Marine Isolation Transformer

[pwrcam]

A client has purchased a used barge and will be using it as a floating dock. Concerns have risen over galvanic corrosion causing problem to the dock. Is it acceptable to utilize a marine isolation transformer on the floating dock?

 

[kwired]

Not saying I am an expert in this area, but IMO you can isolate it all you want - even not connect to any kind of shore power at all and you will still have galvanic corrosion activity. I think you need to look into cathodic protection systems.

 

[GoldDigger]

+1
What the isolation transformer does is allow the ground bonded neutral to be isolated from the grounded neutral on the service side so that the cathodic protection circuit can offset the boat hull ground from shore ground.

 

[don_resqcapt19]

+1
What the isolation transformer does is allow the ground bonded neutral to be isolated from the grounded neutral on the service side so that the cathodic protection circuit can offset the boat hull ground from shore ground.

How does that work under the NEC rules? There will be a primary to secondary grounded conductor connection via the primary and secondary EGCs.

 

[GoldDigger]

I am not sure how it plays out with the NEC (which does not apply to the boats themselves and any transformers or isolators that may be mounted there) but usually the ground connection is made through a diode isolator (back to back diodes in parallel so that a *limited* DC offset is possible).
I guess you could do the EGC isolation at the boat end of the shore line, but you raise a good question about where the neutral bond needs to be in the separately derived system.

 

[jstjohnz]

A marine isolation transformer has no connection from primary (shore) side ground to secondary (boat) side ground. On the boat side the neutral is bonded to the boat's ground system.