I primarily use a Lee 4/20 bottom pour pot, but also have a Lee 4 pound pot I use for this and that (salt bath annealing and small batch different alloy casting). A few weeks ago I was using it and thought I felt a tickle but didn't give it much thought. A few days ago I was using it right after I had been running a hot plate and the 4/20 and had my 20 amp GFI breaker pop a couple times. At first I thought perhaps the breaker was popping because of previous higher current usage, but made a mental note to check the pot.
Today I remembered and popped the cover off to make sure nothing was touching stuff it shouldn't and saw no problems. So I plugged it in and checked the pot carriage/body and found 124 volts. Myself told me, "hey that's not good!" I did some partial disassembly to mostly isolate the heating element from the carriage and pretty much confirmed the short was in the heating element. Fortunately as a "proper prior planning prevents piss poor performance" precaution I had ordered the free replacement parts from Lee (pot, thermostat and heating element) a couple years ago. After a lot of fiddling I finally pulled the original heating element out and installed the new one and viola just like magic, zero volts coming off the carriage or the heating element.
Close inspection of the old element failed to show any abnormalities. The insulation inside each end of the element appears intact, so somewhere inside the element coil something has failed. Frankly I have never given the possibility of a coil short a thought. My thoughts/experience have always been when an element fails it either just quits heating or burns through with a welder like arcing sound. I have never once considered a short like this.
Now I'm thinking I should maybe better replace my Lee two prong power cords with three prong grounded cords.