete 2.2.7.1 Timeous installation

In order not to delay building operations, the Electrical Contractor shall ensure that all conduits and accessories which are to be cast in concrete are placed in position in good time. The Electrical Contractor or his representative shall be in attendance when the concrete is cast.

2.2.7.2 Draw boxes

Draw boxes, expansion joints and round ceiling boxes shall be installed where required and shall be neatly finished to match the finished slab and wall surfaces. Ceiling draw boxes shall be of the deep type. In hollow title slabs, rear-entry draw boxes shall be used. In columns where flush mounted draw boxes are installed, the conduits shall be offset from the surface of the column immediately after leaving the draw box.

2.2.7.3 Elbows

Elbows for conduits of 32 mm dia and smaller and sharp bends will not be allowed in concrete slabs.

2.2.7.4 Cover Plates

Draw boxes and/or inspection boxes shall, where possible, be grouped together under a common approved cover plate. The cover plate shall be secured by means of screws.

2.2.7.5 Neutral Axis

All conduits shall be installed as close as possible to the neutral axis of concrete

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beams, slabs and columns. The conduits shall be rigidly secured to the reinforcing to prevent movement towards the surface of the concrete.

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2.2.7.6 Fixing to the Shuttering

All conduits, draw boxes, etc. shall be securely fixed to the shuttering to prevent displacement when concrete is cast. Draw boxes and outlet boxes shall preferably be secured by means of a bolt and nut installed from the back of the box through the shuttering. Fixing lugs may also be used to screw the boxes to the shuttering. Wire will not be accepted for securing boxes to the shuttering where off-shutter finishes are required. Where fibreglass shuttering is used by the Builder, the equipment shall be fixed to the steel only and no holes shall be drilled or made in shuttering. All draw boxes and outlet boxes shall be plugged with wet paper before they are secured to the shuttering.

2.2.7.7 Expansion Joints

As far as possible, conduits shall not be installed across expansion joints. Where this is unavoidable a conduit expansion joint shall be provided.

The expansion joint shall consist of two draw boxes with an interlinking flexible conduit connection.

The draw box shall be installed adjacent to the expansion joint of the structure and a conduit sleeve, one size larger than that specified for the circuit, shall be provided on the side of the draw box nearest to the joint. The one end of the sleeve shall terminate at the edge of the joint and the other shall be secured to the draw box.

The circuit conduit passing through the sleeve shall be terminated at 40 mm inside the draw box and in the case of metallic conduit, the conduit end shall be fitted with a brass bush. The gap between the sleeve and the conduit at the joint shall be sealed with "Pratley Tic-Tac" or equal sealing compound, to prevent the ingress of wet cement. In the case of metallic conduit, an earth clip shall be fitted to the conduit projection inside the draw box and the conduit bonded to the box by means of 2,5 sq.mm bare copper earth wire and a brass bolt and nut.

The end of the other circuit conduit shall be secured to the draw box by means of locknuts and a brass bush in the case of screwed metallic conduit or a standard bushed adaptor for other conduit types.

In addition to an earth wire which may be specified for the circuit, a 2,5 sq.mm bare copper wire shall be provided between the first conduit box on either side of the joint in the case of metallic conduit. The conduit boxes shall be drilled and tapped and the earth wire shall be bonded to the boxes by means of lugs and brass screws.

Suitable steel cover plates shall be screwed to draw boxes installed along the expansion joint. The cover plates shall be installed before the ceilings are painted.

Where a number of conduits are installed in parallel they shall cross the expansion joint of the structure via a single draw box. A number of draw boxes adjacent to each other will not be allowed.

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2.2.7.8 Screeds

The installation of conduits in floor screeds shall be kept to a minimum. Where conduits are installed in screeds, the top of the conduit shall be at least 20 mm below the surface of the screed. Where the screed is laid directly on the ground, galvanised conduits shall be used. This ruling will always be applicable to the lowest floor of a building. A minimum distance of twice the outside diameter of the conduit shall be left free between adjoining conduits. Conduits shall be secured to the concrete slab at intervals not exceeding 2,0 m. The Electrical Contractor shall ensure that conduits are not visible above the screed where the conduits leave the screed.

