I think the NEC is pretty strange in this area, at least contradictory.
If I sleeve as many cables as I can stuff in a 4" that is 23.999" long "for physical protection only" I don't see where I need to derate at all but if I have an inch and a half in insulation penetrating a top plate I need to derate. 334.80
... or should I get that pointy hat out again?
