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Matthew Shea avatar image
Matthew Shea asked

MultiPlus-II 120 AC-out-1 breaker 75 amp?

From the manual;

  • AC-out-1

    The AC output cable can be connected directly to the terminal block ‘AC-out’.

    From left to right: “N” (neutral) , “L2” (phase 2), “PE” (earth) and “L1” (phase 1)

    With its PowerAssist feature the Multi can add up to 3kVA (that is 3000 / 120 = 25A) to the output L1 during periods of peak power requirement. Together with a maximum input current of 50A this means that the output can supply up to 50 + 25 = 75 A. An earth leakage circuit breaker and a fuse or circuit breaker rated to support the expected load must be included in series with the output, and cable cross-section must be sized accordingly. Victron Energy recommends to use the Blue Sea systems GFCI circuit breakersPN. 309X or 310X. The maximum rating of the fuse or circuit breaker is 75A.


so it looks like a 75A GFCI main coming into the panel is needed. I can't seem to find the part numbers listed on Blue Sea's website nor do I see any GFCI breaker listed at 75A. I also am having a hard time finding an alternative source for a breaker with these specs can I get a link to something that would work?


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1 Answer
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randyoo answered ·

I know it's been nearly 2 years, but for future visitors with the same question, here's what I've found:

Where the Victron documentation states "309X" or "310X", they're using the X to indicate a placeholder for a digit. So, for example, Blue Sea Systems has a variety of GFCI breakers with part numbers 3100, 3102100, 3103, 3104, 3106100, 3091, 3092, and 3093. These can be found on page 57 of the 2014 catalog.

Unfortunately, it looks like those breakers only range from 16A to a maximum of 50A. So a 75A GFCI breaker most likely doesn't exist. In my case, with the MultiPlus Compact 2000, the docs state that energy supplied can be up to 67 amps.

From my understanding, the breaker can be undersized (compared to the wire's ampacity), because its purpose is to protect the wire. Therefore, it would be acceptable to use an 80A breaker in your case, so long as the wire ampacity is capable of handling it. (for 80A, it looks like 4AWG or better if using the 75ºC NEC chart)

Meanwhile, it seems for my service panel, Square D Homeline, the GFCI breakers max out at 50A. I'm not aware of a solution that would meet the demands of the Victron documentation, but I have GFCI protection on individual circuits in areas that need it, such as bathrooms, kitchen, outdoors, and garage.

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Related Resources

MultiPlus-II Product page 

MultiPlus-II Manual

Multiplus-II GX Online Manual

MultiPlus-II 230V Datasheet 

VE.Bus Error codes

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