Spray foam over romex

[pabernathy (Paul Abernathy, CMI®, CMECP® Electrical Code Academy,Inc.)]

@belliott

So since we are not pencil neck geek code inspectors lets talk in the real world.
When is overheating from surrounding environment a factor.
Lets take over packing junction boxes and while we are at it how about running my Christmas light extension cord through conduit.
Maybe go further and discuss extension cords running through walls.

Past code what is the difference and is it all Ok or not ?

Was I wrong ?

I am not sure how to respond to that question either. I do not believe I have ever resembled a “pencil neck”…but I conceded the Geek part.

You are mixing a listed building wiring method with cords and their restricted uses…two different things with two different requirements. Please re-read Jim’s post again because it is very accurate.

We do have rules that govern box fill and how it affects the conductors and subsequent insulation as we have for conductor adjustments or/and corrections where the ambient heat, either by mutual heating or ambient heating can play a role in potentially thermally damaging the conductors.

Something that did change from the NEMA independent testing done back in the 80’s and 90’s was some of the oils and chemicals used in the foam products and how they might react to the PVC Material used in the sheathing. Again, most of the manufacturers of the foam have in their literature that the mixture causes no issues…so we as Wire and Cable folks…take their word on it.

[pabernathy (Paul Abernathy, CMI®, CMECP® Electrical Code Academy,Inc.)]

@mcyr

Huntsman Building Solutions | World-leading polyurethane spray foam company

Type NM-B cable is installed in walls, ceilings, and floors with other types of insulation and the
properties of the spray foam insulation are not different to warrant special consideration.

BOOM…and there you go…totally forgot about that NEMA document…guess thats why I am not a NEMA REP. The study was commissioned on behalf of NEMA Members and the manufacturers of the foam TYPE products.

As long as we take into account the adjustments and corrections, where applicable then the thermal rise should not affect the conductor insulation or the sheathing as well. Just remember that it is always on the manufacturers of the FOAM to ensure continued compliance.

[pabernathy (Paul Abernathy, CMI®, CMECP® Electrical Code Academy,Inc.)]

@sstanczyk

If the NM is reaching temperatures of 194F inside a wall, regardless of whether it is insulated or not there are bigger problems present.

We are talking about 1 or 2 strands of NM running through foam. We are not talking about 8-10-12 strands of NM being stuffed in a larger conduit. Apples and oranges.

True Dat !