I used to have a contractor friend of mine who would not install a single phase breaker in a three phase panel and he would install two panels- One for single phase loads and one for 3 thase loads when he dealt with a Delta 240/120 3 phase service. Not cost effective I agree but this was his standard and I'm not to sure he was wrong. He's gone to his reward now but I always knew why he installed things this way and he never would change. That being the case we can argue all day about system/circuit/ground. He never had any issues doing it his way. My final comment on this issue is a quote from the White Book:
Based on the preceding paragraphs, “slant-rated” breakers (120/240, 480Y/277 V, etc., as opposed to
240, 480 V, etc.) are not intended for use on “slant-rated” delta systems. For example, a 3-pole, 120/240
V breaker is not intended for use on a 240/120 V, 3-phase, 4-wire, delta system, because on the high leg,
the voltage to neutral is 208 V. In this instance, a 3-pole, 240 V breaker should be used.
Edited for spelling
[This message has been edited by George Little (edited 11-03-2006).]
