Rod,
I assure you that the earth as referenced by your hull is different than the
the copper plated steel stake at the distribution transformer. There are
rules in every country that prevent power entry equalization busses to be
much longer than a meter for very good reason. Please keep in mind that an
electric impulse propagates across a conductor at 2 nonoseconds per foot. In
a drag race, an electric pulse will travel to a closer point faster than a
further point, even without consideration of path quality. In that light,
ground is not ground the world around. In real life, there can be thousands
of volts in potential difference between two functioning earth references
and very often is. It is one of the reasons that a lightning strike a mile
away can zap all your appliances without striking your property. Ground
problems are very complex, difficult to analyse and very expensive to
resolve. Please also remember that wiring code only allows one reference to
earth in a building. It is illegal and downright unsafe to use water pipes
and other connections as well as the safety reference from the street.
However, a boat is significantly different. The water makes contact with the
earth across millions of square meters of surface. In comparison, the
distribution transformer has only the surface area of the ground rod to use
and I will point out that the quality of the connection is subject to rod
corrosion and the mineral content of the soil it contacts. It is not unusual
for the electric company to deposit hundred pound bags of salt around this
rod in areas of poor soil conductivity and rinse the salt into the soil with
water to help alleviate this problem. Commercial ships (and myself) use
isolation transformers to alleviate this corrosion risk. In that way the
electric energy is magnetically coupled aboard and no circuit reference
exists to the power net. As an individual, you are in control of your
electric domain and accept the responsibility of good practice and
maintenance of the boat wiring and the appliances you use. The question you
have to ask yourself is "Are you willing to accept the consequences of other
people's faults and stupidity?" I am not and I do not use the earth
connection at the dock.
Steve
"Rod McInnis" wrote in message
...

"Steve Lusardi" wrote in message
...


Secondly, when plugging
in to shore power, never connect the safety earth line.


To not connect the safety ground at the AC input plug would be in direct
violation of accepted wiring for boats. If wired that way it would never
pass survey and if a fire or accident happened and investigators found it
wire this way it could create issues with the insurance.

You could leave the boat wired properly if you modified the power cord to
separate out the ground wire. It would be a shame to break the integrity
of
the outer jacket of the cordset, however. If this cord lays out in the
weather allowing water to penetrate the jacket may eventually cause
problems.

Instead use a line
to your boat earth for the safety connection.

Where does one get a good earth connection on a dock? I suppose that you
could drive a copper rod down into the ground beside your slip, and then
make a connection to it with enough service loop to allow for changes in
water level. You better inspect it often to assure that it hasn't
corroded
away.


Remember, your hull will
always be a better earth connection than the one from the distribution
transformer for the pier or yard

Can you explain what you are saying here? It sounds like you are saying
that the path through the water to "ground" is always better than the path
through copper wire to "ground", which is certainly not true.

Rod