Chasing behind insulated slab

stoneyxox

Hi all just wondering what are the practices for switches and sockets in a insulated slab on block. Can I chase down the conduit and mount the box on the block and bring my cables back entry into the box. Just heard there is an issue with chasing the box into block as box is back to far from the finished surface. Just wondering what all other sparks are doing in this situation.

meercat

stoneyxox wrote: »

Hi all just wondering what are the practices for switches and sockets in a insulated slab on block. Can I chase down the conduit and mount the box on the block and bring my cables back entry into the box. Just heard there is an issue with chasing the box into block as box is back to far from the finished surface. Just wondering what all other sparks are doing in this situation.

yes thats fine.you could use drylining boxs as that sometimes makes it easier and neater to fit the slabs to the wall

stoneyxox

meercat wrote: »

yes thats fine.you could use drylining boxs as that sometimes makes it easier and neater to fit the slabs to the wall

Thanks for the reply meercat. Also upstairs I have two sheets of kings pan behind wall and insulated slab on the wall. Bit of an overkill I know but is there any issues with cables passing through the foil back insulation right through the slab and back entry into the slab box or would I need cables in a copex where they are passing through??

BOARDHOG

Might be best to

BOARDHOG

Might be best to use copex , apparently the insulation can react with the pvc . So if it's touching the insulation I would use copex.

meercat

stoneyxox wrote: »

Thanks for the reply meercat. Also upstairs I have two sheets of kings pan behind wall and insulated slab on the wall. Bit of an overkill I know but is there any issues with cables passing through the foil back insulation right through the slab and back entry into the slab box or would I need cables in a copex where they are passing through??

I haven't come across any issues with kingspan reacting adversely with pvc/pvc cables. The old beaded polystyrene type insulation (also came in white sheets)did create problems but I don't think that's what you have here.
If you're in any doubts then overkill will always be better.

Tuco88

It's polystyrene that attacks the plasticisers in pvc, rigid insulation usually polyurethane is fine... ie kingspan.

Not sure about expanding foam.