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Thread: Mystery Problem

  1. #1
    Join Date
    May 2014
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    Mystery Problem

    I ran into a odd issue at my own place.

    One ckt (1pole gfi-ocpd 20A) was working fine for past 2+yrs until recently. The ocpd trips every other day for no good reason that I can tell.

    The ckt runs outside underground all PVC, about 100ft of 12ga. At the end is a outdoor fridge rated 2A that cycles on/off 24x7. Four ceiling fans each rated 0.8A (but stay off, controlled by bluetooth canopy controllers).

    I have local discos (switches) to the fridge and fans. Leave the switches on, goto reset ocpd, and the ocpd will either quickly trip, OR, it stays on for 3-4sec then trips. Here's the very odd part, reset ocpd and immediately try the manual Test button, and get nothing, then eventually ocpd trips off in the 3-4sec range.

    I then turn off the discos, come back to ocpd and reset it, it sticks on ok, and the Test button works ok for 10 consecutive tests.

    I then go turn on the discos, fridge starts to run, no ocpd trip.

    Bad ocpd ??
    Can you explain the odd no-trip when pressing the Test button?

  2. #2
    Join Date
    Aug 2013
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    New York, NY
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    Quote Originally Posted by FionaZuppa View Post
    I ran into a odd issue at my own place.

    One ckt (1pole gfi-ocpd 20A) was working fine for past 2+yrs until recently. The ocpd trips every other day for no good reason that I can tell.

    The ckt runs outside underground all PVC, about 100ft of 12ga. At the end is a outdoor fridge rated 2A that cycles on/off 24x7. Four ceiling fans each rated 0.8A (but stay off, controlled by bluetooth canopy controllers).

    I have local discos (switches) to the fridge and fans. Leave the switches on, goto reset ocpd, and the ocpd will either quickly trip, OR, it stays on for 3-4sec then trips. Here's the very odd part, reset ocpd and immediately try the manual Test button, and get nothing, then eventually ocpd trips off in the 3-4sec range.

    I then turn off the discos, come back to ocpd and reset it, it sticks on ok, and the Test button works ok for 10 consecutive tests.

    I then go turn on the discos, fridge starts to run, no ocpd trip.

    Bad ocpd ??
    Can you explain the odd no-trip when pressing the Test button?
    Story time:
    I had something similar years ago. I had a small compressor on a moving bridge crane that supplied backup compressed air to the crane's disc brakes (big crane). Building air was piped to the crane, and normally the compressor didn't run. However, when maintenance would take building air offline, the compressor would occasionally run. When it did, we got random trips of the circuit powering it. That circuit also powered the PLC that ran the crane, so it took out the controls when the breaker tripped. It was a supremely stupid design, but I digress.

    I eventually traced it to the wiring for the compressor's enclosure cooling fan. It was in a soundproof enclosure so the compressor would be quiet. Someone had routed the cooling fan motor's wires under and around some of the compressor's piping and the hot wire had chaffed... where it wasn't visible without a complete disassembly.

    It had to be a perfect storm; building air offline, compressor running long enough to get warm, and thermostat calling for the cooling air fan to kick on. Only then would it trip the breaker and knock out the controls for the crane. But only sometimes... It took me two days of crawling around the bridge crane, 100ft over the audience in a theater, in the dark, to find that fault.

    Long story short, check the wiring in the fridge. Compressors wiggle and rattle when they run, and you may very well have an intermittent short circuit or N-G fault caused by chaffed wiring. Your ceiling fans may have a similar intermittent fault too; they wiggle and vibrate when they're on too.


    SceneryDriver

  3. #3
    Join Date
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    You have a GFCI circuit breaker protecting this circuit?

    Put a standard CB in its place and a GFCI device at the load end. See which trips.

    Meg the circuit conductors in the PVC. Here, in NE. the possibility of ice in the conduit damaging conductors is real.

    My spouse once suggested I call someone. I opted for raising the question her instead so you’re already a step ahead.
    Tom
    TBLO

  4. #4
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    If pushing the test button does not immediately trip the breaker, the breaker is bad. I am unaware of any GFCI devices that have a delay in tripping when you push that test button.

    Edited to add... What brand is the breaker? If it is a GE, replacing the breaker or swapping it out would have been my very first action... it has been my observation that these things have an incredibly High failure rate over time


    2nd edit... GFCI can fail in a myriad of perplexing ways although delayed trip is a new one by me. Still, I would replace that breaker
    Last edited by JFletcher; 06-14-18 at 08:13 AM.
    Electricians do it until it Hertz!

  5. #5
    Join Date
    Apr 2005
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    Quote Originally Posted by JFletcher View Post
    If pushing the test button does not immediately trip the breaker, the breaker is bad. I am unaware of any GFCI devices that have a delay in tripping when you push that test button.
    I agree if a breaker or receptacle fails the push button test it should be replaced. There may still be other problems with the circuit but the breaker is bad.
    The 95% of people that you can't trust give the other 5% a bad name.

  6. #6
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    May 2014
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    AZ
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    Quote Originally Posted by growler View Post
    I agree if a breaker or receptacle fails the push button test it should be replaced. There may still be other problems with the circuit but the breaker is bad.
    the breaker passes Test when there was no load on the far end, and consistently.

    the odd part is, after doing a reset w/ load 'on' the far end, the Test button did not appear to work, however, the breaker at that exact moment was in some weird state and then would trip off in about 3sec.

    next odd thing is, if the load(s) are disco'd off i can reset the breaker and then turn the loads back on and all seems ok (for now).

    3rd odd thing, was ok for past two years, until now.

    it's a Eaton breaker, i'll swap it out today.

  7. #7
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    Quote Originally Posted by ptonsparky View Post
    Meg the circuit conductors in the PVC. Here, in NE. the possibility of ice in the conduit damaging conductors is real.
    Hoping nobody objects to this digression...

    Pton', do you think UF (either direct-buried or sleeved in PVC) would be more resistant to a NE winter than individual THHN conductors?

  8. #8
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    Quote Originally Posted by Netpog View Post
    Hoping nobody objects to this digression...

    Pton', do you think UF (either direct-buried or sleeved in PVC) would be more resistant to a NE winter than individual THHN conductors?
    Yes.

    I don’t know what the OP’s climate is. Normally AZ says anything but wet and cold, however I just got back from the North Rim, so that theory is blown.
    Tom
    TBLO

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