I got this extension cord with a used electric oil radiator. I assume the extension cord had been used with the radiator in the past. It looks like a 14g or 16g extension cord.
The extension cord has the factory end pieces on it. I went to use the cord from an exterior gfci outlet. I plugged the cord into the house outlet, walked 50' passing the female end on the way to get an electric lawn mower that I wanted to test, turned around and the female end of the cord was arcing and a 3-4" flame was coming out of the end. I had left the cord end near some tall grass so I ran and unplugged it from the house. I then stomped out still burning fortunately green somewhat lush grass.
I assume the female end of the cord must have been damaged and the insulation between the hot and neutral prong holders must have somehow degraded enough that it started arcing. This really surprised and scared me - if the grass had been dead and dry I could have started a massive fire.
I read an article recently about a man who used an "outdoor" extension cord inside to run his space heater where the cord passed under a rug under his bed. An electric fire ended up burning down his mobile home. The article blamed it on using an outdoor rated cable inside and that you should never do that. Wouldn't an outdoor extension cord be a way safer option than an indoor rated cord?
I suppose the person who got really lucky was the previous owner of the oil filled radiator as they were one use away from burning down their bedroom but maybe the arcing wouldn't have been as bad if something had been plugged in.
I am now paranoid about leaving any kind of extension cord plugged in and unattended. I've often made shortened extension cords out of 100' 12 awg outdoor extension cords and extension cord repair end pieces and I use these all the time inside (typically for diy projects that involve power tools). Similarly I sometimes leave extension cords plugged in outside that aren't immediately in use. How paranoid should I be about an extension cord turning into a flame thrower?
On inspection of the GFCI outlet it was tripped so either it tripped when I pulled the cord or had already tripped after the fire was in action. I guess that is some relief that maybe I didn't need to pull the cord.