O.T. GFCI electrical issue (a bit long)

[CB in central NY]

I know that GFCI issues have been covered here before, but here is mine.

I have a drive-in hay barn / machinery shed, which has two 30-amp Square D Homeline breakers powering two zones (one zone is the hay barn, the other is a cattle run-in shed on the back). The output includes several lights and four 110-volt outlets. I normally run a small vacuum pump and maybe a hay elevator.

Both locations are quite dry. There is no wiring anywhere close to the ground and all the fixtures are high up, even the outlets.

I recently installed a plug-in electric fencer (used to have a solar one). I am also planning to put in a stock tank with a heater for the winter. So I figured, I'd replace the regular breakers with GFCI.

The first thing I learned was that Square D did not make a 30-amp single-pole GFCI breaker and I thought the 20-amp ones were not sufficient. So I bought a 30-amp double-pole GFCI breaker and put it in. The problem is, it trips immediately. I read that tripping could be caused by wire runs over 250 feet, and I am at about 170 max. The other strange thing is that if I separately wire the two "zones" of the barn, only one will trip. And lastly, when I flip a lightswitch, it causes a trip.

So far, I have had no luck tracing the fault, if any. I am thinking that the breaker itself might be at fault. The sub-panel is grounded right at the barn and the neutral and ground are separate.

Thanks for any help /advice. I've done quite a bit of wiring over the years and never had this issue before. The regular breakers have never tripped.

 

[Bkpigs]

How big of a heater are you going to use? Can you just put the old breakers back in and install a GFCI outlet for the heater? That is what I would do if possible.

 

[Ken-Pa]

You read correctly . If there's too much disance after the GFCI protection , you will constantly be tripping it . You need to do some studies on these breakers & do some wiring changes .Set a panel & distribute this mess onto seperate circuits At barns , you should actually drive 2 seperate 8' ground rodas & run one continous bare grd wire across both rods to you panel .The closer you have a receptacle to a GFCI breaker the better the protection & less tripping . Remember these devices are made to trip when just a milli amp short is sensed . Make a drawing & go to your local electrical supplier & have them advise you of proper wiring techniques . HTH ! God bless

 

[MarkB_MI]

Double-pole breakers are for 240-volt loads. And since a GFCI breaker measures the imbalance between the two hot legs, you created a "fault" when you tried to use only one leg.

The best solution is to put your 120 volt outlets on separate GFCIs. If you want the lighting to be GFCI, run it off of an outlet GFCI. Personally I wouldn't GFCI the lighting, because when the GFCI trips you'll be in the dark.

 

[Kirk Grau]

I will second the idea to use a GFCI outlet. If you can return the breakers will probably be a little cash ahead. Anything downstream of the GFCI will be protected so you have some options if you can trace the wiring or know how it is routed. Could add a receptacle somewhere before the other users or replace a receptacle ahead of what you want to protect.

As usual YMMV,

Kirk

 

[CWL]

Is the one circuit that trips the same one with the vac. pump or the elevator? Sometimes motors will leak a little through the windings to ground. I would unplug everthing and then disconnect the lights. See if it still trips. If so your losing voltage somewhere. Either a small short in the wiring or at an outlet. Worst case, unhook everything then reconnect one at a time until you find which outlet or light is tripping the breaker.

 

[JMOR]

(quoted from post at 11:31:43 05/18/10) I know that GFCI issues have been covered here before, but here is mine.

I have a drive-in hay barn / machinery shed, which has two 30-amp Square D Homeline breakers powering two zones (one zone is the hay barn, the other is a cattle run-in shed on the back). The output includes several lights and four 110-volt outlets. I normally run a small vacuum pump and maybe a hay elevator.

Both locations are quite dry. There is no wiring anywhere close to the ground and all the fixtures are high up, even the outlets.

I recently installed a plug-in electric fencer (used to have a solar one). I am also planning to put in a stock tank with a heater for the winter. So I figured, I'd replace the regular breakers with GFCI.

The first thing I learned was that Square D did not make a 30-amp single-pole GFCI breaker and I thought the 20-amp ones were not sufficient. So I bought a 30-amp double-pole GFCI breaker and put it in. The problem is, it trips immediately. I read that tripping could be caused by wire runs over 250 feet, and I am at about 170 max. The other strange thing is that if I separately wire the two "zones" of the barn, only one will trip. And lastly, when I flip a lightswitch, it causes a trip.

