Table 310.15(B)(6) allows the wire to be protected above its ratting as the NEC is well aware a dwelling unit service does not draw the full rating of the service.
I am aware of this fact.
What I'm hearing is that one of the conductor types listed in the heading of the table must be identified either on the conductor or on the cable sheath. Is this the case with SE? I don't have a sample handy to look at, and I never noticed this before.
310.15(B)(6) brings up a whole host of gray areas. What exactly does "main power feeder" mean? I've always assumed that in a dwelling unit, this table can be used with all feeders 100A and up that have load diversity (i.e. not all air conditioning units).
What if the customer wants a 100A feeder to a detached woodworking shop? Is that a dwelling unit load? I asked this question once of a continuing ed instructor who is a master electrician and EE, and he said that 310.15(B)(6) applies here. I went ahead and applied it (THWN in EMT and overhead span of quadruplex), and the AHJ approved it.
Somewhere there must be a judgement call of where 310.15(B)(6) does and does not apply.
Any thoughts?