NOTE

Under no circumstances will conduit having a wall thickness of less than 1,6 mm to be allowed in screeding laid on top of concrete slabs.

2.2.7.9 Inspection

All draw boxes, conduits etc., which are installed in concrete shall be cleaned with compressed air and provided with draw wires two days after removal of the shuttering. Errors that occurred during the installation of the conduits, or any lost draw boxes or blocked conduits shall be immediately reported to the Engineer by telephone and confirmed in writing in order that an alternative route can be planned and approved by the Engineer before the additional concrete is cast. Any additional cost shall be to the Electrical Contractor's account.

2.2.8 Installation in roof spaces 2.2.8.1 Appearance

All conduits shall be installed horizontally or vertically as determined by the route and the Electrical Contractor shall take all measures to ensure a neat installation.

Conduit in roof spaces shall be installed parallel or at right angles to the roof members and shall be secured at intervals not exceeding 1,5 m by means of saddles screwed to the roof timbers.

Where non-metallic conduit has been specified in roof spaces for a particular service, the conduit shall be supported and fixed with saddles with a maximum spacing of 450 mm throughout the installation. The Electrical Contractor shall supply and install all additional supporting timbers in the roof space as required.

Under flat roofs, in false ceilings or where there is less than 0,9 m of clearance, or should the ceilings be insulated with glass wool or other insulating material, the conduit shall be installed in such a manner as to allow for all wiring to be executed from below the ceilings.

Conduit runs from distribution boards shall, where possible, terminate in fabricated sheet steel draw-boxes installed directly above or in close proximity to the boards.

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2.2.8.2 Saddles

Conduits shall be firmly secured by means of saddles and screws and in accordance with SABS 0142, par. 5.4.2.(b) Conduits shall be secured within 150 mm before and after each 90 degrees bend. Nails or crampets will not be allowed.

2.2.8.3 Fixing to Walls

Only approved plugging materials such as fibre plugs or plastic plugs, etc., and round head brass screws shall be used when fixing saddles, switches, plugs etc., to walls. Wood plugs are not acceptable nor should plugs be installed in joints in brick walls.

2.2.9 Chases and Builder's Work

All conduit and conduit accessories shall be built in and no coring shall be allowed without written approval from the Engineer.

Electrical materials to be built in must be supplied, placed and fixed in position by the Electrical Contractor when required to do so by the Builder or Main Contractor. The Electrical Contractor shall also ensure that these materials are installed in the correct positions.

Except where otherwise specified the Builder or Main Contractor shall be responsible for the Builder's work related to the installation of conduits, outlet boxes, switchboard trays, bonding trays and other wall outlet boxes and will undertake the necessary chasing and cutting of walls and the provision of openings in ceilings and floors for luminaires and other electrical outlets. The Electrical Contractor shall notify the Builder of his requirements and the responsibility lies with the Electrical Contractor to ensure that all Builder's work is clearly indicated or marked where necessary and provide in accordance with his requirements.

Where no Builder is available the Electrical Contractor must provide all chases and is required to cover conduits installed in chases by a layer of 4:1 mixture of coarse sand and cement, finished 6 mm below the face of the plaster and roughened. Chases shall be deep enough to ensure that the top of conduits are at least 12 mm below the finished plaster surface.

Where there is no builder available and the Electrical Contractor is responsible for the cutting of chases or the building-in of conduits and other equipment, he will be held responsible for all damage as a result of this work and will be required to make good to the satisfaction of the Engineer. This ruling is particularly applicable but not exclusive to the rewiring and renewal of existing installations. Chases shall be made by means of cutting machine.

Under no circumstances shall face brick walls or finished surfaces be chased or cut without the written permission of the Engineer. Where it is necessary to cut or drill holes in the concrete structure, the prior permission of the Engineer shall be obtained.

