Andina & Chuck,
This is not rocket science. There is NO safety issue by not using shore
safety earth. Shore safety earth ultimately connects with the distribution
transformer nuetral and tied to a ground stake at that transformer. That
ground stake is the reason for having an isolation transformer in the first
place. It will never be a closer reference to earth than your boat. Any
leakage current ANYWHERE in that distribution net will seek your hull to
earth, as it will offer the least resistive path to earth. (It is in the
water!)

The plan is to magnetically couple energy from the primary to the insolated
secondary with the secondary referenced by end tap (110 V) or center tap
(230 V) to the boats ground plate. There must not be any electrical
connection between your boat and shore power. If a fault would occur on
either side of the transformer, fault current will run quite nicely to the
ground plate tripping the feed circuit breaker no matter where it is.

The only reason to use the shore safety earth on the transformer case is if
the transformer is physically mounted on the dock, not in your boat.
Steve


"Andina Marie" wrote in message
oups.com...
Chuck,

I don't agree with your grounding advise.

If you ground the frame of the transformer to the boat ground and there
is an internal short from the shore power primary winding to the frame,
there is no return path for the current so you will not trip the supply
breaker.

In addition, you now have the boat ground, including underwater metal,
live at 110 or 220 volts which can electrocute persons in the water or
boarding from a metal dock.

Andina Marie