GFCI nuisance trip

[mwdkmpr]

I am having problems with 30A, 120V, Square D, GFCI breakers nuisance tripping at a campground. Here are the facts as I know them. There are five 100A, single phase, mains serving five separate loops. Each loop has six risers for campers to plug in to. Each riser has a 20A GFCI breaker serving a duplex, and a 30A GFCI breaker serving a 30A, 120V receptacle. The problem is only with the 30A breakers on only one loop. Between 7:30PM and 9:00PM on most evenings the breaker will trip. The breaker will not reset. If they take an adapter and plug in to the 20A receptacle it will work. The next morning they can reset the 30A and it will work fine. There are some HPS lights for a bathroom on this loop that were on a photo eye. I unhooked the eye and have the lights on all the time now. I do not know of anything else that is on this loop. Park maintenance has changed the breakers and I have checked all connections. No one is aware of anything that might be starting automatically at that time. They have had this problem intermittently for about a month with different campers. The day I was there, there was only one camper on that loop. I asked if they had any problems with the electric. They said that the power had blinked at about 8:00PM but the breaker did not trip.
Any Ideas? Thanks and have a happy Independence Day!

 

[tom baker]

Re: GFCI nuisance trip

I am 99% sure its not the GFCI. Take the lighting off of the GFCI circuit. It should be on its own circuit. Removing the PE won't solve the problem, removing the lights will.

 

[mwdkmpr]

Re: GFCI nuisance trip

Let me clarify. The lighting is not connected to the GFCI breaker, but rather is on the same 100A service with its own branch circuit protection. Alao this has worked as wired for at least 5 years. But, after the holiday, I may try and take the lights completly off and try it. Thanks.

 

[tom baker]

Re: GFCI nuisance trip

Does the GFCI trip when the lights are turned on via the PE? Or when does the GFCI trip. Then find out whats happening at the same time.

 

[al hildenbrand]

Re: GFCI nuisance trip

The Camper's own equipment that is plugged into the 120V 30A GFCI is a wild card. It will be hard to eliminate the possibility of neutral/ground leaks or bonds in the Camper's equipment, as the Camper tends to be here tonight and gone tomorrow. Testing the trip sensitivity of the 20A GFCI to verify that it, in fact, is working will help narrow the field of possibilities.

Am I understanding correctly that the only time the 30A GFCI trips (that is known) is when a Camper is plugged into it and then reports the outage?

 

[ronson]

Re: GFCI nuisance trip

is the wire on 30a ckt large enough? sounds like a possibility of overheating if breaker can be turned back on next morning & works fine until evening when it trips. could there be a break in wire? al, how can i check the sensitivity on a gfi?

[ July 02, 2004, 11:17 AM: Message edited by: ronson ]

 

[al hildenbrand]

Re: GFCI nuisance trip

Ronson,

Kludge an adapter from a 125V 15A receptacle (NEMA 5-15R) to 125V 30A plug (NEMA 5-30P). Then use the standard duplex GFCI tester. I have an older BEHA (now Greenlee) tester that permits me to put 1, 2, 3 and 5 milliamp ground faults on a test receptacle, but any simple GFCI tester will do.

But my point in suggesting the test of the 20A GFCI at the camper hookup was to verify that the 20A GFCI is actually working. The fact that it didn't trip at the time when the 30A GFCI did trip possibly means that the 20A GFCI is no longer tripping on a ground fault.



[ July 02, 2004, 03:01 PM: Message edited by: al hildenbrand ]

 

[mwdkmpr]

Re: GFCI nuisance trip

Tom, the reason I took the photo eye out is to eliminate it and the lights coming on as a possible cause. There is nothing else on the camp ground that starts at that time.

Al, initially it was assumed that the problem was with the campers, but that possibility has been eliminated by the fact that they can switch to the 20A receptacle and it will work. Also they have had this problem intermently for over 2 weeks with different campers.

Ronson, the wire size is adequate and the connections all check out OK. I have never had the opportunity to be there when they are having a problem. I would like to be there so that I could see if it is a hot breaker or a ground fault that is causing the problem.

Thanks for your responses.

 

[jimwalker]

Re: GFCI nuisance trip

are you saying there is 6 30 amp gfci breakers in this loop ? and all 6 trip ?

