3.8 WIRES, CABLES, FEEDERS AND
RELATED ACCESSORIES
PART 1 GENERAL
3.8.1.1 DESCRIPTION OF WORK:
Low voltage (LV
3.8.1.2 CURRENT CARRYING CAPACITIES:
Of conductors have been determined in accordance with the Regulations for specified type of insulation and expected conditions of installation. No change will be accepted in specified type of insulation unless warranted by special conditions and approved by the Engineer. Check various loads and current carrying capacities and report any discrepancies or insufficiency of sizes indicated to the Engineer
.
3.8.1.3 VOLTAGE DROP
Voltage drop shall be less than 5% (main feeder 2% and sub feeder 3%)
3.8.1.4 STANDARDS:
Wires and cables are to comply with IEC or other equally approved standards and are to bear the mark of identification of the Standards to which they are manufactured. Wires and cables not having this identification will be rejected.
3.8.1.5 TECHNICAL DATA:
Submit data including, but not limited to, the following:
Technical data including constructional details, standards to which cables comply, current carrying capacities, derating factors for grouping and temperature
- Manufacturer's catalogue cuts
- Dimensional and electrical characteristics
- Samples of each cable and wire and, if requested by the Engineer, other accessories.
3.8.1.6 CERTIFICATE OF ORIGIN:
For each lot of cable supplied, provide a certificate of origin issued by manufacturer stating origin, date of manufacturing, composition, standards to which it complies and test certificates
3.8.1.7 SHOP AND CONSTRUCTION DRAWINGS:
Submit drawings including, but not limited to, the following:
- Exact routing layouts, sections and profiles of bus ducts, trays, feeder and sub-feeder cables and branch circuits, with indication of any equipment to show and verify coordination between various trades.
- Details of supports and fixings for buses, trays and cables
- Details of connections to transformers, switchboards, panel boards etc.
- Details of terminations, splices and tapping where permitted, glands and bushings at enclosures
- Number and size of conductors in conduit for all branch circuits in accordance with final conduit routing
3.8.1.9 APPROVED MANFUACTURERS:
Obtain wires, cables and feeders from one of the following:
Arab Cables Co. EGYPT
Egyptian Cables Co. EGYPT
or other equal and approved.
PART 2 CABLES, WIRES, FEEDERS AND ACCESSORIES
GENERAL
3.8.2.1 CONDUCTORS:
Unless otherwise specified or shown on the Drawings, cables and other feeders are to have copper conductors.
Cable conductors are to be stranded for sections 4 mm2 and above based on IEC 228 Class 2.
Signal and control cables are to have solid conductors unless otherwise specified.
Flexible cords are to have finely stranded conductors.
Conductors of single core cables 25 mm2 and above are to be compacted.
Multi-core cables 35 mm2 and above are to be of sectoral shape.
3.8.2.2 CONDUCTOR SIZES:
Are to be metric and as shown on the Drawings and schedules. Conductors with cross-sectional area smaller than specified will not be accepted.
3.8.2.3 BUILDING WIRING INSULATION:
Is to be color coded or otherwise identified as required by the Regulations.
- Neutral is to be black or grey
- protective earth is to be green or green/yellow striped
- Phase colors where not specified by the Regulations are suggested as red, yellow, dark blue for 380/220 V systems .Maintain color coding throughout installation.
Phase- conductors for which outer jacket is not color coded are to either have engraved alphanumeric mark (L1, L2, L3) or color coded heat-shrinkable sleeves.
3.8.2.4 BURIED CABLES:
Cables buried directly in the ground are to be armoured type, unless otherwise indicated in particular Sections of the Specification or on the drawings.
PART 3 LOW VOLTAGE WIRES AND CABLES
3.8.3.1 SINGLE CORE PVC INSULATED CABLES (BUILDING WIRES):
Unless otherwise specified, single conductor cables for wiring in conduit are to have annealed copper conductors, generally with concentric strands and insulated with flame retardant, moisture and heat resistant PVC/E to IEC 227 (type 5 to BS 6746), suitable for wet locations and for conductor temperature of 85 deg. C. Wires and cables are to be 450/750 V grade to SSA55.
