Are 3 pole breakers only for 3 phase?

[electrofelon]

I believe that UL item relates to using 3 pole breakers on corner- grounded systems where only 2 poles are being used to interrupt a 3-phase fault.

Think about how a 3 phase breaker may need to open a single L-G fault during normal operation. This is why UL needs to test all of the individual pole combinations of any multi-pole breaker

I'm not sure, I would need some context on that UL statement. From what was posted, it appears a marking would be needed.

 

[skorpioskorpio]

To clarify, yes it's a single (split) phase panel, with a 3 pole breaker to protect 2 circuits, one is a 240V circuit (no neutral) and the other a 120V circuit. Both terminate in the same jbox, both circuits have grounds, not that that should really matter. Obviously the 240V circuit would be in adjacent breaker spaces. There is no 3 phase service involved, this is a question about 3 pole breakers, not 3 phase service. The fact that one is primarily used for the other should be irrelevant just trying to verify that that is indeed the case and that using one for this purpose doesn't violate the NEC in any way. The goal is to common trip the 240V circuit and the 120V circuit together, to both kill the box that contains these 2 circuits and the equipment they are connected to.

Any 3 pole breaker should be rated for 120V relative to ground or I don't see how it would ever be OK to have it in any service panel. Is there ever a case in North America where a hot leg would be rated less than 120V relative to ground that would merit manufacturing breakers for service panels that would not meet this specification? I also don't know of anywhere where split phase service exists in the US where the voltage relative to ground exceeds 120V(ish) either. I assume residential neighborhood transmission lines almost certainly do exceed this voltage and are distributed to those areas as split phase but they are never terminated that way, not that I have ever heard of.

 

[Fred B]

I don't particularly see issue with utilization but would recommend that the 240V circuit wiring be clearly identifiable and differentiated from the 120V on the same 3 Pole breaker. Thinking of future electrician that might have to work on system given that it is all 20A wiring. Don't want the 240V to incentadtially land on the 2 outside poles.

 

[skorpioskorpio]

I don't particularly see issue with utilization but would recommend that the 240V circuit wiring be clearly identifiable and differentiated from the 120V on the same 3 Pole breaker. Thinking of future electrician that might have to work on system given that it is all 20A wiring. Don't want the 240V to incentadtially land on the 2 outside poles.

Yea not a problem there, this is actually to be a move of these circuits from an old sub panel to a new one. They are already labeled on the panel cover, on the breakers, the conductors, and the jbox covers. The conductors are also color coded (black for 120V and red sleeved for 240V) and well to be honest it actually goes so far that all the 120V/20A duplex outlets in this space are black and all the 240V/20A duplex outlets are red. You can identify 120V from 240V from 30ft away, and there are 12 of each, and that'll go to 16 of each once the new panel is in place.