Shore power.

[jamie N]

I have power from an extension lead to my boat in the marina, and it's used for either a 'usual' domestic power tool, or the battery charger, each of which are disconnected when not in use.
A number of posts here seem to link shore power with anode wastage. Obviously, with my items I'm not going to have that, but is it a common issue due to having fridges, or air-con running off of a dedicated and installed 240VAC/inverter system?
Genuine Q, as I've no experience of a 'posh yacht' with all the bits.

 

[VicS]

No problem with your system because you have no connection between the shore power earth and your anodes.

There should be no problem with an inverter if there is no connection with the shore power earth and the anodes

For an occasional shore power hook up like yours consider using a camp site hook up system w ith a circuit breaker and rcd

A galvanic isolator is next to essential with a fixed shorepower installation because there will almost certainly be a connection between the shorepower earth and the anodes. It will prevent the type of corrosion associated with shorepower connections

 

[VicS]

There should be no problem with an inverter if there is no connection with the shore power earth and the anodes

An inverter (or a generator) should however have its external earth terminal connected to the water. This can best be done using a small zinc anode which does not form part of a cathodic protection system

 

[PaulRainbow]

An inverter (or a generator) should however have its external earth terminal connected to the water. This can best be done using a small zinc anode which does not form part of a cathodic protection system

It is a current requirement that all AC sources are connected to the water. Example given in the current ISO are that this can be via the hull of a metal boat, the vessels ground plate or the sacrificial anode. The examples are not exhaustive though, there are vessels where the hull is not metal, there is no ground plate and there is no hull anode. Some Bavarias, for example, have this configuration and the manufacturers fit a small anode to overcome the issue.

Using such an anode is but one solution, it is not necessarily "the best" solution. It would be a pointless solution on a vessel with a steel hull or a grounding plate.

It would equally be pointless on a vessel with a hull anode. There is nothing wrong with using the hull anode, millions of boats do this without issue. It is essential though that a galvanic isolator or isolation transformer are fitted.

In all of those examples it would not only be pointless fitting an additional anode, just to connect the earths to the water, it would be a big waste of money, having to have the vessel lifted just to make another hole in the hull.