Mains Wiring/switching Question

[Pete C]

I have just spent a couple of hours helping my neighbour try to sort out some blown electrics on his "new to him" motorhome (not a VW).

It looks like a home built setup, with either a mains hook-up connection or a 3.5kW inverter driving the mains sockets in the vehicle. It appears that it is possible to have both the mains hook-up and the inverter live at the same time, which to me is a big no-no. Anyway, he managed to switch both hook-up and inverter through the mains sockets at the same time, with the resultant bang and burning smell from the inverter. The inside of the inverter is black in several places, so he is looking at getting a replacement, but needs to know how to prevent this happening again by accident.

We don't have an inverter on our T6, so are not familiar with this issue, but can see that it would be a common one for camper vans. So what is the technical solution ? Is there a black box switch that he can buy to prevent this happening ?

I have advised him to go to a proper automotive electrical engineer who has experience in these things. I would sort it myself in my own van, as I know exactly what all the wiring does, but there are too many unknowns for me on this van.

Thanks for your help,

Pete

 

[Dellmassive]

OMG . . . thats Bad! (surely there must have been a mechanical EHU/Inverter transfer switch for the sockets? (obviously not if it went bang!)

normally you would have either "separate" sockets for EHU and for Inverter ( so one ring would be connected to the EHU side, then a totally separate ring connected to the inverter.. that way the two systems are isolated at all times)

or-

you would use an "inverter charger" that is a combined inverter/charger/AC transfer switch....

like the Victron Multiplus over here > Victron Multiplus | Energy Solutions

or-

or the cheaper option- Auto/mechanical EHU/Inverter transfer switch which would only allow the sockets to be connected to either or 240v supply like this > https://www.travelvolts.net/product-page/230-volt-auto-switch



@travelvolts https://www.travelvolts.net/ may be able to advise you better.




bit more info . . . . >

 

[Pete C]

Cheers Dell, that’s useful thanks. I will pass the info on.

He has a manual switch for each power source, the flaw is that it goes bang if both are on !

And with a 3.5kW inverter fed from 450 Ah of 12 volt battery power, I doubt it was a small bang.

Pete

 

[Dellmassive]

Hmm . . . . the idea/design of the transfer switch is to prevent just that from happening . . . .

Sounds like a sub-par inverter install by a third party . . . . the Van probably had the EHU from factory and at a later date the inverter system was fitted . . . . . but without a transfer switch!

 

[Dieseldonkey]

I purchased and fitted the change over relay set up from Travelvolts. As soon as it detects 240v from the mains hook up, it defaults the supply to your consumer unit/distribution board from the mains and isolates the supply from the inverter. So far so good. Not had a problem with it.

 

[Pete C]

I purchased and fitted the change over relay set up from Travelvolts. As soon as it detects 240v from the mains hook up, it defaults the supply to your consumer unit/distribution board from the mains and isolates the supply from the inverter. So far so good. Not had a problem with it.

Thanks - will pass this on to him.

Pete