Code question

[ravenjoe]

Is it allowable to supply a single phase 480v load with a 3 pole breaker instead of a 2 pole breaker? IE: feed to a single phase 2 wire 480/120 transformer primary with a 3 pole breaker.

 

[bphgravity]

From ANSI/UL 489 (DIVQ GuideInfo):

3-pole circuit breakers are suitable for use on 3-phase systems. A 3-pole breaker used in place of a 2-pole breaker on a 3-phase system, such as a 2-pole breaker used in a branch circuit that is actually two legs of a 3-phase system, is acceptable without the 3-pole breaker being specifically marked.