Hi All I have a bungalow which I am extending so all new wiring will be in loft. My question is: Building regs want me to have 300mm of insulation in 3 overlapping layers. Reading other posts I understand that wiring should not be covered by insulation but at the same time should be clipped to joists and not left hanging around. If I clip to joists I will be covering the cables with the insulation which I don't wont to do. Is it ok to just leave the cables lying on top of the new insulation? Any suggestions please. Thanks KBG
The current carrying capacity of a cable is already adjusted for insulation touching one side only. Which yours would be if you clipped them to the ceiling joists. But good installation practice would be to clip them totally clear of the insulation, althuogh this means nailing lengths of wood along your trusses ( we normally use the 'strappers ' built in by the joiners.
You could use nylon cable ties, to strap cables to the roof truss timbers, this way you save nailing vibration that may loosen roof tiles etc. Using nylon cable ties also allows the circuit to be removed at a later date, for wahatever reason, without any trace or damage to the timbers, no holes etc.
Thanks for your replies. I thought that the best way would be to tack some batten to the rafters just above the ceiling joists and run all the cables along this and then run any cables to lights etc across the insulation to the ceiling fittings. thanks KBG