Abstract: A resettable circuit breaker for protecting an electrical circuit from prolonged overload current conditions. The resettable breaker opens upon prolonged overload current conditions. With an optional resistor, the resettable breaker remains open until the prolonged overload current is removed from the breaker. The breaker comprises a first stationary terminal having a first contact, and a movable terminal comprised of a single metal and having a second contact for engagement, under normal conditions, with the first contact. A shape memory alloy wire is positioned adjacent the movable terminal. The shape memory alloy wire is normally in a relaxed, non-contracted configuration. Upon prolonged overload current conditions, the shape memory alloy wire is heated and contracts to contact and shift the movable terminal and the second contact out of engagement with the first contact.