Abraded Romex -- almost a big problem!

[Foureagles]

'71 Overlander 27', copper conductor AC 12-2 wg Romex. Doing a little work today and happened to bump my refrigerator receptacle, which is in a 2x4 metal surface mounted box on the floor. Heard a brief "spzzzt", then the breaker tripped. On investigation, the cables, both black & white, inside the box were in contact with the metal box, and over time the insulation had worn away at a couple of spots due to over the road vibration. The breaker did its job, but the insulation is melted away for over an inch, and appears that it has been for some time.

I can't say whether this was an original factory installation, but the documentation on this old can is pretty good, and I see nothing pointing to it having been tampered with. Just a tip to anyone doing electrical work: It's never good practice to press insulated conductors against the metal sides of a box, but on something that moves around a lot, it's a very bad idea.

[idroba]

Years ago a neighbor had a '73 Airstream which he plugged into his old two wire, no ground outlet on the side of his old house. I knew the house was wired with BX cable where they used to use the metal cable sheath as a ground, so ground was available at the outlet. He plugged the AS into one of those Cheater adaptors with a green wire which was supposed to attach to the center screw on the cover to provide ground. But he didn't attach the green wire.

I went by one day and said this is not good, no ground at all for the Airstream. So I attached the ground pigtail.

About a week later he came to me and said the trailer was tripping the breaker evey time he plugged it in, could I investigate for him.

It turned out that the hot wire in one outlet had the insulation worn off and like you, foureagles, had contacted the shell of the trailer. When plugged in, the shell was "Hot" but the ground wire I had attached the week prior took the current to ground and popped the breaker.

Had I not attached it, the shell of the trailer would have been "hot" and when someone opened the door they would have made the connection to ground and at least gotten shocked, possibly worse. The rubber tires and the tongue jack on a block of wood insulated the trailer from ground.

I had to educate him about grounds and why you don't cut that little pigtail wire off or not attach it. He became a believer pretty fast.