# GFCI Breaker Good or Bad?



## Mike Guile (Jan 14, 2010)

Had service call. GFCI Breaker was kicking off after 3 secs. Of course, once I showed up it held fine and we cranked everything on that we knew of. Is there a way of determining if the breaker is going bad, bad, on it's way bad?? It was a GE 20 amp with the red button about 7 yrs old. It was either doing it's job or bad. Can't figure which one though? Didn't have one in truck, and was going to switch it with a good one in panel to eliminate, but it held the whole hour I was there. 

Wasn't a short, wasn't an overload, so had to be a ground fault. We eliminated all the culprits. I'm thinking the outside rec. was buried pretty good with snow and when he cleared it, it let some moisture out maybe.


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## MDShunk (Jan 7, 2007)

Mike, you seriously need to get yourself a megger and you could have had this sorted out in about 2 minutes flat.


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## Mike Guile (Jan 14, 2010)

*test*

ACtually, first thing i did was take off ground and neutral. It rang out correctly (infinity). Didn't buy that meggar yet though.


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## Mike Guile (Jan 14, 2010)

*Meggar*

Md, how would the meggar solve the problem better than the multimeter? I've never used a meggar yet so I don't know. I am looking at the model you recommended though


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## LGLS (Nov 10, 2007)

Mike Guile said:


> Had service call. GFCI Breaker was kicking off after 3 secs. Of course, once I showed up it held fine and we cranked everything on that we knew of. Is there a way of determining if the breaker is going bad, bad, on it's way bad?? It was a GE 20 amp with the red button about 7 yrs old. It was either doing it's job or bad. Can't figure which one though? Didn't have one in truck, and was going to switch it with a good one in panel to eliminate, but it held the whole hour I was there.
> 
> Wasn't a short, wasn't an overload, so had to be a ground fault. We eliminated all the culprits. I'm thinking the outside rec. was buried pretty good with snow and when he cleared it, it let some moisture out maybe.


The outdoor outlet seems to be the culprit more often than not. Also, some people simply do not know how to properly reset a circuit breaker.


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## LGLS (Nov 10, 2007)

Mike Guile said:


> Md, how would the meggar solve the problem better than the multimeter? I've never used a meggar yet so I don't know. I am looking at the model you recommended though


The meggar could tell you if there is any neutral wire to ground connection.


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## JackBoot (Feb 14, 2010)

LawnGuyLandSparky said:


> The meggar could tell you if there is any neutral wire to ground connection.


And if there is a slight hot to ground connection.


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## Mike Guile (Jan 14, 2010)

*touching*



LawnGuyLandSparky said:


> The meggar could tell you if there is any neutral wire to ground connection.


If there was any connection neutral/ground Hot/Ground wouldn't your typical ohmeter pick that up? I would think it's either touching or not touching. How would the megaohmeter be better and what readings would you look for on it as well. I'm megaohmeter ignorant.


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## MDShunk (Jan 7, 2007)

Mike Guile said:


> If there was any connection neutral/ground Hot/Ground wouldn't your typical ohmeter pick that up? I would think it's either touching or not touching. How would the megaohmeter be better and what readings would you look for on it as well. I'm megaohmeter ignorant.


No way, Jose.

Reason being, you ohm meter has a couple AA batteries or maybe a 9 volt. The megger is going to impress about 500 volts on the circuit. That'll show your real faults.

Yes, more often than not, when an outdoor receptacle is involved, it's the culprit in tripping the GFCI. I've taken out outdoor receptacles (and those little square receptacles in post lights) that visually look perfect, check out fine with an ohm meter, but ring bad with a megger. A megger is really the ONLY way you'll find the things that trip a GFCI once in a blue moon, like when protecting underground cable runs or outdoor GFCI's. 

Put a megger on your list for Santa Claus and then you won't have to guess so much when you're working on circuits that trip GFCI's and AFCI's. Remember, the GFCI is going to trip at a 6ma current imbalance. That can easily happen with a receptacle that is just damp inside when you impress 120 volts on it. It'll really show up with a megger. You won't get much current to flow with a couple volts from your multimeter.


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## BuzzKill (Oct 27, 2008)

what's a good one run?


