Reverse polarity on shore power (O'Day 35)

[rfkneller]

I have a 1986 O'Day 35 which I purchased two years ago. At my marina I am on a mooring and have never previously used shore power.

Tried to hook up the shore power at the marina I was visiting this weekend and the polarity tester lit up and buzzed. Tried connecting to different outlets and no difference. Can anyone suggest source of problem and what is the fix?

[skipmac]

Could be a nber of things.

1. Bad wiring at the marina. Possible but unlikely.

2. Bad, corroded or broken wire in your shore power cord or plug or switch.

3. Bad, miswired or damage in your wiring panel.

Reverse polarity lights if I recall can activate if there is a voltage difference between the ground and safety wires
A bad connection from any cause on the neutral can show as reverse polarity.

Sent from my SCH-I545 using Cruisers Sailing Forum mobile app

[rwidman]

Originally Posted by rfkneller

I have a 1986 O'Day 35 which I purchased two years ago. At my marina I am on a mooring and have never previously used shore power.

Tried to hook up the shore power at the marina I was visiting this weekend and the polarity tester lit up and buzzed. Tried connecting to different outlets and no difference. Can anyone suggest source of problem and what is the fix?

If you have never connected your boat to shore power before this incident, there is probably a wiring problem on your boat. It's unlikely that several outlets at the marina are miswired. It is possible though. Did you ask any of the other boaters if they had a problem? Did you ask the marina manager about it?

Before you get too involved in this, borrow a shorepower cord from another boater who is not having a problem and connect your boat with his/her cord. If the problem goes away, it's your cord that is causing the problem. If not, there is a wiring or equipment problem on your boat.

On a boat as old as yours, there could be many different things causing the problem including miswiring by a previous owner. I suggest having a qualified marine electrician check find and fix the problem and do an inspection of the entire electrical system. Electricity and water make a lethal combination if things aren't done correctly.

[Calif.Ted]

I'd check the source first, a polarity checker is less than $10, I carry one on the boat.

[rfkneller]

Thanks for the replies. The shore power cord was brand new.

After reading other threads I think I was mistaken about the reverse polarity indicator. I think I was throwing the test switch and it was indicating that the alarm was in working order.

The problem could be the very old GFCI outlet at the electrical panel. I have seen them become non working with age and that one could be about 30 years old.

If it is not that, then it will probably be the wiring in the boat which has been modified and added to by previous owners.

Thanks again.

[reed1v]

polarity problems abound in marinas. The Ala Wai boat harbor was(and probably still is) notorious for polarity issues.

That along with surges, brown outs, and shorts makes life interesting for slip holders most everywhere. Many folks just ignore the polarity issue as well as ungrounded dock wiring. Occasionally a boat will catch fire or someone would loudly swear. Portable GFI at the interface helps at least to prevent getting fried.

[captstu]

If the problem is tripping of the GFI on shore, it may be the marina power is not adequately balanced. If many of the users are 115 volt users the neutral circuit i the marina can rise above ground causing the GFI to trip.

If you are comfortable, measure the difference between the ground and neutral (white and green) on the shore - the round outlet and the longer outlet on a 115 volt outlet - if it is more than about .3 volts, the GFI will trip - and only the marina can fix it - unless you choose to not use the marina ground - something you should do only with care.

[Symphony]

over the years I have seen wiring problems in the marina pedestals serving transients. That's why they become the transient slips!

but, if you haven't used shore power in decades there is likely a problem on your end.

[michaelratinter]

There is also a difference in wiring between 50 amp and 30 amp plugs. Found this out the hard way.

[Cadence]

Originally Posted by rfkneller

I have a 1986 O'Day 35 which I purchased two years ago. At my marina I am on a mooring and have never previously used shore power.

Tried to hook up the shore power at the marina I was visiting this weekend and the polarity tester lit up and buzzed. Tried connecting to different outlets and no difference. Can anyone suggest source of problem and what is the fix?

With a new shore power cable, as you said, rule that out. Get a cheap meter and check the polarity you're getting. If in fact you have a problem check your own wiring. If you don't feel comfortable hire someone. I have read someone else close by that is upside down polarity wise can cause problems with testers.
Not sure I buy it but could be.

[ramblinrod]

Originally Posted by rfkneller

Thanks for the replies. The shore power cord was brand new.

After reading other threads I think I was mistaken about the reverse polarity indicator. I think I was throwing the test switch and it was indicating that the alarm was in working order.

The problem could be the very old GFCI outlet at the electrical panel. I have seen them become non working with age and that one could be about 30 years old.

If it is not that, then it will probably be the wiring in the boat which has been modified and added to by previous owners.

Thanks again.

Correct. Some shore power systems were equipped with a "Test" Switch that enabled one to test the "Reverse Polarity" Indicator light.

For all shore power system equipped with reverse polarity detection:

1. Shut off the marina power post AC breaker that you intend to use.
2. Shut off the vessel main AC breaker.
3. Connect the shore power cord to both power post and vessel.
4. Turn the power post breaker on.
5. With the vessel main AC breaker off, check the reverse polarity light. (It should be off, if RED you have an issue.
6. If equipped, flip the reverse polarity test switch. If the Reverse polarity indicator does not come on, you can't trust the detector, get it fixed before flipping the main AC breaker on.
7. If the reverse polarity indicator is off, when connected to shore power, and on when the test switch is depressed, all is well, turn the vessel main AC breaker on.

[foufou]

I have twice found mis-wired marinas or boatyards. Once was called to investigate why some workers on the boats were getting shocks from the prop and bronze rudder. turned out to be a junction box up the ways just inside the service building. check the source first. the guys getting the shock could have been seriously injured or worse. F

[Defeverboat]

You need to check the breakers at the dock. The last marina put 180 volts into my boat burn't up a a/c unit. Took them a week to put a new breaker in no power for a week!

[SV Bacchus]

Back in my RV'ing days we had something like this:

https://www.amazon.com/Progressive-I.../dp/B002UC2UB8

240V/50A surge protector that also checks the polarity at the source it is plugged into. In campgrounds you would plug this into the power pedestal and your 50A power cord into it.

Would something like this be good in the marine environment? Or is the wiring at the boat's power panel supposed to sort all this out? From all the recommended testing offered by others in the string above I don't believe the boat does sort it out and protect itself.

I just don't know if this $136.00 is a wise investment or a waste of money.

The one I had actually fit in a bay on the RV and the long cord run came from the pedestal, through a hole and into the protector then to the power panel. That setup kept people from stealing it!

[jessehunt]

I had the a similar problem with a Watkins 28, and mine turned out to be the neutral and ground wires on the boat being switched.