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HELP - Strange AFCI Tripping Issue

12K views 40 replies 10 participants last post by  chrispy_g 
#1 · (Edited)
Hi folks, in Googling my problems, I came across this great forum and I looked through some other AFCI threads, but nobody has talked about the kind of problem I have.....

On the circuit that runs 2 of my bedrooms (and the hallway), recently (last month or so), the AFCI breaker was tripping at odd times. Mostly overnight to start with. At first, it was every few days, then it started happening almost nightly.

I should say, nothing in terms of what's plugged in or running has changed at all during this time.

First step was looking at all the outlets for obvious wiring issues and checking them with a volt meter (and checking the basement box and all the visible wiring there). This revealed nothing. So, we replaced the breaker (original was a Siemens 15A, replacement was the same, but now has the LED fault indicator).

I went almost a week without a problem, then bam, tried to turn on my computer and the breaker tripped. Okay, I know the first thing is to unplug and test things one at a time, which I've done several times. This is where it's odd. Once it trips, it seems nearly anything plugged into any of the outlets on the circuit will re-trip it. At one point, I was testing with a simple clock radio and it would trip it with nothing else plugged in. However, with the new breaker, it's become a bit less sensitive. The alarm clock alone won't trip it, but a paper shredder will (or TV, etc.).

HOWEVER.....here's the oddest part I discovered yesterday. This is after my computer went down and I tried the testing with the shredder at various outlets. I got to one outlet in the room and the shredder didn't trip it. I went back to another outlet and it DID trip it like before. So, I started plugging a bunch of stuff (via extension cord) into that one working outlet and could NOT get it to trip (with a computer, TV, and shredder all running). At this point, ALL THE OTHER OUTLETS WERE THEN FINE AS WELL! I could plug the shredder in anywhere and the breaker wouldn't trip (this testing was all done within a 30 minute timeframe). It hasn't tripped since that time yesterday.

There seems to be no pattern to the trips and while it does now seem to have something to do with load, when it's "working" nothing will trip it...and when it's "bad", nearly anything will trip it.

I should also say that when it's "bad" and I leave everything plugged in, the breaker will not reset. I have to unplug everything and then reset it...and then try things one at a time. That's what I did with the "shredder" test yesterday.

Any suggestions would be appreciated. I have no problem calling an electrician in....but the advice I've gotten so far is that an electrician will only be able to find the problem during the "bad" times (which seem to be difficult to predict).

EDIT - I should also add that the other AFCI breaker that covers the other bedrooms NEVER trips. Ever....and I have an LCD TV and space heater that both get used frequently on that circuit. Also, we've been in this house for 5 years without issue (built in 2004).
 
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#2 ·
Hi and welcome to the forum!

You already know, since you say you read through a few posts here, that AFCIs are a quirky bunch!
I'm thinking once it trips, it's warm, and will continue to screw around with your head.
The guys here are real good at problems like this, so I'll sit back and watch them as they help you a bit better than I can, I'm afraid.

*good luck!*

DM
 
#5 ·
Couple of questions

Have you hung any pictures lately? Done any drywall patches? anything that would have caused a nail or screw to be driven into the wall.

Have you tried a non AFCI breaker on that circuit and see if that will trip? (I am suggesting replacing just testing the circuit)

Have you killed the circuit and done any testing at the recepticles from line to ground checking for continuity?
 
#6 ·
Thanks!....answers below...

Have you hung any pictures lately? Done any drywall patches? anything that would have caused a nail or screw to be driven into the wall.

NO...NOTHING CHANGED AT ALL.

Have you tried a non AFCI breaker on that circuit and see if that will trip? (I am suggesting replacing just testing the circuit)

NO...ONLY BECAUSE THE "BAD" TIMES ARE SO INTERMITTENT (COULD BE DAYS APART) AND IT CAN GO FROM "BAD" TO "WORKING" WITHIN MINUTES (LIKE YESTERDAY)...I DIDN'T WANT TO LEAVE A STANDARD BREAKER ON THAT CIRCUIT FOR AN EXTENDED PERIOD. I SHOULD SAY THAT THE INDICATOR ON THE NEW AFCI BREAKER IS INDICATING AN ARC FAULT (ONE LED ON FOR 5 SECONDS AFTER RESET).

