Victron MultiPlus II Jumping Input Line 1 to Line 2


New Member
Apr 9, 2020
Our 2005 Monaco Knight has a 50amp system with a Magnum ME2012 inverter/charger and 4 200ah 6v deep cycle batteries. We are replacing it with a Victron MultiPlus-II hybrid inverter/charger and 4 208ah SOK2 lithium batteries.

Problem -- We have the expected 4-line 50amp shore power cable going to the transfer switch, but the line in to the Magnum inverter from the transfer switch only has one leg. They installed a jumper in the inverter Line In from line 1 to line 2 to make both legs hot.

So, instead of 2 120v hot lines coming in, it is just one hot line jumped.

The output from the Magnum inverter is the expected 4-line to the breaker panel.

Question -- Is it common to have 3-wires coming into a 50amp inverter and jumping line 1 to line 2 a common practice?

Question -- Can I use this same line in jumper with the new Victron inverter?

Thanks in advance,

Mike and Deb Fry
2005 Monaco Knight 38PDQ and 2015 Honda CRV


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Happy Breffast!
Oct 26, 2021
That seems odd.

When you power a 50A RV from a 30A supply, L1 and L2 are jumpered in the 30A to 50A adapter, thus L1 and L2 are the same. 0V to each other, but both are 120V to Neutral, so both legs of the AC panel work.

Do you have the manual for the Magnum? I suspect that it makes a decision based on the voltage between input L1 and L2 If 0V, it outputs the same way. If 120V, it outputs 120/240VAC split phase. This way it will function whether powered by 30A or 50A. If it were wired solely for 50A, when you plugged into 30A, only L1 would work out of the Magnum.

It's all probably moot. Hopefully, you got the MP II with the 2x120V output option where it's smart enough to:

Provide 120VAC to both legs when on 30A power.
Provide 120VAC on L1 and pass through shore power to power L2.


New Member
Jan 29, 2022
Since you have a 50A system, why not wire your Multiplus II between your xfer switch and breaker panel like so . . .