AFCI and GFCI troubleshooting tools and guidelines

[marmathsen]

I'm looking for some advice on steps to be taken and tools to use when doing advanced troubleshooting of tripping AFCI and GFCI circuit breakers.

I can fairly easily troubleshoot and resolve issues where the circuit is constantly tripping or consistently tripping under a specific scenario. If there is a low impedance short between any of the conductors, that is fairly straightforward to track down. Usually by starting in the boxes where multiple circuits are likely to be to look for combined neutrals from more than one circuit. Or split the circuit in half then test the breaker, then split it again and test, etc.

Where I run in to issues is where the tripping breaker is more intermittent and unpredictable. For instance I have project where a kitchen counter circuit was tripping but of course never while we were there. We replaced a Square D Homeline 1 pole 20A Dual Function breaker under the premise that the breaker might be bad. Well of course now that it's a month later, the breaker has started to occasionally trip. But only occasionally.

I have done a lot of digging try to find a good resource for doing more advanced troubleshooting. I have seen a lot of people recommending to "Megger" the circuit. I assume they mean to do an insulation test. This is not a tool that I am familiar with and have never used. It seems like this could be used to find high impedance parallel arcing, but does it work for series arcing? I'm guessing no...but maybe I'm wrong. I even saw one installer mention that they test every circuit first before landing it on the breakers, then if stuff starts tripping after the drywall and other trades come in, the electrician can comfortably say "not our fault, we tested it". Does anyone else do this? Am I totally off base on what a Megger is?

I also have come to realize that BR dual function breakers have a whole suite of error codes that can help to troubleshoot circuits. 6 separate codes to be exact: Series Arcing, Parallel Arcing, Overload, Overvoltage, Ground Fault/Grounded Neutral, Self Test Failure. This seems like a potential diagnostic tool that one could use in a compatible panel on a temporary basis to diagnose, and it seems superior to the limited diagnostics Square D builds in (Square is is our standard). Does anyone out there use the BR breakers as a useful tool in other branded panels?

What techniques and tools do others use to troubleshoot and/or verify your circuits?
Insulation tester?
BR DF breaker?
Thermal Camera?
Sacrificial offering to the electrical gods?

Are there tools that can test for potential series arcing, like a loose connection?
Are there tools that can help locate a fault? It looks like Megger has some but I'm gonna guess that they are $$$$$$$$ since they appear to be intended for industrial and utility uses.

Hopefully you all have some good advice headed my way. I look forward to hearing what you have to say.

Rob

 

[LarryFine]

Substitution.

 

[ptonsparky]

We just don’t have too many problems with them anymore and my guys are pretty tenacious when tracking down the error codes. That said, we have used everything on your list, plus Larry’s. Repeatedly.

No quick fixes.

 

[romex jockey]

I'm looking for some advice on steps to be taken and tools to use when doing advanced troubleshooting of tripping AFCI and GFCI circuit breakers.

I can fairly easily troubleshoot and resolve issues where the circuit is constantly tripping or consistently tripping under a specific scenario. If there is a low impedance short between any of the conductors, that is fairly straightforward to track down. Usually by starting in the boxes where multiple circuits are likely to be to look for combined neutrals from more than one circuit. Or split the circuit in half then test the breaker, then split it again and test, etc.

Where I run in to issues is where the tripping breaker is more intermittent and unpredictable. For instance I have project where a kitchen counter circuit was tripping but of course never while we were there. We replaced a Square D Homeline 1 pole 20A Dual Function breaker under the premise that the breaker might be bad. Well of course now that it's a month later, the breaker has started to occasionally trip. But only occasionally.

I have done a lot of digging try to find a good resource for doing more advanced troubleshooting. I have seen a lot of people recommending to "Megger" the circuit. I assume they mean to do an insulation test. This is not a tool that I am familiar with and have never used. It seems like this could be used to find high impedance parallel arcing, but does it work for series arcing? I'm guessing no...but maybe I'm wrong. I even saw one installer mention that they test every circuit first before landing it on the breakers, then if stuff starts tripping after the drywall and other trades come in, the electrician can comfortably say "not our fault, we tested it". Does anyone else do this? Am I totally off base on what a Megger is?

