ECN Forum Forums Code Related Discussion NEC & other Code issues USE Cable sizing 400A

Just to clarify your thinking on 310.15(B)(6), should it happen to apply to other installations, service wires and feeders aren't the same thing. The definition of main power feeder has to be describing the last of the three conductor choices (feeders). There was no comma between "feeder conductors" and "that serve as the main...". If it was anything else, it wouldn't make any sense to have the service wires in the list.

There can be considerable debate as to where this feeder starts and end. However, I don't think anyone has ever questioned applying 310.15(B)(6) to service conductors (whether drops or laterals). It applies.

Thanks Mark,

I agree with you too. And that's what is kind of anerving about the code book. It sometimes the wording gets tangled. But my AHJ agrees already so I'm ok. I've been doing electric for about 11 years now and this is the first time this issue has come up. And if it comes up again well.... we'll cross that bridge then.

Thanks

dinotats

The power companies many times figure the actual load as about 50% of the NEC load calculations.

They have many years of historical data to back this up.

When was the last time you saw a power company service drop or service lateral to a house fail due to overload?

never,

In fact that very true. Earlier this summer I went to house a I completed 2 years ago to add a receptacle in a bathroom medicine cabinet. there service was 400A and just for the fun of I ammeter on the feeders.

At the time a 50, a 40 and 30a AC were each running. I don't know what else was on in the house but the total draw was just over 67A