Electrical Engineering - AFCI Breaker Tripping Problem

Author

AFCI Breaker Tripping Problem

slowone_@hotmail.com

2007-04-26, 9:25 am

I have a problem where my AFCI breaker (Siemans Type OAF 15amp) trips
in my bedroom. It has done this sporadically over the past 3 years
since the house was built. Sometimes it will clear itself up and
sometimes it will not. I most recently replaced the AFCI breaker and
it is still tripping.

I have nothing plugged into any of the outlets and the ceiling fan/
light switches are off. I reset the breaker and turn on the light
switch, the breaker trips. I pull the cord to turn the light off,
reset the breaker and turn on the switch, the breaker does not trip.
With the light switch off, I then start testing outlets. I plug a
power cord (such as an extension cord or one that goes to a computer)
into an outlet (knowing there is absolutely zero load on the cord) and
the breaker trips.

Where should I now turn to find my suspect. From what i've been able
to see of the wiring in the attic above my room, it looks fine...there
are no anchor nails piercing the shielding of any of the wires. There
have never been any nails placed in the walls since the house was
built. Should I check for loose connections on every outlet? Is the
suspect in any of the unseen wiring somewhere in the walls? Can I
just dump the AFCI and go to a regular breaker?

Thanks all for your help in clearing up this pesky matter.

Long Ranger

2007-04-26, 1:25 pm

<slowone_@hotmail.com> wrote in message
news:1177592211.683679.275950@r30g2000prh.googlegroups.com...
>I have a problem where my AFCI breaker (Siemans Type OAF 15amp) trips
> in my bedroom. It has done this sporadically over the past 3 years
> since the house was built. Sometimes it will clear itself up and
> sometimes it will not. I most recently replaced the AFCI breaker and
> it is still tripping.
>
> I have nothing plugged into any of the outlets and the ceiling fan/
> light switches are off. I reset the breaker and turn on the light
> switch, the breaker trips. I pull the cord to turn the light off,
> reset the breaker and turn on the switch, the breaker does not trip.
> With the light switch off, I then start testing outlets. I plug a
> power cord (such as an extension cord or one that goes to a computer)
> into an outlet (knowing there is absolutely zero load on the cord) and
> the breaker trips.
>
> Where should I now turn to find my suspect. From what i've been able
> to see of the wiring in the attic above my room, it looks fine...there
> are no anchor nails piercing the shielding of any of the wires. There
> have never been any nails placed in the walls since the house was
> built. Should I check for loose connections on every outlet? Is the
> suspect in any of the unseen wiring somewhere in the walls? Can I
> just dump the AFCI and go to a regular breaker?
>
> Thanks all for your help in clearing up this pesky matter.
>
I would isolate that circuit, and disconnect anything like the light/fan and
hit it with a shot of 250volts of megger voltage between each "pair".. Also
go completely through it, and check all the connections including the
neutral connection in the panel. It could also be that it's neutral is mixed
with the neutral of another circuit, and when that other circuit has a load,
it trips your arc fault breaker. One way to test for that is to shut off
every other circuit except the one giving you trouble, then see if it still
happens. If it goes away, you might start looking for a neutral connection
between two circuits that should be isolated. In another scenario, it could
be that your wiring was installed on a piece of 3-wire cable, and it will
never work right until it is rectified, by either re-wiring it, or,
sometimes you can get an arc-fault breaker that will work on a 3-wire
circuit. Hard to tell without being there, but these intermittant problems
have been neutral leakage and neutral miswires in most of the ones I've
worked on.

gfretwell@aol.com

2007-04-26, 1:25 pm

On 26 Apr 2007 05:56:51 -0700, slowone_@hotmail.com wrote:

>I have a problem where my AFCI breaker (Siemans Type OAF 15amp) trips
>in my bedroom. It has done this sporadically over the past 3 years
>since the house was built. Sometimes it will clear itself up and
>sometimes it will not. I most recently replaced the AFCI breaker and
>it is still tripping.
>
>I have nothing plugged into any of the outlets and the ceiling fan/
>light switches are off. I reset the breaker and turn on the light
>switch, the breaker trips. I pull the cord to turn the light off,
>reset the breaker and turn on the switch, the breaker does not trip.
>With the light switch off, I then start testing outlets. I plug a
>power cord (such as an extension cord or one that goes to a computer)
>into an outlet (knowing there is absolutely zero load on the cord) and
>the breaker trips.
>
>Where should I now turn to find my suspect. From what i've been able
>to see of the wiring in the attic above my room, it looks fine...there
>are no anchor nails piercing the shielding of any of the wires. There
>have never been any nails placed in the walls since the house was
>built. Should I check for loose connections on every outlet? Is the
>suspect in any of the unseen wiring somewhere in the walls? Can I
>just dump the AFCI and go to a regular breaker?
>
>Thanks all for your help in clearing up this pesky matter.

Look at the big wirenut full of white wires in the ceiling boxes to be
sure there is no copper showing. When you stuff that all back together
it is easy to short to ground.,

Charles Perry

2007-04-26, 5:25 pm

<slowone_@hotmail.com> wrote in message
news:1177592211.683679.275950@r30g2000prh.googlegroups.com...
>I have a problem where my AFCI breaker (Siemans Type OAF 15amp) trips
> in my bedroom. It has done this sporadically over the past 3 years
> since the house was built. Sometimes it will clear itself up and
> sometimes it will not. I most recently replaced the AFCI breaker and
> it is still tripping.
>
> I have nothing plugged into any of the outlets and the ceiling fan/
> light switches are off. I reset the breaker and turn on the light
> switch, the breaker trips. I pull the cord to turn the light off,
> reset the breaker and turn on the switch, the breaker does not trip.
> With the light switch off, I then start testing outlets. I plug a
> power cord (such as an extension cord or one that goes to a computer)
> into an outlet (knowing there is absolutely zero load on the cord) and
> the breaker trips.
>
> Where should I now turn to find my suspect. From what i've been able
> to see of the wiring in the attic above my room, it looks fine...there
> are no anchor nails piercing the shielding of any of the wires. There
> have never been any nails placed in the walls since the house was
> built. Should I check for loose connections on every outlet? Is the
> suspect in any of the unseen wiring somewhere in the walls? Can I
> just dump the AFCI and go to a regular breaker?
>
> Thanks all for your help in clearing up this pesky matter.

A coworker had the exact same problem. It ended up being a staple that had
pierced the romex and shorted the neutral to the ground. This caused the
GFCI function of the AFCI breaker to trip any time there was load. Lucky
for him it was in a section of wire that was the ONLY exposed portion (atic)
of the entire circuit.

Charles Perry P.E.

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