Thursday, June 23, 2022

Shore Power Reverse Polarity Test at the Boat

110v Disconnect Switch and Reverse Polarity Testing on our Boat

When we purchased our 1087 Catalina 34 in 2015, I was blissfully ignorant about the boat's 110v electrical system. Since then I have learned a lot, hopefully the changes I have made and the changes I plan to make are a whole lot better than what we started with.

The boat had a Reverse Polarity indicator on the Main Electrical Control Panel and it had a 'Test Lamp' switch. Whenever we went to an unfamiliar dock and plugged into the their shore power, I would observe the status of the Reverse Polarity Lamp, it never lit, which meant we were not connected to a reverse polarity 110v Pedestal, I would operate the test switch to check that the lamp was working. It always worked.

The problem was ( as I found out this past week) that the lamp was not connected for reverse polarity indication, just to illuminate when the test switch is pressed.

During my design for the new Electrical Management System, I included a reliable Reverse Polarity Indicator and Test.



The Switch is a On-Off-(On) switch, it's normally Off, can be switched to the On position which would test for reverse Polarity and it can be momentarily switched to the Test Position which would check that the lamp is serviceable.

All of this is installed inside the 'Shoer Power Disconnect Switch' box mounted under the Nav Table a few inches from the Victron Multiplus 12-3000-120

The reason for moving the disconnect to the Input of the Inverter Charger rather than the output is a safety issue.

With this setup, we can move the disconnect switch to the off position, connect the boat to the Shore Power and confirm that power is available as shown by the Green Shore Power Available Lamp. Then operate the Polarity test, in the On position if the lamp lights, then the polarity is reversed, if the lamp does not light, then it should be tested by operating the Momentary On Switch which connects the lamp to the Live and Neutral lines, if the lamp lights, then we're good, if the lamp does not light, then it's a dead lamp. In that case we'll have to test the pedestal with a Multi meter before accepting the power is ok and then closing the disconnect switch.

The procedure for attaching shore power is:
  • Select Off at the Disconnect Switch
  • Connect the shore power cable to the boat
  • Connect the shore power cable to the Pedestal
  • Check for reverse polarity.
  • If ok, then Select On at the Disconnect Switch.
The process for disconnecting Shore power is:
  • Select Off at the Disconnect Switch
  • Disconnect the Shore power cable from the Pedestal
  • Disconnect the Shore power cable from the boat
Another project completed.

See you on the Water.

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