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toyota_mdt_tech
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# Posted: 26 Oct 2014 12:34pm - Edited by: toyota_mdt_tech
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OK, built a tool shed for a good buddy of mine, built it like an adorable cabin, overhang and porch etc. I just ran a single circuit from his home panel (no sub panel). We used 12AWG in underground feeder (UF) through 1" gray PVC conduit underground, few water drains holes on underside, run is about 25 feet max. Used only a 15 amp breaker and inside the toolshed, we used all 14AWG wire. First inside outlet is a GFCI to protect all outlets downstream. We have a few outlets in there and then it goes on to run the lighting circuit. The lights consist of 4 of those florescent tube fixtures plus 2 LED can lights.
All circuits test fine with the tester (2 amber lights illuminate) and pushing on the GFCI bottom trips the GFCI outlet. Power tools all run fine on the outlets.
Problem arises when we turn on the inside tube CFL lights. It hums, then pops the GFCI. Thought, failed lamp fixture. Hooked u p second one, did the same thing. Thought, OK, maybe a poor connection at one of the outlets in the chain, plugged fixture direct into first GFCI outlet. Popped it. So this eliminates all outlets/wiring downstream. Thought, OK, bad GFCI outlet, we tried his lamps in his shop on his GFCI circuits, worked fine. So installed another GFCI outlet in toolshed, popped it. Went to main panel, double checked wire connections at breaker. Black wire to breaker, all tight, white and neutral at grounding bar (this is his main panel and they are bonded) all tight
So I have removed the GFCI outlet in his toolshed now to get the lights working for now.
I have drawn a simple diagram of the circuit. I am very handy on residential electrical, but this has me stumped. I know the GFCI is looking at outgoing vs return and any difference, it pops it.
Black wire hooks to 15A breaker in panel, white and ground are both bonded together at the ground/neutral buss bar inside the homes main panel. I did not use a GFCI breaker in the panel, just a conventional 15 amp singe pole breaker, we used an original Cutler Hammer breaker (same as panel mfg). Then the wire goes underground to GFCI "line" side of outlet, also on gold screws, white wire to silver screw on line side of GFCI, then same for outgoing (load) ie black to gold, white to silver and bare ground to green screws. All ground wires are twisted together inside box, then a copper plated crimp ring is crimped and a single pigtail ground wire hooks to ground screw. After the last outlet inline, it goes to the light switch where all whites are bonded together along with all grounds, while the black or line is split to feed each light circuit, ie inside CFL's and outdoor underporch can lights. I double checked all the wire nuts etc.
GFCI only pops when the CFL lights are turned on.
Help please, I am out of ideas. 
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MtnDon
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# Posted: 26 Oct 2014 01:35pm - Edited by: MtnDon
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Quoting: toyota_mdt_tech After the last outlet inline, it goes to the light switch where all whites are bonded together along with all grounds,
If you mean the white neutrals are bonded to the bare grounds, undo that. If you mean the neutrals are bundled and the grounds are bundled separately, I have no idea just off hand.
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toyota_mdt_tech
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# Posted: 26 Oct 2014 02:04pm - Edited by: toyota_mdt_tech
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Quoting: MtnDon If you mean the white neutrals are bonded to the bare grounds, undo that. If you mean the neutrals are bundled and the grounds are bundled separately, I have no idea just off hand.
Don, they are only bonded at the primary/main panel where the circuit originates, ie the ground and neutrals all tie together (like in any main panel) there and hook into the ground rod also. The ground and the neutrals are on there own anchor point. But on the same buss bar. Past that, they are all separated.
If I cant get this figured out, I'm going to remove the run between last outlet to the lighting and then tie the lighting into the GFCI line (input) side of the GFCI outlet, ie the outlets will all be GFCI protected, but the lighting will not be.
This is the diagram of my proposed fix. 
Thanks for you input too Don, I was hoping you would reply.
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MtnDon
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# Posted: 26 Oct 2014 03:26pm - Edited by: MtnDon
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Removing the CFL lighting from the protected circuit is a good idea. There may be something about the CFL internal ballasts that is causing the issue. G/L
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bldginsp
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# Posted: 26 Oct 2014 03:34pm
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I googled 'fluorescent light trips gfci receptacle' and came up with a bunch of stuff. Here's a link to one with good info-
http://diy.stackexchange.com/questions/42526/why-does-my-fluorescent-ceiling-fixture- trip-the-gfci-sometimes
Possible reasons given were that the ballast voltage surge causes a temporary slight current imbalance which will trip a gfci, cheap Chinese gfcis, electromagnetic interference, older type ballasts that don't have proper filters, etc.
One poster said that in common practice receptacles are kept off lighting circuits so that an overloaded receptacle won't turn out the lights when tripped. So two separate circuits would be best. You said you ran #12 wire in the conduit, so you could set a small subpanel and run two 15 amp circuits off of it. Technically if you did you would need a ground rod at the second building, whereas you don't if its just a single circuit.
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toyota_mdt_tech
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# Posted: 26 Oct 2014 04:16pm
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They are cheap $10 units from Wal Mart and they were made in China. They have a plug on them, and we have 3 switched outlets in the ceiling to make it "flexible" for his lighting needs. I did plug the light into his shop outlet which is GFCI also, worked great, all 3 of them and all 3 failed in the tool shed, worked fine in his shop. We wanted to keep it simple (tool shed circuit). Lighting of course and a few outlets to charge his wife's garden tools, electric start gas mower etc, so we opted for the single circuit.
