Very few people use isolation transformers. Everybody should, but ignorance
prevents them from doing so. If you use one, never connect the safety earth
from shore or you might as well not have an isolation transformer. This
isolates your vessel earth. Afterall, the reason to use these is to protect
your hull from leakage current from Granny's decrepid 30 year old vacuum
cleaner on the other end of the marina.
Steve

wrote in message
oups.com...
A question on isolation transformers and their ground path. I have
seen 2 different wiring diagrams. One has the ground from the copper
screen inside the transformer going to shore ground and the other has
it going to ship earth.

My instinct tells me that the former is correct - if there is a problem
inside the transformer the current path is back to shore. If the shore
supply has a RCD/GFCI then it should be detected and the shore side
supply breaker should trip. If there is no shore RCD/GFCI, then at
least the hull potential is not being raised.

With the latter the current path is to hull - which I think raises the
potential of the hull - not a good idea. If there is no GFCI/RCD on
the shore supply breaker, the leakage may not be detected. The ship's
RCD/GFCI will not detect it either as it is installed downstream of the
transformer.

Former at
http://www.victronenergy.com/upload/...ransformer.pdf

Latter at http://www.sterling-power.com - products - isolation
transformer

Comments/Thoughts???