Multiplus-II Fuse/Wire Size Conflict?

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jm0278 asked Mar 20, '22

Multiplus-II Fuse/Wire Size Conflict?

Hello,

I have a Multiplus-II 12/3000 2x120 and a Lynx Distributor on order and am trying to finalize my wiring configuration. The manual for the Multiplus-II calls for two AWG 1/0 battery cables. But it also calls for a 400 amp fuse! According to my research, an individual 1/0 cable is only rated for 350 amps maximum so a 400 amp fuse on each 1/0 cable would not be adequate. Am I missing something?

I'm thinking of using a single 400 amp fuse in the Lynx Distributor with 4/0 wire running to a Victron On/Off switch, then somehow getting the two 1/0 gauge wires connected between the output side of the switch and the Multiplus-II. Suggestions?

Thanks.

Jim

Multiplus-II wiring fuses

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Answer 1 · 2022-03-20T18:07:32Z

Kevin Windrem answered · Mar 20, 2022 at 06:07 PM

The fuse size is for total current, so if you run two separate wires, you'd need a fuse of half the rated size in each wire. So come off two fused outputs of the distributer with 1/0 wires and 200 amp fuses for each. Make sure the wires are equal length in order to balance the currents.

Remember, at these currents, every connection is a resistor. That is, even low resistance connections will exhibit a voltage drop based on the connection's resistance.

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Answer 2 · 2022-03-20T18:07:56Z

wkirby answered · Mar 20, 2022 at 06:07 PM

The 400A fuse would be rated for the run of two 1/0 cables together. You would not be providing a 400A fuse for each individual 1/0 cable.

You can run a single 4/0 cable to your diconnect switch and then two 1/0 cables out of it on towards your MultiPlus. The 400A fuse would be fine for the 4/0 cable and also the two 1/0 cables as a pair.
Alternatively, take a 4/0 cable from the switch to the cable if that's easier.

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