Use 3 pole for 2 pole Sub Panel
- Thread starter Cletis
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- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Unless...
If your 3 phase panel is 120/240 3ph 4W, aka "High Leg Delta", 2 pole breakers should not be able to plug on to Phase B, the high leg, but a 3 pole will, and that would mean you can inadvertently feed your sub panel with one leg being the high leg and fry some 120V stuff. If you were feeding a 2 pole 240V piece of EQUIPMENT, that high leg wouldn't matter, but if it is a sub panel, it would.
There is no rejection feature for plugging a 2-pole onto the high leg. The same potential for error exists using a 2-pole.
http://ul.com/wp-content/uploads/2014/09/CircuitBreaker_MG.pdf (Page 12, Section 34)
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Since the 2-pole could also for line to line rather than MWBC, yes. But without the rejection feature I imagine it could not be slash rated? Or are they not making it electrician proof?
AFAIK they are not making them idiot proof.
(Electrician proof... :blink:. That would be a major problem.)
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
All I can say is... d'oh! :slaphead:
FREEBALL
Senior Member
- Location
- york pa usa
a lot of old industrial buildings used to land the high leg on C phase so you could use 2 pole breakers for single phase panels for lighting and receptacle loads.
You can use 2-poles when it's B phase, too. For example, in the #5 & #7 spaces.
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