Melting AC

Hi Kevin

I purchased an old 1989 cruiser, a Regal 280 Commodore, and tripped the 20 amp dockside breaker while using a hatch a/c unit and an electric kettle. I have 30 amp service in the boat.

I reset the breaker and then the AC electric system worked for a few minutes and then went dead. Neither the dockside breaker nor onboard breaker tripped, but we smelled a burning smell. I immediately unplugged the AC system and looked behind the AC panel.

At the main breaker switch where the shore power comes in, I found the white wires melted and melting damage to the black wires. I can fix all the wires, but there is also some sort of capacitor that was wired as a jumper between the green and white wires and it is not in the wiring diagram of the boat. It looks like it has been burned out. I want to know what to replace it with, and then if this overall problem is something that points to the result of another problem or if it may have been some old wires getting warm and then touching.

I can replace everything as it was once I know what to put between the black and green wires, but don’t want to do that and then plug it in if there may be other issues that need addressing.

Thanks for your help.


The only connection in your panel between the neutral and ground would be a reverse polarity indicator. Instead of a light, some boats have an alarm. Some of the piezoelectric alarms look like capacitors.

Hope this helps


Self Lifting

Hello Easy,

I came across your site somehow and thought I would send a question.

If I can get my boat onto my lift next year, I am wondering about different ways to power the ac shore station hoist mortar without shore power. Is there an economic way to utilize the boats batteries or use an inverter, or a very small generator that could be on the boat? Last year I left a portable generator on the dock, but I would hate to get it stolen and am just hoping there is a way comparable to using a dc motor (which I don’t have).

My boat is less than 3000 lbs and the motor presses against the wheel to rotate it.



Hi Brian,

It is amazing how low the lakes were last summer. Hopefully they don’t drop too much more.

The most economical solution would be to buy an inverter just large enough to run the AC motor on shore station. The shore station should either have a wattage rating or a current draw (watts=current*120).

Running the inverter for a short period of time to lift your boat should not be enough to completely discharge your boat’s batteries. If your boat has a battery switch, I would make sure it is not in the BOTH position when you are using the hoist to help prevent draining both batteries.

IMPORTANT; If your inverter is not ignition protected, do not run it in the engine room

Hope this helps,


Outlets Out


My 1989 280DA Sea Ray’s shore input was plugged into a 110 volt system at my house. The batteries were being pulled down all the time because I was in the process of changing out all the incandescent lights for LED fixtures, and rewiring as I went.

So, I plugged a battery charger into one of my 110 outlets, and turned it on. The battery charger shorted out. After that none of the 110 receptacles worked.

I have replaced the circuit breaker on the main panel, and have replaced the GFI outlets in the boat. (One guy told me it must be the charger/converter (Professional Mariner New Pro 20/35 3 Bank) So I pulled that out where I could get a look at it. However, I get good 12 volt output from it when it is hooked to a 110v source.

I am not sure what else to do.

Any ideas? If so I would sure appreciate your advice.



Hi Ron,

I would start at the panel to see if you have AC power.

Using a meter, check for AC voltage on both the line and load side of the circuit breaker. Also, check for power when a load, such as the charger is connected. If you have power at the breaker, check at all outlets in the series as they make their way to the battery charger.

You will probably find a bad connection in the line between the ac panel assembly and the charger outlet.

Hope this helps,


AC Out


I have a 1989 SeaRay 280DA.

While plugged into a 110v source at my house, I plugged a battery charger into one of the boat’s 110 AC outlets. The battery charger shorted out, after that I cannot get power to any of the 110 ac outlets on board.

I have checked all the breakers in the main panel, and even replaced all of the AC outlets on board without success. I have checked out the on board battery charger and it is working fine.

Any suggestions?


Hi Earl,

I would start at the source of power and make you way through the boat. If there is a bad connection, it may have voltage with a meter but not enough current to allow the device to work. When you are carefully working your way through the system, try turning devices off and on while testing with a meter to determine where the problem is.

If you have power at the source (the outlet on your house), you should be able to logically trace it through the system. It could be something as simple as a bad connection in your shore power cord causing all of the problems.

Hope this helps,


Ground Charge?


I need your help with a marine electrical shore power question.

My boat is plugged into dockside power and there is a 100 millivolt charge on the green ground wire. I have checked with the marina and they have checked their system which is in perfect conformity to the rules.

There is no indication of this on the shore power plug but it appears when you put a meter to the boat which is in the water and seems to make a ground through the water.

What is the reason for this?



Hi Ray,

How are you measuring the 100 mV?

Is it on the shore power plug before you connect it to your boat or is it on your boat when you compare the green to the white?



It was measured on the boat.



The 100 mV difference is simple to explain.

When current passes down neutral wire there is a slight voltage drop. Voltage = Resistance x current. Since there is no current passing down the ground wire, there is no voltage drop on it.

Your dock box is tied in with several other dock boxes with the same neutral and ground wires. If every boat was disconnected from the system, you would not see the 100 mV difference. At times, it is possible to see voltages higher than 100 mV.

Hope this helps,