reverse polarity warning light

[davidlaw]

I have a SO 39DS and recently noticed that the 'reverse polarity' LED light on the panel is glowing - faintly, not bright like others when switched on. I am not sure if it is just picking up background light from the adjacent 'AV mains' shore power indicator LED.

I had the shore power and on-board 240V mains circuits checked out and all were declared OK.

I looked at a neighbour's 36i and his had the same glow - his panel was different but again it was close to the AV indicator light.

Anyone else got this?

[rhb]

Ours does the same thing on a 42I David - I suspect it's normal. The only way to find out for sure would be to intentionally change the polarity to be 'wrong' and see if it then glows brightly.

We also had a qualified marine electrician check ours and he found that the factory had in fact wired every 230 volt outlet backwards. He changed them all. I don't recall what the reverse light did before he made the change - I think he may have changed them before we ever plugged the boat in.

Roy (Asylum)

[davidlaw]

Thanks Roy

To think I had to write an intergalactic message when I could have strolled down the boards! But that means the 3 Jeanneaus on our jetty - I take it you were there - have the same thing. I will have a look at it when next berthed at Kettering and let you know.

David

[Don Reaves]

The galaxy appreciates knowing when there might be a problem, so it wasn't a waste of time.

Thanks,
Don

[grantgoulding]

The light on the panel is to check the potential between the earth and the neutral. I have had the light appear when abroad and it means that there is a voltage between the earth and the netural on the dockside. In this country (uk) you would normally find the neutral is grounded to the earth so there would be no chance of a shock between the two. The light would also light if the neutral and live were transposed on the dockside connections. So it may be important or not depending.

[davidlaw]

Thanks Grant

There certainly seems be no' transposition'. Can you tell me, when your light went on overseas, did it glow brightly (like the other panel LEDs) of just faintly? Save me having to test!

David

[grantgoulding]

Hi David
It depends upon the voltage between the two. In my case it was bright enough to see but not as bright as the other lights.

[nac]

I had the same problem.Reverse polarity light on. Iwas a bit worried so i changed plug to another socket and the light went off.so it was just an isolated socket. would it have done any harm if i had not noticed it'
nac

[davidlaw]

Thanks everyone

Roy, I think I have solved the puzzle, or at least identified it now, thanks to the feedback from everyone. It turns out that all the Jeanneaus on our pier are showing a faintly glowing reverse polarity indicator. I took my boat to another marina today and the light did not show there, so clearly there is a potential between neg and earth on the KP shorepower source.

Whether this is significant, dangerous etc., or not I do not know, but have reported it to Tasports' electrical engineer to sort out.

QED!

[rhb]

Good catch David - our boat is at the RYCT till March but we'll be back to KP then - good of you to sort out the power for us :-)

[afjjones]

I think it is important to understand that reversed polarity can indeed be dangerous. Some peices of 230volt equipment only have their isolating switches connected in the live conductor. If polarity is reversed then the switch will be in the neutral conductor. Equipment will cease to function, when switched off, but any conductors inside the device will remain live with respect to earth. A shock risk therefore arises should these conductors be inadvertently touched. Therefore always unplug 240volt equipment before servicing!!

[because]

I have had the reverse polarity light, along with a couple of other panels lights glow faintly. I noticed this when I first boat the boat ( 2008 45DS) and had the dealer check it out. Bottom line is they could not find anything that would cause it. Now, sometimes they light up, most of the time they don't. Strange.

[SteveT]

I've had a similar experience on my SO39DS in the following scenarios:

When connected to a portable generator (not earthed) the light glows very slightly.
Very occasionally when connected to shore power at different marinas the light has been slightly on.

However when there was an issue with reverse polarity at a specific marina the light was very bright. The difference is very obvious. The upshot is that I'm not overly worried if there is a very slight glow however I would be if the light was bright.

[deandavis1]

I have the same thing on my 45DS. I was under the impression this was a circuit breaker because unlike the other lights the plastic indicator protrudes out (like a breaker). I will pay more attention to see if it changes at different mariners. It does happen with using the generator as well.

[ubuysa]

Whilst you're investigating reverse polarity issues it's probably also worth looking at some form of galvanic isolator or isolation transformer to prevent galvanic corrosion of your boat's anodes (and then more serious metalwork) because of faulty earth (ground) wiring in some marina shore power systems. This is particularly important if you plan to visit marinas in some of the less well developed parts of the world where the electrical installations may be less than ideal.

We have an isolation transformer, that means there is no direct connection between the boat's mains power supply and the shore power supply. That protects us completely from galvanic corrosion caused by bad marina wiring, but it also means we don't care whether the polarity is reversed in the shore power.

