When sizing a neutral on commercial applications, can 70% be taken? I have a 100 amp. single phase sub panel fed by # 3 copper. What size neutral can I use? I tried to find it in the code, but can't seem to locate it. Can't seem to keep up with it all. Where can I find it in the code? I usually just run the same as phase conductors, but I may need to downsize if I can, to use a smaller pipe size. Thanks a lot. Steve
Is this sub panel supplied from a single phase service or is it supplied from a three phase service. If the feeder is from a three phase service than the grounded current carrying conductor will carry just as much current as the phase conductors.
--
Tom Horne
