Indoor Cables and expanding foam

[MrAmnesia]

Loft builds slowly but surely getting there , about to start running cables and ductings ect .
Ive heard that you cant put expanding foam around cables is this true? Only going to be running some 3 core SY cable into the room to supply two sockets , its got plywood + celotex to go through would it be safe to drill a 25 mm hole put the cable straight through then fill it in with foam?


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[wiltstone]

I'd put a grommet in the hole first. Foam won't hold anything in place, great stuff for insulation though. I hope you can put it around cables my house has a mix of rolmex and knob and tube. The house was insulated 25 years ago just before I bought it and it passed all inspections.

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[wiltstone]

Ah second cup of coffee and I remembered I have a can of great stuff foam insulation. The label says its safe for wires.

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[lilm00re14]

You can certainly use can foam to seal a penetration around a wire. Once it hardens you'd have to dig the foam out but that's literally how it's used in attic flats for penetrations through wall top plates. I used the stuff building out my new flowering/veg room to seal around wires that I brought in to power the lamps and outlets and whatnot into the sealed environmentally controlled box I have built.

 

[Night Hawk]

Get some 3 inch PVC pipe, string the cables through it and spray the foam around the pipe. That way if you ever have to replace or add a line you can do it without having to rip everything up..