GFCI Protection on a Multi Wire Circuit

[threefie]

I came across a situation where I needed to protect a lighting circuit with
GFCI protection. Upon opening up the panel, I determined that this circuit
was part of a multi wire branch circuit.

Is it possible to provide GFCI protection for this circuit with a 2 pole 15
amp GFCI circuit breaker, without the nuisance tripping problem that often
accompanies multi wire circuits?

 

[GoldDigger]

I am approving this conditionally on the assumption that you are retired from a qualified profession under the Forum rules.
If not, this thread will have to be closed as a DYI request.

If a circuit is part of an MWBC, you can still use a receptacle-based GFCI at the first position of the lighting branch as long as that branch has its own neutral from end to end.
But since there is only a single shared neutral at the panel, you are correct that you cannot install a single pole GFCI breaker. If you want, you can use a two pole GFCI breaker even though the other part(s) of the MWBC may not require GFCI protection.
And I would not call it just nuisance tripping since it would trip any time you put a load on the other part(s) of the circuit.

 

[threefie]

Thank you for your response. I could not find the forum rules but I am a retired electrician. I suppose I should already know the answer to my own question but I have not run into this exact situation before.

 

[brycenesbitt]

You could look at this from GE on AFCI's and MWBC's.

https://structuretech1.com/wp-content/uploads/2016/02/DET-719-CAFCI-Shared-Neutral-Guide.pdf

" Until now, using a shared neutral (multiwire branch circuits) on arc fault protection circuits required the use of 2-pole AFCI breakers, since the AFCI circuitry uses a ground fault CT to help it detect arcs. But with GE’s newly developed combination AFCI technology, no ground fault CT is required, so shared neutral circuits can be used with two 1-pole AFCIs connected together with a handle tie (see Figure 1"

Maybe this offers hope for the future on GFCI's on MWBC's?

 

[hbiss]

But with GE’s newly developed combination AFCI technology, no ground fault CT is required,

Ummm, yeah. That's because they just eliminated the GFCI from the breaker. Too many pesky nuisance trips. That'll fix it!

-Hal

 

[don_resqcapt19]

...
Maybe this offers hope for the future on GFCI's on MWBC's?

I don't see how. The GFCI has to see the current on all of the circuit conductors and see that the current sums to zero.