Electrical question

[supersurgilator]

I have a friend that works at a laundromat and today I noticed one of the SQ tops was down. The sign on it said that wires were smoking. I asked her what was going on and she showed me the power cord had literally started melting around the two prongs and had turned the gray color of the cord a burned color. The ground pin was fine, there was some corrosion on the base of the other two pins which is where the melting occured. She also showed me the machine next to it had done the same thing a couple of years ago but not as bad as this one.
My question what would cause this? I wondered if it was the outlet being as these machines both had the same problem, but it looked ok when I looked at it. Secondly would it be safe to repair/replace the cord on these machines?

 

[MrX]

The most likely cause is a loose connection in the socket outlet.

If the plug is making poor contact with the terminals in the socket, or if there's a bad connection in the socket outlet due to a lose or improperly installed wire significant heating can occur.

If the plug's making bad contact with the outlet due to lose parts, then the electricity has to travel through a much smaller surface area of the pin that was intended. This results in very hot pins and is likely to cause burning of the plug itself.

It's unlikely that the machine is suddenly drawing more power than normal.

Changing the cord and plug will be necessary as it's now damaged but it might not solve the problem. The outlet may need to be replaced.

 

[circlew]

If there is corrosion on the plug, there may be moisture getting on it, perhaps from splashing. The overheating most likely results from the plug not making good contact in the receptacle. This is common when cheap receptacles are installed. I have also seen instances where overheating occured because of loose wires at the receptacle terminals, but that would probably cause damage to the receptacle itself.

Regardless of the cause, both the cord set and the receptacle should be replaced. The receptacle should be of the "industrial spec. grade", preferably marked WR (weather resistant) since a laundry is a damp area. If splashing is occuring in this area, a "weatherproof while in use" cover should be used, as is required for exterior use, such as on a patio.