240 V safety

If you use a generator or inverter the vans RCD will not work as both sources are Isolated types of powersupplys. Also earthing the generator wont help either as the earth conection on the generator is only conected to the shell.

Inverters of that power level are not your normal cheapies Ian and I think we would need to know more about it before a definative answer could be given- does handbook refer to your case or describe its earthing status / System.

Hello Ian,

an RCD isn't needed if neither of the 2 wires from the 240V power source is connected to an earth wire (this is called a 'floating' supply).

As long as the wires are kept isolated from the earth (this includes structures you touch with your hand or feet), you could touch either one of them without getting zapped. But of course if you touched both of them at the same time, it's a different story.

Now consider a faulty wire insulation causing a connection between a wire and earth/caravan body/chassis etc. This wire then becomes the 'neutral' wire, while the other one becomes the 'active', or hot wire.
If you touch neutral, nothing happens, but if you touch the hot one, you could get zapped.

How would an RCD protect you in this situation?
You have to keep in mind, that the RCD senses the difference between the two currents in the two wires.
If everything's working as it should, there's no difference, but if one wire suddenly carries less current than the other one, then the RCD trips (opens the circuit).

So how could you make the RCD trip, i.e. how can one wire suddenly carry a smaller current when you touch the active/hot wire?
For this, you have to introduce a third current path, called the earth wire, and provide a connection at the power source between earth and one of the two main conductors, which now becomes 'neutral'. You'd also have to connect the earth wire to the caravan/towing vehicle chassis and gennie chassis, for full protection.

In case you touch the active/hot wire, a small current could start to flow through your body to the earth/caravan body/chassis and back to the power source via the earth wire.
It is this small current which is suddenly missing in the neutral wire going through the RCD, and it trips.

Note that an earthed system without RCD is more dangerous, than a non earthed (floating) system without an RCD.
The best protection is offered by an earthed system with RCD, because the RCD detects any insulation breakdown between active/hot and associated leakage current from this wire to earth. So there's no chance that something can become 'life'.
But if the RCD goes faulty, you end up with a dangerous earthed system without RCD, thus the importance of periodical tests carried out on the RCD.

In a nutshell, if the RCD is already installed inside your van, I'd connect the generator chassis, van and towing vehicle with an earth wire (common negative, or chassis ground is suitable). This earth wire needs to be connected to the 240V power outlet socket on the gennie, and to the neutral on the same socket, via the extension cord between gennie and van.
Ask an electrician who can tell you which one it is.
For the ultimate protection, also use a plugin type RCD at the gennie 240V socket.

Legal disclaimer:
All the above is given on 'technical information only' basis.
Due to the legalities covering all matters 240V, I can't be made responsible for any actions resulting in damage or personal injury/death.

cheers, Peter