gfci + fluorescent lights

Is there any consensus on whether fluorescent lights might normally cause nuiscance gfci trips? And if so, is there anything that can be done? These are the long, 48'' dual-bulb overhead lights, on a 20A GFCI outlet.
Some background on the problem: The lights (3 sets of them) are hanging in a detatched garage, and plugged into a string of outlets on the ceiling, which are connected through a single wall switch.
The _entire_ garage circuit is fed from a dedicated 20A GFCI receptacle-but-not-a-receptacle (looks just like a receptacle, but missing the outlets, and has just the GFCI part) in the basement of the house, about 15' away. The wire runs underground using UF cable to the garage, with ground wire, then to the problematic lighting run and a few unswitched wall outlets.
I think I have narrowed down the tripping to the lighting outlets. The ground path could be in the outlets themselves, the plugs/cords for the lights, or somewhere internal to the fluorescent lights (the ballast/filter, I am guessing).
Previous owner had chopped off all of the ground prongs on the lights, so no tripping, but the lights didn't turn on reliably. I put the prongs back on, so now I get reliable lights, but frequent gfci tripping.
Thanks, -kevin
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I don't know anything about fluorescent lights, but the obvious work around is to remove the GFCI and reinstall it just before the wall outlets. (or toss it and buy a GFCI outlet.)
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GFCI tripping when fluorescent lights are on the protected circuit is fairly common especially if the ballasts powering the lights are the older electromagnetic type. The reason is that there is a fairly large capacitor inside the ballast and current is induced to ground during operation and particularly during turn on or off. My GFCI usually tripped when I turned the lighting fixture off. It was just one fixture with a 2-lamp ballast powering two 4-foot lamps.
Removing the ground from the fixtures reduced the induced current to below the tripping point (about 5 milliamps) for the GFCI; but, as you say, starting became a problem. That's because your fluorescent lamp system is designed to have the lamps about 1/2 inch away from a grounded piece of metal when starting. Otherwise, starting is slow to slower. Fluorescent systems are highly engineered for efficiency and long life, but they have strict requirements.
What can you do?
1. Bypass the GFCI with a feed just for the lighting fixtures and hard wire the fixtures so you'll meet code requirements. Make sure you have a good ground.
2. Replace the ballasts in the fixtures with the newer high-frequency electronic type. You might as well go with a high-efficiency system too; so use T8 rather than T12 lamps (F32T8). They will fit into your existing fixtures.
3. Mount the GFCI where it's easy to reach and live with the occasional tripping.
TKM
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Thanks for the responses. Unfortunately most aren't doable...

The GFCI is protecting all of the outdoor outlets, which are required to have GFCI. I would have to run a new cable back to the panel just for this part of the circuit. And worse, I think that the GFCI is required on the house-side of the (very shallow) underground run.

Same problem -- underground run is shallow, so I think it might need the GFCI (in the house basement) for protection, and hence very inconvenient to the garage, in the dark, on the other side of the house.

high-frequency...
I will look into this one -- it sounds promising. These balasts are indeed quite old.
Regards, -Kevin
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Kevin,
The lights are obviously causing or contributing to your problem. This seems obvious from the fact that restoring the proper grounding of the lights led to the GFCI tripping plus the fact that the previous owner removing the ground plugs for a reason.
I believe that even with newer ballast systems, some fluorescent light systems can confuse GFCI circuitry due to the small capacitive losses created between the bulbs themselves and the metal reflectors which are in close proximity to the bulbs. This is a nuisance ground fault - a genuine loss of current to ground but not a safety issue.
The problem is that background nuisance ground faults are cummulative and they can create nuisance GFCI tripping. If they don't trip the GFCI, then they increase its sensitivity by preloading it with some small level of ground fault.
Before you invest in new ballasts or new fixtures, I'd suggest doing some research to be certain that it is not just the starting cycle of the lights which contributes to the ground faults. Hopefully you'll get some good advise on this newsgroup on the issue of capacitive losses during fluorescent light operation. If not, there is probably a lot of information which can be located with "Google".
Good luck, Gideon
====================== Kevin wrote: Is there any consensus on whether fluorescent lights might normally cause nuiscance gfci trips? And if so, is there anything that can be done? These are the long, 48'' dual-bulb overhead lights, on a 20A GFCI outlet.
Some background on the problem: The lights (3 sets of them) are hanging in a detatched garage, and plugged into a string of outlets on the ceiling, which are connected through a single wall switch.
The _entire_ garage circuit is fed from a dedicated 20A GFCI receptacle-but-not-a-receptacle (looks just like a receptacle, but missing the outlets, and has just the GFCI part) in the basement of the house, about 15' away. The wire runs underground using UF cable to the garage, with ground wire, then to the problematic lighting run and a few unswitched wall outlets.
I think I have narrowed down the tripping to the lighting outlets. The ground path could be in the outlets themselves, the plugs/cords for the lights, or somewhere internal to the fluorescent lights (the ballast/filter, I am guessing).
Previous owner had chopped off all of the ground prongs on the lights, so no tripping, but the lights didn't turn on reliably. I put the prongs back on, so now I get reliable lights, but frequent gfci tripping.
Thanks, -kevin
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