I also have come to realize that BR dual function breakers have a whole suite of error codes that can help to troubleshoot circuits. 6 separate codes to be exact: Series Arcing, Parallel Arcing, Overload, Overvoltage, Ground Fault/Grounded Neutral, Self Test Failure. This seems like a potential diagnostic tool that one could use in a compatible panel on a temporary basis to diagnose, and it seems superior to the limited diagnostics Square D builds in (Square is is our standard). Does anyone out there use the BR breakers as a useful tool in other branded panels?

What techniques and tools do others use to troubleshoot and/or verify your circuits?
Insulation tester?
BR DF breaker?
Thermal Camera?
Sacrificial offering to the electrical gods?

Are there tools that can test for potential series arcing, like a loose connection?
Are there tools that can help locate a fault? It looks like Megger has some but I'm gonna guess that they are $$$$$$$$ since they appear to be intended for industrial and utility uses.

Hopefully you all have some good advice headed my way. I look forward to hearing what you have to say.

Rob

The best thing you can do is educate yourself to just what an AFCI is Rob

http://www.combinationafci.com/resources/doc_ieee_combination_afci.pdf

~RJ~

 

[marmathsen]

Substitution.

Can you elaborate?

Substitution of what?

Sent from my Pixel 4 XL using Tapatalk

 

[marmathsen]

We just don’t have too many problems with them anymore and my guys are pretty tenacious when tracking down the error codes. That said, we have used everything on your list, plus Larry’s. Repeatedly.

No quick fixes.

Do you feel that an insulation tester is a useful tool with investing in? Do you have a make/model you like?

Sent from my Pixel 4 XL using Tapatalk

 

[kwired]

Do you feel that an insulation tester is a useful tool with investing in? Do you have a make/model you like?

Sent from my Pixel 4 XL using Tapatalk

Insulation tester is the same thing as the "megger" you asked about.

It is basically an ohmmeter that uses a higher test voltage than a typical DMM. 500 or 1000 VDC test volts is going to find leakage easier than applying 9 VDC.

 

[Little Bill]

Substitution.

Can you elaborate?

Substitution of what?

Sent from my Pixel 4 XL using Tapatalk

He is talking about swapping the breaker either with a new breaker or another one in the panel. This should tell you if its the breaker or not. One thing you can do is contact the AFCI breaker mfg and see if what you have is the latest version. If not, have them send you the latest.

 

[LarryFine]

Can you elaborate?

Substitution of what?

I got a call for an AFCI breaker that kept tripping because of a particular bedroom light. I swapped the circuit wires with those of another bedroom circuit. No more tripping.

So, substitution of the AFCI device with another.

 

[hbiss]

I have done a lot of digging try to find a good resource for doing more advanced troubleshooting. I have seen a lot of people recommending to "Megger" the circuit. I assume they mean to do an insulation test. This is not a tool that I am familiar with and have never used. It seems like this could be used to find high impedance parallel arcing, but does it work for series arcing? I'm guessing no...but maybe I'm wrong... Am I totally off base on what a Megger is?

You really don't want to use a megger, particularly on completed or existing wiring. A megger applies a high voltage to the circuit and unless you remove everything like lights, dimmers, hard wired equipment, etc.- and of course anything that may be plugged in, they will be destroyed. A megger is usually a last resort for finding damaged wiring. It may find parallel arcing but never series arcing.

There is no magic tool that is going to solve your problem. The only thing that you can do is be logical and thorough in your troubleshooting, keeping in mind that AFCIs themselves can account for most of the problems you can't find the cause of using normal troubleshooting.

I even saw one installer mention that they test every circuit first before landing it on the breakers, then if stuff starts tripping after the drywall and other trades come in, the electrician can comfortably say "not our fault, we tested it"

Have to laugh at that. If breakers trip who do you think is going to be responsible?

-Hal

 

[marmathsen]

I got a call for an AFCI breaker that kept tripping because of a particular bedroom light. I swapped the circuit wires with those of another bedroom circuit. No more tripping.

So, substitution of the AFCI device with another.

I have had the exact same thing happen. I've even put the wiring back onto their original breakers afterward and everything was fine. No evidence of loose wiring was noticed.