 

[ronson]

Re: GFCI nuisance trip

next guess: have you tried pulling the 30a breaker out and reinserting it in another space in panel?

 

[al hildenbrand]

Re: GFCI nuisance trip

mwdkmpr,

Good luck solving this one. There's nothing like an intermittent fault to eat hours of troubleshooting. But it's the challenge!. . .

You didn't actually answer my question. Has the 20A GFCI breaker passed the test (by tripping) of a 5 mA ground fault from an independent test device (not the breaker self test button)?

Also, are the trouble reports citing only a specific camper riser(s), or are the reports on all of the six risers on this one 100A loop?

Bottom line, I disagree with Tom in that I think the trouble is more likely than not to be ground fault current exceeding the trip level. Until both 20A & 30A GCFI breakers are tested with a 5 mA tester plugged into the protected outlets and are shown to perform within spec, one cannot rule out a ground fault in the connected loads, i.e., the camper's equipment.

Al

[ July 03, 2004, 10:54 AM: Message edited by: al hildenbrand ]

 

[don_resqcapt19]

Re: GFCI nuisance trip

Al,

You didn't actually answer my question. Has the 20A GFCI breaker passed the test (by tripping) of a 5 mA ground fault from an independent test device (not the breaker self test button)?

Why do you want to use a plug in test device, in place of the built in test button?
Don

 

[al hildenbrand]

Re: GFCI nuisance trip

Don,

Assuming the GFCI breaker trips when the breaker test button is pressed, is it known that the camper's receptacle goes dead? One way to do two tests at once is to use a polarity tester with integral GFCI button. (Of course, if the camper visibly or audibly loses power, that, also is a good indicator. . .it is not clear yet from this thread's narrative).

That fact that the camp reports that the 20A receptacle solves the 30A GFCI trip problem, at least temporarily, is, to me, not a complete indication that the camper load is ground fault free. The lack of a ground fault trip on the 20A breaker may be a false positive for the actual lack of a ground fault in the camper load.

mwdkmpr,

I, for one, will be curious to hear what you discover in the course of solving this problem indicated by the trouble reports.

Al

 

[renosteinke]

Re: GFCI nuisance trip

A rule of mine: if your first two 'best guesses' fail, it's time to start over, and get systematic.

First: is the breaker tripping because of an overload, or because of a ground fault? At the very least, TEMPORAIRILY replacing with a standard breaker will allow you to measure the amp draw with a clamp meter.
If your park as three-phase power, take readings with both a 'standard' and a 'true RMS' meter. This will help determine if there is a power quality issue.

Likewise, you can measure the amp draw at each space to see if any one party might be the culprit.

Let's assume that, with a normal breaker, everything works and the load is well under the breaker setting. Then, the breaker is probably sensing a ground fault.
Get systematic. Unplug everything, then operate each load individually to see where the leak is. Chances are that somewhere there is a lighting control that uses the ground for a 'neutral,' an unused, untightened screw on a receptacle, or a battery that is not isolated.

If the problem persists with all loads disconnected, the problem is likely with the feeder part of the circuit. Someone versed in the use of a megger can check for bad wire insulation, etc.
While the scheduling of the problem suggests an end-user problem, at this point assume nothing and start troubleshooting from the very beginning.

 

[smiley2]

Re: GFCI nuisance trip

Since the problem seems to be with the 30amp g.f.i., I would tend to lean towards that direction. I would test the outlet with a separate tester(not the one on the receptacle). Have you noticed any tendencies with the type of camper? I am not familiar with the way the power is bonded to the equipment. It seems to only trip when power is being utilized by the campers. I really doubt that the feeder is involved. Another aspect to think of, are you putting two g.f.i.'s in series. They often will trip when power is being utilized but will be stable when idle.

 

[harley]

Re: GFCI nuisance trip

do all 6 30 amp breakers trip on that one loop or just one breaker. If all six I believe some noise on the bus is causing the GF electronics to trip. If just one breaker trips and cannot be reset then either short circuit or GF. I bought a current probe that reads down to 1 milliamp allowing me to read low currents. I clamp around BOTH neutral and hot thus allowing me to read the differential current. I install a thermal mag breaker and if that breaker trips must be overload if not, I can now clamp my meter around wires and see leakage current.