50 amp shore cord and trailer connection fried

youngwillyd · January 5, 2017

This is a neighbors issue. The campground electrician thinks that water got into the plug and caused this. Is that really possible?

Ranger Smith · January 5, 2017

It looks like a bad connection on one of the legs that overheated. That will happen when the contacts get oxidized and or corroded.

Kirk W · January 5, 2017

I'd say possible, but not probable. That sort of short usually would trip the breaker on the pedestal before that happened. In my opinion and experience, the most likely cause was a worn connection in either the cord or the socket, or most likely both. Power cord plugs do go bad and when they do so there is introduced resistance in the connection due to a loose fit. That loose fit can cause arcing in the connection or over heating that then makes this get slowly worse over time. The voltage dropped across that resistance then becomes power that is converted to heat which then weakens the fit even more and things steadily go down hill. When the heat gets bad enough it begins to melt the plastic of the plugs and what you see there happens.

That same thing can and does happen with the plug on your cord that connects to the pedestal as well. It is a good idea to occasionally check the connections of your power cord to see if they feel hot. A little bit warm if using air conditioning or electric heaters is a normal thing but too hot to touch is a very bad sign.

Al F · January 5, 2017

Not water. Worn out connector and/or corrosion.

I would also be pretty sure, since this is winter, that an electric heater was on the same leg of the 50amp power along with something else. The water heater on electric, a convection oven, maybe even 2 electric heaters. If it was summer I would say an air conditioner along with some other load.

Bottom line, any combination of loads which bring the current load up pretty high. It doesn't have to be the full 50 amps. 30-40 amps will cause a lot of heat with a poor connection in the plug/connector.

I had this happen on a Class C in 100* weather with the AC running full bore. No other big load, such as water heater, microwave, etc. So I was probably pulling less than 20amps max. I knew the connector was a little worn and was going to replace it pretty soon.

Ronbo · January 5, 2017

Probably the common wire loosened up in one or the other.

youngwillyd · January 6, 2017

Rondo, funny you should post that today. I didn't know if I could find a loose screw but I wanted to try. I just finished taking the burnt pieces apart and it does appear the problem was in the neutral. It appears the screws are now welded so I can't tell if the neutral screw was loose. A couple of the screws on the trailer receptical I was able to tighten no more than a quarter of a turn.

I guess all these screws on the wires on the receptical and the plug are the ones that should be checked yearly? It makes sense but I don't think I heard of many people doing that.

Ray,IN · January 6, 2017

That pic of the power cord sure looks like a 30A to me. I do agree with Kirk and Al, it used to be an overloaded connection.

Darryl&Rita · January 6, 2017

That pic of the power cord sure looks like a 30A to me. I do agree with Kirk and Al, it used to be an overloaded connection.

Ground connection isn't on one of the pins. It's on a metal contact along the outside edge of the circle.

rvrev2 · January 6, 2017

Yup. It can happen. Happened to me. As best as I could figure out, it was most likely loose or corroded contacts on the plug. I'd attach a picture, but I don't know how.

wtmtnhiker · January 7, 2017

Similar thing happened to me and it was a loose connection at the terminal on the RV end of the 50 amp cord. I bought a new socket and cut back the cable enough to eliminate the burned and charred wires. I was able to clean and reuse my trailer receptacle but it looks like you'll need to replace yours.