Troubleshooting Questions

Discussion in 'Landscape Lighting' started by irrig8r, Dec 15, 2011.

  1. irrig8r

    irrig8r LawnSite Platinum Member
    Messages: 4,553

    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

    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.
  2. irrig8r

    irrig8r LawnSite Platinum Member
    Messages: 4,553

    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.
    Last edited: Dec 15, 2011
  3. Richie@

    Richie@ LawnSite Member
    Messages: 187

    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.
  4. AOLP

    AOLP Inactive
    Messages: 158

    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.
  5. steveparrott

    steveparrott LawnSite Bronze Member
    Messages: 1,276

    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.)
  6. emby

    emby LawnSite Senior Member
    from Ontario
    Messages: 380

    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.

  7. RLI Electric

    RLI Electric LawnSite Senior Member
    Messages: 381

    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.
  8. Steve Atkinson

    Steve Atkinson LawnSite Member
    Messages: 94

    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.
  9. The Lighting Geek

    The Lighting Geek LawnSite Senior Member
    Messages: 886

    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.
  10. Lite4

    Lite4 LawnSite Gold Member
    Messages: 3,187

    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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