Click for Abeking Click for Apollonian Click for Ocean Alexander List Your Boat Click for Nordhavn

Inverter for 240VAC system

Discussion in 'Electronics' started by TahoeJohn, May 4, 2021.

You need to be registered and signed in to view this content.
  1. TahoeJohn

    TahoeJohn Member

    Joined:
    Aug 8, 2020
    Messages:
    138
    Location:
    Tahoe VIsta
    My boat was built in 2001 with an inverter, but it was previously removed (not sure why). I'd like to install a new one.

    The boat is 240VAC/60 Hz, and the 120V loads are roughly divided across both legs. Because of this, I initially assumed that I would need a dual 120V / 240V inverter, but since I'm not finding many options for that, I'm now questioning that assumption.

    For example, Magnum makes a dual 120V output unit, MS4024PAE:
    magnum non-marine.jpg

    However, I don't believe it's marine-rated (no bonding of N and G), as is their single 120V, MS4024, below -- it adds that relay in the center to do the bonding when in inverter mode. This one is also listed under their marine section, while the PAE model is not.
    magnum marine inverter.jpg

    What is the standard approach for powering both 120V legs while meeting ABYC standards? Parallel two 120V inverters?

    Thanks!
  2. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    9,807
    Location:
    Satsuma, FL
  3. TahoeJohn

    TahoeJohn Member

    Joined:
    Aug 8, 2020
    Messages:
    138
    Location:
    Tahoe VIsta
  4. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    9,807
    Location:
    Satsuma, FL
    I do not tie the white and green wires at the inverter.
    Our boats shore power transfer switches to that.
    When on the dock, all is separate and fault current (green wire) goes to the dock to be joined with neutral (white wire) per code.
    If the dock has a power failure, the inverter (UPS) comes on and if any fault current happens, passes to the shore tie per plan.

    When we leave the dock, we switch to the gen-sets.
    Here, the white and green are tied on board and any fault current goes to the water.
    Without the gen-sets running, Green and white are already tied for the inverter.

    BTW, I remember on this Magnum, White is not switched and passes thru.
    Last edited: May 4, 2021
  5. Pascal

    Pascal Senior Member

    Joined:
    Feb 29, 2008
    Messages:
    6,558
    Location:
    Miami, FL
    I m pretty sure that marine inverters must have a relay bonding N and G when in inverter mode. The Magnums i have used before did. I believe it s an ABYC requirement.

    now, yes I shore power goes down and inverter kicks in, they will be bonded as long as the shore power is physically connected. Same if on generator but only as long as the rotary switch is left in generator position otherwise the N will be disconnected
  6. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    13,930
    Location:
    Fort Lauderdale
    Be very careful with the shorepower going down and inverter coming on by itself, if the yacht is un-attended. Also make sure you have a charger to charge the inverter bank in case it goes below 21 volts......inverter will not power on and will not charge it's bank(s). I've managed several yachts where everything went through an inverter, (no bypass) shorepower went down, inverter drained all batteries, inverter wouldn't come on due to batteries being too low, and no way to charge the batteries to get the inverter on.
  7. Pascal

    Pascal Senior Member

    Joined:
    Feb 29, 2008
    Messages:
    6,558
    Location:
    Miami, FL
    All it takes is adjust the low voltage cutout so batteries don’t drop below a set voltage. That’s who I always want my inverter to be powered by a battery bank so that the DC loads still run especially bilge pumps.
  8. TahoeJohn

    TahoeJohn Member

    Joined:
    Aug 8, 2020
    Messages:
    138
    Location:
    Tahoe VIsta
    Thank you all - very helpful. One additional thing: This boat's power selection switches have 5 inputs: SHORE1, SHORE2, GEN1, GEN2, and INVERTER. It sounds like I need to determine what, if anything, these switches do with both Neutral and Ground when switched to INVERTER mode.
  9. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    9,807
    Location:
    Satsuma, FL
    Yes, Sounds like a good starting point before selecting any equipment.
    Also, If the same transfer switch is selecting between shore and gen sets AND IF PROPERLY STRAPPED, then hopefully the inverter would be strapped white to green or easily adaptable.
    Sadly, I have serviced to many boats where green/white where strapped incorrectly when moving from shore to gen-set.
    Seems like a good time to get in vibe with your boat. Have fun checking out under her skirts...

    If you get that Magnum PAE, it is a great unit. Designed for off-grid, it is a work horse. Done VERY well for us.
    Also, the Magnum support folk are great. just a lil slow in getting with you at first, but when the support starts, their on it.
    TahoeJohn likes this.