Thermal> Thermal means “heat.” And thermal switches have a pretty hot trick. Or cool trick, depending on how you look at it.
One type of thermal switch has two strips of different metals. Electric current makes the metals heat up. One metal expands (gets bigger) more than the other. Then the metal strip curls, creating a gap in the circuit. The gap stops the current from flowing.
Soon, the lack of current makes the switch cool off again. The metals contract (get smaller) and uncurl. The gap closes until, finally, the switch closes the circuit. Current starts flowing again.
Guess what happens next? The current heats up the thermal switch again. It curls and opens a gap. And so on. The switch turns “off” and “on” over and over as it heats up and cools off.
Fire safety sprinkler systems have a different type of thermal switch. Fire heats the switch. The switch “flips.” The flipped switch sets off alarm bells and turns on the sprinkler.