3.8.3.2 MULTI-CORE PVC INSULATED CABLES (0.6/1 kV):
Are to have annealed, copper conductors, insulated with PVC/E to IEC 227(type 5 to BS 6746), flame retardant, moisture and heat resistant, suitable for wet locations and conductor temperatures of 85 deg. C, laid up, bedded with suitable filler and over-sheathed with PVC. Armored cables are to have single layer of galvanized steel wire armored with PVC over sheath. Cables are to comply with IEC 502 and IEC 540.
PART 4 22KV MEDIUM VOLTAGE CABLES
3.8.4.1 THREE CORE - MEDIUM VOLTAGE CABLE:
22 kv stranded aluminum or copper conductor XLPE insulation, PVC inner sheath, PVC outer sheath, and having the following characteristics:
conductor : aluminum or copper, circular, stranded and compacted
Conductor screen : extruded semi-conducting layer
insulation : extruded cross-linked polyethylene
Insulation screen:
Non-metallic part : directly applied extrude semi conducting material
Metallic part : layer of copper tape applied with 30%overlap filling and bedding : polypropylene extruded over bedding up cores to form a compact
Outer sheath : extruded PVC (color red) type ST2 to IEC502
3.8.4.2 CABLE JOINTS:
Are to be as recommended by the manufacturer to render joints equal to cable in characteristics, in terms of insulation, stress distribution, water-tightness. Materials and methods of jointing are to be approved before confirmation of order.
PART 5 CONTROL AND SIGNAL CABL
3.8.5.1 MULTI-CORE PVC INSULATED CONTROL CABLES:
0.6/1 kV rating, solid 1.5 mm2, 2.5 mm2 or stranded 4 mm2 plain circular copper conductors with heat resistive PVC/E to IEC 227 (PVC type 5 to BS 6747) rated for 85 deg. C., of 7, 12, 19, 24, 30 or 37 cores. Cores are to be laid up together and filled with non-hygroscopic material, PVC over sheathed to form compact and circular cable for use in switchgear, control gear and generally for control of power and lighting systems.
Armored cable is to have an extruded PVC bedding which may be an integral part of the filling, galvanized steel wire armoring and an over sheath of PVC type ST2 to IEC 502, color black. Core identification is to be in white printed numbers 1, 2, 3 etc. over black color insulation.
3.8.5.2 PRE INSULATED CONTROL AND SIGNAL CABLES
Are to be generally 300 V rating, polyethylene insulated, color coded, tinned copper conductors (0.6 mm diameter), twisted together into pairs.
Multi-pair core assembly covered with binder tape and spirally wound 0.075 mm bare copper shielding tape with overall PVC sheathed.
3.8.5.3 CONTROL AND SIGNAL CABLES:
Enclosed in conduit with power cables, are to be insulated for 600 V.
PART 6 CONNECTORS (LV-POWER)
3.8.6.1 CONNECTOR:
Pressure indent type, for terminating or making T-taps and splices on conductors 10 mm2 and smaller. Connector is to be non-ferrous copper alloy material applied to conductor by mechanical crimping pressure, with vinyl insulating sleeves or phenolic insulating covers.
Bolted pressure split type for terminating or making T-taps and splices on conductors 16 mm2 and larger. Connector is to be cast non-ferrous copper alloy material applied to conductor by clamping with minimum of two screws and provided with phenolic insulating cover.
For connection of aluminum cables with copper busbars use approved bi-metal connector
PART 6 FIELD AND INSTALLATION WORK
WIRING AND CABLING INSTALLATION
3.8.6.1 GENERAL:
Building wires and cables are to be installed in conduit, trunking or ducts indoors and in conduit outdoors, unless otherwise shown on the Drawings
3.8.6.2 CIRCUITS:
Unless otherwise shown on the Drawings, final branch circuit wiring is to be run inside conduits. D.C. wiring is to be run in separate conduits from A.C. wiring. Emergency lighting and power circuits are to be run in separate conduits from normal circuits.
3.8.6.3 BRANCH CIRCUIT WORK:
Wiring from light and power panel boards is to be arranged as shown on the Drawings. Loads on the various phases of a panelboard are to be balanced by the contractor.
3.8.6.4 CONTROL CABLES:
May be fixed to racks, installed on trays or in conduit and trunking indoors, and in underground ducts or in conduit outdoors.
3.8.6.5 BUNCHING OF WIRES IN CONDUITS:
Is not to exceed that indicated on the Drawings or in accordance with conduit filling factors permitted by the Regulations.
3.8.6.6 BEFORE PULLING WIRES IN CONDUITS:
Check that inside of conduit and raceway is free of burrs and is dry and clean.
