Auto changeover relay for inverter

[Techno]

You cannot have both EHU and inverter connected to the load at the same time, the relay will brake before make so it would switch supplies but with a very short break in power supply when the EHU powered the relay.

Theory and practice are very different. Don't do it.

 

[Zigisla]

I have arrived at a site with the inverter on and the sky box still connected, then plugged into EHU. Nothing happened and sky box and inverter all OK, but this was an oversight rather than what I do normally. I have now added "Inverter - Ensure Switched Off" to my ever increasing Pre-Departure list.

 

[JJ]

Doesn't look like a proper installation to me...

No wires twisted together, no electrical tape wrapped around anything, no spare nails lying around to use as fuses... where are the chocolate box connections?

Obviously done by a novice...

JJ

 

[Steve]

This has been asked before but in a different way but Just a what if, but what if the site hook up went off, so you switch to inverter then the site hook up comes back on could this be a problem? Maybe best to remove hook up? All so is this for a dedicated socket or the ring main?

 

[Techno]

It's fine as long as there isn't a heavy load on the inverter
Just being turned on should not have any effect
Vans don't have ring mains sockets will be on one or more radials

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[tonyidle]

An alternative @Techno would be to power the relay from the inverter output. It would hold in the inverter out position until the inverter was switched off at which point it would allow mains to take over. The disadvantage of this arrangement would be continuing using the inverter if you forgot the hook-up was in place. No possible chance of damage though.

 

[Bart]

@Techno thanks for sharing this with us, got mine wired up tonight on 2 out of 3 of my sockets ( not bothered about the 3rd as its beside the TV , but the TV is 12v and runs from said cigarette point beside the A/C socket. )
just one thing i wanted to check with you , when i turn on the inverter no power goes to the sockets untill i press the button's on the RCD's , is not an issue as ill have the inverter on most of the time, just drawing power when needed., i just wanted to make sure that was normal / safe ?

 

[Bart]

I have now added "Inverter - Ensure Switched Off" to my ever increasing Pre-Departure list.

This is me,, ill need to go buy out the local papermill if my list gets much bigger....

 

[Techno]

That should not be necessary so I'll only give you 8 out of 10 for effort.

 

[Bart]

this is the RCD's ,, they are connected as follows : inverter plug >> rcd >>> relay

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[Techno]

You should only need to switch on the RCDs once

 

[Bart]

yip , that is what i meant sorry , once every time i initially turn on the inverter , say after disconnecting the EHU from the home garage, once i have pressed the buttons on the two rcd's all is 100% , untill next time i turn OFF the inverter, i take it it will draw no power from the batteries when its sitting idle ?

 

[Bart]

and ifs thats all normal then can i get a 10/10

 

[Derbyshire wanderer]

yip , that is what i meant sorry , once every time i initially turn on the inverter , say after disconnecting the EHU from the home garage, once i have pressed the buttons on the two rcd's all is 100% , untill next time i turn OFF the inverter, i take it it will draw no power from the batteries when its sitting idle ?

Some RCD's do not need resetting every time. I have 2 at home that drop out with a power cut but those for the MH stay in unless they detect a fault or try the test button.

 

[Reallyretired]

I am about to fit my second attempt at an in line rcd for the inverter. The first was the wrong type (non latching) which meant it had to be reset every time the inverter power was switched off. As the RCD is in an outside locker this was not very convenient. I have since sourced an in-line latching RCD but havent got round to fitting it yet.

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[EuroTrotters]

I have converted from the contactor version of Clive mott that I did three installation of, to the relay version of Techno's here. Albeit I have installed in a different way.

Thanks Techno

 

[Silver-Fox]

Wow that was some reading

I think ill leave it a day or two to get my head around this

Then start to order stuff.
What size flex are people using for the relay jobbie

Ta

 

[EssexBoy]

Hi Andy @Techno
Hoping you can help me please, I think I have a problem with an incompatible Consumer Unit/Fusebox/RDC in my van

I built your autochangeover & installed it without any real problems (thank you), but my issue is that I only have one live socket when on inverter (the one i "broke-into" as the power-out in the instructions). They all work on EHU by the way

I suspect that this is because I have a CBE fusebox that incorporates an RDC as per the pics
Outside

Inside:

I suspect that the electronics in the base of the unit are stopping the distribution of the inverter power to the sockets? If so, I guess I would need to swap out the unit for something that will work? Any suggestions gratefully received

Thank you

Steve

 

[eddie]

The problem will be that your 13 amp sockets are not on a seperate "ring main" as such (I know that you can't have a ring main in a motorhome that is powered by an extension lead (hook up)

You will need to identify which of the plugs on the bottom of your consumer unit supply the sockets and what else they do as well.

Sometimes a single supply from the consumer unit will supply a couple of 13 amp sockets and the mains charger for example in which case it is easier time wise to re-wire the charger

Please ensure that the motorhome is unplugged before messing around. A 13 amp socket with the Neg and Pos joined together with a little piece of fuse wire (we use solder wire) makes identifying 13 amp sockets easy when using an audible circuit tester, with the added safety margin that if you forget and plug the mains back in with your modified circuit tester plugged in, no real harm is done

 

[Techno]

Your circuits are all individually connected to the common rail at the bottom and all protected by what appears to be a 13amp RCBO.
You have likely got two separate cables (radials) to each of your sockets or one to van left side and other to van right side.

The 13 amp protection also means you cannot draw the full 16amps from a hook up continuously

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[Techno]

So assuming you have one radial working via the changeover? you need to find which flex is feeding the other sockets and unplug it from the common rail. Route the cable to your relay and double it up on the "out to sockets"
I would say in your picture that the one and only PVC flex is the charger supply, so your are left with three rubber flexes not counting the feed on extreme left.

They use separate radials for sockets purely for ease of wiring and convenience not because of loading

 

[EssexBoy]

The problem will be that your 13 amp sockets are not on a seperate "ring main" as such (I know that you can't have a ring main in a motorhome that is powered by an extension lead (hook up)

You will need to identify which of the plugs on the bottom of your consumer unit supply the sockets and what else they do as well.

Sometimes a single supply from the consumer unit will supply a couple of 13 amp sockets and the mains charger for example in which case it is easier time wise to re-wire the charger

Please ensure that the motorhome is unplugged before messing around. A 13 amp socket with the Neg and Pos joined together with a little piece of fuse wire (we use solder wire) makes identifying 13 amp sockets easy when using an audible circuit tester, with the added safety margin that if you forget and plug the mains back in with your modified circuit tester plugged in, no real harm is done

Your circuits are all individually connected to the common rail at the bottom and all protected by what appears to be a 13amp RCBO.
You have likely got two separate cables (radials) to each of your sockets or one to van left side and other to van right side.

The 13 amp protection also means you cannot draw the full 16amps from a hook up continuously

So assuming you have one radial working via the changeover? you need to find which flex is feeding the other sockets and unplug it from the common rail. Route the cable to your relay and double it up on the "out to sockets"
I would say in your picture that the one and only PVC flex is the charger supply, so your are left with three rubber flexes not counting the feed on extreme left.

They use separate radials for sockets purely for ease of wiring and convenience not because of loading

Ahhh... Thanks Gents...
The mists have cleared... I was overthinking it again...
The circuits are radial, so looks like I've got a bit of detective work to do tonight

Thanks again...