Circuit breaker and method for emitting a warning upon a threshold being exceeded

A circuit breaker, for interrupting an electrical circuit including electrical conductors, includes an energy converter, a primary side being formed by a conductor and a secondary side being connected to a power supply; a sensor for determining the level of the electric current of an electrical conductor; and a controller, connected to the power supply and the sensor, to cause an interruption of the electrical circuit when current limit values or current/time period limit values are exceeded. The secondary side of the energy converter is connected to the input of a measurement circuit, the output of the energy converter being connected to the controller. The measurement circuit determines an amount of energy and delivers this to the controller, the controller comparing the amount of energy with the level of the current determined by the sensor and emitting a warning signal when a first threshold value is exceeded.