This article explains electrical power cables used in construction works complete with supply, installation, testing and commissioning of High Voltage (HV) and Low Voltage (LV) cables. All cables shall conform to standards of IS 7098-1973, IS 1554-1976 and wiring cables to IS 694-1977 however, contractor shall comply with the latest or superseded versions of IS/BIS to be used for the complete work.
Construction of High Voltage and Low Voltage Power Cables
- All power and lighting cables shall be aluminium conductors, PVC insulated, armored and PVC sheathed. The insulation grade shall be 1100 V. The control cable shall be of copper conductor, PVC insulated, armored, and PVC sheathed of 1.1 KV grade.
- Wiring cables for lighting shall be multi strand, copper conductors, PVC insulated of 1.1. KV grade.
- The HT cables shall be of aluminium conductors, XLPE insulated and armored or as specified in the Bill of Quantities.
Installation, Testing and Commissioning of Cables
- The cable routes shall be established before commencing the installation work.
- All cables to be buried in ground shall be done after digging uniform section trenches. The cables shall be laid with proper spacings (side by side) between adjacent cables. The cables shall then be covered with tiles or bricks and finally back-fillings with sand and earth.
- Cables buried in ground and crossing pathways, roads, etc. shall be laid in GI Pipes/Hume Pipes/PVC pipes, embedded in PCC etc.
- Cables run along prepared trenches or structures and wall shall be suitably clamped and cleared. The spacings of the clamps shall be dependent on the size of the cables. The cables shall be protected from mechanical damage while crossing floors etc. The spacers and saddles shall be of GI. The process of clamping and cleating shall be discussed with Architects/Owners and got approved.
- The use of cable trays, racks or direct clamping shall be determined before commencing the work and the same shall be got approved.
Terminations of Power cables
- All HV cable terminations shall be affected with conical heavy duty brass glands. The armour shall be bonded and securely clamped. The terminations shall be carried out with cable sockets, Raychem type jointing kits. There should not be any strain on the cable.
- The LV cable terminations shall be soldered or crimped on to cable sockets. In case of soldering, the solder and flux shall be of high quality. The terminations to the equipment shall be carried out with brass compression glands.
- After terminations, the individual phase conductors shall be tapped with coloured tapes for identifications.
- The HV/LV cable of terminations shall be pressure tested in the presence of authorities, before commissioning.
All tests of HV and LV cables and terminations shall be conducted as per applicable IS before energizing.