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brn2romethewest's avatar
brn2romethewest
Explorer
Dec 02, 2014

Open Neutral 30 amp service

I have been running on solar/battery and inverter for about two weeks now with no issues. Last night i plug into 30 amp outlet on park pedestal and the tv would not run. I use the plug tester to check status. The plug tester in trailer receptacles showed open neutral and the the volt meter showed 60-88 volts. (I dislike plugging into park power)

Plug tester on the 20 amp GFCI outlet on park pedestal showed good so i plugged into it using adapter on rv cord. All is good until i turn on 20 amp breaker in the RV electrical panel box for converter and then after 5 minutes i get open neutral and 60-80 volts.

Wake up in the morning and remove electrical box and check all connections to include the connections on the transfer switch and all grounding bars. All connections are good to include continuity of RV cord. The inverter is still producing good electricity.

RV is 30 amp service as was the park pedestal. Pedestal had 50/30/20 amp outlets on it. I did plug the 50 to 30 amp adapter into 50 amp outlet but still was open neutral and 88-91 volts.

The trailer electricity was fine about two weeks ago when i was connected to 20 amp service at brother's house. There was no issues.

What should i check next? The trailer is back in storage so i will have to go get it out to do more checking. I am hoping it was pedestal issue and not my rolling condo. Any help is appreciated. Thanks,

Greg

9 Replies

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  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Dec 03, 2014
    Worked on park 20 amp, not on 30 or 50, strongly suggests park pedestal.

    Using a 15-30 amp adapter plug in your three light tester DIRECTLY into the park pedestal.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Dec 03, 2014
    Open neutral issue at all outlets of power pedestal (50A 30A 15A) cause open neutral was at pedestal .

    30A & 15A use one hot leg of 50A and same neutral.
  • DrewE's avatar
    DrewE
    Explorer II
    Dec 03, 2014
    I agree, most likely campground pedestal or possibly shore power cord. Be glad you didn't have a 50A connection with loads on both sides of the split phase circuit—you'd have a high voltage on one side and a low voltage on the other and quite possibly some destroyed appliances. On a 30A circuit, you just have no power.

    You could check the shore power cord by disconnecting all power from the RV (turning off the inverter and/or disconnecting the battery) and shorting the neutral to the ground at one of the RV outlets, and then checking the resistance at the plug. It should be essentially a short circuit no matter how you wiggle the wires around. I'm assuming the transfer switch for the inverter would revert to shore power when the battery is disconnected; if it did not, you would have no power if you plugged in with the battery discharged, which seems unhelpful.

    The voltmeter measurement is bogus, and probably due to capacitive or inductive coupling or to very slight leakage, depending on where the voltmeter is measuring its voltage.
  • enblethen's avatar
    enblethen
    Nomad
    Dec 02, 2014
    I believe the problem was most likely in the campground pedestal.
    You could check the system by running the cord to the inside of the rig and verifying continuity to the electrical panel or even all the way to a receptacle that is not fed from inverter.
  • brn2romethewest's avatar
    brn2romethewest
    Explorer
    Dec 02, 2014
    Thank you for the replies. Automatic transfer switch connections have been checked. No on-board generator. One side of the transfer switch comes from 2000 watt PSW inverter, the other side comes from the 30 amp service cord plugged into a generator or park pedestal when needed. The transfer switch feeds the 120 VAC electrical panel. Again, all connections at the transfer switch and 120 VAC panel are tight.

    Could not rule out park pedestal. For testing i used the plug tester with lights and my volt meter. put one probe in the neutral side and one probe in the hot side. I removed the Marinco twist lock female plug end and trimmed wires back and re-attached to cord. The male end is on tight also. Checked for continuity of each (grnd, Hot, Neutral)leg of the 30 amp cord. All is good. Not sure how to check the actual plug ends to see if they are making good connection.

    Did i mention that i dislike plugging into park power? Again, thank you.

    Greg
  • WTD44's avatar
    WTD44
    Explorer
    Dec 02, 2014
    Sounds like a park power problem to me--did you check the outlet at the pedistal?
  • time2roll's avatar
    time2roll
    Nomad
    Dec 02, 2014
    Are you getting low voltage directly on the pedestal or in the RV some place?
    Need to start with the pedestal.
  • enblethen's avatar
    enblethen
    Nomad
    Dec 02, 2014
    Transfer switch? Do you have a genset installed in the trailer?
    You should not be reading any voltage if you are measuring between neutral and the phase conductor if the neutral is truly open.
    What type of measuring device are you using to read and record voltage?
    Common point could be your 30 amp cord body.
  • wolfe10's avatar
    wolfe10
    Explorer
    Dec 02, 2014
    Most likely suspect (assuming not a CG issue) is the ends of the shore power cord. They are exposed to more "action" than other parts of the electrical system.

    If you have an ATS (Automatic Transfer Switch) be sure to check the connections in there as well.

    Other place (least likely) is the connection at the 120 VAC breaker box in your trailer.

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