20 amp ground fault breaker question

[bleeright]

I am rewiring my barn and decided to go to a square d box with ground fault breakers.The problam I am having is they keep setting when I turn on my lights.I have two flurecent screw in type bulbs 100 watt equivelent on a 20 amp breaker.tried one and it also reset.Everything is wired correct.A non gfi breaker works fine.The distance of the run is 120'. I wanted to wire a 20 amp for my welder and was wondering if I will have the same problem.I bought 2- 15 amp and 2- 20 amp should I return the breakers and go with standard?I tend to power wash every thing in the barn that is why I went with ground fault.I have livestock in my welding shop.

[Sandy]

Well no-one else is leaping in here but maybe I can give a few clues.

Modern GFCI's of the receptacle type, and I don't know why a GFCI breaker would be any different, have a comparative circuitry built in. So for 120v applications this circuitry looks for any difference in current between the Hot (black) and the Nuetral (white). If there is any difference then the circuitry assumes there is a fault and trips. And it does not take much. That is the intent of the GFCI. No residential user will even feel the slightest tingle before the circuit is taken out of service.

So in your case there must be a difference in cuurent between one and the other, which means everything isn't wired right or isn't compatable with GFCI intents. Without more info it is nearly impossible to diagnose something like this.

Here is possibly a hint or two. Perhaps you ran to an outlet or two or three before you ran to the overhead lights. You could have a metallic encased two wire something plugged in that is setting on a wet concrete or dirt floor. You could have a three wire metallic cased something or other plugged in that hase the nuetral and ground tied together in the case like any washers and appliances do. Anything beyond that breaker is subject to it's circuitry.

That's sort of one of the things to watch for when installing GFCI's, everything has to be correct and compatable.

[jer29_11_13]

Try replacing the GFI breaker and using a regular breaker at the panel and then use a GFI receptacle at the destination of the run. A 120' could be the problem with slight variation of wire resistance of each leg, only a thought! :)

Also measure the voltage at the receptacle of each leg to true earth ground at the receptacle, there should be no voltage on the neutral wire if so there is a grounding problem.

Hope this helps...

[MAC702]

A 120' could be the problem with slight variation of wire resistance of each leg, only a thought! :)
Good thought, BUT, GFCIs sense the difference in current, not voltage. Conductor resistance is irrelevent.

Are all of your neutrals independent, and did you land the circuit's neutral to the breaker and the breaker's pigtail to the neutral bus in the panel? No sharing neutrals with GFCI circuits.

In my experiences, I have found the receptacles to be more reliable against nuisance-tripping than the breakers. I prefer using a GFCI receptacle as the first receptacle in a circuit and wiring it to protect the whole circuit when I want to, as opposed to using the breakers.

[enlpck]

The screw-in flourescent probably have electronic ballasts in them, which produce a fair bit of HF harmonic in the power draw. These couple to the ground line quite well. Some ballasts intentionally couple to the ground, using the fixture as a ground plane for striking and sustaining the lamp arc, leading to not insignificant HF ground current, which looks like a leak to the GFCI--all it takes is 6mA (some are lower). The long run from the breaker gives quite ample coupling in either case. It is a common problem, and many manufacturers explicitly recommend (or at least used to) NOT using GFCI feed to fluorescent fixtures.

[Sberry]

Yup, you dont need them on lights anyway, I dont use the breakers either, I install an outlet where I want one.

[Jerry Smith]

I only put GFI outlets near places where I will be using water and maybe a few other places. One of my old neighbors had a GFI breaker on the circuit to her bathroom, great idea, but it was also the breaker for her electric garage door. So when she pushed the button to open her garage, guess what happened?

I like the outlets much better than the breakers, you can be selective about where you have the protection and you wire them not be daisy chained to the next outlet or device.


Jerry

[Pumpkinhead]

The screw-in flourescent probably have electronic ballasts in them, which produce a fair bit of HF harmonic in the power draw. These couple to the ground line quite well. Some ballasts intentionally couple to the ground, using the fixture as a ground plane for striking and sustaining the lamp arc, leading to not insignificant HF ground current, which looks like a leak to the GFCI--all it takes is 6mA (some are lower). The long run from the breaker gives quite ample coupling in either case. It is a common problem, and many manufacturers explicitly recommend (or at least used to) NOT using GFCI feed to fluorescent fixtures.

just screw in some regular bulbs in place of the fluoresents, no trippy, you found your problem! if it trips look elsewhere.