So far, I have had no luck tracing the fault, if any. I am thinking that the breaker itself might be at fault. The sub-panel is grounded right at the barn and the neutral and ground are separate.

Thanks for any help /advice. I've done quite a bit of wiring over the years and never had this issue before. The regular breakers have never tripped.

ssential that whatever current leaves a GFCI must return via the neutral of that same GFCI and/or in the case of a 240v load, must leave on one line and return on the other line of the same GFCI.

 

[NCWayne]

I agree with the others about the cause of the problem being the imbalance in the load caused by using one leg of a two pole breaker. That said something no one else bothered to mention was that GFCI or not the size of the amp rating of the breaker used is determined by the wire size, not by what you think it ought to be. Currently code states that using a 14 guage wire the max breaker you can use is a 15 amp and if your running 12 guage wire you can go to a 20 amp. In your case I"m going to make a guess that your circuits are wired with either 14 or 12 guage wire so a 30 amp breaker is a third more to twice as big as you can legally use so it needs to be changed out anyway. Look at it this way what good does having a GFCI do you when the overcurrent protection being used is too large to actually provide the proper protection?

 

[huntingreen59]

GFCI in itself has nothing to do with over current protection. It is personal protection.

 

[John T]

I would NOT run the lighting via GFCI protected branch circuitry but ONLY the 120 VAC convenience outlets. Then you can use one GFCI receptacle on a typical brnach circuit and other non GFCI outlets downstream from it are ALSO PROTECTED provided its wired correct. I would avoid longggggggg branch circuit lengths which may cause nuisance trips.

Typical 120 VAC GFCI receptacles operate by sensing any imbalance between the current flow out the hot and returned by the Neutral.

John T

 

[36 Coupe]

You cant use gfci breakers on fence chargers period..I have seen many failures in gfis due to lightning strikes on the power lines.dont bet your life on them.I had a large drill that had leakage because cardboard was used as an insulator around the switch,You could feel the leakage but the gfi never tripped.

 

[NCWayne]

I understand that completely and I said nothing about the GFCI providing any type of circuit protection. Maybe I wasn"t clear but what I was trying to get across was that if a GFCI breaker, or any other type for that matter, was to be used in the circuit then it should be one with the proper amp rating for the circuit being protected. Think about it, what good is a GFCI breaker when all it can do is protect someone from getting shocked but could potentially burn down the barn in an overcurrent situation because it was double the amp rating it should have been? Too, given the length of the runs involved here (174 feet I believe it was) I thought having the correct amp rating at the breaker would be of particular importance since the lower the voltage on at the end of the run would result in a higher amp draw on the wiring...and we all know more amps equals more heat and more potential for an overcurrent type problem.

 

[barn E]

If you are sharing a neutral, that will cause problems. Dave

 

[ErnieD]

From a distance here is my 2 cents.

Light circuit has a shared neutral. (As mentioned previously.)

Your fencer is designed to leak current to ground. That is what a gfci is supposed to detect. Try unplugging the electric fencer.

Other than those two thoughts, reduce the circuit till the problem goes away. [unhook sections]

I trust you are using at least 10 gauge wire with the 30 A breaker, the current interrupting device is sized to the wire.

"Sub panel grounded at the barn"; I can read too much into this description, I don't think you want to "ground" sub panels... and there are specific code rules about sub panel distance when to employ grounds.

At this point I would be consulting a real electrician...

 

[Anonymous-0]

when it come too GFI cicuits you cannot share the neutral for two Seperate Loads wheter you have a 3 wire or (2)Two wire circuits.
the GFI will sense the load imbalance over .05 Mili amps and trip.
re-install the breakers you took out and add GFI receptacles.
for the loads you want to protect with a GFI

 

[CWL]

I'm running an electric fencer off of a GFI circuit with no problems. I also have a tester for GFI outlets to check or proper operation. When tested the GFI circuit trips instantly.

 

[CB in central NY]

Thanks to all who replied; it clears the issue quite a bit.

I think I'll go with individual GFCI outlets.

 

[36 Coupe]

You have a poor ground on the fencer.I have looked at gfis that have been hit by lightning.I wont bet my life on one.Too many parts that can fail.