On a service call the other day I found a thermostat ( Caded model C2002, UL5C86, 240V, 22A max, single pole) that caught fire in the middle of the night. Luckily the owner was able to put it out. Somebody replaced one of the baseboards in living room with a 3,000W fan driven heater which increased the total load on the thermostat to 4,500W (or 18.75A )on a 20A circuit. I always load the heating circuits at no more than 80% or 16A in this case, but even 18.75A was well within the thermostat rating of 22A max. I tend to believe that the short happened in the electronic circuitry inside the thermostat ( poor heat dissipation? )
To make a long story short, the problems were corrected but I wander if anybody had similar experiences/what thermostats do you use?