GFCI breaker problem

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sparky_magoo

Senior Member
Location
Reno
Friday I had a call, in a 30+ year old mobile home, where the GFCI breaker wouldn't reset. The load included bath & ext. receptacles. I read an open from hot to ground & nuetral at the panel (with everything unplugged). I measured 1.6 meg ohms from nuetral to ground & open from hot to nuetral. A new GFCI breaker trips as soon as I connect the load. I replaced all of the recetacles on the ckt. I pigtailed & sidewired the new ones.

Shouldn't 1.6 meg be too high of a resistance to bother the GFCI breaker? Wouldn't that be a 75 micro amp fault? The GFCI shouldn't trip until 4 mils. I have a very accurate meter and the conections were good. The ckt. works fine on a regular breaker.

Monday, I will install a regular breaker & install GFCI receptacles in bath & outside with nothing connected to the load term.s. It was after 8:00 PM when I gave up.

My question is, why won't the GFCI breaker work?
 

tryinghard

Senior Member
Location
California
I'm not sure if I follow all your readings but you may have a common neutral with another circuit. It sounds like you have gone through all the devices but do make sure you do not have another GFCI on the circuit, ?stacking? GFI?s can cause this also.

Did this circuit have a GFI breaker before you started, one that worked at some point in time?
 

sparky_magoo

Senior Member
Location
Reno
Yes, this ckt had a working GFI at some point. It had been tripping for some time and finally gave out. There are no other GFI's on the system. I am pretty sure thet are no shared nuetrals. With the nuetral wire dried out at the panel and everything unplugged, I read 1.6 MegOhms from nuetral to ground. I think this resistance should be too high to trip a GFI. I believe the resistance comes from insulation breakdown due to water in the walls. No, I do not have a meggar. This old trailer had a leaky roof for a long time.
 

sparky_magoo

Senior Member
Location
Reno
Ken9876 said:
Is there an outlet under the mobile home, for heat trace?

I didn't look. It seemed there was a jumper I was unaware of when I threw in the towel Friday night. I will check it out tomorrow.
 

tryinghard

Senior Member
Location
California
Try running a temporary home run, bypass the existing, to see if it clears. If it doesn?t continue throughout the circuit until it does.
Also ask if anything has been done around the time it started to fail, even a new picture on the wall. Problems like this can be elusive especially if it is failed wire in a cable.
 

sparky_magoo

Senior Member
Location
Reno
Thanks for all the advice. I believe I can make it work by installing GFI recetacles in bath & outside. Nothing will be connected to load side of GFI's.

My original question remains, why won't the GFCI breaker work. The nuetral to ground fault is 1.6 MegOhms. This resistance should be too high too bother the GFCI breaker.

When I arrived the fault resistance was much lower. In the bath, the wires &receptacle were corroded from water damage. I found the same at the outside receptacle. I replaced all known receptacles. The fault resistance increased from about 100 ohm's to 1.6 MegOhms. Why won't the GFCI breaker work. It is supposed to trip at 4 mills, which is 30 Kohms. I have already advised the HO they may have to replace jumpers. I just want to know why the breaker won't work.
 

tryinghard

Senior Member
Location
California
Re: GFCI breaker problem

sparky_magoo said:
Friday I had a call, in a 30+ year old mobile home, where the GFCI breaker wouldn't reset.

I think the early 70's, and maybe to the late 70's, there was often an outside receptacle at the back door UNDER the mobile home.
 

sparky_magoo

Senior Member
Location
Reno
I really appreciate the advice. I will search out that receptacle tomorrow morning.

The question remains, why won't the breaker work

There is way too much resistance to fault the GFCI breaker. Yes, I will clear the trouble. Your tip is excellent. When I had the CKT. all sperated, I read 1.6 Meg's on two jumpers. This implies the previously unknown outlet below the trailer. I will fix it.
 

allenwayne

Senior Member
Sometimes what is theory will not work in practicality.You have already said you found break down in insulation and a variance of resistance.Line siding gfci`s might cure what you have ,But short of rewiring an old system it probably is the best FOR NOW situation.
A couple of years ago I was asked to assist a 40+ year guy with a service problem.Circuit tripping,we went checked it out and sure enough a 3 wire was shorted across 2 leads.Then in the middle it cleared?OK maybe we missed something.Them it shorted.Long story short,I found at the baseboard on a block home trim carpenters had shot several trim nails in a baseboard,and when the wall heated up the exansion would recreate the short but it was partially cloudy that day and when the sun went away so did the short.Sun beats down on the wall a few minutes later BAM pop.Then sun goes in it cleared.This was after almost 5 service calls to a 3 year old home.BTW I used a tracer to find the problem.No signal generator hooked up just the probe.Running it along the baseboard It buzzed like a hornet at the comprimised position then it lessened and as the sun came out it reoccured.Then as the sun went in it it lessened.
Since then I have used a probe to find burried boxes cut wires etc.A good meter will tell you somethings but a variety of tools will tell you the answer :wink:
 

sparky_magoo

Senior Member
Location
Reno
allenwayne, thanks for the advice. I have seen similar circumstances. Heat is not an issue here. BTW, I just ordred an Ideal61-954 circuit tracer. I can't wait until it arrives.

