Victron 500VA Multiplus - 240V consumer unit MCB & RCD ratings

[TimA]

I am just about to install a Victron Multiplus 12/500/20 500VA inverter charger under my drivers seat and have been provided with a kit from a supplier that includes 2 consumer units, 1 for the incoming supply between the EHU and the Multiplus, and 1 for the outgoing supply between the Multiplus and 240V sockets in the back of the van.

My question is about the ratings of the MCBs & RCDs pre-installed in the consumer units and would welcome your opinions and advice.

The incoming CU is a 1way unit with 25A RCD and a single 10A MCB. The outgoing CU is a 2way unit with the same RCD, 1x10A MCB and 1x6A MCB. Both CUs are the same type with Gacia double pole MCBs/RCDs.

I was told its ok to use these CUs without changing the MCBs/RCDs but in my limited knowledge its bad practice to have:
1. RCDs of the same rating on the first and second CUs
2. An MCB of a lower rating (10A) in the first CU than the combined MCBs rating (16A) in the second CU

It makes sense to me to keep the MCB and RCD sizes in the second CU for the outgoing circuits but what rating MCB and RCD should I use in the first CU?

Cable size throughout is 2.5mm 3core artic blue.

Thanks!

Edit: peak power output of the inverter is 900W, continuous power output is 430W so maybe the MCBs in the second CU are rated too high in total anyway?

 

[Davidm]

I have a very similar proposed setup so will be interested in answers. I have a 16amp/250V Victron shore power connection which can play a role as well. Is that what you have?

 

[Pauly]

I think your looking at it in terms of a single supply/single circuit which it is and isnt !

Im not familiar your your particular Victron unit but does it have a transfer switch ?

You effectively have 2 circuits one supplying the victron and another (from the victron) supplying the sockets, some of the victron units transfer 230 straight through them but some will rectify it so the input and output are actually separate so consideration needs to be given for each of the two circuits and each one fused/protected appropriately also consider that discrimination and/or selectivity of RCDs may not apply through the device

 

[TimA]

I have a very similar proposed setup so will be interested in answers. I have a 16amp/250V Victron shore power connection which can play a role as well. Is that what you have?

Not sure what Victron unit you mean there. My shore power comes into a consumer unit which then supplies the Multiplus.

The Multiplus is a combined inverter and mains battery charger so when I'm hooked up I get charge to the leisure battery and 240V mains at all three of my sockets. I believe the shore power transfers straight through but I'm not 100% sure. There is no manual transfer switch, the unit senses when shore power is connected and switches the inverter off basically. So, all 3 sockets are either on shore power or on inverter supply.

@Pauly If you're right about the 2 separate circuits on the Multiplus, that answers my concerns about discrimination. Anyone know for sure? I can't find anything online or in Victron manual.

 

[Davidm]

Not sure what Victron unit you mean there. My shore power comes into a consumer unit which then supplies the Multiplus.

The Multiplus is a combined inverter and mains battery charger so when I'm hooked up I get charge to the leisure battery and 240V mains at all three of my sockets. I believe the shore power transfers straight through but I'm not 100% sure. There is no manual transfer switch, the unit senses when shore power is connected and switches the inverter off basically. So, all 3 sockets are either on shore power or on inverter supply.

@Pauly If you're right about the 2 separate circuits on the Multiplus, that answers my concerns about discrimination. Anyone know for sure? I can't find anything online or in Victron manual.

Most campervans have 16amp shore power connections as that is what campsites etc offer. Mostly it is large boats that have larger connections eg 30amp or 50amp.. See https://www.asap-supplies.com/produ...-socket-in-polyamide-16a-250v-vc-shp301603000.

I am planning to have sockets off the consumer unit before the inverter so these sockets will only work when on shore power, I can run more powerful appliances and not use the inverter.

 

[TimA]

I see what you mean about the Victron shore power connection now. I have basically the same but under the bonnet.

The setup with separate 240V circuits for shore power and inverter is what I was going to install until I heard about the Multiplus. Suits my purposes but I guess it may not be for everyone. I like the fact I don't need to worry about a transfer switch or which sockets are live depending on whether I'm on hook up or not.