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2.2.10 Surface Mounted Conduit

Wherever possible, the conduit installation is to be concealed in the building work; however, where unavoidable or otherwise specified, conduit installed on the surface must be plumbed or levelled and only straight lengths shall be used.

The use of inspection bends is to be avoided and instead the conduit shall be set uniformly and inspection couplings used where necessary.

No threads will be permitted to show when the conduit installation is complete, except where running couplings have been employed.

Running couplings are only to be used where unavoidable, and shall be fitted with a sliced coupling as a locknut.

Conduit is to be run on approved spacer saddles rigidly secured to the walls.

Alternatively, fittings, tees, boxes, couplings etc., are to be cut into the surface to allow the conduit to fit flush against the surface. Conduit is to be bedded into any wall irregularities to avoid gaps between the surface and the conduit

Crossing of conduits is to be avoided, however, should it be necessary, purpose-made metal boxes are to be provided at the junction. The finish of the boxes and positioning shall be in keeping with the general layout.

Where several conduits are installed side by side, they shall be evenly spaced and grouped under one purpose-made saddle.

Distribution boards, draw-boxes, industrial switches and socket outlets etc. shall be neatly recessed into the surface to avoid double sets.

In situations where there are no ceilings the conduits are to be run along the wall plates and tie beams. In buildings where building operations are to be carried out, all surface conduit will be painted by the building contractor.

In all other instances the Electrical Contractor shall allow for painting of surface conduit with two coats of good quality enamel paint, and the colour shall match the surrounding building finish.

Only approved plugging materials such as aluminium inserts, fibre plugs, plastic plugs, etc., and round-head screws shall be used for fixing saddles, switches, socket outlets, etc., to walls, wood plugs and the plugging in joints in brick walls are not acceptable.

2.3 WIRING 2.3.1 General

Wiring shall consist of PVC insulated 600/1000V grade stranded copper conductors and bare stranded or green PVC insulated copper earth conductors, except where expressly stated otherwise.

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Wiring may only be carried out after the complete conduit installation for a sub-distribution board has been completed. The wiring shall, however, be completed before paintwork commences.

Wiring shall be carried out by means of the loop-in system, except where stated otherwise. Only circuits of the same type may be wired in one tube, with a maximum of two circuits per tube. No more than 4 conduit ends shall appear at any one light outlet. No joining of conductors in tubing shall be allowed.

Where aluminium sheathed or mineral insulated copper sheathed cables are to be employed, they shall be used strictly to the manufacturer's instruction.

The following conductor sizes shall be used except where stated otherwise.

Lighting circuits : 1,5 sq.mm Socket outlet circuits : 4,0 sq.mm Stove circuits : 6,0 sq.mm with a 4 sq.mm

earth conductor

Earthing of fluorescent : 2,5 sq.mm fittings and socket outlets

The colour of conductor insulation shall comply with SABS 0142 para. 5.2.1(d). The colour of conductors for two-way and intermediate switches shall preferably differ from the colour of the phase conductors.

Where cable ends connect onto switches, fittings etc., the end strands must be neatly and tightly twisted together and firmly secured. Cutting away of wire strands of any cable will not be allowed.

2.4 MOUNTING HEIGHT OF DISTRIBUTION BOARDS, SWITCHES AND SOCKET

OUTLETS

Except where stated otherwise, mounting heights shall be as follows:

Distribution boards : top frame 2000 mm above finished floor level Switches : underside 1400 mm above finished floor level. Socket outlets : underside 300 mm above finished floor level Telephone outlets : underside 300 mm above finished floor level

All distribution boards, switches and socket outlets shall be of the flush mounted type except where stated otherwise.

2.5 POSITION OF OUTLETS, EQUIPMENT AND CONDUIT

Positions of light outlets indicated on the plans are approximate. The exact positions of light outlets shall be determined with due regard to ceiling squares, brandering and patterns. Where any doubt arises as to the correct location of outlets, the Engineer and/or Architect shall be consulted.