I guess the sacrificial offering worked that time.

Sent from my Pixel 4 XL using Tapatalk

 

[ptonsparky]

I actually used my cable fault locator in a house one time. We isolated the section but still needed to know who, what, why and when and where. Spikes of the locator pushed to the living room sheet rock found the nail the siding guys used. Guilty. Before AFCIs but hey, it worked.

 

[marmathsen]

I even saw one installer mention that they test every circuit first before landing it on the breakers, then if stuff starts tripping after the drywall and other trades come in, the electrician can comfortably say "not our fault, we tested it"

Have to laugh at that. If breakers trip who do you think is going to be responsible?

-Hal

Very true. I took it to mean that the electrician could go into the troubleshooting under the clear understanding that they will bill for every minute since they tested it all first.

Thanks for the other information as well.

Sent from my Pixel 4 XL using Tapatalk

 

[romex jockey]

You really don't want to use a megger, particularly on completed or existing wiring.

true...
afci instructions state any megging be done w/out them in the circuit.

so one wonders what year after year of mother nature can assume....

Have to laugh at that. If breakers trip who do you think is going to be responsible?

-Hal

On local EC contracts w/afci waver here, essentially creating a callback 'extra'

~RJ~

 

[kwired]

Very true. I took it to mean that the electrician could go into the troubleshooting under the clear understanding that they will bill for every minute since they tested it all first.

Thanks for the other information as well.

Sent from my Pixel 4 XL using Tapatalk

But AFCI's sometimes trip because of problems other than installation issues. So you still need to prove the reason for the tripping before you can accuse the drywallers. Find a nail or screw penetrating the wire, probably their fault - unless you were too shallow in wall, didn't use protective plate, etc.

You can check for conductor to conductor faults with megger before and after and have an idea that maybe something happened in between measurements, but like I said you still need to actually find the problem location before you can put much blame on anyone.

 

[Another C10]

I can fairly easily troubleshoot and resolve issues where the circuit is constantly tripping or consistently tripping under a specific scenario. If there is a low impedance short between any of the conductors, that is fairly straightforward to track down. Usually by starting in the boxes where multiple circuits are likely to be to look for combined neutrals from more than one circuit. Or split the circuit in half then test the breaker, then split it again and test, etc.

I think the section by section process is most reliant at least for me, then once you determine the 1 supply section from one point to the other you'll decide how to either locate the hot spot or replace the wiring period. Good luck

 

[paulengr]

You really don't want to use a megger, particularly on completed or existing wiring. A megger applies a high voltage to the circuit and unless you remove everything like lights, dimmers, hard wired equipment, etc.- and of course anything that may be plugged in, they will be destroyed. A megger is usually a last resort for finding damaged wiring. It may find parallel arcing but never series arcing.

There is no magic tool that is going to solve your problem. The only thing that you can do is be logical and thorough in your troubleshooting, keeping in mind that AFCIs themselves can account for most of the problems you can't find the cause of using normal troubleshooting.



Have to laugh at that. If breakers trip who do you think is going to be responsible?

-Hal

Balderdash. SCRs (dimmers) have the nasty habit of doing self-commutation...they short out on overvoltages, and you get funky results basically measuring the trigger voltage in surge arresters. But either way you are using a 9 V battery scaled up to say 500 V. So they short out at more than about 1 mA. There is no wat you can damage any line powered equipment at that much current. The reason for disconnecting most devices is they show up as a short and invalidate the test. So isolate first.

But the big reason for using one is two fold. First is on motors. A motor is basically a big capacitor unless it is totally burned up. A standard multimeter takes hours charging that capacitor with a 9 V battery so getting the insulation resistance is futile. A megger steps it up to say 500 V so it takes about 10-29 seconds to do the same thing and get valid readings. Second reason is most multimeters only go to kilo-ohms although I have one that goes to 20 Megaohms,

For series faults you need a micro ohm meter and they make meggers look cheap.

I use a mid range Extech megger, it holds up well to abuse which I can’t say fir all of Extechs tools. Runs around $200. Prior to that was the AEMC which runs closer to $400. Fluke private labels and their insulation testers make Biddle Megger look cheap.

