Integrating MultiPlus-II 120/240 2 x 120

DIY
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1

First, thanks for any help you can give me. I have experience with 12 volt and basic 120 volt circuits but not a lot with inverters/chargers.

I have a boat with 50 amp 120/240 volt split phase power. I am installing a MultiPlus-II with four 220 amp hour 6 volt batteries wired in series-parallel. The boat has two outboards that have auxiliary charge leads that I plan on using to charge the inverter bank while running the boat. The boat has an 8 kw Fisher Panda generator wired for 120 volts. The main 120 volt panel in the cabin has circuit breakers/transfer switch that i plan on using the two 120 volt legs from the load side along with the neutral and earth legs to run back over the MultiPlus-II input.

Where I am stuck is where to go with the 120 volt after the MultiPlus-II. I have checked and gone through the example wiring schematics which has helped but I am unsure of what I need as far as circuit protection from the inverter back to the main panel. I don’t know if I need two standard switchable two pole breakers for each 120 volt leg and neutral or something else. I am also unsure of the size of the circuit breakers since the inverter can add up to 25 amps, would that mean going to at least an 80 amp circuit breaker for each leg?

I also am unsure if I need or could possibly use other components to add features to the inverter/charger setup. I have a cerbo gx and a gx touch 50.

Any help you can provide would be greatly appreciated.

Thanks

2

Firstly, if you are unsure as to what you are doing with power circuits, it’s best to get local professional help.

Having said that, I would connect the AC from the generator to the AC input of the multiplus. This circuit should have a double pole circuit breaker of about 40A (8kw/240V, assuming generator is 120-0-120). If you have a shore power connection, then you will need a transfer switch and an isolating transformer in this circuit.

The AC out from the multiplus, also 120-0-120, should then be wired to the main circuit board via another 2 pole breaker, but this should incorporate an ELCB/RCCB as well as over-current. This should also be rated at 40 - 50A.