Is a shared neutral on an Arc Fault Circuit Breaker allowed by NEC?

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teejer

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Is a shared neutral allowed on an Arc Fault Circuit Breaker according to the NEC.
I have one circuit that needs an AFCI breaker and another that does not, but the two circuits share a neutral together. I have heard that this typically causes the AFCI's to trip because they are very sensitive to neutral imbalance. However, in this case, the AFCI is not tripping due to sensitivity and remains in the on position. Am I in the clear with this AFCI or do I have to provide a separate neutral? I want to get it right before the inspector reviews the work.
Thanks in advance.
 
A single 120 volt AFCI breaker won't work properly on a multiwire branch circuit due to the fact that the AFCI breaker has built in GFPE protection.

Is there a load on the multiwire branch circuit? The GFPE protection portion of the AFCI breaker won't trip until an inbalance of 30 to 50 milliamps is detected.

Chris
 
I don't know if it's a NEC violation, but the AFCI's I have installed state they are not to be used on multi-wire circuits. :rolleyes:
 
If the installation instructions state that the AFCI breaker can't be used on a multiwire branch circuit then it would be a violation of 110.3(B) to due so.

Chris
 
raider1 said:
... the AFCI breaker has built in GFPE protection.
Click to expand...

I did not know that :-?

NJ has yet to adapt 210.12(B) ...I appreciate all the info on the subject ...when - and if - NJ ever adapts 210.12(B) I'll be way ahead of the herd.
 
Thanks for the response

Thanks for the response

In retrospect, we hadn't loaded the circuits, which would probably make it trip. Even if it doesn't nuisance trip, we will pull a new separate neutral so we have safe installation. Thanks for the responses!
 
teejer said:
In retrospect, we hadn't loaded the circuits, which would probably make it trip. Even if it doesn't nuisance trip, we will pull a new separate neutral so we have safe installation. Thanks for the responses!
Click to expand...


That is most likely why it did not trip. Since most are set to trip (GFPE) at around 30-40 miliamps, therefore it would take some kind of load. Whereas a GFCI will trip on imbalance when the circuit is energized.
 
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