Weird 110 electrical problem

[Wally Boggus]

I don't know where to start but to say I don't know much about electricity except to stay away from it. First I always leave my boat's electrical at dock on the following:ac main oncharger ondc main onrefer on (to keep the beer cold Here is the chain of events that led to a 110 short:During week someone unplugs my shorepower cord at the dock and the plug ends up in the waterSaturday I arrive at my boat but did not notice that the shorepower cord was unplugged at the dock and was 3 feet underwaterI go down and discover that the switches on my panel are in their normal positions as I left them (see above) but no ledsI look out and discover the shorepower is unplugged and is hanging in the waterI turn off all the breakersPlug in the shorepower at the dockWhen I attempted to turn on the 110 main....POW! Flash!Opened panel and discovered a bunch of fried 110 wiresUpon talking with the marina rigger he said at first he didn't think that it had anything to do with the cord being unplugged and in the water. Later after he thought about it awhile he said that the watered cord may have caused it since I had a DC appliance running and that it may have caused electrolisis(sp?) as the burnt 110 wires exposed a lot of green corrorsion (10 month old fresh water boat). He later spoke with an inspector who said that probably was not the cause.This is way over my head...does anyone know what the hell could have happened?w

 

[Don Alexander]

Blow Up!

Wally,It seems possible that the electrical fault occurred whilst you were not present. It would certainly have taken out the marina supply and so the staff would have gone round unplugging boats until they found the culprit which was taking the breakers out. I expect that this was why your plug was disconnected. I guess it then just fell over the side and so this may be unconnected with the original problem.Wiring damaged by heat implies a high resistance at the point of the damage. As the wiring was damaged at the panel it could mean loose connections right at the panel, or something bridging the connectors at that point. In normal cases the boat wiring will not get hot when carrying the current sufficient to trip your on board breakers so it may not be a fault in any of the equipment on board.Think positively. You have had a lucky escape as your boat could have been destroyed - and several others in your marina too.Suggest you put up with warm beer for the first hour or so of every trip and TURN OFF EVERYTHING BEFORE YOU LEAVE - especially the shore power.Regards,

 

[Wally Boggus]

Pluged-in

The marina unplugged it because my boat is next to the hoist and they needed an outlet so they used mine. Also I was thinking that if the problem occured before they unplugged the shorepower that I would have discovered the breakers tripped, but they were not both the AC main and charger breakers were in the on position. Everyone on our dock leaves the shorepower on and run their battery chargers, dehumidifiers, etc., is that unusual or dangerous??? Never heard that. I'm not trying to blame anyone but rather trying to figure out what happened.w

 

[Dick McKee]

You're probably gona get a lot of advise on ...

this one, so here is my 2 cents. First if your boat is wired properly there is no need to disconnect your shorepower when you leave, otherwise not only will the beer be hot, but the batteries will be dead. I do agree that you should not leave electrical appliances on when you close your boat up and leave, only the chargershould be on. There could be several sources that caused your problem. The first thing I would check is the cord. It is well documented that the shore power connection is the most common cause of electrical porblems. Was it soaked?. Did you dry it out carefully before you plugged it back in?? Is there a direct short inside the cord between the common and positive wire from soaking in sea water?? If there is or was, if the wire in the boat is smaller than the wire in the cord, the wire in the boat will fry frist from a short. If someone was causing problems on the dock causing breakers to trip, and your boat was the cause, why wasn't your shore power breaker thrown?? Good Luck

 

[Wally Boggus]

Dick...

thanks...i think you are following my line of thinking here based on the chain of events. The rigger pulled the cord out of the water, shaked it off and plugged it in. I asked him if water could have caused a short in the cord but he said that he does that all the time and has never had a problem. But that was my first thought that it was water could have soaked into the cord and caused a short. Also everything on the DC side is fine, but my batteries were drained w

 

[Ron Dague]

Power Backward through your Charger

I'll throw my hat into the ring. I beleive that, if your 110 cord plug end was in the water, with your battery charger connected to your batteries, it is possible that, depending on the charger, the batteries put power backwards through your charger. A battery charger is a transformer. It converts 110 to 12 volts. (Okay, more like 14.7 volts.) There are rectifiers, and other circuitry there, and exactly what depends on your charger. But the basic component, the tranformer can reduce voltage from 110 to 12, it also might allow a step-up from 12 volts to 110 volts.With the plug dangling into the salt water, you have a complete circuit, from the batteries, to the battery charger, and then, since the salt water is a decent conductor, the current can run across the plugs. Now the electrical engineers out there will tell you that a DC current won't move across a transformer very efficiently. But my guess is that enough current would still get through to do damage and run down the battery banks. There's a lot of power in those batteries.So the result would be, a direct short running your batteries dead, and heating up the wires in the cord, degrading the insulation. And if salt water could permeate the cord, even worse.I am assuming that you are talking about a proper marine grade cable, such as Marinco. A cheaper hardware store type would fry even quicker.So, that's my best guess...and I'll await the attacks on my theory, offered without any real evidence.Ron DagueFinesse, h34www.ExploreScuba.com

 

[Wally Boggus]

Marinco yep

Fresh water tho, but batteries were drained (could not start the engine). I thought that was odd in that I have 2 group 27 gell cells (battery switch set to "Both") and the cord was only unplugged for 3 days. Also, considering it has been pretty cold here, I don't think my refer would have drained them in 3 days.w

 

[bill walton]

refer?

the refer on my 42 will use about 80 AH/day if I leave it on. If youra ia close to that, it could drain your cells in 3 days.

 

[Tim Schaaf]

my three cents!

