Earthing for a Vehicle Inverter

[King Arthur]

Current DIY project is a van conversion in which I'm installing two leisure batteries, a B2B charger (to charge the leisure batteries from the vehicle battery/alternator when engine is running), a 200W solar panel and a 500W inverter. I'm using Victron units for the three main functions. The inverter will mainly be used to charge Ebike batteries and the only other things powered by the leisure batteries are some additional LED lights and USB outlets. There is no mains hook-up facility (and I don't want one).

The system is not connected to the vehicle chassis at any point so is effectively floating wrt to all the vehicle electrics (the only connection to anything in the vehicle is the van battery, which is connected to the Victron Orion unit, and the input/outputs of this are isolated).

My question relates to the Victron Inverter, which has an earth terminal connected to its chassis. The manual gives various installation examples but not for a vehicle with no mains hook-up, so what would be a sensible earthing point, if any? I've read various sources with various suggestions but so far have found nothing that I'd consider definitive.

One suggestion I've read is that a floating system such as this installation is effectively the same as a shaver socket in a bathroom and is intrinsically safe because there can be no complete circuit between the inverter output and anything in the van. Touch either inverter output (L or N) and no current can flow because there is no reference to 'earth'. This makes some sense to me but I'm not entirely confident about it.

Any thoughts or suggestions?

 

[King Arthur]

I know this is forum is focused on building installations, but are there no takers on this general earthing question?

 

[Gian]

I know this is forum is focused on building installations, but are there no takers on this general earthing question?

I have been questioning similar situations. I recently contacted Hyundai as there new Iq5 ev has like many now the ability to use it's battery to say power appliances or say running a lead into a home to keep the fridge freezer going. I was concerned about similar issues. Now your plugged a appliance into a home you have disconnected a safety feature which is the RCD from the cu. So what about touch voltages . So I contacted Hyundai and it came back that vehicle had protection built in so it would see a broken neutral or CPC then it would disconnect the charger within the car. They did not go into detail which was a shame but my guess it would be similar principle for the open pen fault detection units you can buy. It's a really interesting subject .

 

[Andy™]

717.411.3.1.2 Protective equipotential bonding
Accessible conductive parts of the unit, such as the conductive structure of the unit, shall be connected through the
main protective bonding conductors to the main earthing terminal within the unit. The main protective bonding
conductors shall be finely stranded.

 

[binky]

I know this is forum is focused on building installations, but are there no takers on this general earthing question?

Vehicle electrics are a different discipline

 

[Andy™]

Vehicle electrics are a different discipline

vehicle electrics as in 12v wiring yes, 230v not really much different

 

[Gian]

717.411.3.1.2 Protective equipotential bonding
Accessible conductive parts of the unit, such as the conductive structure of the unit, shall be connected through the
main protective bonding conductors to the main earthing terminal within the unit. The main protective bonding
conductors shall be finely stranded.

Yes that is correct but the ev car in Hyundai set up is using something clever. But note 5 is interesting..

 

[King Arthur]

717.411.3.1.2 Protective equipotential bonding
Accessible conductive parts of the unit, such as the conductive structure of the unit, shall be connected through the
main protective bonding conductors to the main earthing terminal within the unit. The main protective bonding
conductors shall be finely stranded.

As I understand that it's saying I should connect the inverter chassis ground terminal to the vehicle chassis? But in practice what would that achieve given that the inverter output is isolated and therefore floating, IE essentially the same as a shaver socket.

I've also read that vehicle leisure systems should never rely on the vehicle chassis as a ground return because modern construction methods cannot guarantee such a scheme because of the use of composites and glues etc. Hence everything being individually wired and completely isolated from the vehicle wiring.