Electric cables, conduit and eps

[vfrdave]

 

I was chatting with Nick regarding some plumbing bits and bobs and we got onto some electrics.  What would the guidance be for electric cables in conduit in EPS floor insulation. Is there any concern?

I have a few runs for the likes of the kitchen island and sockets under corner windows that have been trunked across the sub floor in pvc conduit.

[A_L]

Given that polystyrene reacts with PVC insulated cable, on a safety first basis I would avoid having PVC conduit in contact with EPS. There will be the issue of de-rating the cable because of restricted heat-loss but I will leave that to the electricians.

[vfrdave]

Yes that is now the concern. I want clarity on it as it is not bear cable but is a pvc conduit. If needs be I can put the DPM over the conduit as a barrier.

[ADLIan]

There is no issue between EPS/XPS and RIGID PVC conduit or pipes. There is the well documented issue of pasticiser migration with FLEXIBLE PVC cable insulation. I'm sure cable needs to be derated too if ran in conduit in any insulation.