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
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?
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.
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?
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.
On 5 Nov 2006 12:59:35 -0800, " email@example.com"
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
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.
tom @ www.WorkAtHomePlans.com
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 tripping is due to a wiring fault. Some of these
faults can be made obvious by applying a large load to each receptacle
to discover where load causes a breaker trip.
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!
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.
Well we aren\'t no thin blue heroes and yet we aren\'t no blackguards to.
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