Shore Power Connector Burned

[Hampton]

Is this one of those topics that gets posted over and over?

I went to work on the AC today (flush with Green, Phosphoric Acid solution from Home Depot). When I went to disconnect the shore power, the cord felt very hot at the shore power box. When I disconnected it from the boat, I found one lead burned and loose in the plastic housing.

I took it apart to find that the wire on the burned lead was badly corroded. I stripped it back almost 2" to find fresh wire. I tested all of the wires for shorts with every possible combination of switches on/off, (always with power off). No problems found. All systems were working when I found the hot/burned connector. I bought a replacement locally today and will wire it in tomorrow.

I took photos, but can't get my new phone and computer to communicate yet. They both want me to put the other one into the discover mode, but don't see eachother when I do (Blue Tooth), but that's another story.

 

[1stSeaRay]

Did it look anything like this?

A poor connection (loose terminal or corrosion at the contact) can increase the resistance of the wire/connector. This makes heat, let it go long enough with a large enough load and you can turn your connector into a molten pile of goo. Good way to start a fire. Glad you found it before any further damage occurred.

It wouldn't be a bad idea to check the connections at the back of your shore power inlet, you want them to be clean and tight.

 

[Southpaw II]

The most common source of this type of issue is that when people disconnect their shore power, either at the boat or the shore power pedestal, they don't take the time to tun off the breaker on the shore power. Sounds insignifficent I know. If you don't turn off the power, there is an arc, or spark when you disconnect. Repeated occurrences will begin to erode the small connectors in the plug. This is when the heat starts. On older boats as well, the connections will eventually become loose, generating heat. Sometimes they get so loose, it is difficult to even make a connection. Turn off the shorepower before you unplug......

 

[Bottom Line]

The most common source of this type of issue is that when people disconnect their shore power, either at the boat or the shore power pedestal, they don't take the time to tun off the breaker on the shore power. Sounds insignifficent I know. If you don't turn off the power, there is an arc, or spark when you disconnect. Repeated occurrences will begin to erode the small connectors in the plug. This is when the heat starts. On older boats as well, the connections will eventually become loose, generating heat. Sometimes they get so loose, it is difficult to even make a connection. Turn off the shorepower before you unplug......

What should you do if you don't have a breaker on your shorepower? I don't have a switch to turn mine off.

 

[Bottom Line]

John....has someone been putting your shore power cord in the water? :grin::grin:

 

[Southpaw II]

What should you do if you don't have a breaker on your shorepower? I don't have a switch to turn mine off.

First of all, ask the marina to install one.....they are not within code. There must be a disconnect. If this can't happen, at the very least, power down whatever is consuming power on your boat, and turn off the main disconnect where the power enters your boat. You don't want a spark when you disconnect shorepower.

 

[Hampton]

John....has someone been putting your shore power cord in the water? :grin::grin:

Now that right there is the botom line.

We do turn the shore power off.

Burned Connector and Corroded wires (strippped back to clean area)

Finally found the "Find Me" mode of new phone.

 

[Bottom Line]

First of all, ask the marina to install one.....they are not within code. There must be a disconnect. If this can't happen, at the very least, power down whatever is consuming power on your boat, and turn off the main disconnect where the power enters your boat. You don't want a spark when you disconnect shorepower.

Thanks for the info. There are breakers that control 6-8 slips, but there are not switches at each shorepower connector. I usually try to remember to flip the breaker in the MDP, before unplugging the shorepower cord.

 

[Skuza]

Truth be told. I never shut the shore power off on the dock or shut the switches down on the main panel in the boat. I have never experienced any of the above. Maybe I'm lucky or maybe its only a matter of time. It's been 7 years. To each his own I guess.

 

[Southpaw II]

Truth be told. I never shut the shore power off on the dock or shut the switches down on the main panel in the boat. I have never experienced any of the above. Maybe I'm lucky or maybe its only a matter of time. It's been 7 years. To each his own I guess.

You're right...it's one of those things that may never happen. I'm sure it's also a function of how often you disconnect and take your boat out as well. The 2 times I've know of it being a problem was on boats over 10 years old. The plugs had become blackened, and inspection of the connection on the boat showed the male plugs were burnt and thinning. It was discovered when the owner noticed the plug was very warm when disconnecting his power from the boat. That's actually when I started shutting off the power before I disconnected my boat.

 

[Sun Chaser]

The wires shown in the picture from Hampton look small. Can you tell me what size they are? I looked in my manual but could not finf this info.

Glenn

 

[Novation]

I shut down the power at the shore box not only to avoid disconnecting and sparking a "live" cord, but I don't want to leave a live cord on the dock. For short trips I often leave the power cord coiled on the dock and don't want to accidently drop a live cord in nor have someone accidently knock it in.

 

[Hampton]

The wires shown in the picture from Hampton look small. Can you tell me what size they are? I looked in my manual but could not finf this info.

Glenn

I don't know the actual size, but they barely fit into the attachment points for either the new 30A outlet or the old one.

Update: I replace the receptacle yesterday afternoon. All is well. I also took the other one off and found some corrosion on the wires, so I stripped them back and re-installed the unit. FrankW advised me to replace the wires from the receptacle to the switch. That's good advice as it's only a short distance. Unfortunately, I didn't have the wire size info and needed to get power back on the boat. It's on the list of things to do.

This morning (middle of the night, actually), when I got up, I checked both ends of both power cords - neither was warm.

 

[Lazy Daze]

Boy, this is certainly one of those things that could have turned into an absolute disaster! I'm sure many people who looked at this thread are feeling their plugs...

By the way, John, that blue rope in your locker... What's that made out of - yarn?:grin:

 

[Hampton]

Boy, this is certainly one of those things that could have turned into an absolute disaster! I'm sure many people who looked at this thread are feeling their plugs...

By the way, John, that blue rope in your locker... What's that made out of - yarn?:grin:

: ) The blue line came with the boat. We use it with the dinghy. I wish it were yarn. It'd be stronger.

I wonder about the fire hazard. It scares me to death, but as you can see from posts above, it's a fairly common occurence. It seems that the wires get really hot and melt the plug. Maybe the plugs are designed for just such a failure? If the wires touch, the circuit breaks to save from further damage. What if the wires were to get a nick somewhere away from the plug. Corrosion would set in, the resistance would go up, then the area would get really hot and melt the casing. After that, who knows what would happen?

The key for me was to learn that as wires corrode, the resistance goes up. Increased resistance leads to increased heat (think about a heating element).

 

[Jack F]

I haven’t been shutting of the breaker at the dock, I will now thanks.

 

[Lazy Daze]

: )
I wonder about the fire hazard.

I agree that it shouldn't cause a problem. As you said, that's exactly what fuses and circuit breakers are designed to avoid. But real life doesn't always follow the rules, you know?:smt001