AFCIs

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jhrper

Member
Hey everyone, just got a job working for a local electrician, and wanted to ask a question or two about afci breakers. I was wondering about some possible reasons for an afci breaker to nuisance trip? A guy at work the other day said that he went out on a service call where this was a problem and apparently the hot in the device boxes was too close to the nuetral and the magnetic field around the hot conductor was affecting the nuetral and causing the breaker to trip. I would have never thought of that and I wanted to see what you guys have ran into with these breakers. Also, is there a good way to tell if the afci is just nuisance tripping for some non-life threatening reason or if there is actually a fastener through the wire or something like that?
 

celtic

Senior Member
Location
NJ
Not having ANY experience in the AFCI department (it's not required in NJ, but that's another story), I feel I am MORE than qualified to answer your inquiry:

jhrper said:
A guy at work the other day said that he went out on a service call where this was a problem and apparently the hot in the device boxes was too close to the nuetral and the magnetic field around the hot conductor was affecting the nuetral and causing the breaker to trip.

So what this fellow is saying is that all the AC and Romex cables with the grounded/ungrounded conductors in close proximity to each other is causing this tripping situation?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
celtic said:
So what this fellow is saying is that all the AC and Romex cables with the grounded/ungrounded conductors in close proximity to each other is causing this tripping situation?

Your sarcasm is great Celtic, (I do enjoy it), but he probably means the wires where they were stripped at their terminations. I have no idea but if it worked I guess so. I would bet that the wire may have been so close that they sometimes touched when there was some vibration in the house (a truck driving by, etc).
 

jhrper

Member
No, I asked the guy about that. He said they were close but not touching, and that the afci would only trip under load. If everything on the circuit was turned off and unplugged, it did not trip. As soon as a switch was flipped it would go. They are a mystery to me too. They monitor the sine wave and turn off in case of an arc, right?
 

mdshunk

Senior Member
Location
Right here.
When the information you're given doesn't add up, the information is bad or incomplete. Things aren't adding up here. I'm going out in a pretty stable limb by saying that something was touching.
 

celtic

Senior Member
Location
NJ
jhrper said:
N If everything on the circuit was turned off and unplugged, it did not trip. As soon as a switch was flipped it would go.
So when there is no load on the circuit it holds - but as soon as a load is applied (by flipping the switch) the circuit trips ~ assuming at both times the CB is "ON"?
 

celtic

Senior Member
Location
NJ
Dennis Alwon said:
Your sarcasm is great Celtic, (I do enjoy it),

It's a God given talent ;) , ranks right up there with my Irish dimplomacy ....for those of you that don't know what "Irish Diplomacy" is:
The ability to tell someone to goto hell and having them look foward to the trip
:D
 

brian john

Senior Member
Location
Leesburg, VA
mdshunk said:
When the information you're given doesn't add up, the information is bad or incomplete. Things aren't adding up here. I'm going out in a pretty stable limb by saying that something was touching.


Amen to that and when you can not explain the cause make something up.
I see this all the time, making stuff up to explain something they do not understand or are able to figure out. Not saying that is the case here BUT!

I would check the switch, circuit breaker, fixtures and wiring.
 

cowboyjwc

Moderator
Staff member
Location
Simi Valley, CA
I agree with brian. It's not just the installed wiring that the arc-fault is protecting, it could be a bad lamp or light fixture or any other appliance for that matter, or a bad switch.

Or as the boss suggested it could just be "magic".

That one was for celtic. : )
 

allenwayne

Senior Member
celtic said:
So when there is no load on the circuit it holds - but as soon as a load is applied (by flipping the switch) the circuit trips ~ assuming at both times the CB is "ON"?

What caused the afci to trip is a neutral to ground fault.It will hold just fine till any load is applied and then it trips out.I have found that the usual cause is in one of the receptacle outlets.Check those and I`d bet you will find the cause and solution.
 

jhrper

Member
Yeah, I hear you. You all have to be right, or else the breakers wouldn't work for anyone anywhere. I talked to the guy about it again and he said something was touching. Sorry guys, it makes sense now.
 

muskiedog

Senior Member
Location
Minnesota
Old line in the ground

Old line in the ground

I had one trip due to an old septic pump wire not being removed when the switched to a sewer system. Contractor just left it in the dirt. Well redoing the house put in AFCi for the bedrooms. ends up they had run off of the same circuit. When there was heavy rain it tripped. Hell I unplugged everything in the house trying to figure out what was up (old cabin hack job). So enough rain would create the arc and tripped the breaker.

Eliminated that old line and haven't had a problem since.
 

360Youth

Senior Member
Location
Newport, NC
mdshunk said:
When the information you're given doesn't add up, the information is bad or incomplete. Things aren't adding up here. I'm going out in a pretty stable limb by saying that something was touching.

I had to do a return on a final inspection this past year because the AHJ said the ArcFault was NOT tripping. I went back and did NOTHING but check it out and all was fine. When she went back, all was fine and said I must have "bumped" something (or something like that, it has been a few months). It seems to me ArcFaults just have quirks. It may be that it was a SquareD, which I think had some recalls. :-?
 

kbsparky

Senior Member
Location
Delmarva, USA
AFI breakers are unusual critters.

IF any load on the circuit immediately trips out the AFI, then I would say check the neutral wire at the panel. All too often, you will find the neutral conductor landed on the neutral bar instead of the proper terminal on the breaker.

2) Before you tear open any of your wiring, check the breaker itself. We had one that refused to reset, and I was about to tear that circuit apart. But experience told me to check the breaker itself first, so we replaced it with another one and it works fine. Saved a couple hours of headaches with that move .. :grin:

3) If both of those remedies have failed, then its time to start opening your circuit up to determine the source/cause of the nuisance tripping. In new construction, the most likey culprits are a ground wire touching a neutral terminal in an outlet box, or a blanked-off ceiling box where the fan or fixture has yet to be installed. Sometimes the neutral wire is not capped off in those, and if it happens to touch the side of the metal box, or be pinched with the bare ground wire, you will experience tripping of the AFI.
 

mattsilkwood

Senior Member
Location
missouri
ive also seen them trip with backstabs when you plug something in it moves the outlet just enough to get a tiny arc. i dont know why they even
put those backstabs on outlets they just cause trouble
 

jhrper

Member
You talking about the holes behind the receptacle for back wiring? Aren't they illegal anyway if you don't pigtail the nuetral first? I cant remember the code section but i do seem to remember that you can not install any device in a manner that if you remove the device you break the path of the nuetral.
 

allenwayne

Senior Member
360Youth said:
I had to do a return on a final inspection this past year because the AHJ said the ArcFault was NOT tripping. I went back and did NOTHING but check it out and all was fine. When she went back, all was fine and said I must have "bumped" something (or something like that, it has been a few months). It seems to me ArcFaults just have quirks. It may be that it was a SquareD, which I think had some recalls. :-?

SQ D`s afci problem was that they failed to trip with the test button.They would still trip out on a neutral to ground fault.
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
I thought the Square D recall was because of the breakers melting or something? My memory's fading, I don't remember the specifics, but I thought there was a fire.
 

allenwayne

Senior Member
georgestolz said:
I thought the Square D recall was because of the breakers melting or something? My memory's fading, I don't remember the specifics, but I thought there was a fire.

Nope the problem was they failed to test trip when the test button was pushed.The actual afci feature worked but they didn`t work on a test trip.The recalled ones had green buttons I think and the replacements had yellow buttons.But I`m almost color blind and they are all the same shade of gray :)
 
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