Have you killed the circuit and done any testing at the recepticles from line to ground checking for continuity?[/quote]

OKAY, YOU'VE REVEALED THE LIMIT OF MY ELETRICAL KNOWLEDGE...WITH THE CIRCUIT KILLED, WE CHECKED EACH OUTLET FOR ANY VOLTAGE. IS THIS WHAT YOU MEAN? FOR THE RECORD, IT WAS SHOWING ZERO, EXCEPT FOR A FEW TIMES WHERE WE GOT IT TO READ "0.3"...BUT THAT WAS SO SMALL, WE CHALKED IT UP TO THE ACCURACY OF THE METER.
 
#7 ·
OKAY, YOU'VE REVEALED THE LIMIT OF MY ELETRICAL KNOWLEDGE...WITH THE CIRCUIT KILLED, WE CHECKED EACH OUTLET FOR ANY VOLTAGE. IS THIS WHAT YOU MEAN? FOR THE RECORD, IT WAS SHOWING ZERO, EXCEPT FOR A FEW TIMES WHERE WE GOT IT TO READ "0.3"...BUT THAT WAS SO SMALL, WE CHALKED IT UP TO THE ACCURACY OF THE METER.
You will need an Ohm meter for this, or a multi meter with an ohm meter scale.

What you are looking for with the circuit off is continuity (ohms) resistance to ground. This test would be from the line side (black) to ground, start by mearsuring resistance from the recepticle line side (should be the shorter of the 2 prongs) to ground.

You should get no reading or "OL" on the meter.

Then repeat the test for each recepticle with the circuit off and the black wire removed from the recepticle, measure from the black wire to ground. Again you should read "OL" don't touch both test probes or you will get a reading, the reading will be the resistance of you to ground.

Ok lets start there.
 
#10 ·
it doesn't matter which lead you plug as resistance does not have a polarity.

I would also suggest that you get a plug tester (you can get them at Cdntire) which is plugged into the the receptical and will ensure that it is wired correctly. do this on every plug that you know is on the circuit.

the little bit of reading i did on AFCI says that another cause of the tripping could be a ground fault as many of the AFCI manufacturers incorporate CFI function into the breaker.

another suggested cause could be from another circuit. if there is a shared neutral somewhere, there could be a slight phase shift that causes the AFCI to trip.

I have not worked with these breakers at all, so do not have any personal experience. but I would first make sure all of the plugs are wired correctly and work from there..

Also, if you are comfortable working in the panel, swap AFCI breakers between your bedroom and this circuit, to rule out a faulty AFCI. While the wire is off of the breaker, that is when I would feel more comfortable doing the meter check for continuity previously suggested... Make sure there is nothing plugged in when doing that testing..

another thought... have you actually pulled any plugs from their recepticals?? I wonder if you have a loose connection... seen plugs where the wire was pushed in become loose and create arcing. an inspection would not be a waste of time...

good luck

rod
 
#13 ·
Jackofall1, I understand that you weren't looking for polarity, but Chrispy_G was asking which test lead went where, and I was simply stating that it didn't matter because resistance does not have polarity. you either have it or you don't. unlike measuring a DC voltage where the reversing of the leads will produce a positive to negative reading.

rod
 
#18 ·
As you have two AFCI circuits, if they are rated for the same ampacity, if you are able to turn off power within the panel where they are located, and if you are comfortable that you can safely do so, you could try reversing the circuits between the breakers, and determine if the fault follows the breaker or the circuit.
 
#19 ·
If the receptacles were wired wrong the circuit would be predictable.

