How Does a Thermal Circuit Breaker Work?

Thermal square d circuit breakers are made with a metallic strip. This strip has two different pieces of metal welded together, each meant to expand when coming in contact with the heat generated from electric current. Having two different kinds of metal in the strip means the expansion rate for each metal is different. The greater the heat, the more severely the metal strip bends. When there is an electric overload, the heat generated is so great that the strip bends enough to pull the circuit level to the off position, protecting the wiring from damage. When a thermal circuit breaker is reset, it is likely to trip again if the overload condition still exists. It may take time for the heat to increase to the previous level, but once it does your Square D circuit breaker will trip once more. It is very important to get to the bottom of a thermal  square D breaker that keeps tripping again and again. You may have a wiring fault that needs repair.