GFI trips with lightbulb screwed in

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Old 08-20-11, 04:11 PM
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GFI trips with lightbulb screwed in

I have a post lamp with a light sensor. The light sensor and lamp are tied into an exterior box with a GFI protected outlet. The trip button didn't trip the GFI so I replaced it today. As soon as I did, the GFI tripped. I did my troubleshootong and here is what I found:
With nothing connected to the LOAD, all is fine - no trip.
With post lamp and light assy connected to the LOAD side, the GFI trips.
I disconnected post lamp and it did not trip so the wire to post seems OK.
I connected the post lamp wiring without the bulbs and no trip.
When i screw in any bulb the GFI trips. Hmmmm?

A little history: Several months ago I noticed the lamp post didn't work. Troubleshooting, I found the wire to the sensor became disconnected from the GFI receptical. It just wouldn't stay in the hole. I can't remember but I think it was on the LINE side & I simply moved it to the LOAD side. In any case, the post lamp worked fine. When I put everything back I noticed the TRIP didn't function so I made a note to buy one. I finally got around to replacing the GFI today when I came across the issue I mentioned...The GFI trips when light bulbs screwed in.

Two questions:
1. Why could screwing in a light bulb cause the GFI to trip?
2. It have been that the postlamp was never on the LOAD side to begin with. As I said I may have simply moved it there because it would stay in the LINE side, and, since the GFI was defective, the lights worked.

I guess I could look and see if moths or such are in the socket.

George
 
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Old 08-20-11, 04:54 PM
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I can't remember but I think it was on the LINE side & I simply moved it to the LOAD side.
So.....which wire was this, the black wire or white wire? Or....did you move both wires to the LOAD side from the LINE side?
 
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Old 08-20-11, 06:24 PM
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I would also check for a pinched neutral on the LOAD side.
 
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Old 08-20-11, 06:35 PM
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both black and white to ther respective locatin on the LOAD side.
 
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Old 08-21-11, 06:09 AM
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Originally Posted by george747 View Post
Two questions:
1. Why could screwing in a light bulb cause the GFI to trip?
Putting the bulb in allowed current to flow. A GFCI won't trip if the portion of the circuit it's protecting doesn't have current flowing. A GFCI works by monitoring the amount of current leaving it compared to the amount of current returning to it. Most will trip if there is 4-6 milliamps difference.

You said "I disconnected post lamp and it did not trip so the wire to post seems OK."
This is not necessarily true. The wiring to the postlamp may have damage that is only being found (by the GFCI) when current is flowing.

Then you said "I connected the post lamp wiring without the bulbs and no trip.
When i screw in any bulb the GFI trips."
This is leading me to think the problem may lie in the neutral side of the circuit. Could be in the wiring from the GFI to the post or in the post itself. I'd look for a neutral wire being nicked or frayed touching the ground wire or grounded metal (like the post itself).

Do you have a meter you can do continuity tests with?
 
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Old 08-21-11, 06:54 AM
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If you don;t have a meter temporarily disconnect the cable to the light at the lantern post. Connect a receptacle and plug in a load such as a lamp. If the GFCI doesn't trip then the then the lamp holder may be the problem.

Is the photocell at the lamp pole? If so you want to do this ahead of the photocell then after the photo cell but before the lamp socket.
 
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Old 08-21-11, 07:09 AM
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I believe the OP has a wire on the load side that should be on the line side. They said a wire would not hold in the clamp and they moved it. If so the GFI is seeing this an an imbalance.
 
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Old 08-21-11, 07:15 AM
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Maybe, but...........................

Originally Posted by george747 View Post
both black and white to ther respective locatin on the LOAD side.
 
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