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HELE MAI OPERATING MANUAL
NW Explorations
4F4: AC Shore Power Connect
The large “GEN - OFF - SHORE 1 - SHORE 2” switch on the AC Power Supply panel are
used to determine the source of AC power for the boat. The “Shore Power” switch
should always be “OFF” whenever you are connecting or disconnecting the boat to
shore. This is true so that you do not draw an arc from the plug due to the load of the
boat on the connector’s pins: such an arc will burn the contacts and eventually cause
them to overheat when in use, creating a fire hazard.
The switch determines which shore power outlet you’re using: “1” is Forward, “2” is Aft.
Select the one you’re using by the switch.
Once connected to shore power, monitor the AC voltmeter and ammeter to be sure you
have not overloaded the circuit.
Important Note: If the house batteries are low when you first hook up to shore power,
and the inverter is turned on (as it should be), the inverter will begin charging its batteries at a very high charging
rate (up to 125 amps of charging), drawing a lot of shore power current. Until this demand reduces (see “AC Inverter
System” above), you should turn “OFF” other high-current AC appliances such as the water heater.
You can then turn on AC appliances as needed. Watch the ammeter to be sure you don’t exceed the dock’s available
supply, typically 30 amps.
Here are some estimates of typical AC power consumption for various appliances:
Water Heater 15 amps
Inverter
up to 30 amps
Hair Dryer
12 amps
TV
1.5 amps
Coffee maker 10 amps
Microwave
12 amps
Toaster
12 amps
Washer/Dryer up to 20 amps
If you overload the shore power connections, you may trip the dock breakers, or the boat’s own breakers on the left of
the switch.
4F5: AC Shore Power Reverse Polarity
Although we tend to think of AC Electricity as having only two conductors, it actually has three. One of these is called
“neutral”; one is “hot”; and one is “ground”, that is, it is supposed to be the same as the water around the boat and the
earth ashore.
The vessel and many of its appliances rely upon these connections having the correct “polarity”, or relationship to one
another and the earth; this is essential to be sure that users of AC equipment do not get a shock when touching and AC
equipment.
Now in a house ashore, it’s easy: We don’t “plug in” the house, for it stays connected to the utility company all the time!
But in a boat when in the harbor, we do plug in using our Shore Power cords (and sometimes using extension cords). If
the outlet to which we plug our cord, or if the cord itself is mis-wired, then these connections can become mixed up, and
then there is a significant chance of getting a shock or just as bad, a chance that running gear outside the boat will be
subject to rapid corrosion, because the boat is immersed in sea water, a good conductor of electricity.
To protect the vessel and its crew from such contingencies, a “Reverse Polarity” light will illuminate when the connection
turned on. The light for the forward power connection is located in the portugese bridge, in the case of the aft
connection it is located in the lazarette.
If the red “Reverse Polarity” light should illuminate when connecting to Shore Power, immediately disconnect the
cable and contact the harbor master advising him/her of the problem. Do not risk shock or system damage!
Shore power/generator selection is
made on the ACPower Supply panel.