Inverter earthing

[xsilvergs]

Inverter Earthing:

Having just fitted my Victron 12/500 Phoenix inverter and tested it, there was just one thing that I needed to sort. Using my trusty plug-top Socket Tester it always showed an earth fault, and so it should as the earth configuration from the inverter does not resemble our UK domestic supply. In the UK Neutral and Earth are similar both being connected to earth back at the substation. The Victron inverter is delivered with the 'UK 3 pin socket' the earth is floating (sort of) hence the Socket Tester showing a fault.

As delivered, Victron probably expect you use their inverter with Class 2, Double Insulated appliances so the earth pin is redundant.

Put the inverter in a motorhome and plug in a fridge, microwave, toaster which are Class 1 appliances and not be Double Insulated, now what?!

The Victron instructions below give the option to ground the Neutral by moving the link as shown. This clears the Earth Fault condition on the Socket Tester.

Without the Earth and Neutral lines being connected together will your van RCD work in the event of a fault (if using the vans 13 Amp sockets)? Fried wife my be hard to explain!

The inverters ground terminal can be connected to the vehicle chassis ground: But should it? Victron also say "the chassis must be connected to a reliable ground".

What consideration do other inverter users give when using their inverter and does it meet with Local Regulations?

Now, don't ask me, I'm a simple electronics engineer (retired) and these days consider anything over 3v3 highly dangerous.

 

[SquirrellCook]

There is a discussion about this with Dave and the multiplus.
If I remember correctly you have two choices.
1. leave it floating and you have two live wires relative to ground and each other.
If you have a fault to the appliances case, you still shouldn't have a shock to ground.
2. Connect up the earth wire and use the inverter though an RCD. This should give you a protected circuit. Dave was going try and prove it, I think.

Anita insists that I set up a test rig to prove it.
If the Multiplus is connected to the mains it will use that earth, If not it disconnects. But they do seem to suggest you have another consumer unit after the multiplus.

 

[xsilvergs]

There is a discussion about this with Dave and the multiplus.
If I remember correctly you have two choices.
1. leave it floating and you have two live wires relative to ground and each other.
If you have a fault to the appliances case, you still shouldn't have a shock to ground.
2. Connect up the earth wire and use the inverter though an RCD. This should give you a protected circuit. Dave was going try and prove it, I think.

Anita insists that I set up a test rig to prove it.
If the Multiplus is connected to the mains it will use that earth, If not it disconnects. But they do seem to suggest you have another consumer unit after the multiplus.

Thanks for reply, my inverter is wired through a DPDT switch so AC input is either is either EHU supply OR inverter. This has allowed me to then use the vans Breakers and RCD to give added safety.

The inverters earth is connected with the originals at the consumer unit.

 

[wildebus]

There is a discussion about this with Dave and the multiplus.
If I remember correctly you have two choices.
1. leave it floating and you have two live wires relative to ground and each other.
If you have a fault to the appliances case, you still shouldn't have a shock to ground.
2. Connect up the earth wire and use the inverter though an RCD. This should give you a protected circuit. Dave was going try and prove it, I think.

Anita insists that I set up a test rig to prove it.
If the Multiplus is connected to the mains it will use that earth, If not it disconnects. But they do seem to suggest you have another consumer unit after the multiplus.

I was, wasn't I?

OK... Just went out and did a test....
Disconnected Multiplus from Hookup; I have two circuits out of my Multiplus - one which has just an MCB on it, and one that has an MCB and RCD on it.

• Socket Tester shows all cables correct on all sockets tested.
• Put my Socket Tester with RCD Check feature on an RCD protected outlet... Press RCD Test Button and the RCD tripped.
• Put my Socket Tester with RCD Check feature on a NON-RCD protected outlet... Press RCD Test Button and nothing happened other than red light came on on Tester.

So the above worked as you would expect and would want.
The Multiplus does feature this Ground Relay setting; I I am fairly sure that the Phoenix Inverters only have Live and Neutral connected on the Inverter outlet and ground is not connected (floating) by default. (From memory, I used to get the same error on a Socket Tester when checking the output. I never moved any internal wires).

This is the option in the Multiplus using VE.Config (default is Ground Relay checked)

This is what Victron say about that option

Based on the above text, if you were to move on the Phoenix Inverter the Earth line from Position 1 (floating) to Position 2 (Neutral connected to PE), it sounds to me like you would have the same setup as the Multiplus is when in Inverter Mode (which the Phoenix is all the time of course).

 

[wildebus]

Thanks for reply, my inverter is wired through a DPDT switch so AC input is either is either EHU supply OR inverter. This has allowed me to then use the vans Breakers and RCD to give added safety.

The inverters earth is connected with the originals at the consumer unit.


View attachment 2842

So you are using a common ground within the CU. I presume your tester was plugged in on the Inverter outlet and not via the DPDT switch, and post switch it tests ok - and the RCD trips on a test?
On the EHU/Inverter Switch mechanisms (either manual or relay style), I have effectively used the chassis ground as the 230V AC PE (and the Earth from the EHU goes to chassis as well of course)

 

[xsilvergs]

So you are using a common ground within the CU. I presume your tester was plugged in on the Inverter outlet and not via the DPDT switch, and post switch it tests ok - and the RCD trips on a test?
On the EHU/Inverter Switch mechanisms (either manual or relay style), I have effectively used the chassis ground as the 230V AC PE (and the Earth from the EHU goes to chassis as well of course)

Having changed the Phoenix wiring the output from inverter and the output after the DPDT switch test OK.

