Firestopping on cable tray penetrations between my lab and house (cc: @whitequark )
@azonenberg @whitequark Those steel pipes look like ideal circuits for stuff to travel through. Here we like plastic tubes for this use case and they require special handling for fire proofing.

@waldi @whitequark That isn't conduit it's actually a premade cable with hot, neutral, and ground conductor inside a plastic strain relief wrap inside a flexible spiral metal armor.

Flex conduit of a similar construction exists but is larger.