Hi Hal, I made my own gal iso from a coouple of bridge rectiviers (35a) from radio
shack and some 2"x4'x1/8" aluminum
bar... Somewhere I read where you needed so many sq inches of surface area(heat sink) to offset the bridges... simple to build with 2 screws to hold the rectifiers together and poprivits to put together the aluminum
... I then separated my ground from the dock
, and wired/soldered it to the rectifier... My buddy tested it with his fluke meter/probe in the water
and it was less than 1 volt. reason for testing was my boat was glass and his was steel
on the same elect wiring
on the dock
hope this helps...included is a note from the site listed below...
just found the article using the bridge rectifiers:
also a good link on the subject:
There are two ways for a galvanic isolator
to fail Either the diodes are shorted, or they are blown open. You can test them with a digital volt meter that can read positive and negative voltages. At any time, with the voltmeter on the DC range, put it across the shore power
side to the boat side of the isolator. There should always be some residual electrolytic voltage (unless you are hauled out) so the meter should read something less than one volt. If it always reads zero, the diodes are shorted out. If it reads greater than about 1.2 volts then the diodes are open circuit. Switch to AC volts and check again since if AC is flowing, the DC meter setting may not show any activity.
Galvanic Isolator Explained
I also have all my grounds inside the boat tied to the same point...ac/dc/whatever
I also have gfci's wired in and have never tripped except in a lightning
storm a while back or guys rewiring the docks...never figured out which one did it...