Inverter RCD question

[dnks34]

Need a bit of advice please

We have a 12v(1000w) inverter which is wired into the sockets on the boat via a rotary changeover switch. The shore supply is RCD protected but at the moment the supply from the inverter isnt. Its a floating system but the chassis of the inverter is earthed to the weed filter tube nearby but nothing else is. Should It have an RCD fitted on its output and would it even trip if a fault occured? Or can anyone suggest a better way of doing it. Eagerly awaiting any advice!

[woodwose]

RCDs work by detecting a imbalance (usually 30mA) between the current flowing in the live and neutral wires. In the case of a mains installation, the neutral is effectively connected to earth, so if you touch a live part of the circuit, some of the current will flow through you to earth instead of via the neutral wire and so the RCD will trip.

In the case of an inverter things are different. Here the go and return is via wires and there is no earth, so if you touch a live part of the circuit, no current should flow through you and so you will not get a shock and an RCD would not trip. Having said this, that's just the theory, the reality will depend on exactly how your boat and inverter are wired up and there are possible circumstances where you might get a shock. You could only be sure by looking at the internal wiring of the inverter and of any appliance plugged into it as well as how your boat is connected to the inverter.

There are scenarios where you could have one hand on one side of the inverter output and the other hand on the other side. In this case, you could get a nasty shock but the RCD would not even notice.

My guess is that an RCD would probably not offer much protection, but depending on the circumstances of your installation, it might.

Sorry if that's not much help.

 

Nigel

Ludham

[dnks34]

Thank you Nigel, thats exactly the sort of advice I was looking for

[MBA Marine]

Why do your two AC sources not go to the AC source selector switch and the common AC out from that switch then to your RCD and on to distribution?

[dnks34]

I think it was wired so the Inverter could only power the sockets and didnt get mixed in with the immersion and chargers,

[MBA Marine]

I think it was wired so the Inverter could only power the sockets and didnt get mixed in with the immersion and chargers,

That would make some sense.