AFCI Madness - help!

[Coppersmith]

Home owner is selling. Home inspector found an AFCI for bedroom-1 (BR1) jury-rigged to work. (I don't know how.) Handyman fixes AFCI wiring, it trips. Handyman replaces AFCI, still trips. I'm called and troubleshoot. AFCI wiring looks proper. BR1 has it's own circuit. Fault appears to be in home run. BR2 next door is also on it's own circuit. I refeed BR1 from a BR2 outlet, BR2's AFCI trips. I disconnect refeed wiring. BR2 AFCI now continues to trip even though it is exactly the same as before I started. (I double checked the refeed connection point for problems). I sub in a new AFCI. Trips. I sub a standard breaker for AFCI, it holds so not a short. Anybody see a reason this might happen?

 

[electricguy61]

Home owner is selling. Home inspector found an AFCI for bedroom-1 (BR1) jury-rigged to work. (I don't know how.) Handyman fixes AFCI wiring, it trips. Handyman replaces AFCI, still trips. I'm called and troubleshoot. AFCI wiring looks proper. BR1 has it's own circuit. Fault appears to be in home run. BR2 next door is also on it's own circuit. I refeed BR1 from a BR2 outlet, BR2's AFCI trips. I disconnect refeed wiring. BR2 AFCI now continues to trip even though it is exactly the same as before I started. (I double checked the refeed connection point for problems). I sub in a new AFCI. Trips. I sub a standard breaker for AFCI, it holds so not a short. Anybody see a reason this might happen?

Is there a bath fan on the circuit? I've had two different experiences of AFCI's not liking Panasonic bath fans

What brand is the AFCI? HomeLine seems to be the worst. You might be able to substitute an Eaton (who's breakers are approved for use in all panels)

Can you just remove the AFCI from the circuit. It's no longer new construction, the owner can do what they want with their electrical system, unless you plan on getting a permit for your repair.

 

[Coppersmith]

Is there a bath fan on the circuit? I've had two different experiences of AFCI's not liking Panasonic bath fans

No, both bedrooms are on their own circuits.

What brand is the AFCI? HomeLine seems to be the worst. You might be able to substitute an Eaton (who's breakers are approved for use in all panels)

Panel and breakers are Square D QO. Neither Eaton BR or CH will fit in panel.

Can you just remove the AFCI from the circuit. It's no longer new construction, the owner can do what they want with their electrical system, unless you plan on getting a permit for your repair.

Seems like a liability issue (and moral concern) to suggest to home owner replacing the AFCI's with standard breakers when they are tripping due to an arc fault. What if a fire happens?

 

[Ponchik]

Suggest rewiring the whole circuit.

 

[Coppersmith]

Suggest rewiring the whole circuit.

I thought about running a roll of NM from the panel through the house to the bedroom just to check my assertion that the home run is bad. It's a two story house with the bedrooms upstairs. Pulling in a new HR would be expensive and messy. I was trying to offer a reasonably priced solution since bedrooms are lightly loaded.

 

[electricguy61]

It is highly unlikely that there is in fact an arc fault situation. But if that is the fear, and you can't add the circuit to an existing one, you must, as Edward suggested, run a new circuit.

 

[Coppersmith]

It is highly unlikely that there is in fact an arc fault situation.

Home run terminates in the 2 gang switchbox for the bedroom. Took apart all the wires and turned on the circuit. I didn't trip immediately but if I put any load on it, it trips. Sounds like an arc fault to me. Probably has a drywall screw through it somewhere.

But if that is the fear, and you can't add the circuit to an existing one, you must, as Edward suggested, run a new circuit.

Why can't I combine the two bedroom circuits? Multiple bedrooms are frequently on one breaker.

 

[zbang]

Probably has a drywall screw through it somewhere.

Wonder if a megger would show up anything here; might help isolate to a single run.

 

[Ponchik]

Disconnect all of the wiring from the devices and from the pigtails. Find out where the homerun comes into and then figure out how the wiring is going. (HR comes into box #1 then to box #2 then....) Draw a map of how the wiring is going.

Then turn the circuit ON put a load on the HR conductors (box#1) and see if the AFCI breaks. If it does not make up that box and move down to # 2. Put a load on it and test the AFCI. If it does not trip then move to box #3 so on and so forth.

