thermal insulation derating

[realolman]

I saw a thread in a heating forum where the poster asked about spray foam insulation being bad for the insulation on romex ... he also asked about the temperature effects of spray foam insulation on romex.

I did a search here and found an old closed thread in which raider posted :

A new paragraph was added to 334.80 that requires 2 or more NM cables that are installed in direct contact with thermal insulation without maintaining spacing to have their ampacities adjusted in accordance with 310.15(B)(2)(a).

You can see the thread at http://forums.mikeholt.com/showthread.php/121136-Derating-NM-cable?highlight=spray+foam

Does anyone have any thoughts re romex in spray foam insulation, and is fiberglass not thermal insulation?

 

[ceb58]

I saw a thread in a heating forum where the poster asked about spray foam insulation being bad for the insulation on romex ... he also asked about the temperature effects of spray foam insulation on romex.

I did a search here and found an old closed thread in which raider posted :

A new paragraph was added to 334.80 that requires 2 or more NM cables that are installed in direct contact with thermal insulation without maintaining spacing to have their ampacities adjusted in accordance with 310.15(B)(2)(a).

You can see the thread at http://forums.mikeholt.com/showthread.php/121136-Derating-NM-cable?highlight=spray+foam

Does anyone have any thoughts re romex in spray foam insulation, and is fiberglass not thermal insulation?

Fiberglass would be thermial insulation. Have see it packed in the drilled hole for draft stop.

 

[Dennis Alwon]

Sure fiberglass is thermal insulation. In terms of spray foam, I don't like it but if the wires aren't bundled it is probably fine.

 

[LarryFine]

To me, the 60C rating is conservative enough for most installations. The insulation probably protects the cable from ambient heat, too.