Galvanic isolators

[maelstrom99]

I am just about to moor my boat (GRP) in a marina and intend to connect 240V mains power to use for a battery charger and domestic use. I have suffered from corrosion in the past and I am considering fitting a galvanic isolater to assist in protecting the boat. I would appreciate any comments good and bad about fitting such devices and of course recommendations for suppliers.

Many thanks

 

[colinmi]

They work very well, are not expensive and are simple to install. I got mine from Merlin electronics who advertise in PBO. But im sure they will be available from many of the suppliers who advertidise in the mags.

Basically thet prevent your zink corroding away to protect other boats in the marina which are not propertly protected themselves.

Regards

Colin

 

[pandos]

I bought one recently and paid much more than my last one because the specs have changed.

My understanding of the problem is this.

Because they intercept your return earth to the mains supply if they "failed open" the elcb which should protect you would not trip.

Many of the cheaper ones were found to fail before the Elcb did actually trip and thus there was effectively less protection from electrocution. ( I think all this happens in nanoseconds but the theory when i read it made sense)

Presumably it could be knackered in one incident and the injury would occur in a subsequent incident.

 

[VicS]

There is a bit of worthwhile reading about galvanic isolators on this site (It's American so it talks about 120volts rather than 240)

And a non technical explanation of electroysis HERE

Basically they work by preventing the current flow from low voltage souces, which is what causes the corrosion when boats are left with the shore power connected permanently in marinas, but still allow the current to pass from high voltage sources which will then trip an RCD or blow the fuse or trip the circuit breaker in the event of a major fault in the absence of an RCD.

They should be rated to with stand the maximum current that your shore power can supply ie the value of the fuse or the setting of the circuit breaker in the pontoon supply.

 

[alan]

Other suppliers,
Index marine
JG tech
Adverc

They do what they are supposed to and are easy to fit.

Alan.

 

[samwise]

I bought the Merlin one and got my cable from B&Q, although the purists will suggest I should have lashed out on marine grade. Easy to fit, you need a reliable crimper to fit the connectors.