Added::>>
when was that portion of the house rewired?? Was AFCI required during that code cycle? If not, then remove AFCI and install regular OCPD. Otherwise, you can give the client the option of rewiring the two rooms or installing a basic breaker. YOU don't worry about the cost let them pay you.

 

[GoldDigger]

1. If circuit trips only with a load, and that load is less than 7A, then it cannot be an arc fault trip. It would have to be a GF trip instead. Does the existing breaker have an indication of which fault produced the trip?
(Search model number on internet to find out!)
2. If it is a ground fault trip, most likely there is a neutral to EGC (wire or raceway) short or a cross connection between two circuit neutrals somewhere. Possibly a skinned neutral? When you did and undid the cross connect you may have accidentally cross connected the two sets of neutrals or skinned a neutral on B2.

Sent from my XT1585 using Tapatalk

 

[big john]

Pop in a GFCI breaker temporarily. My money is on a neutral ground fault.

If the GFCI trips you know this isn't an arc fault problem.

If the GFCI holds then it's an interference problem with the AFCI, because they're garbage and don't detect actual arc faults anyway.

 

[al hildenbrand]

Home run terminates in the 2 gang switchbox for the bedroom. Took apart all the wires and turned on the circuit. It didn't trip immediately but if I put any load on it, it trips. Sounds like an arc fault to me. Probably has a drywall screw through it somewhere.

Lift the AFCI LOAD side hot and neutral and the bare copper from the equipment ground bar, and make sure the other end in the 2 gang switchbox has all its conductors taken apart and separated, and then check for continuity between the conductors. Also, at the breaker end of the branch circuit, with the conductors disconnected, check for continuity from each of them (they should be floating without any electrical connection to anything) to the panel equipment ground.

What you described (red bold italics underline) feels like a ground fault and leads me to suspect that the homerun is not unbroken and is cross neutraled in a junction box to another circuit.

Why can't I combine the two bedroom circuits? Multiple bedrooms are frequently on one breaker..

You can if the total floor area doesn't exceed 600 square feet for a 15 Amp circuit.

 

[growler]

Home owner is selling. Home inspector found an AFCI for bedroom-1 (BR1) jury-rigged to work. (I don't know how.) handyman fixes AFCI wiring, it trips. Handyman replaces AFCI, still trips. I'm called and troubleshoot. AFCI wiring looks proper. BR1 has it's own circuit. Fault appears to be in home run. BR2 next door is also on it's own circuit. I refeed BR1 from a BR2 outlet, BR2's AFCI trips. I disconnect refeed wiring. BR2 AFCI now continues to trip even though it is exactly the same as before I started. (I double checked the refeed connection point for problems). I sub in a new AFCI. Trips. I sub a standard breaker for AFCI, it holds so not a short. Anybody see a reason this might happen?

I think I would gather more information.

What do you mean by rigged AFCI? I don't even know how to rig one.

Go back to the original problem, what was the problem before the handyman started to work on the circuit?

Was this circuit working,when, and what has changed since then.

 

[JFletcher]

I'd start with making sure that the hot and neutral conductors going to the AFCI both* belong together/are from the same circuit. *If it's a MWBC, then 3 conductors to a 2p breaker. Neutral wire from HR to breaker, pigtail (if not a plug-on neutral) to buss.

If that doesnt fix the problem, then I'd go with disconnecting everything plugged into all receptacles, and turn off every light. GFCI receptacles with normally on indicator lights will have to be removed and temporarily bypassed. Remove wires from breaker, leave the ground hooked to its buss bar. Test for continuity across all conductors and to ground buss (H₁N and ground, H² to N and ground, and neutral to ground); everything should be open. If they are (unlikely ime), and the breaker holds, then I'd shut off all other branch circuits and re-energize one at a time to see if it's some sort of interference.

"Home inspector found an AFCI for bedroom-1 (BR1) jury-rigged to work"

In pondering how one would rig an AFCI, the only possible way that comes to mind is a pure AFCI (no GFCI protection) having the branch circuit neutral bypass the breaker and the load less than 7-8A, tho I've no way to test that idea at the moment. Istm it would still function as a standard breaker but fail the self-test (i.e., rigged).

