GFCI problem

[RobA]

I recently started having a problem with a GFCI outlet in our horse barn. The electricity in the barn was run 5 years ago and I've never had a problem. There are no moisture problems. The problem circuit starts with a GFCI outlet wired to a switch which controls another 4 outlets. The 4 outlets are used for stall fans in the summer and heated buckets in the winter. My wife found the heated buckets frozen a few weeks ago and noticed the GFCI outlet was tripped. She reset it without a problem and all was good for a week or so. Then it happened again a few more times. 3 days ago it happened but now the GFCI won't reset unless the switch controlling the downstream outlets is off. In order to rule out bad heated buckets I unplugged everything from the outlets but that didn't help. I opened the box with the GFCI and switch in it and all the connections seem OK.

Any thoughts on how to diagnose this? Replace the switch? Replace all 4 downstream outlets?

 

[/pine]

Replace the GFCI...I've had several go bad...

 

[jaxs]

The GFCI is probably bad but you can test it. Disconnect switch at GFCI,if it will reset and carry a load,post back.

 

[B7510HSD]

Also check all plugs and make sure you don't have a lose connection somewhere.

 

[teejk]

My wife was having similar problems with a heater she used on her fish pond. Turned out it was the heater. Not to say that the GFCI might be bad though. I've had that also. Your downstream outlets can be tested with a cheap plug in tester.

 

[rbtjr]

We had the same problem and it turned out to be a short in one of the outlets that were served by the GFI circuit. We diagnosed it by removing the outlets one by one.

 

[RobA]

Thanks. The wiring is conduit, not NM. I can't test the downstream outlets unless I remove the switch since when the switch is on the GFCI trips. I may start with replacing the GFCI. I'll tackle it tomorrow.

 

[bunyip]

We had a similar problem with one tripping and after much investigation found that moist foggy mornings the moisture was getting into an outdoor 'waterproof' GPO, replaced the seal and problem fixed.
Another time we did have a faulty unit and replaced it, the upside is that they are cheap now, I think a new one we installed less than a year ago on a new circuit was about AU$35.00 compared to about $150+ 10 years ago.

 

[quicksandfarmer]

GFCI will trip if the neutral is touching ground somewhere downstream. This is hard to detect because it doesn't cause any problem other than the GFCI tripping. I would start at the switch, disconnect all three wires going downstream, and check for continuity among all three. There shouldn't be any at all. If you find any continuity disconnect the outlets one by one until you find the problem.

 

[JPRambo]

Are the downstream outlets in metal boxes? When you remove them to check, screw in the side wire terminal screws. That is where any moisture will accumulate and short to the box and trip the GFCI.

 

[bunyip]

Another problem we encounter is tiny little black ants getting into switches, sockets etc and becoming little resistors when they fry.
The also create havoc in antenna baluns building nests and upsetting impedance.
They seem to be able to get past any sort of seal and are masters at causing frustration.

 

[RNeumann]

Any diagnosis works best if it’s systematic. If you don’t want or have a replacement GFCI I’d start at the farthest outlet from the GFCI and undo the wires. Recheck the GFCI. If it trips, undo the next one closer. Check again. This approach will determine where in the circuit the fault is.
I’m guessing it will end up being the GFCI (like most here) but the above approach is the way to diagnose any circuit with a fault since to systematically eliminates each section of the circuit.

 

[quicksandfarmer]

Any diagnosis works best if it’s systematic. If you don’t want or have a replacement GFCI I’d start at the farthest outlet from the GFCI and undo the wires. Recheck the GFCI. If it trips, undo the next one closer. Check again. This approach will determine where in the circuit the fault is.
I’m guessing it will end up being the GFCI (like most here) but the above approach is the way to diagnose any circuit with a fault since to systematically eliminates each section of the circuit.

You can save some time by doing a binary search -- eliminate half in each test. So undo the farthest two. If the problem goes away it's one of those two, otherwise it's one of the nearer two. Then undo one of the suspect ones. You won't save a whole lot with just four devices, with more you can save a lot of time though.

Of course, if it's a wiring problem, most likely it's something that's rubbing somewhere or contaminated. Taking it apart and fiddling will probably fix it without you even realizing. And there's nothing more frustrating than a problem that goes away without an apparent cause.

 

[QRTRHRS]

In a past operation, I ran about 25 heated buckets, each on it's own GFCI on a number of circuits (without doing the math). I had heated buckets stop working but no other issues. A bit more expensive but with boarders, extra insurance just in case. I know licensed electricians whom also own livestock that refuse to use heated water systems. True, it does not take much current to kill an animal.

My preference is also to used plastic conduit and boxes in my barns due to moisture concerns. I have seen EMT that looks good on the outside but is rusted on the inside.

 

[Tractor Seabee]

I had the problem once in my greenhouse. Found a hornet nest inside a light fixture plugged into a GFCI. The nest enclosed the wire nuts. Must have attracted enough moisture to make the trip work.

Ron

 

[kcflhrc]

Start with the 1st outlet downstream and disconnect the wires going to the next outlet and keep doing that until you find the problem. Probably not the GFCI or switch. But why the switch in the first place?

 

[EddieWalker]

By design, GFCI outlets will switch off with the slightest change in current. It doesn't take much, but some are more sensitive then others. From what I understand, they are mostly designed for indoor use, so when used outside, weather, humidity, bugs and dust all take a toll on them. The house that I'm working on right now is on the lake and they have outdoor outlets and lights all over the place with GFCI outlets to protect them. I replaced three and so far, everything is now working great. They just wear out quicker when outdoors.

If for some reason you still have problems after putting a new one in, you will need to go to the next outlet and disconnect it from the other outlets farther away and test to make sure that one is good. Then do it again with the next one, and then the next one. Wires rarely go bad, but outdoor outlet boxes will sometimes fill up with bugs and create all sorts of issues.

 

[teejk]

I've thought some more about it. Since OP was going to change the GFCI anyway, maybe just bypass it so he can test all downstream connections?

 

[Gary Fowler]

I had an outdoor outlet tripping my GFCI with nothing plugged into it. Upon opening up the receptacle, I found some spider webs inside. I cleaned them out and everything was fine afterwards.
Since the OP is in a barn, I would start by opening all the receptacle and clean out any debris that might be inside, then check for a trip.

 

[buickanddeere]

Why have the fans on the GFCI ? For all they cost put a GFCI in each horse stall.