Earthing to water

[Dunx]

Looking for some advice please for a new to me boat

The incoming shore power has a single RCD installed just after entry to the boat. I have opened this unit and there is no earth conductor going to the water. The shore power continues in the boat to a second bus bar about 7m away where there is a second RCD supplying a pair of double pole isolators, one for the domestic sockets, the other does the immersion heater circuit. The immersion heater is plugged in via a two pin connector Socket. From this socket a separate 2.5mm earth wire has been run to a grounding plate.

I have a few concerns, mainly I’m worried the current setup is not as safe as it could be.

I was led to believe that having multiple RCDs in sequence was not a great idea. Is this correct?

The cable used to bond the immersion socket to the water appears undersized. I’m thinking 6mm is more appropriate.

Should I bond the incoming earth at the first RCD to the water? This would be with a 6mm cable to the Anode which is closer.

Are there any Problems likely to emerge with having the shore power bonded to the water at two locations. I have just fitted a galvanic isolator as the previous owner ‘forgot’ to tell me he had removed it to take to his new boat...

 

[BabaYaga]

I have a few concerns, mainly I’m worried the current setup is not as safe as it could be.

From a safety point of view, the apparent lack of any over current protection would be my primary concern. Unless the 'double pole isolators' are in fact double pole circuit breakers?

 

[PaulRainbow]

Looking for some advice please for a new to me boat

The incoming shore power has a single RCD installed just after entry to the boat. I have opened this unit and there is no earth conductor going to the water. The shore power continues in the boat to a second bus bar about 7m away where there is a second RCD supplying a pair of double pole isolators, one for the domestic sockets, the other does the immersion heater circuit. The immersion heater is plugged in via a two pin connector Socket. From this socket a separate 2.5mm earth wire has been run to a grounding plate.

I have a few concerns, mainly I’m worried the current setup is not as safe as it could be.

I was led to believe that having multiple RCDs in sequence was not a great idea. Is this correct?

The cable used to bond the immersion socket to the water appears undersized. I’m thinking 6mm is more appropriate.

Should I bond the incoming earth at the first RCD to the water? This would be with a 6mm cable to the Anode which is closer.

Are there any Problems likely to emerge with having the shore power bonded to the water at two locations. I have just fitted a galvanic isolator as the previous owner ‘forgot’ to tell me he had removed it to take to his new boat...

The immersion heater should be connected via a 3-pin socket not a 2-pin socket and there should be no connection to the grounding plate. Alternatively you can connect the immersion heater directly to the consumer unit making sure that you connect the Earth wire.

There is nothing wrong with having two RCDs in series.

All Earth wires should be the same size as the current carrying wires so in the case of your Shore power 2.5 mm would be correct for a 16 amp supply.

You should only ground the system to the water at a single point, as you have a grounding plate this would be the correct place.

Your galvanic isolator should be connected before the first RCD. You can then connect an earth wire to the grounding plate, this can be from any point after the galvanic isolator whichever is most convenient.

 

[Dunx]

Many thanks to you both I will remedy as advised.