 

[Coppersmith]

1. If circuit trips only with a load, and that load is less than 7A, then it cannot be an arc fault trip.

Please explain further.

It would have to be a GF trip instead.

Does the existing breaker have an indication of which fault produced the trip? If it is a ground fault trip...

If the GFCI trips you know this isn't an arc fault problem.

What you described feels like a ground fault

The description of the AFCI breaker is shown below. There is no indication of a GFCI circuit in it. If there is no GFCI circuit in it, can it be tripping because of a ground fault?

http://www.homedepot.com/p/Square-D-QO-20-Amp-Single-Pole-AFCI-Circuit-Breaker-QO120AFIC/100077019

What do you mean by rigged AFCI? Go back to the original problem, what was the problem before the handyman started to work on the circuit? Was this circuit working,when, and what has changed since then.

According to HO AFCI was rigged so that it didn't trip, perhaps the bedroom was on a standard CB. IDK, I didn't see it.
The handy man just fixed the wiring so the AFCI was properly wired (I can't believe I'm saying this.). When it started tripping, he replaced it thinking the AFCI was bad. The circuit apparently has been "rigged" since the HO bought the place. So technically, it's never worked for him. Whether it was like this since inception, IDK.

 

[mbrooke]

The breaker does not have GFCI (5ma) but it does have the less sensitive GFP (30 or 50ma). Same concept, higher trip threshold. Any current going onto the neutral or another circuit will cause the breaker to trip.

 

[GoldDigger]

Please explain further.
...
The description of the AFCI breaker is shown below. There is no indication of a GFCI circuit in it. If there is no GFCI circuit in it, can it be tripping because of a ground fault?

http://www.homedepot.com/p/Square-D-QO-20-Amp-Single-Pole-AFCI-Circuit-Breaker-QO120AFIC/100077019

Do not trust the displayed specifications at a big box store site, or even a supply house site to be complete.

If you look at page 3 of this PDF, you will see a detailed description of how to determine the cause of a trip.
The GF detection does not constitute GFCI. That is found in dual function AFCI breakers only. It is a higher current (~30ma?) trip which is present to allow the breaker to pass a particular UL test for which the arc signature analysis was not sufficient.
Some AFCI breakers, notably GE, have removed the GF trip after improving the arc detection. But many of us feel that actually removed the major usefulness of the breakers in detecting wiring problems and preventing fires.

The arc signature detection for parallel arcs cannot be activated until the instantaneous current exceeds some very high value (~60A?). It basically just allows the overcurrent trip to happen sooner than it would for a thermal trip and allow it to trip on intermittent (arcing) high current that may not have a high enough time average for the normal thermal trip.
The arc signature detection for series arcs cannot be activated until the instantaneous current exceeds about 7A, to reduce the likelihood of false tripping from noise from other circuits or sources.
That is why I asked what the load current was when you saw it trip.

 

[growler]

The circuit apparently has been "rigged" since the HO bought the place. So technically, it's never worked for him. Whether it was like this since inception, IDK.

At least that is some information to start with. That means it really could be the home run as you suspected.

If you know that the home run goes to a switch box or a receptacle then you could temp wire a receptacle and place a load on the home run. I have a large drill motor is use for such things.

If you have other arc fault breakers available at the job you may even want to try a third breaker to see if it holds. It had one that would hold on everything but a TV set and yet it was a bad breaker because the circuit held when replaced with a new breaker. They can be strange problems at times.

Anyway, lots of luck.

 

[GoldDigger]

If you have other arc fault breakers available at the job you may even want to try a third breaker to see if it holds. It had one that would hold on everything but a TV set and yet it was a bad breaker because the circuit held when replaced with a new breaker. They can be strange problems at times.

The manufacturers are continually updating the arc signature database that their AFCI breakers use. (A closely guarded trade secret, since doing the best job of passing the UL tests and still avoiding false tripping is a commercial advantage).

These updates to the database (program) are generally not announced unless you are working with a factory tech on a specific problem.
Often you will get a shipment of almost identical looking new breakers that will not false trip in your situation. There is no control over the mix of products already in the distribution channel.

 

[SAP]

We had problems like that years ago on some new track homes years ago, if you know were the home run is you can try switching the neutral and hot wire at the panel and first outlet, it worked the few times we had tripping AFCI