Reverse Polarity

Status
Not open for further replies.
R

Rob McClain

.
Dec 2, 2003
67
Hunter 340 N. CA
When I leave the boat at the end of the weekend I turn off the A.C. and D.C. breakers and I also shutdown the main A.C. power at the dockside breaker. I have never encountered a power problem onboard, however, when I visited the boat today I flipped on the dockside A.C. breaker and once onboard I turned on the A.C. power at the distribution panel. Upon doing so the red LED lit as normal, followed immediately by the lighting of the red reverse polarity LED that is located below the A.C. switch. I checked power cord and tried all of the breakers a few times, but there was no change and the reverse polarity indicator came on after I flipped on the A.C.

I am not smart electrically, but I know reverse polarity is a bad thing. Any troubleshooting suggestions or thoughts on what I can safely do myself?

Rob
 
G

Grasshopp

.
Jan 22, 2008
18
Catalina None :( Melbourne, Austrailia
first thing to check

First thing to check is if the marina has done any maintenance on the power at the docks. Some time people make changes with out informing anyone else.

Second thing to check is are others at your marina having the same problem, especially at your dock. That will let you know if the problem is on your boat or a supply problem from the dock.

If you are the only one having the problem them based upon your statement I would call a qualified electrician to your boat for a look.

Cheers,

Shane
 
Roger Long

Roger Long

.
Nov 22, 2008
3,562
Endeavour 32 Portland, Maine
Rob McClain said:
Any troubleshooting suggestions or thoughts on what I can safely do myself?
Click to expand
Go to a marine store and buy one of the adapters that lets you plug a standard extension cord into a marina shore power outlet. Then stop at a hardware store and get one of the little tester plugs with three LED's. You should keep this on board for checking outlets at strange marinas.

Plug the tester into the adapter and check hour shore power box. If it reads OK, the problem is on your boat. If it reads polarity reversed, tell the Marina. Check some other boxes up and down the dock. You might get faster action if you can tell them where the reverse polarity begins. If it's just your box or a few, they might check somewhere else and then have to be prodded into action again. My marina refused to believe me when I told them the polarity was reversed because the wiring was done by an electrician (duh). I pulled the tester out of my pocket and that got them to call the guy in.

I leave the tester plugged into the outlet in my galley. As soon as I turn on shore power, I look at it and check that it reads correctly instead of having to hunt for it.
 
Witzend

Witzend

.
Dec 25, 2008
1,580
catalina 310 Elk River
How does his wiring on the boat just mysteriously change? A reverse polarity indicator can also be designed to illuminate when an open ground is detected.
 
Roger Long

Roger Long

.
Nov 22, 2008
3,562
Endeavour 32 Portland, Maine
Stu Jackson said:
Someone fiddled with the electrical outside his boat. That's what Roger's Detective Story was all about. :)
Click to expand
Are you two sure his polarity indicator was always working properly and didn't suddenly activate when a flaky connection was jarred and let the indicator light come on?

It's always worth checking things. When I first plugged my boat in after I got it, the polarity light came on. I said, "Damn PO" and switched the wires. I'd been chasing so many crazy electrical issues (twisted wire connections with masking tape for example) that I could believe anything and just switched the wires at the plug without researching the proper connections. It was just before launch and I was in a hurry. When I moved the boat to the marina, the polarity light came on again. I told the marina they had a polarity problem. After meeting their electrician a few days before and watching him work, I could believe anything. Turns out they didn't. The boatyard had a reversed connection in their supply to the hard.

So, later, after the marina had done some work on their wiring and my reverse polarity light came on again, they could be forgiven for not believing me. This time, however, I was right.
 
druid

druid

.
Apr 22, 2009
837
Ontario 32 Pender Harbour
Witzend said:
How does his wiring on the boat just mysteriously change? A reverse polarity indicator can also be designed to illuminate when an open ground is detected.
Click to expand
I've had the light go on when one (or more?) of the three wires had fallen off (or at least corroded connection). Check all connections (ESPECIALLY the shorepower socket), replace anything that looks suspicious.

druid
 
R

Rob McClain

.
Dec 2, 2003
67
Hunter 340 N. CA
I greatly appreciate the feedback that has been posted. I've now purchased a tester and plan to spend next weekend working from the dock box breaker back into the boat wiring. I'll also be in touch with the harbor master. I have a spare power cord so I'll give that a shot too, as needed. Thanks to all!
 
cat38skip

cat38skip

.
Jun 6, 2004
173
Catalina 38 San Francisco Bay
Every reverse polarity light I have seen on my boat (I've had at least 3) was caused by a failure at the dock connection. The marina replaced the plug receptacle and all was well again. Try plugging into a neighbor's service and see what happens.
 
