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GFCI on engine power failing

Discussion in 'Electrical Stuff' started by Atalla, Sep 30, 2020.

  1. Atalla

    Atalla Member

    32
    Sep 1, 2020
    2007 Sundancer 38
    Twin Merc 8.1 S Horizon V-Drives
    On my 38DA, there is a GFCI behind the door to the salon. It is a new GFCI outlet, installed earlier this summer after we faced this same issue and thought it was a failing outlet. The issue is that we seem to lose power to this outlet under engine power. On shore power, all is good. We pull short power, power up the engines and it turns out no power there. This also means no power to the outlet under the helm where I plug in my supplemental iPad. If I try to test/reset the GFCI, no joy. Then I get back on shore power and the GFCI resets fine and all is good.

    Thoughts?
     
  2. cod

    cod Active Member GOLD Sponsor

    801
    Nov 25, 2010
    Bonita Springs, Fl.
    2005 500 Sedan Bridge
    Cummins QSM 11's
    The engines do not provide power to 120 volt receptacles. They run on only 12 volts. The only way any 120 volt receptacles or devices will work when not plugged into shore power is if you have a generator or an inverter. Do you have either?
     
    Chris-380 likes this.
  3. Atalla

    Atalla Member

    32
    Sep 1, 2020
    2007 Sundancer 38
    Twin Merc 8.1 S Horizon V-Drives
    Yes, sorry. Both. The issue seems very localized this this one circuit and specifically when the engines are fired up and the generator is not running. The cockpit refrigerator is on this circuit as well and I have a memory of the previous owner telling me that he always had trouble with that refrigerator working. I had zeroed into the old GFCI outlet as the issue with the frig, but now am trying to figure out why that whole circuit is troublesome.
     
  4. Stee6043

    Stee6043 Well-Known Member

    Jun 1, 2015
    West Michigan
    1997 Sundancer 400
    7.4L Gassers
    Sounds to me like an inverter issue. Can you recreate the GFI issue when the inverter is off, generator is running?
     
  5. Atalla

    Atalla Member

    32
    Sep 1, 2020
    2007 Sundancer 38
    Twin Merc 8.1 S Horizon V-Drives
    No. All is good on generator or shore power. It's odd that it is so localized. I will continue to troubleshoot and maybe have somebody take a look at the inverter.
     
  6. GnrlPatton

    GnrlPatton Active Member GOLD Sponsor

    356
    Jul 12, 2010
    Maple Valley, WA
    Current: 1998 370 Express Cruiser
    Sold:1988 230 Weekender
    Twin Cat 3116T
    Sounds like a problem with the grounding loop on that circuit to the inverter. What else is on the circuit besides the fridge and outlet? I'd inspect the hot, neutral and ground on that circuit to see if there's some anomaly with any of them, but likely something with the ground.
     
    Atalla likes this.
  7. cod

    cod Active Member GOLD Sponsor

    801
    Nov 25, 2010
    Bonita Springs, Fl.
    2005 500 Sedan Bridge
    Cummins QSM 11's
    So just to be clear, there are other outlets that work (excluding the refrigerator outlet)? The refrigerator is probably 120 volt and 12 volt, so it will continue to run when disconnected from shore power and the 12 volt breaker is on.
     
  8. Atalla

    Atalla Member

    32
    Sep 1, 2020
    2007 Sundancer 38
    Twin Merc 8.1 S Horizon V-Drives
    Correct. The below deck circuit that leads with a different GFCI is all good. The cockpit has a single circuit served by a GFCI, a second outlet the AC/DC frig is plugged into and then an outlet by the helm which has only really ever been used to plug in a USB device. It is only this circuit presenting this behavior.
     

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