Funny story, ended up buying my buddy a new self retracting extension cord (ceiling mounted) for his garage. Thought I had pulled it all the way out when I plugged in to charge. To avoid the coil of self heating doom.
I was wrong, it bound up and I thought I was fully extended. Didn't burn anything down because i only charged for a couple hours while at the bbq. When I rolled it up everything was fine. When he tried to use it a couple days later he pulled the sheath off on several sections. Yay exposed wire.
We laughed, looked into the specs on the unit and it wasn't even solid enough to run his miter box. I felt bad but he's safer now with the upgrade I helped him buy and install. Don't use retracting or coiled cables, they do heat up and if left may melt and arc if the conditions are just wrong.