Help with Reverse Polarity Issue

Overextended

Member
Feb 13, 2007
307
chesapeake
Boat Info
36
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cummins
Here is the set up - 2 x 30 Amp 110 V circuits on my dock. Two 30 Amp breakers in the fuse panel at my house, wired to two 30 Amp sockets down on the dock (mounted in one of those lighthouse looking towers). Boat has been plugged into the shore power for the last three weeks with two green lights and everything functioning as it should. Today I go out and one of the reverse polarity lights is on....nothing has physically changed in the set up (in my house, on the dock, or in the boat). What gives? How does this happen?? I can understand if it is at some marina and the dockmaster or someone goobers up the connection, but it was fine, nothing was changed and now it is not fine.

Any advice from any electrical gurus would be appreciated.

Thanks!
 
I am not an electrical guru but did have a similar problem last fall with my shore power. The shore power functioned fine then one day it did not and we got the RP light and no power to teh boat. After some searching it turned out to be where the shore power plugged into the transom receptacle. Behind the receptacle box on the boat side , one of the wires was corroded and was causing a malfunction. When the cover was opened up you could see where there had been some arching. The mechanic replace a piece of wire about 6 inches long and we were off, well after we recharged the batteries.
 
I have a shore power cable that one of the leads has a brake in it. If it opens up the voltage drops to 55 volts and I get a polarity red indication. I can make it come and go by flexing the cable.

Look for an open connection and reduced voltage.
 
Cannot comment on the fault, but my number one tried and true troubleshooting method is turn everything off, then turn it back on and see if the fault clears. Doesn't work with my kids but with almost everything else. If the fault reappears, then it is a real issue.

Other than this, how is the new boat doing?
 
I agree with faulty connections if nothing else changed. It is amazing how fast things break on a boat. I had the same problem when I moved 2 miles from one marina to another. I thought it was the second marina's fault, because I just left the last marina with no problems. WRONG. My boat broke in that amount of time. I had one leg of my 50 amp come apart from the connector which made the RP lilght come on. Remember undervoltage causes this as well as real Reverse Polarity because it is just a "quick" check of relative voltage across the different legs.
 
Very odd...traced all the wires (from the dock tower to the breaker panel in the house), good connections all the way to the dock, new cordsets, new boat. Had same intermittant (sp?) problem with power when I had my 320 down there also...which rules out the new boat, b/c it did it with the old boat.

I went down after checking all the connections and checked with a volt meter, plenty of juice but the polarity was reveresed, threw the breakers and unplugged the boat, turned the power back on and the polarity was correct. Next door neighbor advised moving the two 30 Amp breakers in my breaker box (inside the house) from being right next to each other - to being separated by another breaker. So I shut the house power down, opened the box, rearranged the breakers in the house breaker box, and powered everything back up. Good as gold, no reverse polarity yet...seems that may have fixed the issue?? Any ideas on what gives now?
 

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