To monitor the safety of at least one consumer, the unit (1) has series resistors (17 to 19) on a ceramic substrate (3), which serve simultaneously as a controlled heating sytem, and are exposed to an air flow in a channel (10). Depending on the temperature of the substrate (3), which acts as a heat sensor (40), a contact breaker (20) is held either closed or open and in the open state fixed by an automatic holding system. The substrate is arranged on a metallic support (6) and secured by this or by conducting intermediate connections (32) to a connection member (5) consisting of an insulating material. In this way, the resistors (17 to 19) can be designed in the form of an integrated circuit as thick-film resistors, and the contact breaker (20) can be directly attached with a protection element (29) to the substrate (3), and be connected in a heat-conducting manner with the latter or be formed by it.