Earth Connection On Boat

[Wonderwall]

Looking for some info here.
Recently I was on my friends boat, which has a 240 supply , through an inverter which you can run a micro wave , hair dryer etc, preferably of course if the engine is running.
It got me thinking, how do they achieve a path to earth on such systems?
What prevents , during a possible fault the metal parts of a class one piece of equipment becoming live and a potential harm to humans. RCDs can and do fail .And as we know , are not allowed to be the sole point of protection.
Enlighten me with your wisdom folks please
Cheers

 

[Marvo]

Marine electrical systems can get complicated because standard earthing arrangements such as TN-C-S can cause rapid galvanic corrosion of the hull. Several different systems are used including isolating transformers. What type of boat is this?

Also when you say RCD's aren't allowed to be the sole method of protection, what protection are you referring to? RCD's are always the sole protection against inadvertant earth leakage currents that could prove fatal to an installation user.

 

[Wonderwall]

Thanks for reply.
It is a wooden cabin cruiser. That's the best I can explain!,
What I meant regarding rcds is we back them up by means of a cpc, in the event the rcd does not operate .
I can't get my head round how a boat achieves this path to earth? I'm probably not explaining it well, or perhaps I'm missing something obvious.
I have mentioned it to a couple of sparks and both had different takes on it.

 

[Clive P]

Hi, Without going into a lot of detail, the easiest thing to do is to look at ISO 13297- Small craft AC systems and ISO 10133 Small craft DC systems, available free on the internet.

Regards.

 

[HandySparks]

What I meant regarding rcds is we back them up by means of a cpc, in the event the rcd does not operate .
I can't get my head round how a boat achieves this path to earth?

For earth fault protection via a cpc, the cpc doesn't need to be connected to earth, just a connection to the neutral of the supply at the origin (in this case, the inverter), ie TN-S.