Originally Posted by
Richard Abrams
Watch Bundling of romex cables as anything over 4 wires would have to be derated. Especially if insulation material is installed in these cavitys.
If even two NM cables (any multi-wire cable for that matter) are bundled or spacing was not maintained, then derating takes affect.
The code references "more than 3" but is also references "multi-conductor cables", because if you have 2 2-conductor cables (i.e., 2 multi-conductor cables), you have 4 conductors.
Derating then becomes
4-6 conductors - derate to 80%
7-9 conductors - derate to 70%
10-20 conductors - derate to 50%
21-30 conductors - derate to 45%
31-40 conductors - derate to 40%
41+ conductors - derate to 35%
Arguing with an inspector is like wrestling a pig in the mud, pretty soon you realize the pig enjoys it.