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## Bob Badger (Apr 19, 2009)

Mike Guile said:


> If there was any connection neutral/ground Hot/Ground wouldn't your typical ohmeter pick that up?


Nope not always. 

Consider that mega meters are designed specifically to find these types of problems.

The one I have tests between 50 and 1000 VDC and it has found a bad cable that I could not find with a normal ohmmeter.


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## MDShunk (Jan 7, 2007)

BuzzKill said:


> what's a good one run?


I guess most ordinary electricians who own one probably have one that's in the 300-400 dollar range. This particular problem the OP post about, however, could be easily troubleshot with the cheapest 100 dollar meggers. If you want to, you can spend in the thousands or tens of thousands of dollars for one. It just depends on the test voltage you want to acheive. The rule of thumb is that you megger the circuit at twice the normal operating voltage. For romex, most guys will test it at 500 volts. If you megger at too far above the cable or conductor's rating, you can actually create a problem (blow a hole in the insulation). For MC on 480 circuits, for instance, you'd use the 1000V setting. I think that the ordinary electrician would be best served with a megger that does up to a 1000V test. If you mostly do resi, you're fine with one that just goes up to 500V. If you ordinarily work with medium voltage cable and above, you already know what a megger is and you already own one.


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## BuzzKill (Oct 27, 2008)

hence Bob's 50-1000v example for 480volt 3ph


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## Mike Guile (Jan 14, 2010)

*xmas*

Well, xmas is coming early baby. I'm whipping out the visa tonight and buying one. 

Since were on that now. Let's say a garage is very damp and tripping a bath gfci. What type of reading will that show on a meggar?? 


On a side note: How long do GE GFCI breakers hold on avg?


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## NolaTigaBait (Oct 19, 2008)

I thought you can test at 1000v for romex with 600v insulation. So it's double the operating voltage or the insulation voltage?


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## Bob Badger (Apr 19, 2009)

BuzzKill said:


> hence Bob's 50-1000v example for 480volt 3ph


It was Marc's posts from long ago that convinced me to get one. Now I have had it for a while and have used it about 1/2 dozen times. It nailed the bad factory cable from a ballast to the lamp sockets in a supermarket meat case.

The lamps kept blowing out and the Tech from Hill-Phonix (The maker of the case) had been out a number of times replacing ballasts, sockets and lamps and every time he would get the lamps working for a day or two but then they would go out again. I was asked to help and grabbed the mega-meter, we tested the cables one by one and found one that had much different readings from the rest.


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## Bob Badger (Apr 19, 2009)

Mike Guile said:


> Well, xmas is coming early baby. I'm whipping out the visa tonight and buying one.
> 
> Since were on that now. Let's say a garage is very damp and tripping a bath gfci. What type of reading will that show on a meggar??


Download, print and read this link. *A Stitch In Time*


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## user4818 (Jan 15, 2009)

I still don't own a megger. 

Oh wait, I suck at electrical work so I don't need one. Carry on.


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## Charlie K (Aug 14, 2008)

Bob Badger said:


> Download, print and read this link. *A Stitch In Time*


You beat me to it. I was trying to find the link. A Stitch In Time is an excellent resource.

Charlie:thumbup:


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## BuzzKill (Oct 27, 2008)

Peter D said:


> I still don't own a megger.
> 
> Oh wait, I suck at electrical work so I don't need one. Carry on.


 I'm feeling your pain, Peter D


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## BuzzKill (Oct 27, 2008)

Bob Badger said:


> Download, print and read this link. *A Stitch In Time*


 Holy cr*p Bob, thanks for that!
Yeah Marc is a wealth of info.
(somebody please wipe my nose)


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## MDShunk (Jan 7, 2007)

NolaTigaBait said:


> I thought you can test at 1000v for romex with 600v insulation. So it's double the operating voltage or the insulation voltage?


Nola, you probably can, since that's not too far over the cable's rating. They probably do worse things to the cable in quality control. I just can't think of any reason why you should. If you ring out okay at twice the normal operating voltage of the circuit in question, you're going to be okay at the normal operating voltage.