1), for sure your refer could drain the batteries.2), not only could your shore-power cable have shorted, the corrosion could dramatically increase the resistance within the cord, causing heat.3), for numerous reasons I doubt very much that your charger was acting as an inverter.....unless it is one of those designed specifically to do so, and that has a transfer switch that activates it when there is no AC coming in........? So, what type of charger are you running?

 

[Wally Boggus]

Charger

It is one of those small type smart chargers the best I can tell...it is Hunter original equipment year 2000 vintage.w

 

[Gene B. s/v Paradigm]

What Type of Connector

I haven't checked HOW in a few days. This is an interesting thread. I'm an electrical engineer, maybe I can help. Was the shorepower connector a marine-grade 3-prong, or was it some sort of 2-prong? Are you saying (in your original post) that you had all breakers off, including the battery switch, and you only turned on the AC breaker, with all outlet service breakers, breaker to refer, DC main, etc off? Is the refer DC? Is it connected through a breaker?

 

[Tim Schaaf]

Not the charger

Wally, one of those little smart chargers can't produce AC unless it is also an inverter. And besides, if installed correctly, it will have a fuse in the DC side of the wiring (to protect the wiring), in addition to the internal fuse it comes with to protect its innards. The fuse in the wire will prevent a short circuit from getting very far!

 

[R.W.Landau]

Wally, some thoughts..

Have you looked to see where the wires fried together? On which side of the breakers did the fry the dock side or the load side?If the cord was in the water and it shorted, it would have shorted the source, the shore power.Another way to look at is that if the charger were an inverter, if the cord shorted, there is no fusable devise between the switch and the cord end.Another thought, If the batteries had drained completely, when the cord was plugged-in the charger would have really put out some current possibly within the amp rating of the fuse/breaker but hot enough to melt insulation and cause a short.r.w.landau

 

[R.W.Landau]

Something else,

Wally,You said that there was corrosion.A terminal with corrosion or a loose terminal will not make a good connection. It is actually like a welder in that it stays within the amp rating of the fuse/breaker, but alot of the power is transimitted as heat while it arcs across the gap or through corrosion. I would really try to see which wire melted first.r.w.landau

 

[Steve Dion]

Looks like something for the Insurance Co.

Wally:This is a good chance to see how 'good' or 'bad' your insurance carrier is. They should be able to send a surveyor over to diagnosis the probelm and pay for the repairs.I just read something (but cannot find it again 'CRS'), about plugging in the power cord if/when it falls in the water. The article said something about taking it apart and drying it out etc etc. I think that without a doubt the moisture in the plug caused your problem.Good luck and let us know how you come out on this deal.

 

[Yves Langlois]

Electrical wizard

If everything you said is true and I believe it is, you better find or hire someone who know's a lot about boat electrical.Being an electonic technician and having worked in electricity for a while and having been a boat owner for the last 5 years, I can't give you a quick fix on this site.I honestly believe that you have a serious problem.Good luckYves S/V OPIUM

 

[Andy Falls]

Lightining?

Could one of those Texas thunderstorms passed through? Maybe lighting stuck while the cord was in the water..and zapp..boom..hssssss, the AC side is fried. Three days later, the beer gets warm as the the batteries slowly die. Oh this is such a sad story. Better buy a 6 pack, new cord (btw, on sale at West), 2 batteries, a roll of wire, connectors, etc, ahhh there right of spring!

 

[red coles]

Barn door

Hi Wally: I know this is like closing the barn dooe after the horse is gone, but wouldn't a GFCI at the dock outlet solve your problems. Good luck red

 

[Peter Albright]

GFCI's on shore power

I don't think you will ever see GFCI (Ground Fault Circuit Interrupting) circuit breakers installed on marine dock pedestals. The way most marinas are wired, they would always be tripped.GFCI breakers are made to protect people, and will trip at about .005 amps (5 milli-amps) of differential current. The current coming in on the "Hot"(Black) lead is compared to the current going back on the "Neutral"(White) lead. If they are not the same, the breaker will trip. These breakers detect power shorted to ground, and are very sensitive.The best solution is to buy a 30-amp GFCI breaker with incoming lugs. This style breaker is made to be used without a panelboard. Mount the breaker in a non-metallic box, and install it close to the shore power inlet. Find someone with a ABYC standards book. They show several different diagrams.Note that this will not prevent problems caused by current on the "Ground" (Green) wire. The use of isolators or isolation transformers is needed for these problems.GFCI breakers do not help with shorts between the "Hot" and "Neutral" wires. They work the same as other breakers, based on the thermal heating or magnetic inrush of the circuit. A "dead" short will usually trip breakers with no damage to anything. The cause of damage is poor connections, that cause resistance (Heat). Short circuits combined with bad connections can cause the bad connections to burn up before the breaker senses a strong enough short to trip.Circuit breakers act on an inverse time principal. The larger the overload, the faster the trip. The resistance of a bad connection reduces the current flow in the circuit, causing the breaker to trip more slowly. Only at the end of the process do you get the "Bang". It is important to keep connection tight, clean, and free from corrosion.

 

[Wally Boggus]

Mystery short

Thanks for all the help as I never expected such interest in my whacky problem. To update, the mechanic/electrician tested the shore cord and found that at least now it was OK. The wire that seemed to be most fried was a big one (non-electrician's term) coming off the outlet breaker going to the bus. The short appeared to be located at the bus as it was fried on the end where the wire was attached to the bus and not at the point where it attaches to the breaker. We have ordered a few parts and should get it back together by next week. Andy's lightning theory sounds plausable to me also, I just wish I could remember if we had a storm that week. I have not called Hunter or my dealer on this, but Eddie called me this morning and left a message and offered to help That really made me happy. Perhaps the slogan should be Hunter and their owners go the distance. At any rate it is nice to know that people care about my boat.w