Wiring Installation General Guidelines and Wiring Termination

Wiring Installation General Guidelines and Wiring Termination

Wiring

All wiring shall be installed in raceway systems, cable tray as indicated on the contract drawings. Wiring installed in below-grade concrete pits, manholes, pull boxes, or wireways shall be supported from, and secured to, cable trays or similar supports. Cable racks shall be provided on manhole walls to route and support cables along the perimeter of the walls. Keywords used for this article: Wiring Installation General Guidelines and Wiring Termination. Splices in Wiring. Taping of lugs and busses. Torquing of Bolted Connections.

Whenever possible, all wire and cable shall be fed directly from spools or reels into conduits or manholes to prevent cable damage caused by dragging the cable over the ground during cable pulling. If pulling the cable over the ground is necessary, the ground surface must be smooth, clear of sharp gravel, and covered with protective material.

Splices in Wiring

Wire and cable runs for 480 volt or higher system voltages must be continuous and without splice.

 Splices in 120 volt control, alarm, instrumentation, and thermocouple wires are only permitted to be made on terminals as identified on the contract drawings for that purpose.

 Splices in lighting and convenience receptacle circuits shall be made with indent-type splicing sleeves insulated with ScotchÒ 33+ tape 3M “ScotchlokÔ” electrical spring connectors, or equivalent, and secured to the wires with ScotchÒ 33+ tape. All splices must be accessible and in approved enclosures.

 Termination’s to solenoid valves and pig-tailed devices shall be according to standards drawings. All other switches and devices shall be wired directly without intermediate terminations.

 All field wiring installed within panels or equipment enclosures shall be neatly bundled and adequately secured unless wiring ducts are provided for field wiring. Bundles shall be secured by the attachment of the cable ties to the internal structure of the enclosure or to screw‑attached or epoxide cable tie mounts. Self-adhesive cable tie mounts shall not be used.

Wherever type TC multiconductor power and control cable, or equivalent, enters an enclosure or motor control center wireway, the outer jacket shall be completely removed within 50 mm (2 in) of entry.

A cable-pulling compound shall be used with all cables or wires as required for underground or long above-ground conduit pulls. The compound shall be certified by the manufacturer of the cable as being harmless to the type cable used. No alkaline soap compounds shall be used.

Whenever aluminum conductors are terminated, they shall be treated with a corrosion inhibitor and oxide penetrating compound (such as “Penetrox A” manufactured by the Burndy Company).

 Taping of lugs and busses

The contractor shall not perform taping or boot installation until requested by the field representative.                                     

 All terminal lugs for low voltage AC power wiring that are not terminated on terminal strips or under terminal screws (for example, motor leads to field conductors in motor terminal boxes) shall be insulated using 3MÒ “Motor Lead Splicing Kits” 5300 Series, sized as required. If necessary, taping may also be used as an alternate method using the following procedure and materials.

1st        Release Layer: Two, half-lapped layers of ScotchÒ 33+ tape, sticky side out
2nd       Insulation: Three, half-lapped layers of ScotchÒ 130C tape
3rd       Jacket: Two, half-lapped layers of ScotchÒ 33+ tape

 Non-insulated busses of bus duct in motor control centers, switch gear, and all non-insulated motor control center (MCC)/switch gear bus splice connectors shall be taped using the following procedure and materials. Removable molded insulating boots (Raychem type BCIC or equivalent) may be used instead of taping, if the boots are of the suitable voltage rating and applied to match the exact bus/cable or bus/bus configuration. Heat-shrink-type insulation systems are not acceptable.

Low Voltage
1st           Release Layer: Two, half-lapped layers of ScotchÒ 33+ tape, sticky side out
2nd             Insulation: Two, half-lapped layers of ScotchÒ 33+ tape
Medium Voltage, 5 to 15kv
1st           Release Layer: Two, half-lapped layers of ScotchÒ 70 tape
2nd             Insulation: Three, half-lapped layers of ScotchÒ 130C tape
3rd          Jacket: Two, half-lapped layers of ScotchÒ 70 tape

 

Torquing of Bolted Connections

All low and medium voltage power cable connections to lugged connectors and the joints of bus sections regardless of voltage shall be torqued per the manufacturer’s requirements. Connections shall be made using a calibrated hand torque wrench. These terminations must be witnessed by and signed off by the field representative. When the manufacturer’s data is not available, consult the field representative for proper torque values to be used.

Spare Wires—All spare wires and instrument pairs/triads shall be neatly bundled, coiled, and individually labeled “SPARE” and the appropriate conduit or cable tag, that is, “SPARE-MV21” wire length shall be long enough to reach any termination point within the enclosure or programmable electronic system (PES) and motor control centers lineups. Spare wires entering motor control centers via pits shall be coiled in the top horizontal wireway. All 600V spare wires and conductors in multiconductor cables shall be grounded at both ends using split bolt connectors or equivalent. Ensure the grounding conductor in multiconductor cable is identified with a green surface according to the note in paragraph. The contractor shall not ground spare conductors until requested by the field representative.

 Continuously wrapped pre-bundling of individual ac control and power wiring is prohibited. This is prohibited to prevent overheating of the innermost wires of the pull bundles.

Protection of Wiring

Where wiring passes through access holes between adjacent metal or fiberglass enclosures, (for example, rear of motor terminal boxes for motor lead access, wire routing cut-outs between motor control center, and switchgear sections) either field cut by the contractor or provided by the equipment manufacturer, contractor shall protect wiring from damage caused by sharp edges around the entire opening using a poly-cushioned, nylon-coated stainless steel push-on grommet strip.

Keywords used for this article: Wiring Installation General Guidelines and Wiring Termination. Splices in Wiring. Taping of lugs and busses. Torquing of Bolted Connections.

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