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## Bob Badger (Apr 19, 2009)

BuzzKill said:


> Holy cr*p Bob, thanks for that!


No problem, it did not cost me anything.



> Yeah Marc is a wealth of info.


Yes he is.



> (somebody please wipe my nose)


We will pretend this never happened. :thumbsup:


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## NolaTigaBait (Oct 19, 2008)

MDShunk said:


> Nola, you probably can, since that's not too far over the cable's rating. They probably do worse things to the cable in quality control. I just can't think of any reason why you should. If you ring out okay at twice the normal operating voltage of the circuit in question, you're going to be okay at the normal operating voltage.


Phewww, I've been testing 600v insulation @ 1000v...I'll kick it down a notch:thumbsup:


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## JackBoot (Feb 14, 2010)

NolaTigaBait said:


> Phewww, I've been testing 600v insulation @ 1000v...I'll kick it down a notch:thumbsup:


At least you have the proper tool in hand to see if you arc out thru the insulation :thumbsup:


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## NolaTigaBait (Oct 19, 2008)

JackBoot said:


> At least you have the proper tool in hand to see if you arc out thru the insulation :thumbsup:


Hey, I'm new at it. Live and learn. I've only used it about 4 times so far.


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## Mike Guile (Jan 14, 2010)

*Bob*

thanks bob. I appreciate that. I should have that done tonight. I love buying new toys. I'm still thinking the problem was the snow covering the bubble cover outside, creating a greenhouse effect. Once he knocked it off, about 1 hr later I showed up and the breaker didn't kick. 

Just got a call. Gas furnace, 2 Basement freezers kicked off. They are apparently fed from a powder room on 1st floor???? I'm probably going to at least get them on line side for tonight, and try to talk her into a new circuit or 2 for the freezers and furnace. 

Later. Wish I had my megameter now:icon_cry:


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## MDShunk (Jan 7, 2007)

Mike Guile said:


> Since were on that now. Let's say a garage is very damp and tripping a bath gfci. What type of reading will that show on a meggar??


You should read the "stitch in time" link. It's old, but it's the standard text on megger use. What you'll find though, related to specific readings will be somewhat disappointing. That document is probably 100 years old (literally) and talks about taking historical readings and tracking them on a card. This is what factory maintenance guys and HVAC mechanics do with motors and compressors. That's somewhat what Bob did in his example of the deli case, where he compared his readings between known good cables. If you don't have historical readings of a particular romex circuit to go by, in the case of your GFCI circuit, what do you do?

I'll share something tonight I don't think I've ever shared before. There are no "rules" as to what megger readings are clearly good or clearly bad, but I have some of my own history to go by. Bookmark this link.

When testing at 500V, if you get a reading above 100 megohms, the cable, circuit, or device can be considered "good". If you get a reading less than 100 megohms, but greater than 30 megohms, that's probably not tripping your AFCI or GFCI, but something serious has happened. If you get that reading pinned down to a particular device (like a receptacle or an exposed run of romex), replace it, because it's on its way out. If you're doing a fire and water damage survey, replace any circuit that measures less than 100 megohms. It's insurance money, more than likely, and you can clearly say something has happened to that circuit. If you get a reading less than 30 megohms, that is absolutely tripping your AFCI or GFCI. Sectionalize that circuit until you find the offending device or section of cable and replace it. 




Mike Guile said:


> On a side note: How long do GE GFCI breakers hold on avg?


It really doesn't matter what brand. The amount of time it takes for a GFCI breaker to trip depends on the nature of the fault and, often, the moisture conditions that cause it. For instance, it would not be unusual for a GFCI protected pool feeder to hold for weeks, then only trip on a rainy day. I've seen GFCI's only trip after hours and hours, for no clear reason related to the weather, but the circuit megg's bad.


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## MDShunk (Jan 7, 2007)

Mike, it's still entirely possible that you are dealing with a bad GFCI breaker (I'm not a huge fan of GE residential equipment), but you can never say, for sure, until you meg out the circuit. If the circuit megs out fine, you can safely replace the breaker with confidence that you've done a good job and simply didn't take your best guess.

