122volts from 4volts ac, after a small spark?

[ketchcng]

My shore power dropped from 122 volts to 4 volts the last few days. I worked my way down the wires with a multimeter and had 122 volts the whole way. Once I got to the black and white ac wires that run from inlet to main ac panel, a small spark happened from the test probe and then I had 122 volts in the entire system again. I am leaving the boat for the next five months. What could be causing this problem?

Thanks

Christian

[Corvidae]

It was probably a loose connection that was welded when the probe shorted it. Double check every connection. One of them is in a very dangerous state. If you're going to be leaving the boat, shut down everything that hasn't been carefully checked. Disconnect what you're not very sure about.

[ketchcng]

I’m not a welder, but are you saying the hot and neutral wires we’re arching and welding in a way and when I tested the wires, that somehow stopped the transfer from hot to neutral or vice verse?

[Corvidae]

Without seeing it for myself there's no way to tell for sure what connection was made or broken where. However if an arc happened and then you could read voltage where you couldn't before, then either something melted or something arc welded. Either case can be bad if left unattended. The main danger is if something arced by barely being bumped, then it could happen again when you're not there, resulting in a fire. If you're going to be gone for a while, disconnect the suspect circuits until you can be there to track down the culprit. Or make sure your insurance is paid up and cross your fingers.

[rwidman]

Originally Posted by ketchcng

My shore power dropped from 122 volts to 4 volts the last few days. I worked my way down the wires with a multimeter and had 122 volts the whole way. Once I got to the black and white ac wires that run from inlet to main ac panel, a small spark happened from the test probe and then I had 122 volts in the entire system again. I am leaving the boat for the next five months. What could be causing this problem?

Thanks

Christian

Two choices:

1) Hire a marine electrician to find and fix the problem.

2) Disconnect the boat from shore power while you are away and hire a marine electrician when you return.