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posted to rec.boats.electronics
chuck
 
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Default Power cord ground terminal grounded to thru-hulls

Larry wrote:
chuck wrote in news:1150477032_23465
@sp6iad.superfeed.net:

f the water heater is on a 250/125 volt
circuit there can be no GFCI.


Huh?? The boat's plugged into a GFCI, it's got a GFCI!


Then the boat is plugged into a 125 volt
circuit and not a 250/125 volt circuit,
isn't it?

Remember what is meant by a 250/125 volt
circuit: center tapped 250 volt
secondary which supplies one or two 125
volt circuits and one 250 volt circuit.
If your shore power cable connects to
the 250 volt receptacle, it will not
have GFCI protection at the pedestal.
Your boat will NOT be plugged into a
GFCI on the dock in that case.

The ONLY way you can use GFCI protection
with a 250 volt circuit is if the center
tap is grounded and no 125 volt circuits
are connected. Pure 250 volt: L1,L2,G.
If you connect one or two 125 volt
circuits using the center tap as
neutral, the two hot legs will almost
always be unbalanced (i.e., unequal
loads) and using the presence of a
differential current as an indication of
a ground fault will be futile. There
will almost always be a differential
current of more than 4 milliamperes.



Do you see a lot of water heaters
operating at 125 volts?


All the boat hot water heaters on the boats I have anything to do with are
125VAC...


Yeah, I didn't realize that the 125 volt
models were so popular. Appreciate the
recalibration though. But they do make
250 volt models also.

Chuck


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