E

elessard

.
Jan 11, 2010
1
Irwin 34 Citation Warwick Cove
First you need to understand how the reverse polarity works. In most installations it is simply a neon bulb between the white (neutral ) wire and the green ( ground ) wire. Under normal conditions there is no current flow between the white and green. If the black (hot) gets reversed with the white (neutral) wire then power hot side appears on the white wire and current flows through the neon bulb to green and the bulb will lights.
The second condition is when everything is connected properly but the white wire (neutral) is open or corroded (usually at the shore tie connection on the boat). This will cause the white wire to float up to a voltage that can light the neon bulb. In this case the problem is current is restricted from flowing out the white wire and uses the neon bulb to ground as a path. AC devices may or may not operate properly depending on the current they draw.

Hope this helps.

Gene
 
T

tbrantigan

.
Oct 8, 2008
1
Catalina 387 -
Reverse Polarity False Positives

There has been a long discussion of this recently on the Catalina380 yahoo groups site.

What struck me about the original message in this thread was that the light went on only after the boat's shore power switch was turned on. If shore power was at fault, the red light should have come on if the dock switch was on and the boat's shore power switch was OFF.

In my case, I discovered that the light would only come on -- and then only partially -- when I had a 1500 watt space heater turned on. Evidently, a voltage drop caused by a lot of current draw can also make the light glow.
 
B

Barry B.

.
Feb 28, 2005
184
Catalina 22 1909 North East, Md.
When you buy one of the small plug in testers make sure that you get one with a small push button on it, that button tests your ground fault interrupters.
 
zeehag

zeehag

.
Mar 26, 2009
3,198
1976 formosa 41 yankee clipper santa barbara. ca.(not there)
check all of your connections and seee if something didnt corrode or deteriorate....trat your connections if possible with dielectric grease for protection.....
 
Chuckbear

Chuckbear

.
Jan 3, 2009
821
Marine Trader 34 Where Ever I am
Barry B. said:
When you buy one of the small plug in testers make sure that you get one with a small push button on it, that button tests your ground fault interrupters.
Click to expand
These plug in type testers are for home outlets and do give false readings when used on a boat. I find them of little value. Chuck
 
Ron20324

Ron20324

.
Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
Last year while visiting a marina, three times the shore power cord partially came out of a not-so-good receptical on the dock. All three times we were warned via the reverse polarity light coming on. Not exactly sure why that happened, but after the third time we tied it in place. Problem solved.
 
Roger Long

Roger Long

.
Nov 22, 2008
3,562
Endeavour 32 Portland, Maine
Chuckbear said:
These plug in type testers are for home outlets and do give false readings when used on a boat. I find them of little value.
Click to expand
Are you talking about when running from an onboard generator or inverter or from shore power? I've never found mine to give false indications on shore power.

If you are getting false readings on shore power, I would have to wonder if they are really false. Come to think of it though, like many boats, I don't have an isolation transformer. I don't know if they work through one of those. I never spent enough time on shore power to justify the cost of adding one.
 
Chuckbear

Chuckbear

.
Jan 3, 2009
821
Marine Trader 34 Where Ever I am
Roger Long said:
Are you talking about when running from an onboard generator or inverter or from shore power? I've never found mine to give false indications on shore power.

If you are getting false readings on shore power, I would have to wonder if they are really false. Come to think of it though, like many boats, I don't have an isolation transformer. I don't know if they work through one of those. I never spent enough time on shore power to justify the cost of adding one.
Click to expand
These plugs are designed to look for faults using household wiring for the ground and neutrals and boats are done a bit differently. It may not be a problem showing false readings on your boat but they do give false readings in many situations on a boat and this is with shore power, inverters, or generators. My point being that the tests for faults on a boat need to be done with the proper meters and done by someone that has knowledge in doing this properly. Chuck
 
Status
Not open for further replies.

Top Bottom