Don, when turned on, the first light tube lights up, then it hums while trying to start the second tube and then it trips. I also tested those ceiling light outlets with that plug in tester, both amber's light up, red stays off and pushing the button trips it. He is closing in the inside walls now (he insulated it because it was getting too hot with southern facing wall against the summer sun on wall), I told him to leave it open between the GFCI outlet and switches. I think I'm going to just tap the lights off of the GFCI "line" side (input as in my second wiring diagram). Problem solved. But it bothers me as to why I cant find the trouble. If the lights didn't work plugged into his shop GFCI circuit, I'd be OK knowing its the fixtures, but they work fine there.
Thanks for the link bldg insp, I will follow the advice one said, part of my original plan too, "remove light from GFCI protection", but still use the same circuit. 
I figured this one would be a fun puzzle for our resident electrical guys too.
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bldginsp
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# Posted: 26 Oct 2014 05:19pm
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Not really sure what's going on here, but I think what it boils down to is that different manufacturers of fluorescent light fixtures and GFCI receptacles use different electronics with different characteristics, and a bad combination of the two results in the GFCI tripping. Could be that eventually standards will be created (voluntarily or not) and used by the manufacturers of both devices to avoid the problem.
We had a similar problem with AFCIs in my building dept. We were given gadgets that supposedly tested AFCI circuit breakers by plugging them into the receptacle and pressing a button which would trip a properly operating AFCI. But sometimes the testers worked, and sometimes not. It was really baffling until we figured out that the tester only worked on certain brands of AFCI breakers and not others. I don't know what the manufacturers of the tester were thinking, but they got a lot of our money.
AFCIs and GFCIs are still relatively new and they haven't ironed out all the wrinkles. As time goes by and we allow ourselves to become more dependent on electronics, we become more subject to their foibles and unanticipated design problems. The new Ford C-max I drive at work is a rolling Ipad. So what happens when the circuitry in this gadget goes bonkers?
My first car was a 61 Ford Falcon station wagon. Should have kept it.
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toyota_mdt_tech
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# Posted: 26 Oct 2014 06:07pm
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I think you nailed in bldg insp, I can find no error on my work at all and know I did my wiring correct. At first, I thought I had overlooked something. But in the end, I think its a combination of several things out of my control, ie GFCI outlet and cheap chinese fixtures.
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Borrego
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# Posted: 27 Oct 2014 10:49am
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Receptacles and lights are usually run on different circuits, probably for reasons like this.............
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creeky
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# Posted: 28 Oct 2014 04:03pm
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toyota ... if it makes you feel better. i destroyed a really good inverter with a gfci and cheap "security light."
throw that light out. jeez borrego. now you tell me. ;)
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toyota_mdt_tech
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# Posted: 28 Oct 2014 09:03pm
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Quoting: Borrego Receptacles and lights are usually run on different circuits, probably for reasons like this.............
Yes, and that is how we wired his shop. But this was just a simple circuit for a toolshed. He wanted lights and a few outlets.
So I will follow my second revised wiring diagram, have a single circuit, but no GFCI on the lights. Strange thing was all those same lights plugged into his big shop outlets that were GFCI and worked fine.
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MtnDon
Member
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# Posted: 28 Oct 2014 09:27pm
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different brand GFCI?
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toyota_mdt_tech
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# Posted: 28 Oct 2014 09:45pm
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No, both Leviton, and the same model. I am flat stumped Don.
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MtnDon
Member
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# Posted: 28 Oct 2014 09:59pm
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gremlins... Halloween is nigh
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Truecabin
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# Posted: 28 Oct 2014 11:40pm
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function of a ballast is to regulate the current while the fluorescent light starts up. it does all kinda funny business until the lamp reaches steady state, not surprised a gfci doesn't like it
gfci is for outlets to protect people not light circuits that have all plastic switches
they are expensive and not that reliable id use them near a tub or shower not a toolshed unless theres a large sink in toolshed
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toyota_mdt_tech
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# Posted: 29 Oct 2014 10:31am
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The toolshed has 2 outdoor outlets (wet locations), he wanted it for his smoker. That is the reason we used the GFCI to protect the circuits. Another option would be to replace the outdoor outlets as a "stand alone" GFCI outlets, ie wired to "input" only. That would be easier than running the extra wire from the first GFCI input to the lighting switch box.
That would be even an easier solution than the second proposed wiring diagram, though, both would work, one is eaiser to do. Especially since his wife has aldreay closed in the walls with insulation.
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toyota_mdt_tech
Member
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# Posted: 3 Nov 2014 09:07am
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OK, solution fixed. Never did find anything wrong with the wiring itself. I think it was a combination of certain things, ie GFCI and CFL lights.
I remove the GFCI outlet that protected the entire circuit (outlets and lights, I know, lighting separate, but this was to be a simple circuit for lights and a few outlets in a toolshed) so with the inside being dry, I remove the GFCI and installed it as a "stand alone" on each of the 2 outdoor outlets. In other words, I wired the line to the "line side" of the outlet and the load (past that outlet) also to the "line" side. The new GFCI outlets have nice holes to stick the wires in and tighten the screws to clamp them in place. Makes this task easy without having to use some wire nuts.
So this is now a closed issue and thanks for all your
input/help. 
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