3.8.6.7 LUBRICANTS:
Are to be used for pulling wire or cable if character of pull would otherwise damage conductors, insulation or jacket. Lubricants are to be approved by the Engineer.
3.8.6.8 SUPPORT:
Cables and wires pulled inside conduits are to be supported at upper end of risers and at intermediate points by means of split rubber grommets in order to relieve any stresses on the conductors where required.
3.8.6.9 EXTRA LENGTH:
At every branch circuit outlet and pull-box, every cable passing through is to be left slack to allow inspection and connections to be made. Cables terminating in outlet boxes are to be left with at least 250 mm extra length for terminations.
3.8.6.10 JOINTS OR TAPS:
In wires and cables, if permitted, are to be permanently accessible and made only in boxes or cabinet gutters.
3.8.6.11 CONNECTORS:
For terminating or making T-taps and splices on conductors 10 mm2 or smaller are to be Type A-1. Connectors for conductors 16 mm2 and larger are to be Type A-2. Connectors for branch-circuit and fixture wiring are to be Type B-1.
3.8.6.12 INSULATING COVER:
Is to be applied to all connectors so that bare conductor will not be exposed.
3.8.6.13 SWITCH LEGS:
For local wall switches are to have distinctive color to be selected as complementary to cable color coding used in the project.
3.8.6.14 TERMINATIONS:
Conductors of wires and cables up to 16 mm2 are to be tightly twisted and where possible doubled back before being clamped with set screws. Where two or more wires are looped into same terminal these conductors are to be tightly twisted together before being inserted into terminals. In no case is bare conductor to be allowed to project beyond any insulated shrouding or mounting of a line terminal. Cables of sizes 16 mm2 and greater are to terminate in tunnel lugs with set-screw or by using bolted or sweated compression connectors.
3.8.6.15 TAGGING:
Tag main and feeder cables in pull-boxes, wire ways and wiring gutters of panel boards or distribution cabinets. Tags are to identify cable or circuit number and conductor size in accordance with the Schedules.
Where two or more circuits are run to or through a control device, outlet box or ceiling junction box, each circuit is to be tagged as a guide in making connections.
3.8.6.16 FEEDER AND SUB-FEEDER INSTALLATION (0.6/1KV)
3.8.6.16 .1 CABLES:
In general are to be run through duct-banks, shafts or special recesses, clamped to steel racks or cable trays. Cable run through ventilation shafts are to be installed in steel conduits.
3.8.6.16 .2 FIXING:
Single cables over false-ceilings or concealed spaces are to be fixed directly to walls or ceilings and must be accessible. Where two or more cables are run in parallel, they are to be fixed on galvanized steel perforated trays or on other approved special cable supporting and protecting arrangement.
8.8.6.16 .3 CLAMPS:
Cables are to be fixed to steel trays or supporting structures with approved galvanized cast steel clamps or molded plastic clamps (for single core cables) at distances not exceeding 20 diameters. This applies to cables in riser shafts or where an individual cable run is required.
3.8.6.16 .4 JOINTS OR SPLICES:
Will not be accepted on main and sub-feeders. Cables are to be supplied in lengths sufficient for straight-through unjointed termination to termination pull.
3.8.6.16 .5 DIRECTLY BURIED CABLES:
Crossing under roads, pipe banks or other services inside and outside buildings are to be laid in heavy duty PVC duct banks. In no case are cables to be directly buried in concrete, in masonry or in screed under floor tiles.
3.8.6.16 .6 PROTECTIONS:
Buried cables liable to mechanical damage, are to be drawn through PVC conduit or asbestos cement pipe. If steel conduit is used, all three phase conductors neutral and protective earth circuits are to be in the same conduit.
3.8.6.16 .7 EXPOSURE TO HEAT:
Route wires and cables to prevent exposure to excessive heat or to corrosive agents. If such condition is unavoidable, cables are to be of type designed for the particular condition.
3.8.6.16 .8 INSULATING COVERS:
Are to be applied to prevent exposure of bare cable connections. Insulating cover is to be purpose made and is to provide minimum insulation level equal to that of conductor insulation.
3.8.6.16 . GLANDS:
For various single-core and multi-core cables are to be purpose made and suitable for rigid mounting to equipment enclosure.
