"Steve Lusardi" wrote in message
...
Rod,


Please also remember that wiring code only allows one reference to
earth in a building.

Are you referring to the safety ground (a non current carrying circuit) or
the "neutral" ground?

It is illegal and downright unsafe to use water pipes
and other connections as well as the safety reference from the street.

What country are you in? If you had said "instead of" I might agree with
you, but my experience sure doesn't support "as well as".

I admit to not being well versed in the various building codes across the
USA, but I have done a fair amount of house and business wiring here in
California. I have also built a number of products that are sold in the USA
and have had to pass UL and CSA safety agency approval.

The standard configuration that I have always encountered is that "Neutral"
connects back to the power company's transformer (which usually has a
connection to a copper rod driven into the ground) while the safety ground
is referenced to a copper rod driven into the ground at the point of entry.

In addition to the safety ground wired throughout the house it is common for
certain appliances and equipment to establish a separate safety ground.
This is especially important when installing equipment into older homes that
were not wired with the three terminal receptacles. It is very common for
the washing machine to have a extra safety ground. Dishwashers, garbage
disposals, gas dryers, and other appliances that connect to both electrical
and gas/water lines may establish a separate path to ground just by their
very nature.

Many businesses, especially those that work with sensitive electronic
components, will go to elaborate steps to ground all the work benches as
part of their anti-static protection.

Here in the USA it is common for people to install satellite dishes on their
rooftops. The standard installation kit includes a separate ground rod that
provides a safety ground connection to the satellite dish. This in turn
gets connected to the received via the coax cable.

Likewise, cable TV introduces another version of what could be considered
"ground". The shield of the cable coax is connected to ground at the cable
company's equipment. This makes the entire chassis of the cable box "cable
ground". If the cable box has a grounded plug then the two are connected at
that point. Every piece of equipment that connects to the cable box,
including the TV, VCR, stereo, etc. will then have their chassis ground
referenced to some combination of house entry ground, satellite dish ground
and cable company ground.

It is unwise and perhaps illegal to use a water pipe as "the" safety ground.
It would be very difficult to maintain isolation between separate references
and here in the USA it is intentionally done all the time.


However, a boat is significantly different. The water makes contact with
the
earth across millions of square meters of surface.

Yes, but the water itself (especially freshwater) is not a perfect
conductor. The amount of surface area that the water has to the ground is
irrelevant as the water to earth resistance is not significant compared to
the resistance of the water alone. In addition, unless you have a steel
hulled boat the surface area of possibly energized parts of the boat (prop,
shaft, rudder, strut, zincs and through hull fittings) will be very small.



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.

I challenge the concept that breaking the accepted and standard method of
grounding your boat and providing your own is "good practice".

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.

You I fear most of all.

Are you implying that you rely on the water to provide your safety ground
connection? Or have you driven a copper rod into the earth below your dock
and religiously connect it? Do you inspect this installation on a regular
basis (including diving down to inspect the entire length of the rod?)

If you installed an appropriate ground and maintain it properly then you
will be safe. Please convert your boat back to a standard configuration
before you sell it or let anyone else use it.

If you are relying on the water to provide your safety ground then you are
the dangerous one. Okay, you mentioned that you use an isolation
transformer, which would certainly reduce the risk considerably. Without
the isolation transformer, however, your advice is an accident waiting to
happen.

Rod