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From: ahmet erkan (no email)
Date: Sat Jul 02 2005 - 10:11:45 EDT
>We now have a 2 core shore connection, that goes direct to the isolation
>transformer. The core >of the txfmr is ground, and the rest of the boat is
>connected to that, including all the appliances.
>
>The moral of the story if you have a metal boat, watch out for electrical
>activity close to the dock >you are tying up at. There are commercial
>devices for measuring this activity, but a multimeter is >just as good.
>This is a huge subject and it cannot be done justice in an email, there are
>many >good books. Suffice it to say, if you lift your ground wire, and
>measure DC voltage between it and >the docks ground, LOOK FURTHER, you do
>have a problem, but it might be your neighbours >boat, or the steel in the
>concrete of the dock itself, or it might be the radio alarm clock next to
> >your bed.
I agree with Gilana above that a quick measurement should be made prior to
mating the shore connector. (See NOTE 2 Docking procedure of the Shore Power
Interface schematic at http://home.comcast.net/~aerkan/ )
Measurement of current rather than voltage might be more useful. Any
recommendations or measured data about acceptable levels of leakage current
is welcome to put numbers in place of the TBD’s (ie: To Be Determined)
Grounding the isolation transformer core to the boat ground could destroy
the Galvanic isolators and cause other problems if the transformer fails.
Isolation transformer frame should be insulated from the boat and connected
securely to the shore power ground. (see NOTE 12)
Electrical discussions can get very confusing and boring when the big
picture is not seen. To enhance the readability of postings about electrical
matters, my suggestion is to include the boat’s wiring diagrams in a
website. Lengthy explanations and ambiguities might be avoided if your ideas
are documented in a schematic with accurate notes.
Fair Winds,
Ahmet
SV8827
http://home.comcast.net/~aerkan/
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