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AFCI breaker


JEuriech
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I received a call last week on a house that I inspected two years ago. Bedroom number two AFCI breaker kicks off when the ceiling fan is turned on in bedroom number three. However, the fan and outlets in bedroom number three stay on. Only the outlets in bedroom number two go off.

The house is currently being rented and bedroom number two is only being used for storage. The owner is not going to do any repairs currently until the renters move out in about three weeks.

The owner called an electrician to find out what the problem was and how much it was going to cost to repair. The electrician told him that it sounded like a "shared neutral" problem and they can be expensive to track down and repair.

If the neutral wires going to the two AFCI breakers got reversed, would the same type of problem happen? When an AFCI breaker kicks off, does the neutral portion of the circuit open also or is it only the hot side?

Thanks

Jeff Euriech

Peoria Arizona

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Originally posted by JEuriech

When an AFCI breaker kicks off, does the neutral portion of the circuit open also or is it only the hot side?

Excellent question! I know that a GFCI receptacle does open hot and neutral but had no idea on an AFCI breaker, and I can't find the answer online. This isn't THE definitive answer, but I just ran a test on the only AFCI circuit I have in my own house (new bedroom, new circuit).

I tested the continuity between the neutral and ground at a receptacle, then tripped the breaker and retested. I still had full continuity. So it appears that only the hot is disconnected. It's a brand new, dedicated circuit, so there shouldn't be any cross connections, but the ultimate test would be to check the breaker at the panel (or a spare breaker). Sorry, I don't feel like tearing the cover off at the moment. Maybe later.

You shouldn't have any deliberately shared neutrals on the AFCI circuits in a new home. Last time I checked, they don't make 2-pole AFCI breakers to handle that yet. But, yes, I can see a cross connection or accidentally shared neutral causing the problem. One problem that evidently seems to crop up occasionally is with three way switches when they grab the neutral from the wrong circuit at one of them. Another common problem is ground to neutral faults at receptacles (bare ground in contact with the neutral terminal, etc). See the following...

http://www.workingelectrician.org/resou ... +trips.pdf

One way I can think of to check in your situation would be disconnecting the neutral wire at one of the AFCIs (turning the breaker off first of course) and seeing if there is still continuity between neutral and ground at the outlets that AFCI serves. There shouldn't be. That seems like a simple enough test to determine if there is a cross connection, but could still be a bear to find if there is one.

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Jim

When the ceiling fan is turned on, the fan and all the outlets in that bedroom stay on. However, the outlets in the other bedroom go off. The AFCI breaker for the other bedroom has kicked off.

The house was prewired for fans in each bedroom when the house was built. The fan was added to bedroom number three after I did the inspection.

Jeff Euriech

Peoria Arizona

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Originally posted by JEuriech

Jim

When the ceiling fan is turned on, the fan and all the outlets in that bedroom stay on. However, the outlets in the other bedroom go off. The AFCI breaker for the other bedroom has kicked off.

The house was prewired for fans in each bedroom when the house was built. The fan was added to bedroom number three after I did the inspection.

Well, clearly, there's a problem with either the fan or the fan's switch circuit that's causing the AFCI to trip. In addition, it sounds as if there's a swapped neutral somewhere.

However, I'm suspicious of the whole thing because, first of all, customers almost never describe electrical problems properly -- they always leave something out or fill something in by assumption.

Next, electricians almost never wire one AFCI per bedroom. They mix them up. Given a common wall between two bedrooms, would you connect all of the receptacles on one side of the wall to one circuit and all of the receptacles on the other side to a different circuit? I usually see the receptacles for two or three bedrooms on one AFCI and the lights & smokes on another. But the electrician will do it whichever way makes the most efficient use of his time & cable.

And finally, it sounds as if someone did his own ceiling fan wiring. If so, no one knows what debauchery was inflicted on the circuit.

In short, this kind of problem is difficult to diagnose over the phone because the parameters are almost always incomplete, if not downright wrong.

- Jim Katen, Oregon

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