Oh and there was a zap and a burning smell when my screwdriver touched the metal faceplate of the junction box the thermistor shares with the single pole light switch on 240v. Maybe it was static electricity... I hit the breaker and pulled the light switch out and while I couldn't see the copper, there sure were four or five deep scores on the hot wire that were jammed up against the various items in the junction box. I love household wiring, always a surprise. (I taped it up just in case.)