Re: maximum conductors in conduit
(oh no) Bob, I guess I should never have used any field terminolgy, just in case some new electricians are reading any of this. I suppose we should stick to strict code language. Sorry.
But yes, I don't know where or even if for a fact that it is a NEC requirement, I thought that it was a new code. We have installed 4 recent large jobs that the cities required and the local inspectors required the upsize of the nuetral when pulled in a multi conductor branch circuit. This was required by the electrical engineer in the approved drawings, and we have been checked on it by local inspectors when it wasn't called for in the drawings. When just two phases are in the multi conductor circuit, the load is not extremely unbalanced, whereas when there are three phases, the load can be extremely unbalanced, possibly more ampacity than the #12 nuetral is rated at... thus the #10.
I don't recall when I first ran into this, but I too questioned it and was told that the third wire created the unbalanced load that is a culprit in problems related to computer voltage spikes and harmonics.
Could all be a huge multi-person misunderstanding. I surely would like to know if they are right, because it is truly a pain in the arse to pull the 10 with the 12's.
Another requirement is the sizing of conduit ond fill on these larger comm/Ind installations. 1 multi conductor in a half inch, 2 in a three quarter inch, and 3 in a 1 inch.
Anybody else hear of the upsizing of the nuetral? I know we get called on it here in sunny southern California.
Frogg