Heres my take on AFCIs. They are an absolute PAIN IN THE BUTT.

as far as "shared" neutrals go, any electrician that wired a house with AFCIs would NOT share neutrals. Again, it would be a predictable trip.

Inductive loads such as motors almost ALWAYS trip AFCIs. Also, electronics and transformers will trip it regularly. (Computer have power supplies)

Heres my recommendation:

get a power strip that has SURGE PROTECTION on it and put it on everything that is on that circuit ESPECIALLY electronics, motors and the like.

If that doesnt work, remove the AFCI and replace with a standard breaker.

If you keep tripping that AFCI it wont be worth a darn in a year. (worn out)


AFCIs work by detecting current spikes from Arcs. Thats it.
 
#21 ·
Intermittent neutral-ground fault

The symptoms you describe sound like the result of an intermittent fault from neutral to ground. When the neutral and ground make contact on an AFCI (or GFCI) protected circuit, applying any load on the circuit will cause a trip fairly quickly because some of the load current returns on the grounding conductor and the AFCI senses an imbalance. This will only happen when a load is applied, not just when the neutral and ground contact each other.

My advice would be to wait until the problem is really bad (breaker won't reset), then open the panel and disconnect the circuit neutral from the breaker. Check for continuity between the neutral and ground. If your meter shows anything other than an open circuit, you've identified the problem. You may need to keep testing for awhile to catch the problem in action - intermittent connections can be hard to diagnose.

Be careful working in the panel. Though your circuit will be turned off, the rest of the panel is still hot. If you are not comfortable with this, hire an electrician. Troubleshooting a frustrating problem like this is not a friendly first electrical project.
 
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#22 · (Edited)
AFCI's have such a bad rap its not funny. However so did GFI's when they first came out. Due to what I believe two factors, one new tech, two poorly manufactured stuff that by that time had become standard. It was common practice to allow some current to leak to ground and nobody cared. Enter GFI. Any well designed electrical appliance even a motor will not leak current under normal operation.

AFCI's are (in theory) to detect arcs at current levels way to low to cause a overload and wake a breaker. These arcs are the most dangerous quirk of electricity as they create way more heat than necessary to ignite the always surrounding flammable material. (cause most home fires) Now I am willing to apply my two previous rules to AFCI's. Part and I suspect a large part is faulty tech rushed too quickly to market. (I refuse to install them) The other part is a lot of stuff has low budget design. Switching power supplies(read computers), is I suspect a common culprit as well as extremely poor design and efficiency(transients and noise). So apart from their failures we must also consider that they might be doing their job. I have been told, and have no reason not to believe, that wiring stapled too hard will cause damage to the wire which might arc. This could be hidden, intermittent, and not show up for some time. Which makes these all the much harder to troubleshoot.(gonna need a scattergun)

I hesitate to denounce the practice of ohming out a trouble some circuit with a multimeter, but I suspect that our chances of catching a high resistance short is next to a game of craps. I also hazard to say that any problem would not be between neutral and ground, but between hot and neutral. Unless it was the GFI portion of the breaker upset, which could be tested by installation of a GFCI breaker or plugging in a s GFI extension cord.
 
#24 ·
Thanks for all the help so far guys! I did check all the outlets (with everything unplugged) with the ohm meter (circuit off) and they all read zero. To be sure I plugged a couple things in (circuit still off) and I could get a 14 reading on the outlets.

I took another close look at the breaker box and the 2 wires going to the 2 AFCI breakers come in the same grommet...and boy is it tight in there. The plastic from the grommet does seem to be putting pressure on the wire. However, the other breaker never trips.....still, it might be worth taking a closer look.

Is it also worth trying to move the AFCI breaker in question to another place in the breaker box? Maybe even move it from left to right?

