Catalina 350 International Association

Pictured below is my shore power receptacle. The female end of the shore power cord was burned as well.
For the past week or so I have been noticing a faint smell of something burning on my boat while at the dock. I checked everything I could think of - battery charger, air conditioner, water heater, refrigeration but couldn't find anything. I never thought to check the shore power connections. This week I noticed that my shore power plug was very hot when I disconnected it. I almost fell over when I saw the plug on the cord and the receptacle on the boat!

Ken, did you twist/turn the plug to "lock" it in. If not, it will not get a good connection and could have caused this problem.

Wally & Connie Conway
S/V Arkeoo #467
Orange Beach AL

wcconway wrote:Ken, did you twist/turn the plug to "lock" it in. If not, it will not get a good connection and could have caused this problem

Yes, I'm pretty meticulous about twisting the plug and making sure the locking collar is tight when I plug in.

Ken,
Do you only have one shore power connection on your boat ? If that is the case you need a second shore power line for you a/c.
This happened to my boat about 3 years ago. I kept getting power failures and thought it was the marina connection. The marina electrican said "we fixed it" . Two weeks later my power cord connection on the boat was fried.
Good luck !

I found a similar thing, just not as severe. I've got a slight burn on one leg of the plug and the boat. I noticed it at the end of last year when I was at anchor and stressed the boat out with the Honda Portable generator. It's a 30 amp cord, 30 amp connector and a 30 amp breaker. Possibly the boat 30 amp breaker has malfunctioned and won't trip? I'm not yet convinced if this since the dock upstream breaker did not trip (and I am only supposed to have 20 amps of service). My best guess is poor mating connections on the cord and outlet. I have to investigate this. I don't want my boat burning up while I'm not there.

This is not an uncommon problem, and is caused by a poor connection between the cord and receptacle. Poor connection= Resistance. Resistance= Heat, particularly at high amp loads.

The connection can become poor because it is loose, corroded, a screw loose in the cord or the receptacle.

If corrosion is the cause, using DeOxit or other commercial electrical cleaner works well:

http://store.caig.com/s.nl/sc.2/category.827/.f

BTW, this also happens to RV connections, though the marine environment is much tougher on electrical components.

Brett

I ended up replacing both with a Smart Plug. It promises to have better connections, 7 year warranty, but most of all, it has a thermal overload switch to shut it off if it detects heat. $250 was not cheap. It was also recommend to me to use dielectric grease on metal connections to help prevent corrosion, and to make sure there is not movement on the plug by the boat moving around in the slip.

With over twenty years of marina maintenance under my belt, I will add my two cents. Before plugging in your shore power cord, always visually check the condition of the receptacle first. A burnt and melted receptacle will only offer you a poor connection, and ultimately will damage your plug. Many of the receptacle plastic covers will not automatically snap shut, the resulting electrical connection similar to my hands at the dentist... wet and salty. I've even seen many boaters, either desperate or stupid, force their plug into any receptacle with no consideration as to whether to is 20A, 30A, or 50A. I've had a close look at the Smart Plug... awesome!

Can I assume this happened on the dock side of the cord. Without a secruing ring, like the boat end, the connection to the dock electric always seems marginal. Without a good connection you get hot spots which can start to melt things, including the plug prongs. While a Smat Plug will help on the boat side it doesn't help on the dock side connection. All you can really do is be careful making your dock side connection.

yodagwb wrote:Can I assume this happened on the dock side of the cord.

Actually it happened on the boat connection.

Same thing happenend to me a couple of years ago. traced the issue to a dissconnected grounding wire in the shore power plug on the stern of the boat.

jonnjones wrote:Same thing happenend to me a couple of years ago. traced the issue to a dissconnected grounding wire in the shore power plug on the stern of the boat.

A disconnected ground wire should NOT cause an overheating situation on a shore power cord or outlet. The ground wire should be carrying zero amps unless there is a wiring problem with the boat, cord or dock.

Probable causes include:
Loose or oxidized contacts (either male and/or female)
Overloading the design amp capacity of the cord/receptacles.

And by far the most common, a combination of the two!

Brett

I also had a problem with the shore power connectors on the boat getting warm with normal load (Under 20 Amps)
No damage but was lucky to find it!
Close inspection of the inlet connectors found loose screws on the internal wire connections. I tightened all connections on both shore power inlets and the problem was solved. I also cleaned the plug electrodes both male and female to remove any oxidation/corrosion. I now include this as a recommissioning check.

Leigh Weiss Brisa #155

wolfe10 wrote:

jonnjones wrote:Same thing happenend to me a couple of years ago. traced the issue to a dissconnected grounding wire in the shore power plug on the stern of the boat.

A disconnected ground wire should NOT cause an overheating situation on a shore power cord or outlet. The ground wire should be carrying zero amps unless there is a wiring problem with the boat, cord or dock.

Probable causes include:
Loose or oxidized contacts (either male and/or female)
Overloading the design amp capacity of the cord/receptacles.

And by far the most common, a combination of the two!

Brett

Agree that the ground should not be carrying a current. I suspect that some other issue like loose connections at the receptical may have allowed for stray current. With the ground unattached, there was no where for that current to go, so it heated up the plug, receptical and the wires. The receptical was melted as were the wires in the boat for about a foot, so I could not exactly determine what failed, but I still think the disconnected ground wire is what caused the melting to occur as fast as it did.

When it happen to me, it to happened on the boat side but I would have to say it was my fault. Evidently the securing ring, which always seems to be a battle, was not tightened completely, causing the hot spot. If and when it happens again I will switch to the smart plug on the boat side.