Electrical cables in pumped cavity

SodiumCooled

Hi, I am arranging my cavity pumping and I was reading the documents on the bead to be used. I noticed it stated that electrical cables should not come into contact with the bead and did some reading and see that PVC insulation around the cable can be degraded by the EPS beads. We have quite a few electrical cables crossing the cavity for external lights and sockets and more importantly the main SWA cable from the meter box is running down from ceiling height and across the cavity? Is this something to be concerned about or just an overcautious advice from the bead makers?

I can't see how else external wiring could be run especially the SWA as it has to cross the cavity and nearly all new houses are pumped now?

meercat

When you say “crossing the cavity “, do you mean the attic space?

you’re right also that the bead should not come into contact with pvc cables as it breaks down the insulation

could you not insulate the attic conventionally

SodiumCooled

https://www.boards.ie/discussion/comment/121924830#Comment_121924830

No not the attic, I mean the cavity between the inner and outer leafs of block work. For example there is a hole drilled above the back door and a wire fed from inside the house through the inner block work across the cavity and out through a hole in the outer blocks. A light will be wired to this then.

This is done in probably 7 or 8 places for lights or outdoor sockets and not much can be done now so just wondering will the wires be ok in the long run.

Daniel son

https://www.boards.ie/discussion/comment/121925048#Comment_121925048

Open the hole a little at put conduit around the cable. Seal it all up again.

SodiumCooled

https://www.boards.ie/discussion/comment/121925973#Comment_121925973

Maybe possible for some of them - if electrician is willing to do it which he may not be and time is not on our side as pumping is happening very soon. It will be messy too especially as I have thick layers of airtight paint over may of the holes on the inside). Impossible for the SWA to the meter box though and for wires for lights on a stone fronted section as the hole cannot be widened on the external leaf due to the stone

Surely this must not be too big a problem as any older house being pumped will have wiring in the cavity you would think and it's never touched?

tomhammer..

https://www.boards.ie/discussion/comment/121927056#Comment_121927056

Older 3-bed houses will probably have back and front light and main tails in contact with the bead when done, maybe outside socket too

Not much else

SodiumCooled

https://www.boards.ie/discussion/comment/121927392#Comment_121927392

I will probably have 6 lights, two outdoor sockets, gene hook up and main tails in contact with bead so not massively more.

SodiumCooled

Does it make any difference if it is NYM cable used - I am told this is allowed in cavities without a conduit?

cnocbui

https://www.boards.ie/discussion/comment/121927056#Comment_121927056

You can bore holes in stone quite readily with diamond hole saws. I have done it through granite.

SodiumCooled

https://www.boards.ie/discussion/comment/121940746#Comment_121940746

It wasn't getting through the stone it was more that the cables are bedded into a deep mortar joint between two stones and freeing it would be messy. They are also very much bedded internally with a very thick hard layer of airtight paint.

Anyway having spoken to both the insulation provider and my electrician they both see no issue as the outer sleeve on an NYM cable provides sufficient protection without conduit. My electrician said this was an issue 20+ years ago but not something he is concerned about with modern cabling.