A thermal breaker is a relatively simple device which uses a specially formed bimetal strip as a key component. Current passing through the breaker flows through the bimetal which has one of the breaker’s contacts  attached directly to it. When an over-current situation occurs, the bimetal heats up to the point that it snaps into a position that causes the contacts to open and break the circuit. When this occurs, a spring forces an insulator to slide into position between the contacts. Even after the bimetal cools down and returns to its original form, the insulator will hold the contacts open until the breaker is manually reset. Thermal breakers in low current ratings typically incorporate a heater wire or resistor in their design and cost a bit more than higher rated versions of the same series. As noted previously, thermal breakers are temperature sensitive. The ambient temperature causes the current level at which they trip in a certain length of time to vary. The higher the application temperature is over 25°C ambient, the lower the amperage capability of the breaker. Thus, a higher amperage breaker is required to compensate. Conversely, at an application temperature under 25°C ambient, the higher the amperage capability of the breaker. Thus, a lower amperage breaker needs to be used. Temperature compensation information is included in the product literature.