2 pole breakers for multiwire branch circuits?

[jahilliard]

I have been informed by a local inspector that I cannot use a 2P breaker (QO220) to simultaneously disconnect a multiwire branch circuit. To correct this he is requiring that we install single pole breakers with approved handle ties. Is anyone aware of this requirement? These breakers are labeled 120/240V and the system and the source transformer is 120/240V Single Phase.

 

[wwhitney]

I have been informed by a local inspector that I cannot use a 2P breaker (QO220) to simultaneously disconnect a multiwire branch circuit. To correct this he is requiring that we install single pole breakers with approved handle ties. Is anyone aware of this requirement?

False per the NEC. Ask for a code citation.

Cheers, Wayne

 

[retirede]

Inspector is making things up. Ask him to tell you what code section is violated.

 

[LarryFine]

If anything, the 2p breaker affords "better" protection than two 1p breakers.

His opinion is, at best, a design choice. There is no disadvantage to the 2p.

 

[kwired]

common trip type or handle ties are acceptable.

The rule is all about simultaneous disconnection of all ungrounded conductors when manually turning the circuit off. tripping of just one pole when there is an overcurrent condition is acceptable which many handle ties allow that to happen.

 

[kwired]

If anything, the 2p breaker affords "better" protection than two 1p breakers.

His opinion is, at best, a design choice. There is no disadvantage to the 2p.

Haven't figured lately but at one time I figured 2 single pole QO's plus handle tie cost about same price as a two pole QO.
A three pole however is much higher than three single poles and handle tie.

 

[jaggedben]

If anything, the 2p breaker affords "better" protection than two 1p breakers.

His opinion is, at best, a design choice. There is no disadvantage to the 2p.

The disadvantage to a 2 pole is that the customer necessarily loses power to more stuff when pole one trips. Some handle ties don't do that. But to be clear, the inspector is totally wrong. There is no prohibition on common trip for an MWBC.

 

[infinity]

If the inspector gave you the code reference and actually read it before citing it he would realize that he was wrong. Overall a multipole breaker is better because anyone can come along and remove the handle tie.

 

[ramsy]

The disadvantage to a 2 pole

Its easier to isolate legs with single poles.

Some inspectors are retired contractors, perhaps not familiar with 2-Pole MWBC's, or who typically relied on their JW code wonks.

No one tracks every code cycle change, much less inspectors known as listing experts first, and code wonks last.

Rather than phrase a challenge, the code cycle where this change took place could be provided, or handle ties can be used.

 

[ramsy]

If the inspector gave you the code reference and actually read it before citing it he would realize that he was wrong. Overall a multipole breaker is better because anyone can come along and remove the handle tie.

Inspector may be accustomed to seeing over fused 2-Pole breakers installed on smaller wire.

20A breakers on 15A wire is typical, but 2-Pole 40A on 20A wire is not unusual.

 

[Christoph]

common trip type or handle ties are acceptable.

The rule is all about simultaneous disconnection of all ungrounded conductors when manually turning the circuit off. tripping of just one pole when there is an overcurrent condition is acceptable which many handle ties allow that to happen.

210.4(B) states that each multiwire branch circuit shall be provided with a means that will simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates. It is therefore NOT acceptable if a handle tie allows one ungrounded conductor to remain energized once the other one trips. If this happens the handle tie is not doing its job or the wrong kind is used.
Although I am doubting myself now and wondering if this is the case. I do know that they are flimsy and you might be right. I would appreciate some more education on this from others.

 

[wwhitney]

210.4(B) states that each multiwire branch circuit shall be provided with a means that will simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates.

Yes, this refers to manual operation of the handle, so a handle tie suffices. It does not refer to automatic operation; such a reference occurs in 210.4(C) Exception 2. Simultaneous automatic operation would require a 2 pole breaker.

It is therefore NOT acceptable if a handle tie allows one ungrounded conductor to remain energized once the other one trips. If this happens the handle tie is not doing its job or the wrong kind is used.

That is not correct. Handle ties are not intended to cause automatic operation of one pole to result in operation of the other pole.

Cheers, Wayne

 

[infinity]

Yes, this refers to manual operation of the handle,

That is correct. The purpose of the handle tie is to ensure that if you want to shut off one or two circuits of a 3 or 4 wire MWBC the other circuit(s) do not stay energized.

 

[kwired]

210.4(B) states that each multiwire branch circuit shall be provided with a means that will simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates. It is therefore NOT acceptable if a handle tie allows one ungrounded conductor to remain energized once the other one trips. If this happens the handle tie is not doing its job or the wrong kind is used.
Although I am doubting myself now and wondering if this is the case. I do know that they are flimsy and you might be right. I would appreciate some more education on this from others.

Though some have disagreed with me before on this, I have never seen a handle tie pull the other breaker off with QO or Homeline breakers, the ones I am most familiar with. I could see Eaton's CH possibly doing that since they don't move the handle to a mid position when tripped, but I also am not familiar with what they have for a handle tie device either. Most others (that are still considered in current production) all trip to mid position.

 

[kwired]

That is correct. The purpose of the handle tie is to ensure that if you want to shut off one or two circuits of a 3 or 4 wire MWBC the other circuit(s) do not stay energized.

But at same time you often will end up shutting all of them off in order to reset the one that tripped, it just won't shut down the other pole(s) at time of the trip.

 

[jaggedben]

Note that since in the tripped position the handle does not travel as far as in the off position it is possible to design a handle tie that reliably turns off two handles when one is turned off manually, but doesn't trip both handles when one trips automatically. I think what I've actually seen in the field is that more often when one trips it actually does turn off the other. But I've definitely seen that not happen as well. (Not a huge sample size, thankfully.)

 

[infinity]

But at same time you often will end up shutting all of them off in order to reset the one that tripped, it just won't shut down the other pole(s) at time of the trip.

I agree but tripping has nothing to do with the requirement. It's purpose is purely for the safety of someone working on one or more of the circuits sharing a neutral.

 

[LarryFine]

It doesn't matter if a handle-tie can trip other poles.

If that is necessary, a multi-pole breaker is required.