The positions of other outlets, equipment and conduit are also approximate. The exact positions shall be determined on site in consultation with the Engineer

1/2/33

and/or Architect. 2.6 MOUNTING OF LIGHT FITTINGS

Light fittings shall be mounted such that each fitting may in its entirety be easily removed. Fluorescent fittings shall be mounted such that they fit tightly against the ceiling and no sagging occurs at the ends. In the case of a ceiling with an open roof space 50 x 76 mm wooden bearers shall be supplied to support fluorescent fittings.

2.7 CONNECTIONS 2.7.1 Outlets

Connection between the circuit wiring and that of appliances or equipment shall be by means of porcelain connectors with heavy brass terminals. Where the temperature at a connection point may exceed 57 degrees C (135 degrees F) only asbestos covered conductors are to be used from the appliances or pieces of equipment to the connection point.

2.7.2 Electric Hot Water Geysers

Circuit wiring for geysers shall consist of 2 x 4 sq.mm PVC conductors and a 2,5 sq.mm earth wire in 20 mm diameter conduit terminating at an adequately rated surface isolator near the geyser. The final connection from this outlet to the geyser shall consist of heat resistant conductors in flexible conduit.

2.7.3 Electric Stoves

Stoves shall be provided with a single or three-phase feeds as required in the Detail Specification.

Behind every stove shall be mounted a double pole isolator (for single-phase connections), flush in the wall, underside 1400 mm above floor level.

A 25 mm diameter conduit shall be installed flush in the wall from this isolator to a point behind the stove 450 mm above floor level, the end being set out of the wall, pointing downwards, and provided with a brass bush.

The connection shall be made by means of 6 sq.mm PVC cable with a suitable cable gland. Cables shall be of sufficient length to allow the stove being moved at least 600 mm from its normal position, for cleaning purposes.

Wiring shall be carried out with 2 x 6 sq.mm conductors for single-phase connections and 4 x 6 sq.mm conductors for three-phase connections, with 4 sq.mm earth conductor.

2.7.4 Incinerators

The supply to an incinerator shall be connected by means of 2 x 4 sq.mm conductors with 2,5 sq.mm earth wire in 20 mm diameter conduit. A flush mounted 30 ampere double pole micro-gap isolator shall be mounted next to the incinerator, flush in the wall, 1400 mm above floor level. The incinerator shall be mounted with the lower edge 1000 mm above floor level.

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2.7.5 Panel Heaters

A round draw box shall be mounted behind the heater terminal block, flush in the wall.

Wiring to the draw box shall be carried out by means of 2 x 4 sq.mm conductors with 2,5 sq.mm earth wire in 200 mm diameter conduit, to the aforementioned draw box.

Connection to the heater shall be by means of a 3-core, rubber insulated, asbestos-sheathed cotton covered flexible cord, connected to the PVC conductors by means of a porcelain connector.

2.8 TELEPHONE OUTLETS

Except where otherwise specified, a telephone outlet shall consist of a 100 x 100 x 50 mm deep wall box mounted flush in the wall, with the underside 300 mm above finished floor level.

The wall box shall be provided with a cover plate with a 10 mm diameter hole drilled on the horizontal centre line, 30 mm from the vertical centre line. A rubber grommet shall be provided in the hole.

2.9 SOLDER, INSULATION TAPE, ETC.

Solder, insulation tape and any other minor items of material usually employed by electricians in their trade, do not appear as separate items in the schedules or Bills of Quantities. It will, however, be assumed that the Electrical Contractor has allowed therefore in his prices.

2.10 EARTHING 2.10.1 General

The whole installation together with the associated buildings and structures shall be earthed properly in accordance with SABS 0142 and the Code of Practice for the "Selection, Handling and Installation of Electrical Power Cables". The local Municipal bye-laws should also be observed in this respect.

