Faulty GFI??

[Zzz]

Anyone have any experience with unexplainable gfi tripping?

Brief history. Bought house and inherited pool. Equipment was fine for last 9 years. Last season had lights on one day for a few hrs and GFI tripped for first time ever. would not stay on more than 10 seconds after each reset. I opened first electric box in circuit path and disconnected light closest to panel. Reset GFI and far light came on and stayed on. I isolated problem to first light. Pulled light from niche and opened. interior was bone dry. I figured water got past insulation in cable and light was toast. Time for new lights.

Just installed 2 intellibrite 5G LED's and wired them up. Dang GFI tripped immediately. I thought to myself this cant be happening so I disconnect first light and reset GFI. The new far light comes on and stays on. Same scenario as original problem. I reconnect first light and gfi trips immediately. looks like I may have a defective light. Lets see, so I disconnect all wires going to second light and only wire up bad light to GFI. The bad light (or so I thought) comes on and stays on. Now I'm scratching my head. Each light comes on and stays on when wired to GFI individually but when both lights are connected the GFI trips.

I don't get it. It just doesn't make any sense to me.

As an afterthought I may have not needed new lights as I didn't diagnose any further with the original problem once I isolated the problem to the first light.

 

[danpik]

Is this a GFI recepticle or a circuit breaker that keeps tripping? Either way, I would try swapping it with another one or replacing it to see if the problem goes away. GFI's do go bad sometimes. I would also try running a test wire from the gfi to the light junction boxes to eliminate anything there. GFI's trip on current imbalance from the hot to the neutral. If the current coming back on the neutral does not match the current going out on the hot (withing a certain %) then the GFI trips off.

 

[onlyjeeps]

10 or 15 mA depending on the quality of the GFCI. That's the percentage of current imbalance between hot and neutral mentioned above before tripping unless damaged. In most cases when a GFCI becomes damaged, it actually will not trip...and that's why they all say to test monthly (or weekly) or they will not reset.

I want to say carefully check your wiring and make sure everything is connected correctly (hot's, neutral's and grounds) but since this same set up has worked for years before now I guess that's not valid. Still that's my first instinct. So let's break it down. Is this a GFCI breaker or an outlet that both lights are wired to?

If it's a breaker, how is it wired? Are both lights' hot wires together under the breaker hot terminal and both lights' neutrals together under the breaker's neutral terminal and the breaker's separate neutral wire is wired to the panels neutral bus and the breaker's ground wired to the ground bus?

Similar wiring if they are wired to an outlet where both lights' hots are together under the outlet's "load" hot terminal and both lights' neutrals together under the outlet's "load" neutral terminal and grounds all together. Only the breaker feed wire is connected to the outlet's "line" terminals.

This is a start for the wiring. Post what your setup is and we'll see if we can help.

 

[Zzz]

Its a panel breaker, not a receptacle. White pigtail to neutral bus. Neutral wire to breaker neutral lug. There is one 3 wire pvc conduit feed (H,N,G) to the first pool light box where HNG is spliced to light and G is also spliced and connected to brass jbox with brass conduit connecting to niche. A second 4 wire conduit (1 wire not used) exits the jbox with only HNG connected and enters a post mounted pvc splice box where HNG are spliced exit into a 3 wire pvc conduit which lead to second pool light where HNG connect to light and G is spliced and connected to brass jbox and niche conduit.

What I cant comprehend is with only the far light connected, I am sending power through all of the buried conduit and a current imbalance should trip GFI. I then connect my brand new light which should have zero current imbalance about midpoint in the circuit and "click" goes the GFI. When I disconnect far light and leave near light connected the GFI allows me to reset it and near light stays on.

The strange thing is tonight I was able to have both lights on simultaneously for about 15 minutes before tripping GFI. I picked up new GFI breaker and will swap out tomorrow and see what happens.

 

[danpik]

What kind of wire is in the conduit? Idealy it should be THWN rated wire. I have seen where people have pulled regular romex wire into the conduit. It is not rated for that and will start to break down over time.

 

[Zzz]

What kind of wire is in the conduit? Idealy it should be THWN rated wire. I have seen where people have pulled regular romex wire into the conduit. It is not rated for that and will start to break down over time.

Call me another one of those people. When I bought the house, it needed a lot of work inside and out due to previous owner neglect. A tree planted near the first light box needed to be removed and the roots had intertwined with the conduits. I was only able to salvage the run from the panel to the first light box. I had to cut back the brass niche pipe, rethread it, and bend it into place without any damage to light wire. The exiting pvc conduit also needed to be cut back and reformed however that wire was shredded and too short to make a connection. my electrician was doing work in the house and had a ton of romex on site so I asked him for a piece so I can pull through the repaired conduit. I know romex is not for direct burial but I didn't think it would be a problem in a buried conduit.
I pulled the romex about 7 years ago. it was the type you find at the Depot, 12/3 with un-insulated ground inside yellow jacket.

I'm guessing now that swapping the gfi wont do a thing and I will have to pull some new wire through the conduit.

 

[danpik]

What kind of wire is in the conduit? Idealy it should be THWN rated wire. I have seen where people have pulled regular romex wire into the conduit. It is not rated for that and will start to break down over time.

I know romex is not for direct burial but I didn't think it would be a problem in a buried conduit.

correct, it is not rated for direct burrial. However, conduit is not clasified as water tight and can/will leak over time. Don't feel too bad about it, I know I am on borrowed time with a conduit in my yard. The previous owner decided to run power to a shed in the back yard. I am 101% certain he pulled romex thru it as well. I have it on my list to fix, just have not gotten to it.

I well be willing to bet that this is where your problem lies. A simple test would be to run a test line out to bypass that stretch of wire and see if the problem goes away. If so, get the appropriate lengths of THWN wire and replace the romex (you should anyway)

Best of luck to you

 

[Zzz]

Well, I swapped the GFI breaker to see what happens and both lights are on for over 3 hours, so it looks like it was the breaker after all. Nevertheless, I bought some THHN/THWN to replace the romex as well this weekend. Thank you for the responses.