ckdckd
Member
- Location
- branford, ct
Does NEC 2011 article 240.4(B) apply to conductors in parallel? I can not seem to find an exclusion regarding parallel conductors, but I thought there was one.
A specific example would be if two parallel runs of 500 KCMIL (75 degree C) are permitted to be protected with an 800 Amp breaker, since the combined ampacity is 760 which does not correspond to a standard breaker size and the next standard size is 800?
I know 240.4(B) allows me to protect a single set of 500 KCMIL (380A at 75 degree C) with a 400 Amp breaker, but for some reason I think I remember seeing something prohibiting it for parallel conductors.....I just can not find it now. So, I'm wondering if it was code or just something somebody said but without code backup.
A specific example would be if two parallel runs of 500 KCMIL (75 degree C) are permitted to be protected with an 800 Amp breaker, since the combined ampacity is 760 which does not correspond to a standard breaker size and the next standard size is 800?
I know 240.4(B) allows me to protect a single set of 500 KCMIL (380A at 75 degree C) with a 400 Amp breaker, but for some reason I think I remember seeing something prohibiting it for parallel conductors.....I just can not find it now. So, I'm wondering if it was code or just something somebody said but without code backup.