By Capt. Bill Pike

Galvanic Guardian

1 I removed the old galvanic isolator and discovered it was not working.

Now and again, I serendipitously stumble across an onboard problem well before it snowballs into something expensive. For example, I was recently talking with my industrial-electrician brother and the subject of multimeters came up. “You should have one on your boat at all times,” Mike said, “and don’t go chintzy—spend at least $70 and get something decent.” Of course, I took this last bit of advice with a grain of salt—I, like many, have been struggling with boat-related budgetary concerns of late—and purchased something slightly less expensive.
My new Ancor seven-function digital multimeter ($45 at West Marine) was an intriguing device nevertheless, and I simply had to give it a try as soon as I got back aboard Betty Jane. So, in accordance with a test procedure Mike outlined during a subsequent call I made from Betty’s saloon, I shut down my shore power dockside, disconnected the shore power cord from Betty’s transom-mounted power inlet for good measure and then using wire cutters, removed the el cheapo galvanic isolator (boat-related budgetary concerns again) I’d installed in the lazarette two years before. The plan was to give it a checkup while parenthetically checking out the new multimeter.  READ ARTICLE 
http://powerandmotoryacht.com/maintenance/checking_and_changing_your_galvanic_isolator/