AFCI/shared neutral

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nizak

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How many here have had problems installing a Combination AFCI breaker on a circuit with a shared neutral? Breaker in question is a QO115 Comb AFCI.I've talked to local EC's, some say they won't work others have had no problems. Reason for asking is I'm quoting a large residential remodel, the whole house (general purpose receptacles and lighting)was wired with 14-3 home runs and I'm wondering if I'll need to figure pulling indv. circuits for the bedrooms. Thanks
 
nizak said:
How many here have had problems installing a Combination AFCI breaker on a circuit with a shared neutral? Breaker in question is a QO115 Comb AFCI.I've talked to local EC's, some say they won't work others have had no problems. Reason for asking is I'm quoting a large residential remodel, the whole house (general purpose receptacles and lighting)was wired with 14-3 home runs and I'm wondering if I'll need to figure pulling indv. circuits for the bedrooms. Thanks
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The only way it would would is with 2 pole breakers. Would really like to know how some EC's got them to work... :roll:
 
My advice to you is to pull individual circuits. Or you can use 14/2/2. It has 2 neutrals and 2 hots #14 conductors and a ground.
 
Evaluate the cost of repulling new runs to the bedrooms to replace those 14-3's versus installing a Cutler-Hammer subpanel and installing some of their 2-pole AFCI's. You might also evaluate the load on those 14-3's to determine if they really need to be 2-circuits, or if you can just double the red and black up on one circuit.

Regardless of what you might have hears, you absolutely cannot serve a 14-3 with two single pole AFCI's. Somebody's pulling your leg or you misunderstood.
 
If they are getting it to work then they are using a technique that I have no knowledge of.

I Install GE Panels and Breakers and I know from experience that even if you short Neutral to Ground they trip instantly (load or not). The Last time I installed a SQ D It tripped with a N-G Short under load.

That will be a trick. Getting Combo 2 pole AFIs.
 
One other possibility, electrically feasible but gaudy:

Place a 2-space breaker box at the load end of each home run, where the shared neutral splits into two, and install two 1-pole combo breakers there.
 
LarryFine said:
One other possibility, electrically feasible but gaudy:

Place a 2-space breaker box at the load end of each home run, where the shared neutral splits into two, and install two 1-pole combo breakers there.
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If I remember correctly, code requires the entire circuit to be arc fault protected, which means from the panel, unless you can convince the AHJ that the 2 space breaker box is where the circuit starts.
 
hillbilly1 said:
If I remember correctly, code requires the entire circuit to be arc fault protected, which means from the panel, unless you can convince the AHJ that the 2 space breaker box is where the circuit starts.
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A branch circuit begins at the final OCPD, so the AFCI breaker is where it starts.
 
Two s/p arc fault breakers will work on a three wire. The problem is that you get nuisance tripping on the other circuit that doesn't have the fault. So, which one is the problem when you have a fault?
 
Chamuit said:
Two s/p arc fault breakers will work on a three wire. The problem is that you get nuisance tripping on the other circuit that doesn't have the fault. So, which one is the problem when you have a fault?
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I have never seen 2 sp arc faults that would work on a mwbc. It would trip the breakers constantly. BTW- sq.d homeline doesn't even make a dp arc fault. At least it didn't a few months ago.
 
Putting two SP AFCI breakers on a MWBC would be the same as putting two SP GFCI breakers on a MWBC, since AFCI breakers also include GFCI protection (but at a higher amperage than a GFCI device). The GFCI protection will trip as soon as a load is placed on the circuit as the hot and neutral current will probably not be balanced.
 
Had a service call the other day and found a 2pole AFCI on a shared neutral 12/3 home run that had nuisance tripping, actually wouldnt stay on period. Thinking that there might be a legitimate reason I first unplugged everything from the devices, then checked for any continuity between neatral and ground...all looks ok...then lifted the wires off the breaker and couldnt keep the breaker "on" without a load tied to it. Then found another 2 pole with the same problem. Called a friend which wired the house and he said the've had alot of problems with these breakers and this shared neutral scenario.

Two questions...

1. Do you concure that this breaker (s) is bad?

2. And, two different supply houses say that these C/H 2pole breakers are back ordered with no delivery date in site. Any one had the same experience?

Thanks
 
I know I see it all the time, but is it really wise to run two seperate branch circuits off of one 2p breaker?
Gene
 
With the reliability of these breakers in question, No I dont think it is wise. These two circuits are bedrooms, and Im thinking about combining them onto one 1pole afci and using the 800 sq ft rule....haha
 
abbreviation

abbreviation

.ok guys i really speak English as second language ,what is mwbc, BTW and where can i learn more about those abbreviation .
 
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