Hello Eric,

Thanks for clarifying.

I believe you are correct. You are talking about
high-resistance onboard leakages that generate currents too
small to be detected by the GFI circuit or the breakers. The
isolator diodes would probably not conduct under those
circumstances and a capacitor would help.

UL requires the GFI to trip at a 5 ma unbalance, so 24,000
ohms of leakage would trip it. Actually, the isolator diodes
would probably pass 5 ma in that circuit without a
capacitor. The capacitor would be necessary when the leakage
resistance was in the megohms and the currents in the
microamps.

Would rather not have that stuff flowing through my ground
connections through the water to adjacent boats, even at
those low current levels. This underscores the importance of
making sure you don't have dangerous leakages onboard in the
first place. Easy enough to check, but how many regularly
test their GFIs?

We sure agree on the isolation transformer, too.

Thanks again, Eric.

Chuck