Arc fault breaker

C

Captorofsin1

Member
Location
Florida
Occupation
Electrical contractor
Hello everyone. Just need a "sounding board".

Qo panel.

Yesterday I was at a call. Any load on the circuit would trip the combination art fault breaker (just want to make it clear that it's not an old school AFCI).

Any receptacle I plug a lamp into and turn the lamp on it would flash and then the breaker wood trip. Same thing with the ceiling fans and the light kit on the ceiling fan. Turn on for split second and then break her trip.

Tried swapping out to a new breaker. Same scenario.

Reinstalled CAFCI breaker. Then I got the right idea of removing just the neutral (leaving hot and pigtail connected). Even with the load neutral disconnected off the arc fall breaker it would trip as soon as I turned on any lamp plugged into any receptacal on the circuit. I would flip the wall switches (ceiling fan would light kit) and same thing (motor would turn briefly and/or light would flash briefly and then arc fault breaker would trip).

*This was only when there was a load. If I had the ceiling fan (light or motor) turned off (pull strings) and turned wall switches to "on" position, it would hold. I could plug a lamp into any receptacle and as soon as I turned on lamp, breaker wood trip.

That small flash of light tells me that the circuit is finding a path back home somewhere else

*JUST TO REITERATE, THIS IS WITH THE LOAD NEUTRAL DISCONNECTED FROM THE ART FALL BREAKER*


The house appeared (as per what I saw in the panel, new receptacles, in the wiring going to the receptacle) to have been rewired in the last 10(?) years. In my professional opinion, the rewire was done by an electrical contractor. This tells me that (more than likely, but you never know 😀) that know neutrals were crossed anywhere. My intuition's telling me that more than likely somebody got overzealous with the staples when they were stapling the Romex and caused a break in the neutral (inside the jacket)... Fill in the blanks...

Opinions?
 
It's not a staple. The neutral is mixed with another circuit or an EGC is in contact with the neutral somewhere in the circuit.

Disconnect both hot and neutral from the breaker. Check continuity between the circuit neutral and ground or neutral buss. It will show continuity. Start searching.

If this circuit operated fine for 10 years you need to start questions about what work was done recently. Any work, not just electrical.
 
Yes I would guess the neutral is shorted to ground. I had this happen on a ceiling fan bad piece of romex. Disconnect the ground and see what happens. Breakers stays on that means ground is probably carrying neutral current
 
Eddie702 said:
Yes I would guess the neutral is shorted to ground. I had this happen on a ceiling fan bad piece of romex. Disconnect the ground and see what happens. Breakers stays on that means ground is probably carrying neutral current
Click to expand...
When I was in the field a couple years I had a grounded neutral. I called the shop and they got a laugh thinking neutral are
supposed indicate ground. I said NO this is actually grounded besides the disconnect. So there ya go.
 
Immediately after replacing my FedPac panel with QO, one CAFCI breaker serving a pair of bedrooms would trip in the same manner you describe. It was chased down to a ground wire that had worked free of its receptacle screw. Perhaps most annoyingly, said receptacle didn't even have anything plugged in, and near as I could tell, the ground wasn't shorting against anything, either.
 
hbiss said:
So, how would you explain that tripping the AFCI?

-Hal
Click to expand...
I will, with no shame, admit that I have absolutely zero inkling of even the wildest nonsense theory about why. Only that after putting that wire back on the screw, the breaker hasn't tripped once in nearly six years.
 
ModbusMan said:
I will, with no shame, admit that I have absolutely zero inkling of even the wildest nonsense theory about why. Only that after putting that wire back on the screw, the breaker hasn't tripped once in nearly six years.
Click to expand...
And I, as an unashamed, lowly, "non - electrician", am also admitting, that any experience excellent person such as @ModbusMan, is not afraid to be open & honest.... well... as much as he may hate it... he just advanced to be in my top 5 pick! (Sorry buddy... Hee hee...)

Thank u Sir....
Bill
:)
 
We always have to remember that no tech problem is mystical. In the end all makes sense if we stay with it long enough.
But some electrical problems still seem mystical.
 
DooWop said:
We always have to remember that no tech problem is mystical. In the end all makes sense if we stay with it long enough.
But some electrical problems still seem mystical.
Click to expand...
And some mysteries are not worth solving once they go away!

Boss man: "What was the problem?"
Me: "I dunno, but it isn't a problem any more. I told the customer that I had to re-initialize the marzelframs in the encabulator, they bought it."
Boss man: "Good man!"

In the OP's issue, I just want to point out that there are TWO types of Arc Faults, Series and Parallel. In a parallel fault, the arc is jumping from line to neutral or ground or to another line that is out of phase (i.e. L1 to L2), but in a SERIES fault, it is jumping across a gap in the line, not to anywhere else. So if the problem is a bad connection on a line terminal, there is no fault if there is no current flow, and there is no current flow until there is a load. So your description sounds like it was a Series arc fault.

A CAFCI means "Combination Arc Fault Circuit Interrupter", meaning a combination of Series and Parallel. In a lot of older (prior to 2008) AFCI breakers, they were one or the other, mostly parallel. I've seen situations where people update their old AFCI breakers to CAFCI and discover that they had loose connections that the old one never detected.
 
I had a call for an AFCI tripping a few years ago in a bedroom. I took every receptacle and switch apart in the room and found nothing. I put them all back and as soon as any load was applied the breaker would trip. I even went into the attic and visually traced the NM from where it entered the attic, all across the attic, and down into the room. No breaks in the cable anywhere.
While scratching my head, I looked up and saw the ceiling fan, which I hadn't considered.

I took the canopy loose to look at the wiring. I finally saw what was happening. A neutral had partially slipped out of the wire nut. The bare EGC had found it's way to the exposed part of the neutral. So a neutral to ground fault was the problem.

To the OP: you might try looking in fans, lights, etc. for a ground and neutral touching.
 
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