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Ground fault interrupter keeps tripping.?
I wired some outlets in my tractor shed for use whith a small generator when I need some lights. Works just fine with my little Honda generator. But when I run 3 long extension cords (about 100 ft each) from my detached shop/garage so I can run the shop vac in the shed the GFI trips every time I plug in the extension cords. This happens even when there is nothing connected to the outlets in the tractor shed; no lights, no vac, nothing connected. What is the GFI telling me? Bad extension cord(s)? Bad wiring in the shed? Is the GFI in a detached garage per code? Can I take the d**n thing out?
The GFI is in the detached garage.
KCKC - I swapped out 2 or the 3 extension cords to some nearly new ones and the 3rd old one to one that's in really good condition but smaller gauge. No difference. The GFI still trips. I've got extension cords; probably got 5 at 100 ft and 5 at 50 ft . Been swapping them around. No diff.
I'm pretty sure that the GFI is on a 20 Amp circuit and rated at 20 Amps, but I am not absolutely certain. It is on the circuit with wall outlets in my garage/shop.
Greg: I'm gonna plug in the extension cords to an outlet in the shop in my house. They don't have a GFI. (Too many shops and sheds. Wearing this old man out walking all around the place!!)
MVB: Thanks for the info. With all this good input it has become clear to me that the GFI tripped due to an extension cord capacitive leakage issue. After all, the 3 concatonated extension cords are essentially a 300 ft capacitor. That must be the leakage that the GFI detects. FYI: I plugged the extension cords into the house and ran the vac in the tractor shed just fine. Nice and clean now. Such an ordeal. UGH!!
Update 6: I have further investigated this issue. Greg's answer is the correct one. Because of the length of the extension cords I used the distributed capacitance between the wires in the cable provide a sufficient amount of leakage to cause the GFI to trip. The only way to do a long cable is to run separate wires for the hot, neutral and ground and keep them separated by 3 or 4 inches to minimize the distributed capacitance..
8 Answers
- 1 decade agoFavorite Answer
Believe it or not, the length of cord is too long. Normally you cannot run much more than 100ft cord on a GFI. You may want to have an alternate circuit without a GFI, and use a GFI tap at the end of the extension for safety. If you are going to use 300ft, you may want to use the heavy duty (10ga) extension cords. The other alternative is to run an underground circuit to the shed with a GFI at the shed.
In addition, turn off the breaker and check the neutral and ground for tightness. If you have a loose connection on either it will trip the GFI.
I bow to MVB, as he is more accurate and concise with the proper response.
Source(s): contractor - 6 years ago
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Ground fault interrupter keeps tripping.?
I wired some outlets in my tractor shed for use whith a small generator when I need some lights. Works just fine with my little Honda generator. But when I run 3 long extension cords (about 100 ft each) from my detached shop/garage so I can run the shop vac in the shed the GFI trips every time I...
Source(s): ground fault interrupter tripping: https://shortly.im/deAx3 - 1 decade ago
A GFI should not trip when wire is too small, because it trips from sensing a difference in potential to ground.
Your extension cord is most likely the cause. Probably and exposed knick.
Best way is plug in shop vac at GFI with no cords, this will tell if its the vac.
You should keep GFI in places water could be a factor, like a shed where you stretch out cords across yard.
FYI: Having a GFI circuit powering a light, will also cause trips.
Also, always unplug cords before you roll them up, or that exposed nick you have will hurt ya.
PS. KCKC, he would have either a 15 or 20 amp GFI, if that helps you give a better answer.
NOTE: nice answer MVB, you said the same thing i did, but with big college words.
Ive been union electrician for 21 years, and my answer was not at all dangerous. I believe I actually offered other good tips too.
Questioner never seemed to try plugging in shop vac directly to GFI, so guess we'll never know. well, maybe u should know.
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- MVBLv 61 decade ago
The first three responses are example of a little knowledge being dangerous, although these folks all have good intentions. Let's start with the basics:
A GFI outlet senses precisely one thing, and that is the difference, if any, of the current in the hot wire and the neutral wire. When you plug in a load, 100.00000 percent of the current that flows "into" one side MUST return via the other. If there is even one microamp missing, it must have flowed to ground -- this represents a leak. The circuit is designed to ope (trip) if it senses a leak, because a leak could be dangerous.
Your GFI is tripping because something that your plugging into it is leaking to ground. It is NOT a function of wire length, gauge or breaker rating, nor is there a short here. Somewhere a load is defective. Start with that. Long extension cords have more places to leak, especially if they're old.
I would find the leak rather than trying to defeat the function of the GFI -- it could save your life. Reading your question again, I would suspect the extension cords -- three long, old extension cords might just have too much leakage in them.
Source(s): Electrical and electronics engineer, thoroughly trained and experienced in power distribution and house wiring. - 1 decade ago
Dont forget you will alson have nuisance trips with GFI's meaning they occasionally trip for no apparent reason.
Source(s): 40 hrs a week of hands on electrical work :) - 1 decade ago
It might be that the extension cord are not a heavy enough gauge to run all 3 at the same time. or one of them may have a short in it. Try using only one and the two and see what happens. You may have to switch them out to find the bad one or use 12 gauge extension cords. 14 gauge will get hot and trip the breaker. Also I need to know how many amps the gfi is rated for 20 amp 30 amp or what?
