Neil avatar image
Neil asked

Multiplus-II 230v 12/3000/120 - components to use on AC-In, and AC-Outs

I'm hoping the collective mind can help me here.

I've just purchased a Mutliplus-II 12/3000/120, the 230v version as I'm UK based, for my campervan. I think I'm clued up and understanding the 12v side of things, but the AC side of things has got me all confused. Rest assured that I will be getting my system signed-off by a qualified electrician before using it, but I'm hoping to save some money by wiring it all myself so I need to order all of the consumer units, RCDs, MCBs, RCBOs and/or RCCBs but there seems to be very little on the web (unless I'm missing something!) that tells me exactly what's needed, and/or what I do read is conflicted on the next webpage that I read.

Here's what I'll have in my system...

  • Mutliplus-II 12/3000/120 - 230v
  • Digital Multi Control 200/200A GX
  • 3000kw inverter generator (max 13a output)
  • shore connection

Here's what I think I need to purchase...

  • AC-In
    • RCD (32 Amp, Type A) - for shore power input
    • RCD (32 Amp, Type A) - for generator input
    • both above will feed a 2-way changeover switch
    • MCB (32 Amp, Curve C) - Multiplus
    • MCB (16 Amp, Curve C) - one socket

  • AC-Out 1 (inverter and gen/shore passthrough, max 45 Amps)
    • RCD (63 Amp, Type A)
    • MCB (16 Amp, Curve C) - passenger's side sockets
    • MCB (16 Amp, Curve C) - driver's side sockets
    • MCB (16 Amp, Curve C) - front sockets

  • AC-Out 2 (gen/shore supply only, max 32 Amps)
    • RCD (32 Amp, Type A)
    • MCB (16 Amp, Curve C) - hot water heater
    • MCB (16 Amp, Curve C) - vehicle battery charger
    • MCB (16 Amp, Curve C) - TBC

Have I understood correctly? If not, please can someone tell me what's wrong and what I should order instead?

In case it helps in any way, here's a picture of my wiring diagram (yes, I know, I have too much time on my hands!) - if you open it in a new window you will be able to zoom in.


Thanks in advance!

Multiplus-IIwiringwiring diagramcampervan
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2 Answers
sharpener avatar image
sharpener answered ·

Fast work! Yes they look OK to me. AC1-Out would be better as a 50A RCD if you can find one.

A single common earth star point or failing that a tree structure is preferred for two reasons:

  1. it avoids loops which can be problematic as they can have induced circulating currents or cause hum on audio installations (my background)
  2. avoids the problem of removing one item for maintenance then mistakenly disconnecting the earth to other live equipment which can occur if earth is daisy-chained from one item to the next.
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Neil avatar image Neil commented ·
Thanks Sharpener. I can't find a 50a RCD anywhere so I guess a 63a one will have to do. With regards to the earthing point, as mentioned in my last reply there's a good chance that all devices will be earthed to the same point so that should be ok, hopefully :-).
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sharpener avatar image
sharpener answered ·

Choice of mains accessories seems mostly OK. If the battery charger is fixed equipment then it should perhaps have a spur box like the water heater.

My main criticism would be your colour conventions. AC mains wiring should be shown as brown (live) blue (neutral) and green (protective earth/ground). Your terminology showing the green wires as a Neutral bus is not correct, it is the black wires in your diagram that are neutral (not Negative). All this may massively confuse anyone else who works on the vehicle now or later.

You do not show the full earthing arrangements. Bringing it all back to a star point at or near the inverter as you show is certainly desirable. Whether and where you earth the generator and/or have a separate ground spike I will leave to others to advise (!)

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Neil avatar image Neil commented ·

Thanks Sharperner, I've corrected my colour/naming conventions for AC system. The battery charger is not going to be a permanent fixture, hence why I put it on a socket rather than spur.

With regards to the earthing arrangements; from my understanding of the Multiplus manual, and Victron's system schematics, earthing the Multiplus to the chassis is sufficient to ensure the correct operation of the relevant RCDs. For convenience I have not connected all of the chassis connections to one point but they are very likely to all be connected the same spot on the chassis anyway, but does that really matter? The generator does have an earthing point so I shall connect that to the chassis too (updated in schematic below).

Are you able to confirm if I have used the correct RCDs and MCBs, and that I've rated them correctly?


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