120 VAC romex

[Salty]

I had a problem recently with a 12VDC fuse blowing in the converter on the switched light circuit. The circuit I refer to is the lights in the forward section of my trailer with the switches next to the door that turn on the indirect lighting, porch lights and overhead light center ceiling front. The problem there was a B+ wire shorted to the skin, but not why I'm writing this post.
What I discovered while repairing this was a 120VAC romex wire that had been repaired over the door. Having opened the interior skin over the door I discovered a two foot section of 12/3 romex that had the outer insulation stripped away and spliced with butt connectors. This circuit ran down the drivers side, around the front and back down the curb side all the way to the bathroom. A full ring. All fed from a single 15 amp breaker.
The solution here was to Isolate the circuit, starting at the feed, which in my case was at a receptacle curbside over the credenza adjacent the curved window. Then disconnect the input at a receptacle at the after part of the dinette area and back feed the power from the bathroom receptacle. Adding a twin 20 amp breaker to the old power center and using marine 12/3 as the back feed splice completed the repair.