polystyrene and electical cable
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A local electrician here in Scotland advises against using polystyrene (the type of stuff used for making that ‘peanut’ shaped packing) in attic insulation because it reacts with the plastic sheathing on electrical cable, making it brittle in the long term. Anyone out there had any experience of this?
NICK
Replies
I have not heard of that. "Peanuts" would make lousy insulation anyway because of the large air passages between them.
It doesn't seem to me like there could be that much of a risk with regular packing peanuts. Romex sheathing (here in the US) is fairly thick, so it would take decades for stuff to leach out of the peanuts and most of the way through the sheathing (if it happens at all) and only the small areas in contact with the peanuts would be affected. Even with solid sheets of the material, the areas of contact would be limited to maybe 10-20% of the surface.
Then the actual wire is wrapped in paper, which will not support leaching. The wire insulation will never be touched. So at worst you might get some small cracks in the sheathing.
I do wonder about the dangers associated with using some of the spray foams on cable sheathing, but I've never heard of a problem.