Wayne.B brought forth on stone tablets:
On Mon, 21 May 2007 23:08:46 -0400, Wayne.B
wrote:


Let's hope that
neutral and ground are not tied together somewhere.


Well, it seems that neutral and ground are tied together somewhere on
the boat. It's not entirely clear to me what the consequences are but
in the short run it is making it really difficult to identify the
wiring.


Please make sure that you have all your AC appliances unplugged when you
are checking...

bob
s/v Eolian
Seattle

RW Salnick wrote:


Please make sure that you have all your AC appliances unplugged when you
are checking...



Also, recall Paul's point that if the
neutral and ground are switched at just
a single receptacle, then the two will
be indistinguishable everywhere.

It is difficult to offer relevant advice
since we really don't know what you are
trying to do. Is it your plan to
correctly wire all the outlets and
appliances? Are there three of these or
thirty? We still don't know if you have
an isolation transformer on board. That
kind of stuff.

Chuck


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On Tue, 22 May 2007 15:10:54 -0700, RW Salnick
wrote:

Please make sure that you have all your AC appliances unplugged when you
are checking...

I had all circuit breakers off.

Whatever your original project was that got you asking this question
(I would like to know that answer also), your single minded priority
now should be either

1) finding a qualified electrician to take over the original project,
or who will at the very least evaulate your boat before you next plug
back into shore power. Such an evaluation can only be successful if
you labeled all the wires as recommended in this thread, and such
qualified electrican tests your work with a meter and inspects each
area you stated you modified.

2) if your not going to do #1 above, then identifying and
disconnecting the place in the boat where nuetral and ground are
connected together and undoing must override anything else your
thinking about doing next. You cannot reliable trace the wires, and it
is commonly recognized as bad wiring practice to have them connected.

3) If even better than #2, just stop and don't do anything if you
cannot do #1. If this project does not kill you, it could kill a
future visitor to your boat if the ground protection isn't working,
could kill someone in the water near your boat while it is plugged
into shore power, and can bring with it numerous problems of stray
current to your boat or those nearby.

On 23 May 2007 08:19:00 -0700, b393capt
wrote:

Whatever your original project was that got you asking this question
(I would like to know that answer also), your single minded priority
now should be either

The original project was to undo some haywire installed by a previous
owner for a battery charger. I also need to run in a new circuit to
an unused breaker on the AC panel.

Whatever the cause of neutral and ground being tied together
somewhere, I suspect it has been that way for quite awhile.

I'm probably missing something but I don't see too much immediate
danger unless we end up somewhere with the shore power backwards.
That's dangerous in any case.

What are the other risks?

On Tue, 22 May 2007 02:54:15 +0000, Larry wrote:

The
ground pin on the dock plug is plainly marked. It's L shaped.

It turns out that the L shaped pin is ground only on the 20 and 30 amp
connectors. On a 50 amp connector it is neutral:

http://www.marinco.com/docs/guides/Boater'sGuidetoACElectrical.pdf