Articles: Power

Connecting and Disconnecting from Shore Power

There is a suggested sequence for connecting and disconnecting from shore power and sound reasoning for it.  When connecting to shore power, first make sure the main AC disconnect switch is in the “off” position and connect to the boat side inlet before connecting to the dockside receptacle.  Once connected to the dockside receptacle, check the boat's AC panel for line power and ensure that the reverse polarity indicator is not illuminated. If all is good, turn the main AC disconnect switch to the "on" position. Ideally all the panel distribution circuits would be in the off position also allowing the circuits to be connected individually one at a time, to slowly bring the power demand up to normal usage levels. To disconnect from shore power, simply reverse the above procedure.

The reason for having the circuit breakers off prior to connecting to shore power is the same as turning breakers off before disconnecting; to avoid power spikes from arcing that can occur with connection and/or disconnection of circuits under load.  Arcing, and the resulting power spikes, can harm personnel and equipment faster than protective hardware can react.  Additionally, having the main breaker off before connecting allows a chance to check for dangerous reversed polarity. The reason to connect to the boat first is that if you initially connect to the dockside receptacle, you will be carrying a live circuit for the brief time before you connect to the boat inlet.

- Lyle
PYS Electrical Technician

Comments (3)

  1. Drew:
    Jan 08, 2015 at 01:16 PM

    Is the "main AC disconnect switch" located on the boat or on the shore?

  2. Thomas Arnould:
    Feb 04, 2015 at 10:01 PM

    I agree with the steps you outline. What I wonder is why Marinco seems to think it is a good idea to have a small light at the boat end of the power cord which would presumably be powered by being plugged in on shore, thereby not following the steps you outline.

  3. PYS:
    Feb 05, 2015 at 02:25 PM

    Providing a light at the end of a shorepower is an excellent way of knowing that your shorepower cord is still plugged from the dock. While disconnecting your boat from shorepower, you should always disconnect the dock side end first. The light at the boat side provides a method of confirming weather this step was completed or not.

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