Larry is correct. If you have an older boat that has accumulated fine
salt deposits over the years, AC leakage to ground can diminish the
effectiveness of Galvanic Isolators. You can test very easily after
installing the galvanic isolator. If the AC voltage you read across
it is more than about 0.3 volts you are starting to lose isolation.
Typically the worst case loss is only up to about 50% as the DC rides
through on one of the AC polarities when the diodes go into
conduction. On the other polarity of the AC it is bucking the DC.

You can solve this problem with a Galvanic Capacitor. It is just a
large capacitor that you put in parallel with the Galvanic Isolator so
the AC goes through it instead of the isolator. Some manufacturers
include a capacitor in the isolator but so far as I can see, not a
single manufacturer will tell you the capacity of it and since the
space occupied in their isolators is inadequate I feel sure they are
just putting in a small token capacitor so they can say it is there.

Our isolators have no capacitor. If you find you need one, we sell a
Galvanic Capacitor that is rated for 5 amps AC continuous that you
connect in parallel with the isolator. This would permit up to 5 amps
ground leakage before it compromises the galvanic isolator efficiency.

On Mon, 7 Jan 2008 06:49:19 -0800 (PST), Andina Marie
wrote:

snip

Our isolators have no capacitor. If you find you need one, we sell a
Galvanic Capacitor that is rated for 5 amps AC continuous that you
connect in parallel with the isolator. This would permit up to 5 amps
ground leakage before it compromises the galvanic isolator efficiency.

With 5 amps of leakage current, there is a serious problem that ought
to be fixed aside from any compromising effect on galvanic isolation.
Sounds like an electrocution waiting to happen. All it takes is a
corroded (or non-existing) grounding connection to the cabinet of a
refrigerator.

However, a functioning GFCI will trip immediately with 5 amps of
leakage through the green grounding conductor. Most will trip with a
thousandth of that current (5-6 mA).

Chuck

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