What is reversed polarity?
I have heard a few people trying to explain it and getting it woefully wrong, but actually its very straightforward.
Basically, in a standard mains electrical system there are 3 wires;
Phase/hot/live — the main current carrying conductor or wire.
Neutral — the second current carrying conductor required for completing the circuit.
Earth/ground — the safety wire in case of an electrical problem.
In a perfect world, all the correct wires are connected to their respective same wires any time mains electricity meets, the most common time that reverse polarity will occur on a boat is when connecting to shore power, when you go from your home port (or sometimes even to a different mooring in the same port), for whatever reason, the wires in the dockside pedestal are not wired the same as on your boat, so the neutral of the boat is connected to the phase on the dock and the phase of the boat is connected to the neutral of the dock, this is reversed polarity.
A lot of boats (especially older European ones) do not necessarily have a polarity indicator to tell you when things are or are not connected correctly, the problem potentially is that your current protection will now be on the neutral wire instead of the phase wire. It has to be said the USA built boats seem to be much more up on this subject, it´s very common to have the mains electrical panel with a polarity indicator.
Fixing the problem
Actually it´s very simple, unplug the boat from the shore power and swap over the neutral and phase wires in the plug that goes into the dockside, plug the shorepower back in and the problem should be solved. Never move the earth wire to another terminal.
The usual sign of reversed polarity is immediate tripping of the dockside breaker when you switch on main breaker on your boats electrical panel.
If changing over the phase and neutral wires does not cure the problem, please stop and seek a qualified electrician. It might not be a boat problem and could be a dockside pedestal problem, either way you do not want to risk leaving it unchecked.
Retrofitting a polarity indicator
Polarity indicator main switch. Most boats have the main breaker for the boat located on the AC electrical panel, sometimes there is another breaker in between the shore power inlet and the main electrical panel too (when the distance between the inlet on the boat and the main breaker in the electrical panel is long). Replace the main breaker with one that contains a polarity indicator, Blue Seas Systems make polarity indicator main breaker panels.
In summary, you now know what reversed polarity means, how it affects you and your boat and how to solve the problem.
I hope you have enjoyed reading this post. Please feel free to follow me on social media.
Comments
Post a Comment