When it comes to micro ohm readings hands down the DLRO or Ductor are the favorites. Typical contact readings vary all over the place but if it’s 1 milliohm it higher, something is seriously wrong. If you are measuring “through” a wall you will need a length of similar (same gauge) cable. Otherwise you would have to use a scope meter and watch for faults (surges) just like the AFCI,

But hey I’m a motor shop tech. These are my standard tools of the trade but not something that 99% of electricians will have. I strongly encourage having a megger but micro ohm and milli ohm meters are getting way off the beaten path.

 

[GeorgeB]

For GFCI, and the GFCI of dual function devices, it took me over 5 years to find the issue with one I fought for 5 years. I've since seen my issue addressed by another poster.

There was a power strip with the common surge suppressor circuit, 3 MOVs, L-N, L-G, N-G. I assume that the L-G aged and leaked. Removal of the power strip resolved their problem. I did not do any measurements, just cut the cord off and threw it away.

 

[ptonsparky]

For GFCI, and the GFCI of dual function devices, it took me over 5 years to find the issue with one I fought for 5 years. I've since seen my issue addressed by another poster.

There was a power strip with the common surge suppressor circuit, 3 MOVs, L-N, L-G, N-G. I assume that the L-G aged and leaked. Removal of the power strip resolved their problem. I did not do any measurements, just cut the cord off and threw it away.

I’ve seen it. I just threw it out.

 

[marmathsen]

For anyone who may find this helpful...

I have a residential customer who has a pair of Siemens panels that were installed in 2012. Over the last few years we have gone out there several times to troubleshoot tripping arc fault breakers. Our easiest first step was to replace the breaker with a new one, it would hold, we would tell them "let us know if it continues to be an issue and we'll come back and dig deeper." No issues for months. Then there's a problem with a DIFFERENT circuit. Same procedure, swap it out, it holds, walk away. Then yet another circuit, and so on and so on. We felt that it might be logical because we have been installing newer generations of breakers that are likely less susceptible to improper nuisance tripping. None of the replaced breakers ever had issues again.

Well over the last year it has been getting progressively more frequent. And finally it got to the point that the new breakers were continuing to trip after being replaced. There are 63 circuits in the house and 21 AFCI many of which had been problematic over the years. I wasn't sure where to begin.

Well I called Siemens to discuss what appeared originally to be a bunch of failed breakers but now was something else. Mike (from Siemens) sent me a bunch of documentation and recommended I try to get a hold of an Intelli-Arc tool then call him back when I was on site. Well we called him when we were on site and with the Intelli-Arc were immediately able to tell that there was some sort of "noise" that was registering as arching and propagating through the entire system. Very quickly we were able to determine that there were a bunch of TRENDnet ethernet over powerline adapters on multiple circuits causing the majority of the problems.

I know some people on here have rolled their eyes at the Intelli-Arc but after using one today for the first time, I'm a believer. I know I would have been pulling my already thinning hair out with how systemic the problem seemed to be and how intermittent the tripping was.

Credit where credit is due; Mike at Siemens was very knowledgeable, patient and informative. The Intelli-Arc is very useful for "noise" induced problems over multiple circuits.

(For the record, we almost exclusively install Square D. Although this sounds like a paid advertisement for Siemens, it's not. )

- Rob



Here are a bunch of links and documents that are very helpful as references:

https://forums.mikeholt.com/threads/afci-testing-diagnostic-tools.129943/

https://forums.mikeholt.com/threads/zwave-and-afci-tripping-issues.2551392/#post-2553931

https://www.eldoled.com/cms_file.php?fromDB=8935&forceDownload

https://www.downloads.siemens.com/d...aspx?pos=download&fct=getasset&id1=BTLV_40705

https://www.afcisafety.org/wp-content/uploads/2017/05/Troubleshooting-with-AFCI.pdf

https://www.eaton.com/ecm/groups/public/@pub/@electrical/documents/content/ct_206788.pdf

http://thecircuitdetective.com/afci_circuit_breakers.php

https://media.distributordatasolutions.com/schneider/2018q1/3e01143b5f3cfdfe3d2fd6ffb5d7f7081b14dfa7