All earth conductors shall be stranded copper with or without green PVC insulation. The conductor sizes shall be determined in accordance with SABS 0142 paragraph 4.6 where the earth does not form an integral part of the cable.

Under no circumstances shall any connection points, bolts, screws, etc., used for earthing be utilized for any other purpose.

2.10.2 Earthing of Sub-stations

All sub-stations shall be earthed in accordance with the requirements of the Supply Authority. If no earthing method is specified and no specific requirements of the Supply Authority exist, the following method may be adopted.

2.10.2.1 Main Earth Bar

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A main earth bar (minimum cross-sectional area 50 mm x 6 mm and of HDHC copper) must be provided and fixed to the high voltage room wall by means of shock proof insulators. Suitable space shall be provided between the earth bar and the wall.

All earth wires must be secured to the earthing bar by means of 10 mm diameter brass bolts. Locknuts shall be provided for all terminals.

The following connections shall be made from this earthing bar system:

i) 70 sq.mm insulated stranded conductor to transformer neutral.

ii) Copper busbar to transformer tank (where applicable) and frame (25 x 6 mm)

iii) 70 sq.mm bare copper earth wire to HT switchgear frames.

iv) 70 sq.mm copper earth wire to switchgear frame and board.

v) 2 x 70 sq.mm bare copper earth wires to earth electrodes/earth rods.

vi) 70 sq.mm bare copper earth wire to the Municipal main water feed.

Where necessary, earth connections shall be protected against mechanical damage and corrosion.

2.10.2.2 Earth Rods

Two earth rods shall be driven into the ground in the immediate vicinity of the substation at least 3 m apart with their tops not less than 600 mm below ground level. The rods shall be interconnected with a 70 sq.mm bare copper conductor buried at a depth of not less than 750 mm. A 70 sq.mm earth conductor shall be taken from each of the two earth rods to the main earthing bar in the high tension room.

2.10.3 Miniature Substation Earthing

The earthing of mini-substations is similar to the earthing requirements of substations described above except that a main earth bar is not required. The earthing bar in the LV compartment shall become the main earth bar. The HV switch, transformer earth terminal and neutral busbar shall be bonded to the earthing bar in the LV compartment as described for sub-stations.

2.10.4 Switch Room

The earthing of switch rooms utilizing earth rods is similar to the earthing requirements of substations described above. A main earth bar is required to which the earthing rods and the HV switchboard shall be bonded by means of 70 sq.mm earth wires.

2.10.5 Outdoor Equipment

In cases where substations contain transformers or switchgear installed

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outdoors, the compulsory fence, if no other method is specified, shall be earthed as follows :

i) A 70 sq.mm earth wire shall be installed 400 mm below ground level and

500 mm from the fence on the outside of the substation along the entire length of the fence. This earth wire shall be earthed at each corner by means of a 1,8 m earth rod and the rod and earth wire bonded to the fence. The earth wire shall also be bonded, at least at two points, to the main earthing system.

ii) A 70 sq.mm earth wire shall be buried at a depth of 400 mm around each transformer and switch and bonded to the main earthing system.

2.10.6 L.T. System

A separate earth connection shall be installed from every sub-distribution board to the earth terminal on the main distribution board. These earth connections shall consist of bare copper conductors, drawn into conduit or piping, together with PVC conductors or cables.

Socket outlets shall be connected with a 2,5 sq.mm earth conductor to the earth busbar in the relative distribution board.

The earth terminals of fluorescent light fittings shall be connected to the nearest earth terminals by means of 2,5 sq.mm stranded copper conductors.

The earth terminals on the main distribution board shall be earthed by means of a 70 sq.mm bare copper conductor connected to the cold water main.

2.10.7 Buildings

All hot and cold water pipes and discharge pipes shall be interconnected by means of 12 x 1,6 mm solid or perforated copper tape and clamped with brass bolts and nuts. Copper tapes shall be fixed to walls by means of brass screws at intervals not exceeding 250 mm.

