Boarding loft with too much insulation

topgun06 · 24 Sep 2017 at 18:26

So this white lighting cable in this image... Is it bad practice to hide it under the loft boards or should it be clipped in place over the top? Or doesn't it really matter?

Buffman · 24 Sep 2017 at 18:50

If it's above the insulation then it probably won't matter. The reason they say not to put it under insulation is the cable might not be sufficiently sized to allow the load thru them (to recent BS should be fine).

Im sure someone will be in to tell me otherwise, but I'd just hide it underneath the insulation. Eg lighting circuits will have lower loads thru them these days due to LED lights etc.

topgun06 · 24 Sep 2017 at 21:02

I'm boarding over the top of the insulation, I was just wondering if I should conceal the cable under the board or to run it over the top since the cable would be so close the surface.

I'll probably hide it under the board.

robj20 · 25 Sep 2017 at 07:56

If your lights are LED dont worry about the rating of cables. Just dont go putting insulation over the top of things like shower cables as these can and do get hot if they are on the limit of their rating.
Typically lighting tends to be 1 or 1.5mm, which is 8 and 10A respectively insulated. LED at 8w is only 0.03A.

nutcase · 25 Sep 2017 at 13:38

You either need less insulation or taller legs - there's no airgap there.

topgun06 · 25 Sep 2017 at 14:34

I had read about that. But got very mixed views. Some say its recommended some say there is no need.

I was stood on some old loft boarding to take that photo. I've now ripped it up, but that had 0 air gap and looks to have been down for many many years.

robj20 · 25 Sep 2017 at 15:00

You won't need an air gap with that insulation its high breathable.

Buffman · 25 Sep 2017 at 16:02

Yeah you don't need an air gap (you effectively have an air gap above the boards). You may find as you increase the volume due point of hot air kept within the house you may have to ventilate the roof space better if it's a impermeable bitumen roof. I did mine by putting in roof lap vents. Once I added insulation my roof was sweating with condensation! but the roof lap vents quickly solved it.

Also yes I'd just put the cable under the boards.

nutcase · 25 Sep 2017 at 16:33

Oh ok - if that's the case please ignore but I've not read that anywhere?

topgun06 · 25 Sep 2017 at 17:20

I've just had another look online and everyone has a mixed opinion. I'll keep an eye on it. So tonight I'll get the next row of boards screwed down with the cable under the board.