[TOMWELDS]

Also, are there wires for 'another' circuit in the same conduit? This can cause nuisance tripping. In this case i would go with the GFI recep. as Mac stated. I would also test the circuit wires from: ground - neutral, ground - hot, with an ohmmeter to test for ground leakage. If there's no reading, those bulbs could be causing a nuisance trip. Bottom line; you dont want current on the ground wire. Another thought; test the ground that's supplying the panel. And, try another GFI breaker.

[drizler]

They supposedly can be handy but I don't do electric things standing in water which is about what they are good for. The other thing they will do is catch on fire if there is a surge. When my generator lagged and froze a brush on my furnace motor during the great ice storm of 1998 it fried a few thing which pissed me off. What really pissed me off was that the ****ed GFI in the bathroom caught on fire which I put out with a towl. I never replaced the thing. I can trust myself not to stand in the tub and dunk a hair dryer since they all have built in gfi anyways these days. What I can't stand is something that catches fire. Some things aren't what they are cracked up to be. The one in my garage trips way to often as well. Some of those safety devices never should have been invented..............................If you really need one just put it on the last outlet in the circuit where it can't screw up anything else before it. If you need to have it to sell the place later on just switch it to the first electric outlet in the circuit and let it bother someone else.

[MAC702]

They are required on all OSHA jobsites for very good reason. Any power tool which is held in the hands can be a hazard if the double-insulation or grounding fails. The presence of water only serves to lower resistance between faults and potential grounds (including people) so they are even more important there, and have saved many lives, both with and without water present. I've never seen a GFI catch fire before, but you should be blaming your generator, not the GFI. If you have one that trips, there's a reason why. Are you plugging in a homemade extension cord; What IS plugged in there? They don't just trip for the fun of it. Could be you have a small fault that doesn't bother YOU; but it's still there. In their early days, they did have a higher failure ratio, but usually it's because they wouldn't reset. They are very effective, safe, and reliable devices these days.

You can put one ANYWHERE in the circuit without affecting the rest of the circuit. It's all in how you wire it on the backside. You can opt to have it protect only itself, OR everything else downstream in the circuit (provided you aren't sharing a neutral with another phase.)

More on topic: They are senstive to electrical storms. NEVER plug refrigerators or freezers into them in the garage. I've been called out to too many jobs only to reset a GFI in a garage after someone gets home from vacation to a load of rotten meat. The GFI breakers in a panel are more sensitive to storms than the receptacles are.

[jer29_11_13]

Good thought, BUT, GFCIs sense the difference in current, not voltage. Conductor resistance is irrelevent.

Are all of your neutrals independent, and did you land the circuit's neutral to the breaker and the breaker's pigtail to the neutral bus in the panel? No sharing neutrals with GFCI circuits.

In my experiences, I have found the receptacles to be more reliable against nuisance-tripping than the breakers. I prefer using a GFCI receptacle as the first receptacle in a circuit and wiring it to protect the whole circuit when I want to, as opposed to using the breakers.

The purpose in measuring ground is to make sure you have it, a true ground. I have seen slight voltage readings on supposedly good "ground wires". A long run could be sufficient to give a slight variation in the current due to resistance variation (V=I*R) which would trip the GFI breaker.

I agree that it's always best to put the outlet where you actually need the protection.

[TOMWELDS]

A GFI caught on fire? I would send it back to Leviton or whoever and have it investigated. Ive had them on circuits that were hit with lightning and they 'fail', Never saw one catch fire.

[MAC702]

The purpose in measuring ground is to make sure you have it, a true ground. I have seen slight voltage readings on supposedly good "ground wires". A long run could be sufficient to give a slight variation in the current due to resistance variation (V=I*R) which would trip the GFI breaker.
GFCI's don't measure the ground, they measure the difference between hot and neutral. You don't even need to hook up the ground, and they will work fine. And you are misapplying Ohm's Law. Current doesn't care what the resistance is. As long as there is no short, and there is sufficient voltage to overcome what resistance there is, 100% of the current that leaves on the hot will return on the neutral.

[bleeright]

Thanks for the info guys.I have decided to use standard breakers.I was sharing a neutral.I used three wire two seperate breakers same neutral. I will try shutting the electric down in barn all the way when I power wash it.It usually takes 9 hours of water work to do a complete job I will just do it stages from now on.I also run animal water heaters in the winter and don't want to gamble on having a faulse break.

[INTP]

I didn't see this mentioned, but try to keep the lights on a separate circuit from the receptacles. If a tool trips a breaker, it's better to not be in the dark if possible.

Also, I had trouble with the cheap GFCI receptacles (Leviton) tripping with my HF TIG on a separate circuit. I upgraded to some commercial grade receptacles and the problem went away.

[fwilliams]

when you wire your outlets& lights test them with a circut tester, better to be safe than sorry