What DC fuse and battery cable does a MultiPlus-II 12/3000 2x120V need?

Answered by RV Parts Giant · Upland, CA · October 7, 2026

Short answer: Victron's manual for the MultiPlus-II 2x120V specifies a 400 A DC fuse for the 12/3000/120 and two positive plus two negative cables of AWG 1/0 for runs up to 5 m, or AWG 2/0 for 5 to 10 m, on a 400 to 1200 Ah bank. On the AC side it wants a 50 A breaker and AWG 6 on the input, with AC-out-1 protected at no more than 75 A.

The MultiPlus-II 2x120V manual puts the figures in one table, and they are not the same as the older MultiPlus 12/3000, so do not copy a build from a thread about that unit.

Victron's table for the 2x120V models

Model	Battery bank	DC fuse	Per terminal, 0 to 5 m	Per terminal, 5 to 10 m
12/3000/120	400 to 1200 Ah	400 A	2x AWG 1/0	2x AWG 2/0
12/4k/160	400 to 1200 Ah	600 A	2x AWG 2/0	2x AWG 4/0
24/3000/70	200 to 700 Ah	300 A	AWG 1/0	2x AWG 1/0

"2x" means two positive and two negative cables, which is why the 12 V units have two pairs of M8 studs. Victron also lists the matching lugs: Molex 19221-0240 for AWG 1/0 and 19221-0243 for AWG 2/0. Torque the M8 nuts to 12 Nm with an insulated socket, connector first, then flat washer, lock washer, nut. Cable must be copper rated 90 °C, and the manual says not to run battery cables inside a closed conduit.

The run length is the distance from battery to inverter, with the table already written per cable, so a 4 m cable run falls in the first column.

Which 400 A fuse

The ceramic MEGA-fuse comes in 400 A and sits in a Lynx Distributor position or a single holder. On a lithium bank, read our answer on Class-T versus ANL and MEGA fuses first: the fuse nearest the battery also has to interrupt the bank's short-circuit current, and the Lynx Class-T Power In is the Victron way to put a Class-T there.

The AC side, which forum threads usually skip

Terminal	Rated current	Breaker or fuse	Minimum wire
AC-in	50 A	50 A or less	AWG 6
AC-out-1	75 A	up to 75 A	AWG 6
AC-out-2	50 A	50 A	AWG 6

AC-out-1 is rated above the input because PowerAssist can add 25 A of battery power to the 50 A coming in. Victron asks for a ground-fault breaker in series with that output and names Blue Sea's 309X and 310X GFCI breakers. If your pedestal or generator is rated below 50 A, the input breaker comes down to match. The terminals are spring-loaded and take a 2.5 mm blade tool; strip 18 mm.

Two mistakes the manual warns about

Every installation needs a way to disconnect both the AC and the DC circuits. Breakers can serve as disconnects; if you use fuses, you need separate disconnect switches between the source and the fuses. And the unit is not to be connected to a vehicle's electrical system directly: it belongs on its own house bank with the fusing above.

We stock the MultiPlus-II in the 2x120V variants, the fuses and the Lynx parts, shipped from Upland, California. Send us the bank size and cable run and we will check the sizing before you order.