That largest EC in my area, with hundreds and hundreds of men on the payroll, had two men working at a house for days on a pretty spread out GFCI circuit for landscape lighting and flower bed receptacles that was tripping the GFCI breaker. Several thousand dollars later, and with no result, the homeowner kicked them off the job. I was called in, and with a megger, I isolated the nature of the fault to a run of UF cable under a grade-level wooden deck. I found the problem in less than 30 minutes, and a couple hours later I was done with the repair and rolling down the road. I guarantee you that he's a customer for life. I have not had to do any more work at that particular house, but he has referred me to several of his neighbors in his development.


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## nrp3 (Jan 24, 2009)

Hey, thanks for sharing that info. I bought a Megger MIT series not long ago and still truthfully had no idea what I was doing. Mainly trying not to damage what I was working on. I have the stitch in time book and there wasn't much in there for what I was working on, like romex residential circuits.

Would those readings work for UF? Its springtime/pole light/ UF splice season coming up at the apartment complexes I work at. I have three with shorts already waiting for the ground to thaw.


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## MDShunk (Jan 7, 2007)

nrp3 said:


> Would those readings work for UF? Its springtime/pole light/ UF splice season coming up at the apartment complexes I work at. I have three with shorts already waiting for the ground to thaw.


Yeah, you betcha. You can put my rules of thumb in your hip pocket for whatever you test at 500 volts. Others may dispute those numbers, but I think I'm pretty safe in saying that I've meggered more low-voltage circuits in the field than anyone that I know of that participates on electrician message boards. I have a lot of historical readings of my own to go by.

The funny thing about pole light circuts is that they're normally on regular, non GFCI, breakers, but they'll occasionally trip that regular breaker. By the time you get there, the ground has dried out a bit, and the breaker is probably holding fine. The megger will prove you have a problem. That problem is often the underground run of UF, but if you take the wire nuts apart at the fixture, sometimes you'll find that the lampholder in the fixture is contaminated enough with whatever-the-hell gets in there that it megs bad. Some post light fixtures have those round, postline, HID ballasts inside the post that will suffer from insulation breakdown that will only show up on the megger. On a damp day, that postline ballast will start to draw crazy amps and trip the breaker.


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## nrp3 (Jan 24, 2009)

Do you send your meter out for calibration? I bought mine used and it seems to work fine, but wondering if its worth it. I'll put those notes right in the case with the meter.


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## BuzzKill (Oct 27, 2008)

It is so cheap running UF...lay the pipe!


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## JackBoot (Feb 14, 2010)

MDShunk said:


> Bookmark this link.
> 
> When testing at 500V, if you get a reading above 100 megohms, the cable, circuit, or device can be considered "good". If you get a reading less than 100 megohms, but greater than 30 megohms, that's probably not tripping your AFCI or GFCI, but something serious has happened. If you get that reading pinned down to a particular device (like a receptacle or an exposed run of romex), replace it, because it's on its way out. If you're doing a fire and water damage survey, replace any circuit that measures less than 100 megohms. It's insurance money, more than likely, and you can clearly say something has happened to that circuit. If you get a reading less than 30 megohms, that is absolutely tripping your AFCI or GFCI. Sectionalize that circuit until you find the offending device or section of cable and replace it.


 Saved :thumbup:


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## MDShunk (Jan 7, 2007)

nrp3 said:


> Do you send your meter out for calibration? I bought mine used and it seems to work fine, but wondering if its worth it. I'll put those notes right in the case with the meter.


For ordinary troubleshooting, I think that using a calibrated meter is fairly unimportant. I only have a few meters meters that I have calibrated (only one of them is a megger) and I save them to specially use on jobs where using a calibrated meter is required. Commissioning new equipment and preparing a report of findings for an insurance company are about the only two times I feel compelled to use a calibrated meter. I think you're okay if you just save that money. Maybe have it calibrated once to see where you're at, since it's a new-to-you used meter. You'll probably spend around 100 bucks to have an MIT calibrated, if it doesn't need any repair.


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## MDShunk (Jan 7, 2007)

BuzzKill said:


> It is so cheap running UF...lay the pipe!


I agree, but you don't really get to choose when you get called in to work on something. You'll find tons and tons of direct buried UF and URD. Even the odd run of lead sheath to an old garage.


