Multiwire circuit and single pole breakers...

[ToolHound]

Two individual single-pole breakers, without handle tie, ever allowed ?


I am on the 2008 Code cycle. Though the language of the main Code text of 210.4 may not be 100% bullet proof, it would be easy to conclude from 210.4 Code text combined with the related Handbook commentary that if one uses individual single-pole breakers on a multiwire circuit (e.g., L-L 240, L-N 120) then one is "mandated" to have identified handle ties on the breakers.

However, 240.15(B)(1) would seem to throw ambiguity into the situation:, quote:

240.15 Ungrounded Conductors.

(B) Circuit Breaker as Overcurrent Device. Circuit breakers shall open all ungrounded conductors of the circuit both manually and automatically unless otherwise permitted in 240.15(B)(1), (B)(2), and (B)(3).

(1) Multiwire Branch Circuit. Except where limited by 210.4(B), individual single-pole circuit breakers, with or without identified handle ties, shall be permitted as the protection for each ungrounded conductor of multiwire branch circuits that serve only single-phase line-to-neutral loads. ( my underline added ).

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Looking for some solid ground on this subject...so by 2008 Code would you say there is ever any situation where individual single pole breakers, without handle times, would be code compliant? If so, by what Code section ?


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Would you interprent any part of 210.4 to say that the only complaint breakers for a multiwire circuit would be either double pole or single poles with handle tie ( therefore prohibiting use of two individual single-pole breakers without handle ties ) ?

If so, what part of 210.4 ?


Thanks, ToolHound

( P.S. -- I would hope always just to use double pole breaker, or handle tie, and thereby circumvent any potential danger and any issues about single-pole breakers and compliance. But, just for purposes of knowing the intended meaning and parameters of the Code, 2008, I dare ask these questions herein. )

 

[darekelec]

Single pole breakers with listed handle ties are ok if supply line to neutral loads because...
I am the Law!:lol:

 

[infinity]

Prior to the 2008 NEC handle ties or multi-pole CB's were not required for MWBC's.

 

[480sparky]

Prior to the 2008 NEC handle ties or multi-pole CB's were not required for MWBC's.

The rule first appeared in 1981, and applied only to dwelling units where both circuits shared a common yoke on a device.

 

[kwired]

Perhaps your controversy is just something that has been overlooked and never changed since the requirement to use multipole or handle ties was requried for all multiwire branch circuits?

 

[infinity]

The rule first appeared in 1981, and applied only to dwelling units where both circuits shared a common yoke on a device.

True, I didn't see a common yoke device in the OP so I was referring to the general rule change in 2008. Also in earlier versions of the NEC, Multi-pole CB's or handle ties were required for free standing office furniture MWBC's.

 

[jumper]

2011 NEC amended 240.15(B)(1) so that sections matched. It was simply an oversight that 2008 had that quirk.

240.14(B)(1) Multiwire Branch Circuit. Individual single-pole circuit
breakers, with identified handle ties, shall be permitted
as the protection for each ungrounded conductor of multiwire
branch circuits that serve only single-phase line-toneutral
loads.