Galvanic Isolator or Iso Transformer - To Bond or Not ?

[Andina Marie]

Abslolutely Nick, you are proving my point. If you CAN afford the cost and weight of an Isolation Transformer there is no question it is a much better solution. Again you look at the cost.

You decide you need galvanic protection and you also need a watermaker but you can't afford both. Life is a compromise. You don't HAVE to purchase an IT because it is better if there is a compromise that will fit your budget. You don't HAVE to have a watermaker if you think galvanic isolation is more important. In life you are faced with choices.

ABYC puts out a reference to which we should all revere but not all of us can afford perfection.

[sailcruiser]

The galvanic isolator protects up to approximately 1.2 volts which is cited in the linked article. As I understand it anything above bleeds over. Here is another good link from BoatUS. I don't want my saildrive to look like the pictured outdrive someday. SC
http://www.boatus.com/seaworthy/galvanic/default.asp

[s/v Jedi]

Originally Posted by Andina Marie

Abslolutely Nick, you are proving my point. If you CAN afford the cost and weight of an Isolation Transformer there is no question it is a much better solution. Again you look at the cost.

You make it sound very expensive, which it is not. A watermaker costs many thousands of dollars while an IT only cost a couple hundred more than a GI.

You make room for an IT. People find room for 2000Ah battery banks, 144 cases of beer but not for a simple IT? I do not accept that. It's all excuses to take the cheap and easy way out, and then when it goes wrong, we're not allowed to say "told you so" again, or they go sue somebody.

Last time we had a guy here who even refused to disconnect his shorepower because he didn't believe he was causing his own bubbling underwater metals... and got angry at us for not telling him to sue people... go figure! We told him to move his boat out that marina or at least the slip. He refused and called his lawyer instead or something like that!

ciao!
Nick.

[goboatingnow]

Just getting back to the OP point, the boat isn't bonded, as is the case with most European boats,its fiberglass. I also suspect the AC and DC circuit grounds are interconnected and most likely it has a whole boat RCD.

Why bother with either a IT or an isolator.

Dave

[CHM]

Thanks for all the comments. The point about this being a European boat is excellent. It has the original receptacles and switches, so I am sure The electrical system has not been refit. It looks like I need to get a marine electrician aboard to look at these issues. I have no doubt the DC is adequately grounded, but the AC is questionable with 2 prong receptacles installed. Having said that, I am sure the new AC unit and new reefer are grounded through separate circuits. The hot water heater is not connected and runs off the heat exchanger. Leaving the shore power disconnected unless we are using it seems like the best solution until the boat looked over. My gut tells me the circuit for the receptacle will need to be desired with a ground wire and receptacles replaced with GFCI types. I can also look at the space between the shore power inlet and the panel to figure whether or not an IT can be mounted. It's obviously the best solution. If theism option proves too costly, the GI would be a compromise with regular inspections to insure it is operational.

[Pete7]

Originally Posted by CHM

but the AC is questionable with 2 prong receptacles installed.

If they are anything like the standard German household plugs then YUK! as they don't have a fuse in the plug. Had to use them when I lived in Germany but can't say I ever trusted them, all cut off when I returned to UK and fused plugs fitted.

Pete

[Pete7]

Another thought, Beneteau will have done a good job of properly wiring her up when built, to European standards. However, are you now feeding 120v at high amperage through wiring designed for 240v at a lower amperage? I am not an electrician but thought it worth raising the question.

Fun this boating malarky isn't it

Pete

[DotDun]

Originally Posted by Pete7

Another thought, Beneteau will have done a good job of properly wiring her up when built, to European standards. However, are you now feeding 120v at high amperage through wiring designed for 240v at a lower amperage? I am not an electrician but thought it worth raising the question.

Fun this boating malarky isn't it

Pete

A 240v 16a circuit breaker offers the same protection at 120v 16a. The wire is protected to 16a, that's important piece.

[mitiempo]

Yes but in the US it is 120 volt 30 amp service.

[s/v Jedi]

Originally Posted by mitiempo

Yes but in the US it is 120 volt 30 amp service.

Exactly: if you want to use the same amount of power that you are used to with 230V 16A service, then you will need to upgrade both the 16A breaker to a 30A version, plus all the cabling to double the amperage rating. Very few boats wired for 230V will have big enough diameter wiring for 115V.

ciao!
Nick.

[CHM]

It's a 110 V boat, but the receptacles will accept either our flat 2 prong plugs or the European 220 V round prongs. My suspicion is that the boat was wired for either 110 or 220 depending on the Moorings contract. Details of these vessels are lacking. I will be on the boat next week with a multimeter to check the complete system and have a marine electrician set up as well.

[DotDun]

Originally Posted by mitiempo

Yes but in the US it is 120 volt 30 amp service.

I would certainly hope the breaker I referred to is between the 30 amp shore power and the branch circuit. If not, there are multiple issues with the wiring on that boat.