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## nrp3 (Jan 24, 2009)

Any new installs in pipe for sure, but a chunk of my spring income goes to fixing UF problems. They almost never go for wholesale replacement of the UF. They are aware of the benefits.


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## MDShunk (Jan 7, 2007)

nrp3 said:


> Any new installs in pipe for sure, but a chunk of my spring income goes to fixing UF problems. They almost never go for wholesale replacement of the UF. They are aware of the benefits.


Any change of seaon (winter to spring or summer to fall) also seems to be when a buttload of photocell, motion sensor, and HID fixture calls seem to come in. It seems to me that a change in season completely takes out a photocell, motion sensor, or HID ballast that was hanging in the balance.


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## BuzzKill (Oct 27, 2008)

MDShunk said:


> I agree, but you don't really get to choose when you get called in to work on something. You'll find tons and tons of direct buried UF and URD. Even the odd run of lead sheath to an old garage.


 lead sheath??? Never heard of it or seen it!


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## NolaTigaBait (Oct 19, 2008)

BuzzKill said:


> lead sheath??? Never heard of it or seen it!


That must be teh same type of stuff that the utility co's use for underground around here.


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## Greenblinker (Aug 4, 2008)

I believe this is the lead sheath you speak of. I pulled it up a while back on a job and was flabbergasted when I saw it. Never heard of it or seen it in my short life.


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## BuzzKill (Oct 27, 2008)

yaaar!


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## nrp3 (Jan 24, 2009)

Not to drag this old post up again, but I was also wondering how long you test romex or UF to get results similar to what Mark previously posted. I have to use the megger on some Flextherm floor heat for part of the installation as well as chase a bad circuit in a new customers house over the next week. Thought of this thread.


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## Mike_586 (Mar 24, 2009)

Greenblinker said:


> I believe this is the lead sheath you speak of. I pulled it up a while back on a job and was flabbergasted when I saw it. Never heard of it or seen it in my short life.


Oh I've heard of it and seen it mentioned in the CEC many times, but that picture is the first time I've ever even seen the stuff :thumbsup:


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## TOOL_5150 (Aug 27, 2007)

MDShunk said:


> I guess most ordinary electricians who own one probably have one that's in the 300-400 dollar range. This particular problem the OP post about, however, could be easily troubleshot with the cheapest 100 dollar meggers. If you want to, you can spend in the thousands or tens of thousands of dollars for one. It just depends on the test voltage you want to acheive. The rule of thumb is that you megger the circuit at twice the normal operating voltage. For romex, most guys will test it at 500 volts. If you megger at too far above the cable or conductor's rating, you can actually create a problem (blow a hole in the insulation). For MC on 480 circuits, for instance, you'd use the 1000V setting. I think that the ordinary electrician would be best served with a megger that does up to a 1000V test. If you mostly do resi, you're fine with one that just goes up to 500V. If you ordinarily work with medium voltage cable and above, you already know what a megger is and you already own one.



And here I was, testing romex at 250v, thinking I should only test the voltage that the circuit will have.

Is it save to test at 500V with devices [recepts, switches in off position] in the circuit?

~Matt


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## cdnelectrician (Mar 14, 2008)

Mike_586 said:


> Oh I've heard of it and seen it mentioned in the CEC many times, but that picture is the first time I've ever even seen the stuff :thumbsup:


I still see it sometimes, it's either just got a lead sheath over two conductors or it is lead wound with steel armour like BX. It was called "BX-L". There was also an aluminum sheathed version of it, that came in single and multiconductor types. There is quite a bit of it around here.


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## Smoke (Feb 25, 2011)

> For romex, most guys will test it at 500 volts. If you megger at too far above the cable or conductor's rating, you can actually create a problem (blow a hole in the insulation). For MC on 480 circuits, for instance, you'd use the 1000V setting.


this is totally wrong in my opinion, you never want to exceed the voltage rating of the conductor. it makes no difference if its 120 or 480, you test to the ability of the cable.
" For MC on 480 circuits, for instance, you'd use the 1000V setting"
400v over the conductors rating is a bit too far dont ya think?


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