Originally Posted by Fearnow
Now I'm having the same problem. Nothing has changed at the marina. The only thing I did was plug in an electric heater for a few hours and the next day the light was on. I came on a few months ago, briefly, but no problem since. I checked all the wires at the panel and the main ac breaker.
Any other ideas? Will a loose connection somewhere cause this?
Is this the reverse polarity light on the charger
or is it a separate RP light/circuit.
Things are always changing at the marina - corrosion
etc. in the shore box for example.
The quickest test is to plug the shore power
into a different shore box, making sure it is a different supply circuit and not the same leg of the shore power
. Then try a different shore plug/cable.
This may isolate shore box vs. boat vs. cable.
The next step is to isolate all the A/C circuits on the boat one at a time. Activating each circuit one at a time to see if you can isolate the circuit causing the fault (you state the heater might be suspect).
So far this can all be done without a meter or opening stuff up.
After that you are likely going to have to get a meter out and start metering stuff. This can kill you and you may want to let a pro step in depending on your experience level.
If you don't have it get Nigel Calder's book, "Boatowners Mechanical and Electrical
Read and reread the chapter on reverse polarity and then read the table on A/C electrical circuit troubleshooting. If you can't grasp it get a professional sparky involved.
BTW - if the RP light is on and the charger
is still supplying power to the boat (and hasn't auto shut down) you must assume that neutral is hot right now.
There is a condition that will result in what you describe. Because reverse polarity is checked by potential from Neutral to Ground. Under a high load situation (heater) a high resistance in the Neutral circuit - all the way back to the shore box can create a voltage drop in the Neutral leg that changes to potential between Neutral and Ground that is read as a reverse polarity.
In this case you must make sure that the wiring
to the high load device (heater) especially the Neutral leg is adequate sized and clean and low resistance. A high resistance in the shore plug conneciton can do this also - clean all shore power conections and inspect the shore power plugs and receptacles.
The most common failure in shore powere is plugs, receptacles and connections.