Reversed Polarity Indicator

[Steve]

I'd appreciate any feedback on this topic- I'm stumped but that's not saying too much sinece my experience with AC circuits on boats is minimal. Here's the situation-- We've keept our sail boat at a condo in Florida for the last three years- same boat, same shore power so no changes there. We had air conditioning installed recently and the installer reported everything was working fine. When we arrived at the condo today and I connected the shore power the "Reversed Polarity" light came on. This was the first time I've seen it come on since owning the boat so I'm not too sure what could cause the problem. Since the air con was the only known variable I disconnected the air con circuit completely from the breaker panel but still got the "revered Ploarity" indicator.What else could likely cause this problem? I believe it is supposed to indicate the neutral wire is the grounded conductor and not "hot"??? COuld the main AC breaker have gone bad? If I switch the main AC breaker to the "on" position and check the shore power input connector there is no resistance between any three of the leads.As I said- any info would be appreciated

 

[Bill]

Reversed Polarity

Steve,I awoke one morning recently and had the reverse polarity light showing on the electric panel. I checked the boat and everything was okay. I went over to the dock outlet and found the problem was there. The marina told me later in the day that the neutral wire burned up underground near my boat.Hope this helps,Bill

 

[Don]

I had the same mystery

What kind of boat do you have? I just bought a '93 37.5 that worked fine when I first saw it. Next visit, the reverse polarity light went on during my visit (I was running the heater.) We searched and tried everything but could not determine the problem..Problem was one of the two breakers in the aft lazerette (which I did not even know there there at first),on the battery switch panel had tripped. My father can explain much more of the electronics that I can, but resetting the breaker fixed the problem. There is a breach on each of the black and white sides of the line (not a good idea as I hear it now.)In fact, the breaker was weak and kept tripping with any sort of load. I ordered another one from Hunter, installed it and all has been fine since.My case was a mystery because everyone, including the broker knew there was no problem at first. Luckliy my father is the genuis in the family. Since you've installed a new a/c, could be the breaker is weak and tripped.Try it. And good luck.Don

 

[Rodney Kidd]

Reverse Polarity Light

Steve,This is can be a very dangerous situation, I'll try to explain. The light (a 110 volt neon light) is wired between the ground (green wire) and the neutral (white wire) of your shore power inlet. The neutral and ground wires should be at the same potential voltage wise. In other words, A voltmeter attached to the ground and neutral wires should read no voltage. If for some reason, the dock outlet, shore power inlet on the boat, or the shore power cord is miswired and reverses the hot (black wire) with the neutral wire, the light will come on to warn about the "reverse polarity. Reversed polarity connects the hot side of the shore power to the wrong side of various appliances you may have on your boat. For example, if you have an electric drill with a metal case, normally the case is connected to neutral, and the hot runs the motor. Reverse it, and now the case is hot! If you were holding the drill and contacted anything grounded, mast, keel bolts, engine, etc., ZZZAAAAAAAP! You become the conductor which is not good for your health. The bad part is that most appliances will work properly. This situation is like a snake waiting to strike. In this scenario, the reverse polarity light would be lit brightly. If the polarity light is lit only dimly, the problem is either a broken or bad ground or neutral wire. The problem could be as simple as a worn out shore power connector. Make sure you check both ends. This is dangerous as well since any fault in the tool or appliance will once again cause you to be the conductor if the right circumstances are present. The polarity could truly be reversed especially if the marina has had electrical work done recently, you've changed the shore power inlet on the boat, changed either end of the shore power cord, and less likely, bought a new shore power cord. Call me at 925-692-8013 days if you want to discuss further or e-mail me at rodney_k@hotmail.com.Rodney KiddC-38 #297, Flying Bear

 

[Brad Elbein]

Many thanks

Rodney: This is one of those things on my C30 I've always wondered about. Thank you for your explanation. I read this site regularly for education, and your post ranks up there with the best.