Re: 3 phase panels wired with single phase
The jumpers I mentioned would be against NEC unless "B" phase was equipped with a lug designed and rated to handle 2 conductors, i.e. a 2 barrel lug.
NEC 110.14(A) paragraph two: "Terminals for more than one conductor and terminals used to connect aluminum shall be so identified."
There might be other reasons also. I just didn't take the time to look them up.
It also seems to me that if a 2-pole breaker was accidentally installed on the unused bus, there would be a really wierd voltage backfeed from the energized bus through the equiptment to the unused bus. It seems to me that would be similar to an unsafe situation caused by a backfed wire capped off in a panel.(see : 1 circuit fed by 2 single pole breakers in nec forum).
Also, no offense, but why go to the expense and risk the potential confusion of installing a 3 phase panel on a single phase service? The next guy that goes to work on this panel or add circuits to it is in for a rude suprise unless he knows about the condition beforehand. The next guy could be a newly minted service electrician for your company that didn't get the info because it never occurred to those folks that knew about the condition that the new guy didn't know about it.
Lastly, we all have that one hard core inspector that absolutely would not pass such an install no matter what code says. You can appeal, and might win, but we all know that is something you usually only do once. After that, you tend to have a terrible time passing inspections.
[ February 14, 2006, 12:44 AM: Message edited by: Matt Harp ]