Last night, I plugged some things in and it didn't trip....but then I plugged in the simple plug tester and all the outlets checked out fine until I got to the last one....the tester caused the breaker to trip when I plugged it in. I reset the breaker and tried it again...same result. Then I unplugged everything and tried just the tester and it didn't trip. Plugged some things back in, still didn't trip....then tried the tester again and it tripped. Then tried it again from scratch and it wouldn't trip no matter what. Went back a bit later and then I got it to trip again with the tester (other stuff still plugged in). The most frustrating thing is thinking I've found a pattern only to have it break 2 minutes later...
 
#28 ·
Is it also worth trying to move the AFCI breaker in question to another place in the breaker box? Maybe even move it from left to right?

Last night, I plugged some things in and it didn't trip....but then I plugged in the simple plug tester and all the outlets checked out fine until I got to the last one....the tester caused the breaker to trip when I plugged it in. I reset the breaker and tried it again...same result. Then I unplugged everything and tried just the tester and it didn't trip. Plugged some things back in, still didn't trip....then tried the tester again and it tripped. Then tried it again from scratch and it wouldn't trip no matter what. Went back a bit later and then I got it to trip again with the tester (other stuff still plugged in). The most frustrating thing is thinking I've found a pattern only to have it break 2 minutes later...
If you are going to move the breaker in the panel, I would suggest to move it to the other phase. otherwise I agree with Jack, that it won't make a difference.

Also, I think you found a slight pattern with the last outlet causing the breaker to trip a few times. Pull that receptical out and disconnect it, checking for how well the wires are connected. what i don't recall is if you have done that yet. I know some folks use the push-in way of connecting the wires, which I personally don't like. these sometimes become loose and may be cause intermittent problems.

rod
 
#26 ·
Moving the breaker in the box I don't believe will solve anything.

You have tested and proved that there is no short circuit, I am at a loss as to further investigation, short of either installing a standard breaker for short circuit protection, or ripping down all the drywall and replacing the wire, both options I am sure you don't want to exercise.

I guess the next step I would personally try is go out and purchase new recepticles to replace the ones that are in service either that or some magic dust to reverse the AFCI evil spell.

I guess something else to try, just guessing now, is disconnect each recepticle starting with the last on in the chain, and see if you can isolate it to a leg between recepticles.
 
#27 ·
Bad receptacle? I'm willing to try that....that only costs $20 and an hour of my time.

I really hope (for obvious reasons) that I can eliminate wiring as the cause. The house was built in 2004 without there ever being an issue, so I would hope a wiring problem would've popped up before.

As I said, I don't have a problem having an electrician come in....but I really wish I could reliably duplicate the problem so as not to waste time and money. The problem is that there are times where I literally can't get the breaker to trip....and it can go for days without a problem and then act up so bad that I can't even reset the breaker without unplugging everything.

The name of the electric company that did the original wiring is on the breaker box....so calling them in might be a good step. I would hope they would know better than anyone what might be going wrong.
 
#33 ·
Yes just the recepticle one at a time if you want, but don't use the stab connection, actually put the wire on a terminal.

If you find that the recepticle is wired by use of the stab terminals, thats all you may have to do, is change the wire to the recepticle terminal.
 
#39 ·
I know it's pretty "low tech" as a trouble shooting method, but...

If this is a branch circuit problem (likely if it's occurring on two different breakers tested by connection to the same circuit, and with no load on the circuit) you might try temporally interrupting the circuit at a mid-point outlet and see if the problem still occurs.

If it does, start shortening the circuit upstream 'till the problem is no longer present.

If it does not, start lengthening the circuit downstream until it reoccurs.

If it's a long (many outlets) circuit, you can speed things up by "halving" the test segment each time.
 
#41 ·
It's only occurring on that one AFCI breaker, never the other one....and the breaker is indicating that it's an arc fault causing the trip.

The problem is so intermittent that your method would be unlikely to go through with....I can go days without being able to trip it and then go through a period where nearly any load will trip it over and over again....and then magically it will be okay again.

I didn't get a chance to take apart the receptacles yet to see if they're all wired properly to the screw terminals and not just the stab terminals.
 
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