I can't remember what result I got when checking the EHU to chassis connection.

This van is Italian, I think their EU standards are different .

 

[SquirrellCook]

I should have, as Murky was evolving I put an auto changeover switch in the consumer unit. My auto changeover relay is after the consumer unit, so I have floating 240 AC power. I just have to make sure that when Anita touches something live I don't hold her hand whilst standing outside in the rain.

This is one of the things that sold me on the Multiplus, it just makes life easier I believe.

 

[xsilvergs]

I should have, as Murky was evolving I put an auto changeover switch in the consumer unit. My auto changeover relay is after the consumer unit, so I have floating 240 AC power. I just have to make sure that when Anita touches something live I don't hold her hand whilst standing outside in the rain.

This is one of the things that sold me on the Multiplus, it just makes life easier I believe.

My thoughts were to include the consumer unit with its RCD and breakers. My wife wouldn't know how to handle a live wire.

The Phoenix appears to make things safe, I just wonder how safe is it to use cheaper inverters and do the users know the risk.

Risk isn't so bad if you know and understand the consequences.

 

[wildebus]

One thing on your setup I would prefer to change is having an RCD between the EHU Socket and the DPST Switch. Would mean having two RCDs in play when on Hookup, but it just seems a touch safer.
Having said that, I do have some Sockets that do not have any RCD protection when on Inverter only, but the ones I see as potentially risky (near water or external (so power tool useage)) are on an RCD out of the Multiplus).

 

[xsilvergs]

One thing on your setup I would prefer to change is having an RCD between the EHU Socket and the DPST Switch.

David, please explain the additional RCD between the EHU Socket and DPDT Switch?

As i see it there will be one at the campsite EHU post which protects the EHU lead to the van whether it's connected at the van end or not. From the back of the EHU Socket in the van to the DPDT Switch will be still protected by the campsite EHU post when connected.

 

[wildebus]

I just wouldn't trust an external RCD that you cannot be sure of as out of your control. So the RCD I am talking about is essentially a 'replacement' for the campsite one (if you were happy to rely on the campsite RCD for hookup, you wouldn't bother with an RCD at all in a van without an inverter - and it is very rare you see a Camper Consumer Unit without an RCD)

 

[xsilvergs]

Just remembered watching this the other week:

It just gets more fun

 

[xsilvergs]

I just wouldn't trust an external RCD that you cannot be sure of as out of your control. So the RCD I am talking about is essentially a 'replacement' for the campsite one (if you were happy to rely on the campsite RCD for hookup, you wouldn't bother with an RCD at all in a van without an inverter - and it is very rare you see a Camper Consumer Unit without an RCD)

I see where you're coming from. Is there an in-line device that could plug into the campsite EHU post and into which the EHU lead plugs into?

On the rare occasions we hook-up I do wonder on those damp days.

The last connection I make is to the post and the first disconnection is from the post, if nothing else so that should there be any arcing it's not on the vans EHU Socket.

 

[wildebus]

This kind of thing - https://amzn.to/2XQD76Y

That is just an example. I am sure they can be bought for a lot less money! I guess you could wire up one of these with a male and female Blue 16A 'Commando' Plug/Socket and use it when you had doubts about the EHU source?


This is more like it ... https://amzn.to/3isYWBm

 

[SquirrellCook]

This reminds me of a horrible or funny story from school depending on your sensitivity. One child was chasing another with a piece of electrical wire, shouting “earth him, earth him”. The poor victim believed he was running for his life. Children can be so nice........

 

[trevskoda]

I just earthed mine to the black battery wire which is run to the van body,it should run through the carbon in the tyres to ground,mind you no shock if you dont touch ground,only my fridge uses a smart inverter,and im sure the unit is isolated.

 

[xsilvergs]

Update:

I have been testing the Victron 12/500 inverter and although not that big as inverters go it proved very successful in powering our 3-way Thetford fridge at the New Forest, Stratford-Upon-Avon and Hereford camping events organised through Motorhomer.

But when using the Remoska or VonChef, the RCD in the van would trip.

I contacted On Board Energy who I purchased it from, they said if it works OK with the fridge Victron would say there's nothing wrong with it.

I have tried the different earth connection methods as post #1, neither method made any difference, the RCD tripped when switching a device off. So I have changed the wiring for now as per this diagram until I can get more information.

Thoughts appreciated and hopefully this may help others in future.

 

[wildebus]

I would have expected your original setup would have been fine. strange.

Interestingly, earlier today I reworked the 240V wiring of a motorhome to be just the same as your diagram above except in place of a DPDT Switch I used a DP Auto Relay.

 

[xsilvergs]

I would have expected your original setup would have been fine. strange.

Interestingly, earlier today I reworked the 240V wiring of a motorhome to be just the same as your diagram above except in place of a DPDT Switch I used a DP Auto Relay.

I was slightly annoyed as I didn't expect this. Is this a Victron thing, or is my RCD too sensitive?

OBEnergy thought this would not happen on a domestic system as any spikes could be absorbed by the grid.

David, hopefully, if the motorhome you worked on had an inverter fitted it doesn't have the issue.

 

[SquirrellCook]

I wonder as I mentioned before, is not the output from an inverter neither or either live and neutral? To make one live and one neutral, the neutral has to be tied to ground.