Insulating around the supply cable

[Tricky Dicky]

Following the recent thread about cables passing through insulation it has left me with a dilemma regards the supply cable.

My supply cable emerges out of the sub-floor and passes through an approx. 50mm gap between the first joist and the wall. However the run of the cable is not vertical due to the alignment between the entry point and the cutout the alignment is approx. 150 - 200mm out and the result is that the cable forms a lazy S in the space between joist and wall. This makes sleeving impossible.

Originally, I was simply going to PU foam the gap but the previous thread has made me a bit cautious. I could possibly get some of that flexible corrugated sleeving and split it along its length to get it around the cable but suspect there would be gaps at the bends allowing PU in against the cable. To my mind the gap in insulation is too great to ignore so I would welcome any advice please.

Richard

[spuorgelgoog]

Move the cutout? :-)

Just squirty foam it and say it was like that when you moved in.

Owain

[Roger Hayter]

Are you worried about insulation derating the cable or chemical effects on the cable jacket? I must admit I would assume in both cases it is designed to go in some unpredictable unsavoury places and would be ok. But I have no basis for saying that.

[Tricky Dicky]

Roger it is about derating the cable, I know the PU should not react with the cable. Previously it was buried maybe not intentionally in a thick lump of plaster which fell away when I pulled the old floorboards out and was finally able to see the situation.

Owain, I take it from the smiley moving the cutout was not a serious suggestion, apart from involving the DNO again there is nowhere for it to go things are very tight around that area with the CU and meters.

Richard

[The Natural Philosopher]

foam doesn't affect the wiring chemically but the insulation may cause overheating in some home wiring cases. I doubt this is relevant for a short run of armoured or 100A tails.

[The Natural Philosopher]

A foot of foam on a meter of fat copper cable is not going to derate anything significantly.

Copper conducts heat damned well

I am fairly sure my armoured incoming comes up a foam filled pipe...

[Andrew]

Unless you are trying to exclude creepy crawly's or stop a nasty cold draught, just ignore it.

[Dave Liquorice]

between

Fix some bits of wood to joist projecting to wall either side of the incommer to form a box for it. Squirty foam outside of the box, lightly stuff box with fibre glass insulation and ali tape over.

Presumably you're insulating under the floor, 50mm is wide enough for celotetx to be installed. I'd avoid glueing the joist to wall with squirty foam, even if the wall is dry. Some squirty foams are porous...

Hum, even with the remote chance that the foam will damage the cable the though of a short on the incomer before the cutout doesn't sound like a good idea.

[spuorgelgoog]

You can move them too :-)

Owain

[Brian Gaff (Sofa]

I'd seriously doubt foam there on a short run of cable would make any difference at all, indeed because its quite easy to dig out one would not really have aan issue to get at the cable. Brian

[Tricky Dicky]

The latest, straight from the horse?s mouth, I got in touch with the DNO and their advice is not to use PU foam around the supply cable. So I will stuff the gap with some Rockwool on one side and I can get a bit of wood down the other side so I can fill that with PU and then a bit of judicious use of sealing tape should leave it insulated as best can and as air tight as possible. Thanks for all the suggestions.

Richard

[spuorgelgoog]

ooops.

Owain