Arc Fault Breaker Problem

[wizard12342002]

Hi all,

I have a spare bedroom that is serviced throughan arc fault breaker. Over the past several months, the breaker would [once in a great while] trip. Nothing was running in the room when the breaker would trip. Typically, the breaker would allow me to reset it. Recently, the breaker tripped and will not reset. I used an ohm meter and checked all connections in the bedroom - 6 outlets, light switch and light - and all seem fine. I even flicked the light switch "on" and measured

17 Ohms at each outlet, indicated no shorts or opens [the lightbulb was connected across the circuit]. In addition, I measured the resistance between each neutral and ground, and the resistance is low [less than 1 ohm].

I am not an electrician and I am at a loss. Is it common to have problems with the breaker itself or is this more likely something I missed in the wiring?

Thanks,

-JJ

[Smarty]

The breaker may think it is seeing an arc and thus tripping to prevent a fire. An oscilloscope (and not a voltmeter) would allow you to see if this is true. Alternately, the breaker itself may be bad. You would need to substitute a known good breaker to see if it also trips, thus confirming the suspicion that there is indeed a dangerous arc condition.

[Tony Hwang]

Hi, Mu gut feeling, the breaker is bad or it's feeding more than that bedroom not in use.

[terry]

. If there is another identical breaker can you temporarily swap over the connections? That might prove if it is the breaker or the circuit at fault. Any possibility of dampness in wall outlets etc. that might cause leakage current that could trip the breaker?

[Charles Schuler]

Arc fault circuit interrupters look for the signature of an arcing circuit ... that basically means that they are looking for the higher frequencies that are generated by arcing. The earliest radio transmitters used a spark-gap to generate the high frequencies needed.

Like ground-fault breakers, they are subject to falsing. They are fairly sophisticated devices and can be fooled by nearby lightning strikes, RF fields, and so on. And they can just simply fail. Yours might have failed. Try a new one.

[Tom The Great]

Best case, the breaker is faulty. Worse case, you have an arc. Both are better than worst of worst, you have an arc, no breaker trip, than a fire.

Get yourself an electrician to check out the circuit. There is a reason why the NEC wants bedrooms first [only required] on afci's, because they do happen most there.

Good luck, and tell us what happened.

later,

tom @

[w_tom]

Arc fault breakers are also ground fault breakers. Rarely does a breaker go bad. Far more common are wiring problems. For example, with higher humidity, a partially conducting wire could be enough to trip a breaker. A white wire pressed against a safety ground short can cause strange failures. Only an arc-fault or GFCI breaker would detect this miswire. If neutral for an arc-faulted circuit was somehow connected to neutral wire for another circuit, then larger current draw on that other circuit could trip the arc-fault breaker.

Generally, such tripp> ...

[wizard12342002]

Hello all,

Thanks for your excellent inputs. I had an electrician visit today, and [of course] everything worked fine after he arrived. [Kind of like when you visit the doctor and your symptoms vanish for the duration of the visit...] He did not have the correct breaker type with him - so he couldn't replace the breaker. We agreed that if it happens again, he will replace the breaker.

In the mean-time, I might try that heavy load test. I'll keep you all posted. Thanks again!

-JJ

w_tom wrote:

[Thomas D. Horne, FF EMT]

An Arc Fault Breaker includes a thirty milliamp Ground Fault Protection of Equipment function. With the breaker open remove the neutral conductor of the circuit from the neutral terminal of the Arc Fault Circuit Interrupter. Then test between the both current carrying conductors and ground if any measurable resistance is found you have a ground fault on the circuit that you will have to find and clear.