question

mattestlea avatar image
mattestlea asked

Transfer Switch for Victron Multiplus 12/3000

Hi all,

I'm currently planning out my wiring for a van conversion and looking at getting a Multiplus 12/3000. As a newbie to wiring and someone who's British tendencies tend to make me quite modest, I'm damn proud at how confident I feel about electrics after the amount of research I've done. (Main thanks to the author of Wiring Unlimited.)

That being said, I can't for the life of me figure out how this transfer switch relates to van conversions. Most of the info I've read online seems to relate to fitting into buildings rather than vans. But even then I'm struggling to understand it as there seems to be a variety of uses.

What's more, after zooming in on other peoples videos and guides I can see there's roughly a 50/50 split between those who use the 50a and those who use the 16a. But frustratingly, they mention all the reasons and specs as to why they purchased the unit, other than talk about the transfer switch rating.

victron.png

Is anyone able to explain in simple terms what a transfer switch is and what it will do for me in relation to a van conversion? Main things I'm worried about are blowing shore feeds when hooked up at campsites, or over/underpowering my systems.

That being said, my main source of power will be the 525w solar array I plan on installing as well as the Orion DC-DC charger feeding into 2x200ah Victron Lithium Smart Batteries.

Also while I'm here, in Wiring Unlimited it mentions creating a bypass switch for the inverter. (Section 6.6)

bypass.png

I can understand the reasons behind this. But firstly, it looks like a lot of people doing van conversions don't seem to bother with it. Secondly, how do you actually go about wiring this to connect to a comsumer unit?

Cheers!

wiringshorepowerswitch
victron.png (18.7 KiB)
bypass.png (30.3 KiB)
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1 Answer
gyzko avatar image
gyzko answered ·

The bypass transfer switch is a manual transfer switch that provides you the option to repair/replace/service a broken multiplus without powering off the load. For van conversion project, this is probably overkill. This is why people do not spend money on that.

The wiring of such unit is typically provided in the user manual of this piece of equipment. This is typically a box with 2x AC IN and 1x AC OUT.

Why 16 vs 50 A? I am not familiar with British standard but in North America, there is not an unlimited choice of breaking capacity. As this is a piece of specialized equipment, there is no such thing as a 17, 18 or 19 A transfert switch. So, if you need 18.5 A capable transfer switch, you need to install a 50 A model. I suppose 16A and 50A are the typical size in Europe (I am just guessing).

If you use your 3000VA to its maximum capacity, the 16A model might be little bit short. Rough estimate is 3000/230 = ~13 A. (Here, I do not take in account the difference between true power and apparent power).

If you plan to use your multiplus at just <50% of its capacity, the 16A is then probably enough. Having said that, in any case, it doesn't hurt to use a manual transfer switch with higher rating. It just cost more and require more space.

Regards,

-François


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