reverse polarity alarm

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dave

Have been having recurrent alarms from a reverse polarity alarm buzzer and indicator light on an O'Day 28. Boat was rewired by a previous owner and this was a lingering problem, which I don't think was ever solved. Basically the buzzer and light come on when attached to shore power and a load is put on any of the circuits (receptacles, or hot water heater). Shore power is correct, good cord, tight connections, correct polarity at the dock connection. This reverse polarity detector (buzzer) was wired in like this: the red lead was attached to the top of the AC main breaker with other white wires. The black lead was attached to the 12V negative bus bar, which seemed strange and incorrect?? Does anyone know if that was the correct hook up? Is this just some sort of buzzer unit basically? I have removed it and everything seems okay. The receptacles test indicate correct polarity, water heater works, and remaining reverse polarity indicator warning light is NOT on. Was the buzzer unit pictured wired correctly? Anyone know how to test this thing? Perhaps there is still a lingering wiring problem...it's a fair mess. Thanks for any help, insight, info. dave
 
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Bob

White and Black

Hi Dave, The AC hot lead is black. The white lead is common and ~ ground potential. The Green lead is ground potential. (per code) DC common is black and ~ ground potential. DC 12 volts is red. Think reverse polarity indicator would connect red to AC hot and black to AC common. Wire colors used are not standard for AC wiring - standard for DC wiring. AC WIRING AC hot (black) connects to the line side of the ac at the circuit breaker panel and ac netural (white) to common side. Circuit breakers connect to ac hot. Each load like a hot water heater will have a black wire (connect to circuit breaker) and white wire (connect to ac common) to power the device. You need to be sure the AC wiring is right -reversed is unsafe and potentionally lethal. Any marine equipment installer can check / correct. Good Luck, Bob
 
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R.W.Landau

Sounds like

Dave, It sounds like the previous owner wired it as if it were a 12 volt DC device. I would disconnect the device, test the circuits with a hand held polarity tester then try to rewire it with black being hot, Then test again. r.w.landau
 
Jun 2, 2004
1,438
Oday 25 pittsburgh
rethought

Dave, I would remove it, and test your circuits. I have rethought this and I would not wire the device back in. Call the manufacture and request info on your device. It could be that this is a 12 volt polarity device that your owner wired into 110. r.w.landau
 

RAD

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Jun 3, 2004
2,330
Catalina 30 Bay Shore, N.Y.
Had the same device on my 32 ODay

I'm a master electrician and while rewiring my boat I came across the same device. It was disconnected and being a little hokey looking I decided to remove it, I purchased a new ac panel with LED reverse polarity indicator built in. I do know that none of those wires should be connected to the dc system.
 
Jun 8, 2004
100
Oday 35 Toronto, Ontario
My 35' O'Day...

has the same buzzer. I have a schematic that I drew last summer of the wiring and although I didn't indicate the colour of the wires for the buzzer, one side goes to the pilot light and the other side goes to the AC main white neutral wire. The other side of the pilot light goes to AC main black (hot). I also have a reverse polarity light that has one side connected to the AC ground green wire and the other side goes to a toggle switch which is normally connected to the AC Main neutral white wire. The other side of the switch (in test mode) goes to the AC main black wire. I once connected to a marina outlet that had the hot (black) and neutral (white) wires reversed. The buzzer sounded and the reverse polarity light came on. I disconnected quickly.
 
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dave

update

I appreciate all the thoughts and information. I called Raritan today and it's a 120V reverse polarity indicator, basically a "buzzer in a box" is really all it is. The red wire attaches to the white AC neutral wire at the main breaker on the boat panel, I think he said on the incoming side of the breaker, so when you plug into shore power which has reversed polarity the buzzer will come on immediately. The black wire attaches to the AC green ground somewhere, which leads back to the ground at the shore power box. Thus, if white is "hot" for some reason (reversed polarity), the buzzer will buzz since it is grounded. I'm learning about this and still confused about the AC grounding system (bonding), green wires, being connected (or not??) to the DC negative system, but I'm still reading... thanks again for the responses, dave
 
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RAD

Good books on the subject

Boatowners wiring handbook by Charles Wing & Boatowner’s Mechanical and Electrical Manual by Nigal Calder
 
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