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Old 12-15-2011, 03:39 PM
irrig8r irrig8r is offline
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Troubleshooting Questions

I have a customer for whom I installed four Kichler 15732 LED uplights
in his yard August 2010.

He is happy with the lights except that (coincidentally I think), his
GFI trips intermittently.

I checked the system for shorts and couldn't find any. It's a 10 year
old Unique transformer with a fuse, and the fuse does not blow. It's
just the GFI tripping.

I concluded that the had to be either the GFI itself, the line voltage
side of the transformer, or maybe some other device on the same
circuit with a big power demand turning on at the same times as the
lights.

I think what I am going to do is take a spare transformer over and
temporarily replace his (I have a Vista MT on hand I think.)

What would you do? What about the notion of something else on the
circuit that turns on at night? He doesn't seem to know what else is on it.
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Old 12-15-2011, 03:55 PM
irrig8r irrig8r is offline
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Correction: I was *able to* sort them out only by....

One more thing I should add: The new fixtures were on a new cable run, #12/2 and only Ace connectors used on that run.
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Last edited by irrig8r; 12-15-2011 at 04:03 PM.
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Old 12-15-2011, 04:06 PM
Richie@ Richie@ is offline
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Does the circuit breaker in the house electrical panel also trip , if not then it is more than likely related to the GFCI.

It could be moisture or loose connections on the GFCI or within the transformer , also if the GFCI doesn't have whats called an In use device cover I would put one of those on , you can get one at home depot for around $ 9 just ask for an in use bubble cover for a GFCI.
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Old 12-15-2011, 05:55 PM
AOLP AOLP is offline
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Quote:
Originally Posted by irrig8r View Post
I have a customer for whom I installed four Kichler 15732 LED uplights
in his yard August 2010.

He is happy with the lights except that (coincidentally I think), his
GFI trips intermittently.

I checked the system for shorts and couldn't find any. It's a 10 year
old Unique transformer with a fuse, and the fuse does not blow. It's
just the GFI tripping.

I concluded that the had to be either the GFI itself, the line voltage
side of the transformer, or maybe some other device on the same
circuit with a big power demand turning on at the same times as the
lights.

I think what I am going to do is take a spare transformer over and
temporarily replace his (I have a Vista MT on hand I think.)

What would you do? What about the notion of something else on the
circuit that turns on at night? He doesn't seem to know what else is on it.
first off, I am going to guess u have an in use cover in place. why a ten year old unique transformer? Was it there before and u added to it? did u install it new and its been in your shop for ten years? Answer this question and we'll trouble shoot on.
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Old 12-15-2011, 06:01 PM
steveparrott steveparrott is online now
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Nearly all cases like this are caused by problems with the GFI itself - usually moisture penetration. It only takes a thin coating of moisture on the plastic at the plug end (between hot or neutral blade and ground pin) to create enough current differential to trip the GFI. Drying the plug and the face of the outlet and having a good in-use cover could solve the problem from this cause.

Such moisture problems often arise with very wet weather or high humidity combined with cool nights.

The second most likely cause is a faulty GFI - they sometimes need to be replaced.

A transformer problem is possible but unlikely - there would need to be current flowing from neutral or hot to ground. Only possible if a wire has come loose and is contacting the cabinet or an energized conductor. (It is a very old transformer!) If this is the problem - be very careful - a 120-v energized cabinet is bad news.

A short circuit in a fixture is highly unlikely to trip a GFCI since both the hot and neutral secondaries are isolated from hot and neutral on the primary. The secondary neutral, on the other hand, is connected to the ground and shared with the primary ground. So, in a scenario where a short has occurred in a fixture, there may be current flowing to ground, but I don't think the GFCI would trip - it should still see a balance between the primary neutral and hot - since those are not connected to the secondary. (I could be wrong about this.)
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Old 12-15-2011, 08:03 PM
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emby emby is offline
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GFCI (Ground Fault Circuit Interruptor)

A GFCI receptacle is designed to prevent electrical shock. This device constantly monitors the current flow in the hot and neutral conductors.

The current in the hot and neutral conductors should match. If the current flow doesn't match, the device disconnects itself and any receptacles it protects from the electrical source.

Because the device does not actually check the ground current, it can be installed without a ground wire. A GFCI wired in this manner, or any receptacles protected by it, is required to be marked "NO EQUIPMENT GROUND" and is an allowable method of changing two-wire ungrounded receptacles to three-wire grounding receptacles.

Change the GFCI first, then if it still is tripping inspect the cord on the transformer really well for bite marks or damage.

Ken
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Old 12-15-2011, 09:01 PM
RLI Electric RLI Electric is offline
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It used to be a GFI had a shelf life of 6 to 7 years. That is of course a generalization. It is highly likely that if the system is 10 years old that the gfi can be that old or older. I concur with everyone, change the gfi.
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Old 12-15-2011, 10:42 PM
Steve Atkinson Steve Atkinson is offline
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Hi Gregg,

Today I hosted a workshop with Shawn Knudson, the Vista rep in Oregon, and during the discussion, this very topic came up. He said electricians will always blame the GFCI but it may be that the transformer is creating such a large inrush of current that the GFCI naturally trips off.

His recommendation is to try running a temporary extension cord to the transformer from a receptacle and circuit that is farther away from the transformer. If that circuit breaker trips off when the transformer activates, it's a safe bet that the transformer is suspect. If not, it may be the GFCI is weak. He also suggested that one should use a, I believe he said, a MAC Breaker. A heavy-duty product that you will not find at HD or Lowes, so may have to go to an electrical supply store.

Hope this helps.
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Old 12-15-2011, 11:14 PM
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The Lighting Geek The Lighting Geek is offline
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It has been my experience that the GFCI is bad. I would replace it with a new bubble cover and 90% of the time problem solved.

Is the transformer fully loaded? Usually I don't have in rush issues unless it is close to max. I have had issues if the line between the GFCI and the breaker is short, less than 20' or so.

If you have a bad LED, or a short, it would show up in your amp probe reading of the home runs.
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Old 12-16-2011, 08:52 AM
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Lite4 Lite4 is online now
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I have had some inrush issues in the past (Trans within 10 of the panel by wire distance). I added a 100' loop of UF and buried it (problem solved).
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