9.1 SURFACE WIRING
Surface wiring shall be carried out with PVC insulated PVC sheathed cables of 300/500 V grade to MS 136 and 600/1000 V grade to MS 274. The conductors shall be of stranded plain annealed copper to MS 69 and MS 280.
The insulation shall be suitable for continuous operation at a maximum cable temperature of 70 0C and comply with MS 138. The cables shall be run on the surface of the walls, floor slabs and in the ceiling spaces. The cables shall be secured by lead alloy saddles. Not more than 10 cables shall be cleated together using the same saddles.
For wiring on plaster or brickwork the cables shall be run on `treated’ hardwood battens secured on the surface with brass screw spaced at not more than 600 mm apart and atplaces where necessary.
Cables crossing metal surface shall be enclosed in PVC conduit or PVC casing. Saddles shall be fixed by brass nails and spaced at not more than 150 mm apart. Wiring in ceiling spaces shall be protected by galvanised steel conduits. Downdrop from the ceiling rose to luminaire shall be of 3-core PVC insulated sheathed flexible cord of size no less than 0.75 mm to MS 136.