Loft insulation and lighting circuit

24 Sep 2004
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United Kingdom
I realise there are numerous similar posts to this but I'm asking here as I want to be sure I won't compromise the electrical safety of our home.

I'm planning on insulating the loft and boarding out the centre area for storage. The roof is a truss roof spaced at 610mm with 120mm joists. The lighting circuit is wired in 1.0mm twin and earth and cables are currently clipped to the side of the joists. The circuit is protected by a 6amp mcb.

I intend on laying 100mm thick fibreglass insulation between the joists and then boarding over the centre with loft panels. This would leave a void of 20mm between the top of the insulation and the bottom of the loft floor.

My question is should I unclip the cables and lay them on top of the insulation in the 20mm void? Or should I leave them where they are which means they will end up sandwiched between the edge of the insulation and the joist?

Also, what should be done with the insulation when a cable passes through it to get to an accessory such as ceiling rose or switch plate? Should the insulation be cut away slightly to ensure the cable doesn't overheat?

Your thoughts would be appreciated.

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It is a good idea to clear as many cables away from insulation as possible.
Although upstairs lighting circuits are rarely loaded to full capacity (unless you have floodlighting off it or a rogue appliance!) and insulation would not be too much of an issue it is better to do the job correctly.
If you can clip the cables to the top part of the side of the joist then that should clear it as I read it.

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