Installation (continued)
It is possible to verify most connections using an ohmmeter before power is applied. These procedures take a little time, but are recommended, especially if some elements of a previous installation might not have been clearly or correctly labeled or follow the expected color codes.
There are many possible sources that may be selected using this switch, and they may be arranged in any order. The following test instructions are generally suitable for shore and generator installations. The third source may be another shore power inlet
or an inverter or other specialized source.
]Test Shore Connection to Switch
Disconnect the shore power cord from the shore power source and bring the shore plug aboard to a point close to the switch panel. Connect the other end of the shore cord to the boat’s power inlet. Turn ON the shore power circuit breaker between the inlet and the selector switch. Set the selector switch to OFF.
a.Use an ohmmeter to check for continuity from the shore ground plug to the green wire at the electrical panel.
b.Check for continuity from the power cord plug neutral pin to the neutral wire (white typically in US, light blue typically in Europe) at the selector switch.
c.Check for continuity between the line pin of the shore plug and the line wire (typically black in US, brown in Europe) at the selector switch.
d.Check that there is a high resistance between (>1000 Ohms) the neutral conductor and the grounding conductor.
e.Verify that there is a high resistance between (>1000 Ohms) between the shore cord plug neutral pin and line pin. There may be indicator lamps in the circuit, but no more than that with the selector switch in the off position.
]Verify Switch Selects Shore Input
With the shore cord still disconnected from the shore and available onboard, and the generator set not operating, set the load circuit breakers to off, so there is no load at the output side of the selector switch.
a.Verify that the there is a high resistance between the line and neutral of the load side terminals of the selector switch. There may be indicator lamps still attached, so it may not read open circuit.
b.Set the selector switch to SHORE. The ohmmeter should still indicate a high resistance.
c.Short the line pin to the neutral pin of the shore cord and verify that the line and neutral at the load side of the selector show a low resistance when these are shorted and a high resistance when they are not.
]Verify the Generator Wiring
Turn the generator circuit breaker to OFF and set the selector switch to the generator position. All load circuit breakers should still be off. Leave the shore input circuit breaker in the on position.
a.Verify that there is a high resistance (>1000 Ohms) from the line to neutral.
b.Verify that there is a low resistance from the neutral to ground at the load connections.
c.With the generator still not running, close the generator circuit breaker at the generator. Verify that there is a now a low resistance from line to neutral where the generator windings are now connected across the circuit.
d.Verify that there is still a high resistance from neutral to ground and neutral to line at the shore power plug.
]Test the third source in a similar manner.
]Set the Selector switch to OFF, turn the shore power breaker to OFF, and leave the load panel circuit breakers in the OFF position. Complete the mounting of the switch.
]Set your multimeter to volts.
]Test Shore Power
Connect the shore power cable to the shore power source. Turn on the shore source to make power available to the boat.
a.Turn the selector switch to SHORE. No Reverse Polarity lights should be lit, and power available should be indicated. If any red Reverse Polarity lights are on, turn off the shore power circuit breaker and disconnect the shore cord at the shore source. Either the hot and neutral or hot and ground wires have been reversed. Starting at the distribution panel, trace the connections as far back as necessary to locate the error.
b.If there are no indications of reverse polarity, check to see that power is available. If the electrical distribution panel has a meter, verify that shore power is available and at the proper voltage. If there is no meter, turn on the load circuit breaker for an AC circuit powering a convenience outlet and use a voltmeter to verify that power is available from line to neutral at the plug. Verify that there is no voltage between ground and neutral.
]Test Generator System
Turn the circuit breaker at the shore source to OFF. Set the selector switch to OFF. The shore power available lights should all be off. Start the generator and turn the generator breaker to ON.
a.If there are power available lights for the generator output, they should light.
b.There should be no power available indication at the shore power circuit breaker.
c.Set the selector switch to GENERATOR. Power should be available at the power distribution panel. If the electrical distribution panel has a meter, verify that power is available and at the proper voltage.
d.There should be no power available lights indicating at the shore circuit breaker.
]Test the third source in a similar manner.
The Purpose of the AC Source Selector Switch
Alternating Current (AC) power changes polarity 60 times per second in the US, Canada and Latin America and 50 times per second in Europe. This is the frequency of the power and is referred to as Hertz (or the now outdated term “cycle”). Because of this alternating nature of AC power, two live sources of AC power, such as shore power and inverter power, or shore power and a generator, cannot be electrically connected. The AC Source Selector switch is designed to connect two sources of AC power to a common circuit while preventing both sources from being connected to the circuit simultaneously.
Useful Reference Books
•Calder, Nigel (2005). Boatowner’s Mechanical and Electrical Manual (3d ed). Camden, ME: International Marine / McGraw-Hill.
•Wing, Charlie (2006). Boatowner’s Illustrated Electrical Handbook (2d ed). Camden, ME: International Marine / McGraw-Hill.
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•360 Panel System
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