A switch for controlling an electrical appliance has a switch housing, an actuation element, a display, and a microprocessor disposed in the switch housing. The actuation element can activate an identifier through the display, which identifier is determined by the microprocessor. Selection of an appropriate system state and an associated maximum value is effected by again actuating the actuation element, specifically while the corresponding identifier associated with this system state is active or displayed. Reaching or exceeding the maximum value is indicated by a signal that is produced by the microprocessor. The microprocessor can optionally be activated once again for a reset mode and/or for a change mode.