3.8.6.17 FEEDER CABLE JOINTING AND TERMINAT
3.8.6.17.1 THROUGH JOINTS:
Will not be allowed in feeder cables where adequate manufacturer’s lengths are available. In case a joint is necessary, it has to be made inside boxes, hand holes or manholes.
3.8.6.17.2 RECOMMENDATIONS:
Through joints and terminations are to be carried out strictly in accordance with cable manufacturer's recommendations. Joints and terminations are to be complete, made with correct specified materials, boxes, tapes, compounds or mixtures, stress cones, glands and bonds as applicable.
3.8.6.17.3 JOINTING:
Skilled jointers are to be employed for jointing of cables. Qualifications of jointers are to be submitted to the Engineer prior to work commencing on site. Joints are to be filled with epoxy resin after taping unless contrary to cable manufacturer’s recommendations. Sample site constructed cable terminations and through-joints are to be submitted to the Engineer prior to commencing work on site. Samples are to be constructed in the presence of the Engineer and are to be available to the Engineer for test and inspection in accordance with manufacturer's recommendations.
3.8.6.17.4 CUTTING TOOLS:
For jointing and terminating cables are to be purpose made to prevent damage to insulation in general and cable shielding in case of medium voltage cables.
3.8.6.17.5 CLEANING LACQUER:
On conductors is to be by use of 'Scotch Brite' sponge and white spirit or equal approved.
PART7 TEST
3.8.7.1 CABLE TESTS:
Are to be carried out in accordance with the requirements of the IEC and BS standard.
3.8.7.2 TESTING EQUIPMENT:
Provide megger testers of various ranges as applicable, and high-voltage
test equipment as necessary for testing medium voltage installations. Use 1000 V megger on cables rated 0.6/1 kV; 500 V megger on cables rated below 500 volts, and 5000 V megger on medium voltage cables (up to 12 kV) for initial checks.
3.8.7.3 INSULATION RESISTANCE:
Is to be carried out in accordance with IEE Regulations Section 613-5 through 613-8 for low voltage power and lighting installations.
3.8.7.4 INSULATION RESISTANCE:
For control and signal cables is to be minimum 10000 Megohm/km for PE insulated cables and 100 Megohm/km for PVC insulated cables.
Provide cable test set (FOSTER model 50 or equivalent) with d.c. Readings
Busway higher than 500 Ampere
· The busway is a 3 phase, 4 wire with 100% neutral and 50% integral housing ground with voltage and current ratings as indicated on the contract drawings.
· The busway should have a sandwich type non ventilated configuration.
· The busway should keep a true sandwich design for both feeder and plug-in busway.
· The busway and associated fittings shall consist of copper conductors totally enclosed in aluminum housing.
· Fittings such as elbows, tees, flanges etc. shall be identical for use with both plug-in and feeder types of busway.
· The busway shall be capable of being mounted flatwise, edgewise, or vertically without derating.
· The busway shall consist of standard 3 meter section with special sections and fittings provided to suit the installation.
· Horizontal runs shall be suitable for hanging on 3 meter maximum centers.
· On vertical runs provide one adjustable hanger per floor.
· Busbars shall be fabricated from high strength 98% conductivity copper at least.
· Busbars at the contact surfaces and joints should be tin coated or silver plated.
· Busbars shall be insulated over their entire length, except at joints and contact surfaces with non-flammable 130oC insulation material.
· The busway should be able to withstand a high potential test of 2.2 kV for one minute.
· The busway shall be capable of carrying rated current continuously without exceeding a temperature rise of 55 o C based on a 40 o C ambient temperature.
· The busway joints shall be a single bolt design and de-energization of busway shall not be required for safe testing of joint tightness.
· The busway enclosure is made of aluminum with minimum thickness of 2.5 mm. The enclosure finish shall be epoxy powder paint applied by an electrostatic process.
· Minimum ingress of protection shall be: IP43 for indoor and IP54 for outdoor installation respectively.
· For plug-in type tape off points shall be available each 1 meter.
· Plug-in units shall be mechanically interlocked with the housing to prevent their installation or removal while the breaker is in the on-position.
· All plug-in units shall be equipped with an interlock to prevent the cover from being opened while the switch is in the ON position.
· The plug-in operating handle and mechanism shall remain in control of the circuit breaker at all times, permitting its easy operation from the floor by means of a hookstick or chain.
· Circuit breaker shall have an interrupting rating of not less than
End Of this Section
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