The problem remains. I have a 1.6 MegOhm fault from nuetral to ground. This resistance should be too high to bother a GFCI breaker.

Can anyone explain why the breaker won't reset?
 

tryinghard

Senior Member
Location
California
Re: GFCI breaker problem

sparky_magoo said:
the GFCI breaker wouldn't reset...I measured 1.6 meg ohms from nuetral to ground & open from hot to nuetral. A new GFCI breaker trips as soon as I connect the load.

A reading between the neutral and ground should be zero as they are common at the main; and an new breaker does not mean it's good (sad to say)

sparky_magoo said:
Shouldn't 1.6 meg be too high of a resistance to bother the GFCI breaker? ...The GFCI shouldn't trip until 4 mils.

I do not understand this quote but I believe the GFI breaker should be labeled to trip at 4 milliamps. Also your GFI should work (correctly and safely) without a ground so I still do not understand why a resistance test is necessary between ground and neutral.

sparky_magoo said:
Monday, I will install a regular breaker & install GFCI receptacles in bath & outside with nothing connected to the load term.s.

The GFI breaker is most likely doing its job and if you have a failing wire in a cable replacing only the receptacles with GFCI's may leave the real problem unaddressed.

sparky_magoo said:
My question is, why won't the GFCI breaker work?

If it is tripping due to a 4 milliamp or greater short from hot to ground or neutral to ground or hot to neutral than it is working. If it simply wont reset due to a faulty part than the best test for this is a different new GFI breaker. You may be convinced your new breaker is not working because you know you have a short and it will not trip at the labeled minimum milliamp or greater.
Again I don?t know if I fully understand why your testing for resistance, I am certainly glad to grow but also glad to help.
 

sparky_magoo

Senior Member
Location
Reno
I made the nuetral to ground resistance readings with the nuetral and ground wires lifted at the panel. All three wires for the CKT were disconected when I took the readings. Nothing downstream was connected. The 1.6 MegOhm fault was measured with the wires DXed at the panel and all loads DXed. Why won't the breaker reset? 1.6 MegOhms should be too high to bother the breaker.

I tried several new GFCI breakers on my truck. I know they have a high failure rate. All have the same result.
 

shocker3218

Senior Member
but checking resistance at a low voltage level will give vastly different results than testing at line voltage. A moisture problem would trip a GFI breaker, but still read high resitance with a meter.
 

benaround

Senior Member
Location
Arizona
Sparky-magoo,

This could be a long shot, 30 yr. old alum. trailer maybe had an outside light changed at one time or another and just maybe the neutral wire of that light is touching the metal siding of the trailer.

I know that it is on another circuit but neutral to ground will trip a GFCI, and the circuit your on probally has a metal box,or cover on that outside recpt that is grounded properly but it's touching the siding and the siding is touching the neutral of the light.

Or not!
 

stars13bars2

Senior Member
I'm with shocker on this, check for water in a receptacle or light fixture, (could be inside or outside) or on something that is plugged in and laying in a mud puddle in the yard. Like you said the circuit had been getting wet, maybe there is a junction box with water in it somewhere. The GFCI is doing what it is supposed to do, and the problem is in the circuit. You are familiar with fantom voltage readings because there is no load, so this is a phantom resistance reading because there is no voltage. I think, maybe, possibly, well it sounded good when I was convincing myself.
 

A/A Fuel GTX

Senior Member
Location
WI & AZ
Occupation
Electrician
The neutral to ground reading should be open for the gfi breaker to function properly. Somewhere on the branch circuit you have contact between the two.
 

haskindm

Senior Member
Location
Maryland
As others have said, don't get hung up on the resistance you are getting from ground to neutral. GFI's work by sensing a diference between the current that is going out on the hot versus the current returning on the neutral, the ground does not even need to be connected. When this difference exceeds somewhere around 7 milliamps the GFCI will open. That current could be returning through the grounding conductor, a water pipe, the metal siding, or through you. While you have the neutral disconnected from the panel, measure the voltage from the disconnected neutral wire to the neutral bar in the panel, this will tell you if you have current from another circuit travelling on your neutral. I suspect you will find another outlet on the GFCI circuit that is causing the problem. Does the GFCI stay on if there is nothing connected to the load side of the bathroom receptacle. If so you know the problem is downstream from the receptacle. Don't let your meter make this problem more complicated than it really is.
 
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