Iron roofs, gutters, down-pipes, etc., shall be interconnected in the same way. Connections shall be carried out with brass bolts and nuts (not self-tapping screws).

Iron roofs shall be connected at intervals not exceeding 15 m with a common earth conductor or bare copper wire. The common earth conductor shall run under the roof over the full length firmly fixed to the upper purlin.

This earth conductor shall also be connected to the main earth conductor of every distribution board.

When plastic conduit is used, a 2,5 sq.mm bare copper conductor shall be installed throughout for earth continuity.

This copper conductor shall be securely fixed to all metal appliances and equipment, including switch boxes, socket outlet boxes, draw boxes, switchboards, luminaires, etc.

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2.10.8 Sub-distribution boards

A separate earth connection shall be supplied between the earth busbar in each sub-distribution board and the earth busbar in the Main Switchboard. These connections shall consist of bare or insulated stranded copper conductors installed along the same routes as the supply cables or in the same conduit as the supply conductors. Alternatively armoured cables with earth continuity conductors included in the armouring may be utilized where specified or approved.

2.10.9 Sub-circuits

The earth conductors of all sub-circuits shall be connected to the earth busbar in the supply board in accordance with SABS 0142.

2.10.10 Ring Mains

Common earth conductors may be used where various circuits are installed in the same wireway in accordance with SABS 0142. In such instances the sizes of earth conductors shall be equivalent to that of the largest current carrying conductor installed in the wireway, alternatively the size of the conductor shall be as directed by the Engineer. Earth conductors for individual circuits branching from the ring main shall be connected to the common earth conductor with T-ferrules or soldered. The common earth shall not be broken.

2.10.11 Non Metallic Conduit

Where non-metallic conduit is specified or allowed, the conduit and accessories shall be in accordance with SABS 950. Stranded copper earth conductors shall be installed in the conduits and fixed securely to all metal appliances and equipment, including metal switch boxes, socket-outlet boxes, draw-boxes, switchboards, luminaires, etc. The securing of earth conductors by means of self-threading screws will not be permitted.

2.10.12 Flexible Conduit

An earth conductor shall be installed in all non-metal flexible conduit. This earth conductor shall not be installed externally to the flexible conduit but within the conduit with the other conductors. The earth conductor shall be connected to the earth terminals at both ends of the circuit.

2.10.13 Connections

Under no circumstances shall any connection points, bolts, screws, etc., used for earthing be utilized for any other purpose. It will be the responsibility of the Electrical Contractor to supply and fit earth terminals or clamps on equipment and materials that must be earthed where these are not provided. Unless earth conductors are connected to proper terminals, the end shall be tinned and lugged.

2.11 SUB-STATION ACCESSORIES

The Electrical Contractor shall provide and fix in each individual room of the new

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sub-station, in suitable approved frames, the following notices which are to be displayed in terms of the "Factories, Machinery and Building Work Act" of 1941.

i) A notice prohibiting unauthorised persons from entering such premises. ii) A notice prohibiting unauthorised persons from handling or interfering

with electrical apparatus. iii) A notice containing directions as to procedure in case of fire.

iv) A notice containing directions as to restoration of persons suffering from

the effects of electric shock.

In addition a cast aluminium plate, bearing the inscription "Danger high tension apparatus. No admittance to unauthorised persons" in both official languages and one Black language, as well as a standard danger plate of suitable size bearing scull and cross bones shall be provided and securely fixed to the outside of all substation doors. The lettering on the plate shall be raised and polished against red background.

The Electrical Contractor shall also provide the following items of substation equipment in the LT rooms of substations :

i) Two fire extinguishers with 2,25 kg capacity with long range nozzles,

similar to MSA 51502, fixed to the wall near the door. ii) A first aid box, suitably stocked with the necessary equipment for the

immediate treatment of persons suffering from burns and/or electric shock.

iii) One pair of rubber gloves.

The above items are to be properly mounted on suitable racks secured to the walls.