installing loft insulation OVER electrical wires

[summertike]

Please help. We recently bought a house. We want to instal the recommended 270mm worth of loft insulation. There are however lots of electrical cables (we think all lighting) running across the floor of the loft with very little slack (ie we cannot pull them up to go over the loft insulation). All the loft insulation packaging says that loft insulation must not be placed over electrical cables. Do we need to get everything rewired or is there a product out there that you can place over the cables?

Thanks very much

 

[mointainwalker]

Lighting wiring very unlikely to cause any problems due to light (sorry ) loading.

 

[Chri5]

Electrical cable loading is altered by insulation, the reason is operating temp goes from x in free air to y in insulation.

Derating can be as much as 60%.

In general most lighting circuits are fused at 6 amps at the board and run in either 1.0mm TE or 1.5mm TE which can handle about between 10 and 14 amps.

The best thing would be to audit you lighting circuit, so turn off the 1st lighting at the board to confirm the fittings on the circuit (which may include security lights and loft lights). Then add up all the wattage values of all the fittings lamps.

Watts divided by 230v equals amps. If the circuit is on or near to 6 amp ( very unlikely, but check anyway) then it might be best to get some trunking and contain the cables before the insulation is done.

As a further note, if you have spot lamps in the ceiling that make the split between 1st floor and loft they must have airspace.

http://www.tlc-direct.co.uk/Main_In...nlights_Index/Fire_Cover_Downlight/index.html