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WASTATELIVING's avatar
WASTATELIVING
Explorer
Nov 01, 2021

Electrical issue on 50amp service

I've got a new fifth wheel on 50 amp service. Recently we have lost power to all of our outlets and both electric fire places. After checking each plug, checking to ensure no breakers are popped, all fuses are intact, and the source is good this is what I've discovered.

The power supply cord is supplying 120v on both legs. When plugged into the RV our LED light above plugs shows power. At the breaker panel however, the red leg shows 120v and the black leg shows 70v. which matches the voltage I'm getting at the outlets. This is BEFORE it even reaches the breaker. I am assuming that the issue is in the inlet plug on the wall of the RV. Either a loose wire or it just needs to be replaced. I'll be opening it up tomorrow to take a look and replace it.

Any other ideas, something I might be missing?
Thanks
-Dre
  • WASTATELIVING's avatar
    WASTATELIVING
    Explorer
    Nov 01, 2021
    Home. On a subpanel. I've checked the main panel and the sub and haven't found any issues or popped breakers there.
  • way2roll's avatar
    way2roll
    Navigator II
    Nov 01, 2021
    WASTATELIVING wrote:
    Home. On a subpanel. I've checked the main panel and the sub and haven't found any issues or popped breakers there.


    When you say sub panel, what do you mean? The most common method for plugging in at home is a dogbone to plug into a 20 A outlet. Do you have an inverter? Most newer RV's have an inverter that controls the outlets.
  • dougrainer's avatar
    dougrainer
    Nomad
    Nov 01, 2021
    You state Sub panel. Is this something you or an electrician installed JUST to power your RV? The CORRECT voltage on 50 amp is 120 on EACH Leg. THEN there should be 240 volts when testing between each Leg. IF NOT, you do not have a correctly wired 50 amp sub panel. usually that 70 volts means you have miswired the subpanel and do not have the correct Neutral leg connection. We are assuming that you had NO PROBLEM either at the Dealership or at a Campground with 50 amp service. You just have this problem at your home receptacle. Doug

    PS, I have 42 years as a RV tech and one thing I have learned over those years is that even LICENSED ELECTRICIANS, have problems understanding 30 and 50 amp RV plugs.
  • WASTATELIVING's avatar
    WASTATELIVING
    Explorer
    Nov 01, 2021
    Thanks Doug,

    I said home to make it easy. We are staying at a friends home and have been for 2.5 months now. No issues what so ever until just a few nights ago. Which makes me think that its not a problem at the source. I can clarify that on the power cord I've got 120v on EACH leg.
  • WASTATELIVING's avatar
    WASTATELIVING
    Explorer
    Nov 01, 2021
    way2roll wrote:
    WASTATELIVING wrote:
    Home. On a subpanel. I've checked the main panel and the sub and haven't found any issues or popped breakers there.


    When you say sub panel, what do you mean? The most common method for plugging in at home is a dogbone to plug into a 20 A outlet. Do you have an inverter? Most newer RV's have an inverter that controls the outlets.


    By subpanel I mean that the panel we are plugged into is controlled by another breaker on the opposite side of the wall. Not my preference but I did not wire that as we are staying at a friend's place. Its seemingly correctly wired, we've been living in it for 2.5 months now without any issue. I do have an inverter and have had that set so the 120v is passing through it as it should.

    Thanks
  • DrewE's avatar
    DrewE
    Explorer II
    Nov 01, 2021
    I suspect you have an open hot wire, or a very nearly open hot wire, and are measuring the voltage with a high-impedance voltmeter (such as a typical digital multimeter) that is showing you the "phantom" voltage in the wire due to capacitive and/or inductive coupling.

    "Open hot wire" could mean something as simple as a blown fuse or tripped breaker on one leg of the circuit. For breakers, they are supposed to be controlled with a two-pole breaker such that both legs are disconnected when either is overloaded, but it's not beyond the realm of believability that your friend's place is improperly set up with two single pole breakers. For fuses, the legs are independent of each other.
  • vermilye's avatar
    vermilye
    Explorer
    Nov 01, 2021
    Check all the neutral connections. A loose or open neutral can cause different voltages between legs.
  • Cummins12V98's avatar
    Cummins12V98
    Explorer III
    Nov 01, 2021
    Disconnect your RV from shore power and check every single electrical connection from the junction box your RV cord connects to the RV to the panel and every breaker.
  • dougrainer's avatar
    dougrainer
    Nomad
    Nov 01, 2021
    WASTATELIVING wrote:
    Thanks Doug,

    I said home to make it easy. We are staying at a friends home and have been for 2.5 months now. No issues what so ever until just a few nights ago. Which makes me think that its not a problem at the source. I can clarify that on the power cord I've got 120v on EACH leg.


    Measure the voltage across EACH leg. It should be 240 volts. Report back. 2 probe wires. 1 goes into the 1 leg the 2nd goes to the other leg. Voltage you have made. Neutral to each leg or Ground to each leg? Doug

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