In article . net, chuck wrote:
Yes and no. The type of shield you are thinking about was indeed
intended to reduce noise, and it typically was grounded on the side most
likely to be noisy. The Faraday shields in those "non-marine" isolation
transformers are designed to handle signal-level currents.

My understanding of shields in general, is that the shield should be connected to
the ground with the least noise.

greg




Marine-type isolation transformers (as contemplated by the ABYC) utilize
shields designed to handle the full current rating of the transformer.
Presumably the presence of that shield would cause primary leakage
currents to flow through the shield to the shore grounding wire (thus
tripping a GFCI breaker) rather than through the transformer core to the
secondary. The shield is intended to provide belt and suspenders safety,
rather than noise reduction, although it undoubtedly offers up some of
that as well.

Chuck





Terry K wrote:
As I recall from training many years ago, the shield is a noise remedy.
It seems it should connect to the vessel's signal ground /
counterpoise through a radio frequency capacitor, to cancel and block
noise from the radio circuits, via the ship's neutral connector. The
transformer case and frame should be connected to shoreside "Earth",
and neutral at the power pole / entrance.

This presumes that the shield is not connected to the frame of the
transformer. If it were, I would try it both sides and disconnected, to
satisfy noise and galvanic requirements while at the dock.