Galvanic Isolator Question

[karista]

Since installing a new galvanic isolator this spring, I have not seen any improvement in zinc replacements. The question I have, is whether the isolator ground wiring connection is directional? The instructions do not indicate a directional (in-out) connection. However a dock-mate engineer said they are directional as they are made-up with diodes, thus I may have the wiring reversed. In e-mailing Newmar, they replied it makes no difference how the ground wires are connected. Any comments!!

[Stu Jackson]

Bernd,

A google on galvanic isolators leads to many hits, inclduing this one:  http://www.boatus.com/seaworthy/galvanic/default.asp

Yes, they contain diodes, so check the installation manual again.  Seems if the manufacturer says no, what can I tell you???    If you have Calder's I'd check his discussion, too.

[rirvine]

I just installed one (Quest 2530P) and the ground terminals were clearly marked – boat ground and shore ground.  The installation of an isolator only solves one of the possible issues – a ground loop with neighboring boats through the AC ground system.  Hence may have no impact on the rate of zinc usage in some situations.

Just my 2 cents,  Ray

[jmnpe]

Galvanic isolators have diodes in them, but it is a pair of them in parallel and back-to-back. There is no polarity sensitivity associated with their connection between the ship's ground and the shore power ground.

John

[karista]

John
Thanks for the explanantion that the Isolator connections are not directional.
I now won't tear it back out and reverse the connections. As far as results/improvements, there have been none, my zinc still needs replacement at the same time interval as prior to the galvanic isolator installation, a total waste of money!

[jmnpe]

Bernd,

Next thing to check is your shore power connection on the marina side of things. I appears that some percentage of marina wiring was performed by very old monkeys using a broken screw driver and a bent pair of pliars............ Make sure that some "genius" didn't tie the neutral and ground wires together inside the box, or even worse, have the neutral and line wires reversed.

Never assume anything in a marina...........

John