Re: grounding
#12 AWG no way. 8 AWG minimum. Or use conduit listed in 250.118 and forget about the EGC. You need to read 250.122(B) very carefully.
I do not agree with the code on the formula because on a 50 amp breaker using 8 AWG supply conductor requires a 10 AWG EGC. But the code is what we have to go by and a ratio of 2.53 gives you an 8 AWG EGC.
[ May 21, 2003, 11:14 PM: Message edited by: dereckbc ]