We have a 3 phase 4wire 120/208 panelboard and I want to run three 120V, 20amp circuits with a common neutral. This will be for a new office. Would 3 single pole breakers rated 120/240 with handle ties work for this application or would it need to be a 3 pole 120/240 common trip breaker? I am thinking the 3 single pole breakers with tie because each line can run up to 16amps. I never really understood the real difference between 3 single pole breakers and a 3pole common trip breaker.
Multiwire Branch Circuit Question
- Thread starter User2
- Start date
- Status
A 2- or 3-pole common trip breaker will de-energize all poles on overcurrent of any single pole.
An independent trip 2- or 3-pole breaker and handle-tied single pole breakers are only required to de-energize the culprit pole. That said, a single-pole trip may inadvertently de-energize the other pole(s)... and re-energizing a tripped pole requires resetting all poles.
rlundsrud
Senior Member
- Location
- chicago, il, USA
So are you saying that you can't use the handle tied singles?
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I don't think that is what smart is saying.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
The requirement is that the act of manually turning off one pole, as in for maintenance, must also cause the other poles to become deenergized. What happens when one of the poles experiences an overcurrent condition is not relevant to the rule. As Smart said, after a pole trips on overcurrent, regardless of whether that also causes one or both other poles to trip, you will have to turn off all three, in order to restore power.
- Status