closet light trips GFCI

9 years ago

A couple of months ago, I wired a 2-tube, T5 fluorescent fixture in my closet. I took the power off of a nearby receptacle, with a simple switch to control the light. Everything worked fine, until I replaced the first receptacle with a GFCI unit. When I turned on the switch, the GFCI tripped. I opened up the fluorescent fixture to check if everything was wired correctly. Before reassembling it, I reset the GFCI and turned on the light. Nothing tripped. I then put in one tube, and repeated. Nothing tripped and the light worked. I put in the second tube, and the GFCI tripped. I tried moving the tubes around, but whenever both tubes were installed, the GFCI trips whenever I turn on the light. If a single tube is installed, either tube in either position, the GFCI doesn't trip. Any suggestions?

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Comments (8)

Ron Natalie
9 years ago
Make sure that all the hot/neutral connections pass back through the LOAD terminals of the GFCI. Make sure that neutral and ground do not touch anywhere after the GFCI (well they shouldn't touch before either but that won't cause the GFCI to trip).
mtvhike
Original Author
9 years ago
I think I've checked those so I thought maybe there's something in the fluorescent lamp wiring. I've used the receptacles in the chain for other things with no problems, including testing them with those 3-light testers (I do that on every receptacle). Are there any other tests?
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Ron Natalie
9 years ago
Again, if anything touches ground-to-neutral, you'll have problems. If hte neutral touches some grounded object you'll have problems.
User
9 years ago
last modified: 9 years ago
Those types of fluorescent tube fixtures trip GFCI breakers. By the time you put in the second tube, you have more than 5ma of current leakage between the tube and the grounded case that facilitates the starting of the tube. If you take out the GFCI, AND disconnect any and all grounding of the metal case, you should be able to see that the tubes have a hard time starting cold without the ground connected...
mtvhike
Original Author
9 years ago
So, Fred, what's the solution? Before I put it on the GFCI circuit, it seemed to start fine. I'm sure the ballast and case are fully grounded (green ground wire PLUS metallic sheathing! Is there another way to test this?

By the way, I have always noted (since the 1970s at least), that fluorescent shop lights don't work well unless they are on grounded circuits.
User
9 years ago
last modified: 9 years ago
Since the fixture is working properly, and it will not work on a GFCI, then you either get rid of the GFCI, or find another type of fixture. However, other types of fixtures may not be allowed by the NEC in the same area of a closet that the fluorescent is allowed.

Just put the fixture on the line side of the GFCI instead of the load side.
mtvhike
Original Author
9 years ago
Do you think the GFCI might be defective? Putting it on the line side is not practical because the string of devices between the GFCI and the light is loooong. I put it on that string because there is a receptacle nearby. Maybe I should put it on the lighting circuit for the adjacent bedroom.
User
9 years ago
last modified: 9 years ago
No, the GFCI is not defective. Just admit to yourself what you have known since 1970. Yes, put it on the lighting circuit for the adjacent bedroom.