Reverse Polarity

"I am an expert of electricity. My father occupied the chair of applied electricity at the state prison."  - W. C. Fields

Reverse polarity is something that most boaters don't really worry about. Those big yellow (and expensive) shore cords that we use to connect to shore power have carefully designed prongs that keep us from plugging them in backwards.

Our boat has two reverse polarity indicators (tiny red lights) on our power panel and neither of these has ever lit up.

On Saturday evening of Labor Day weekend, we were aboard and Frances was busy preparing dinner. Yes, she was drawing a lot of current, what with both stove elements lit up brightly and the toaster oven just getting warmed up.  That was in addition to the battery charger and the hot water heater. Then the lights went out.

No problem. We know what to check. Circuit breakers?  All on. The breaker at the dock? On and ready. Shore power cords connected? Yes, nice and tight. What the hell? There goes cocktail hour!

Since Bill didn't have any useful ideas, we decided to go to bed and sleep on the problem.

The next morning, Bill assembled all of his tools and got access to the breaker panel (with the boat unplugged from the dock, of course). His theory, based on a good night's sleep, was that the main breaker was faulty. Sounded good and he soon swapped in a new one. But that didn't work either. 

Then he went for the socket into which one of the shore plugs connects to the boat. Unfortunately, that looked good too. Nothing black and burnt.

Then it was down on the wet deck to look up behind the shore power inlet plugs. Maybe a wire had broken off somewhere? Yes, this was a desperation play because we had zero additional ideas. Fumbling up behind the plug we could feel the three wires (black (hot), white (neutral) and green, (ground). Each was routed neatly forward into the boat except the black (hot) wire that first detoured into a fixture mounted between the two power inlets. That fixture was our 1980-era reverse polarity indicator that had never worked. In fact it had been ignored for all the years we have owned the boat and we would never have known its function except for the faint words "Reverse polarity" stamped on its face.

The excitement built as Bill disassembled it and pulled it out of its mounting hole. It had a tiny bulb, long since dissolved in corrosion. Hmm. Black wire goes in energized and come out dead. Time for some quick rewiring!

The original Silverton reverse polarity light removed. No continuity between those two contacts meant no juice to all of the boat except the air conditioning.

It took only a few minutes to butt-splice those lengths of black #10 wire together and fasten the power wires back in place. Even with the door closed, we could hear Frances cheering as all the lights came back on.

Now we have some holes where the old light lived. We'll have to fit something in there. We'll bet that Frances has some ideas!