In our winter marina (on Crete in Greece) our pontoon is known as the "anode eater" because most boats moored on it suffer excessive anode corrosion (probably from bad shore power wiring). We do not suffer from this problem at all.

[Vivacité]

My 2012 SO 409 (USA Hull No. 54, South Carolina production) is exhibiting this glowing A/C reverse polarity light as well. It does not happen all of the time. My slip is in a new marina, and the staff was kind enough to hire an electrician to come out and do a thorough testing of my dock's shore power...ALL GOOD.

In addition, while my dealer was troubleshooting other electrical problems on my 409, including this glowing reverse polarity indicator, they too found NO problems with the shore power at my slip.

I do have a galvanic isolator installed as well.

Many electrical mysteries on my boat, since delivery, still not solved.

[Vivacité]

Vivacité's Panel showing electrical gremlins:

GOOD: Bright LED's: AC Power LED with shore power applied to vessel, switched on DC Cabin Lights and switched on Bilge Pump in Auto (proper LED indications here)

BAD: Glowing reverse polarity indication on AC...

Also BAD: faintly glowing Deck Light LED (switch off) and faintly glowing Steaming Light LED (switch off). The dealer isolated the VHF antenna on the mast and then these two LED's quit glowing. Except when it rains...Hmmm

I apologize for the grainy photo, I had to take the photo in low light to expose the glowing LED's.

[Vivacité]

GOOD: Photo of Vivacité's Panel Behaving...Normal Indications.

VHF Antenna Isolation Seemed to solve glowing LED's of Deck Light and Steaming Lights when both in switched off positions...except when raining.

And in my same slip on shore power...note: no glowing AC Reverse Polarity indication. This to date is still an intermittent problem, at my marina and others.

[mpj]

My take on the symptoms.

VHF antenna isolation: Solved the symptom, but did not cure the underlying problem. Isolation cuts the current path from antenna to the wires of the motoring and deck light, so no glowing. Rainwater acts as a conductor, bypassing the isolation and the LEDs glow. Somehow there is a voltage difference between the VHF antenna (the antenna and VHF unit ground) and the switchboard LED ground AND there is a current path from VHF ground to the positive wires of the steaming & deck lights. As they both glow, this is likely to be through the ground of the lights and then through the bulbs (at least in my boat they have a common ground wire). However this would require that the light ground is also poorly connected to both the VHF ground AND the switchboard ground. All prevuious just pure guesswork based on the symptoms

Reverse polarity warning light: Most likely just an indicator that there is a heavy load (e.g. one or more boats with water heaters on) on the shore power supply. This causes voltage difference between the neutral and protective earth, so the LED glows. Quite normal situation (in modern installations where the PE is wired with a separate conductor to the main fusebox of the system). Galvanic isolator increases the voltage difference that is required for the LED to start glowing. When the load on the shore power goes off (or becomes lower) the LED stops glowing.

[Vivacité]

Yup, I have similar results. Dealer isolated the VHF antennae, and that seemed to "fix" the glowing LED's in dry conditions. However, when it rains, the current path is there...which should not be with the fixtures on the mast having ground wires to the negative buss bar on the panel.

Herein lies the problem, is it a poorly designed panel or did Schieber source cheap components from China to build the board?

Thanks for the input.

[Trevor]

Just a note on the glimmering reverse power light. It is common for a corroded neutral pin on the shore power connector to cause this slightly concerning symptom. In fact nothing is wrong with active /neutral polarity but the poor connection cause some resistance causing a little bit of voltage drop between boat neutral and shore neutral. That little voltage is enough to make the globe glimmer a little bit. It will glimmer more brightly when more devices are turned on in the boat.

Replacing the connector on the shore power lead or on the dock usually fixes the problem. It is a little intermittent because when you plug the lead in you may have a good or poor connection on that neutral pin.

I hope this helps,

Regards,

Trevor

[Caxton]

I have the same issue of the flickering reverse polarity light here in the US with 120v.  I checked the sockets with a multimeter and the voltage was correct 116V between the neutral and the small socket.  Neutral to the large socket was 0v.

Thanks for the info above.  My guess is a new boat drawing heavier loads moved to our dock recently since I hadn't noticed this in prior years.

[Trevor]

That makes sense. If you have a large current thought the neutral on your arm of the marina, a small amount of voltage drop may develop across the conductor between where the earth and neutral are tied and the outlet to feed your boat. Assuming not much current through the earth conductor means that a small amount of voltage exists between the neutral at your boat and the earth at your boat. That causes the little light to glimmer. If the current delivered by the service is reduced , the voltage drop reduces and the glimmer goes out.........at least that's my plausible story....

Regards,

Trevor