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Wiring a transfer switch - Trailer with an AC breaker box

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  • Wiring a transfer switch - Trailer with an AC breaker box

    It has been a while since I've posted on here. I wasn't sure where else to ask this question, so I hope it's okay to ask here.

    I recently bought a trailer that had been used by an electrician at jobsites, and has a breaker box. They had removed the wiring that feed the breaker box prior to sale.

    I have a few solar panels that I'll be mounting to the roof, and already have a functioning solar system (battery, charge controller, inverter) that I've been tinkering with as a hobby for a few years (will be using new batteries for this application).

    The breaker box needs 2 120V AC connections (preferably opposite phases) to activate all the circuits.
    I also have a generator that can output 240V AC.

    See the diagram below for how I plan to set it up. I have a few questions I'd like to settle before attempting any wiring. I'm trying to provide lots of background info.Diagram - Wiring.png

    I also will be using two manual power transfer boxes (see

    My questions:

    What do I connect the ground coming from the generator to?
    Can I split the neutral connection from the generator through the two power transfer switches to carry the neutral through?
    The 120V from the solar will also have a ground wire, What do I connect it to?
    Do I need to carry the neutral through to the breaker box?

    Is there anything I'm missing in this? I'm trying to do my homework before I embark on installing anything.

    Thank you!

    Attached Files

  • #2
    Do you have a 240V split phase solar inverter that you will feed the box with ?

    I advise against trying to "cheap out" and use 120VAC wired to both L1 & L2 of the panel. It seems like it may work, but the panel & trailer wiring neutral is designed to cope with half the amps, because it's a 240V design. If you use a auto-transformer to create true 240V split phase, it would be fine. Something like a PSX-240
    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A



    • #3
      I appreciate your response. I was thinking that two inputs of the same phase 120V AC would work, as it would only be lights and maybe some cell phone chargers on the solar, but didn't consider the tolerance of the neutral in the panel. I'll have to check that out. I was unaware of the issues with running the same phase on both the L1 and L2 of the panel. Would it be okay to just use one of the leads into the panel from the solar? This would still power everything I would want (mainly lights at night).

      I still wonder where I would want to connect the ground wires from both the generator and the solar.

      Thanks again.


      • #4
        Xantrex automatic transfer switch solved the problem of keeping a none critical 120v AC load continuously powered for convenience. My system now fails-over to an alternate AC power source when the DC input from the solar array battery bank is so weak to cause the inverter to shutdown. The automatic transfer switch is well constructed and has operated flawlessly. It would have been nice if the device had the secondary plug and output receptical included and installed, but I was aware beforehand that I would need to provide my own plug and receptical when ordering. this device.