Electrics on top of celotex

[baker332]

Hi,

On building an extension, I opted for cold roof and in order to gain max thermal performance decided to not run electrics for spotlights. Now I need to add lighting such as LED track lights, is it possible to run the cable ontop of the celoxte under/in the plasterboard? The plasterboard is screwed directly onto the celotex therefore assume I need to remove a channel in the plasterboard and run the cable in conduit then skim over the top.

Is this feasible how much air gap would be required or conduit? The run is quite small to the light around 30cm or so.

Thanks

 

[chivers67]

I tend to opt for conduit and a round conduit box for maintenance Using 1.5mm to Feed lights and channel a small amount the celotex (depending on how thick it is) given it's not that big it's hardly going to compromise the insulation.

 

[baker332]

I tend to opt for conduit and a round conduit box for maintenance Using 1.5mm to Feed lights and channel a small amount the celotex (depending on how thick it is) given it's not that big it's hardly going to compromise the insulation.

Thanks - Celotex is 40mm on top of 100mm, I could channel out some of the 40mm if required. So the question is, is it safe as the cables surrounded by insulation? And should this just be boxed in plastic conduit and then filler over the top of it?

 

[chivers67]

There are derating factors to take into account when running cable through insulation hence the 1.5mm which should cover it without getting too technical, I don't think there are any cross polymerisation issues with Celotex with PVC cables (unlike polystyrene) but if it's in a small length of conduit of trunking it should be protected.

 

[baker332]

There are derating factors to take into account when running cable through insulation hence the 1.5mm which should cover it without getting too technical, I don't think there are any cross polymerisation issues with Celotex with PVC cables (unlike polystyrene) but if it's in a small length of conduit of trunking it should be protected.

Thanks Chivers - I'll carry on and may uprate the cable just for peace of mind.