According to statistics, 32 percent of all fires occur in electronics installations. Electronic control cabinets and switchboards with their active and passive electrical components have a particularly high potential for danger. Starting in the control cabinets, a fire can spread throughout the wires in a building due to the fire load. In order to prevent such fires, the scientists at the Fraunhofer IMS tackled the problem with wireless sensor transponders. A specific antenna concept makes it possible for the transponder to be fitted onto the metallic busbar in the electrical cabinet. Based on the results of an analysis of the electromagnetic field distribution in electrical cabinets, several readout antennas were skillfully arranged inside the cabinet so that the readout of the transponder is possible in every position required. By using wireless temperature transponders, no wiring to the measuring point is necessary. With such an arrangement, 60 or more transponders can be operated in a single electrical cabinet! Furthermore the transponder system can be used for the monitoring of hot water lines to minimize the possibility of legionella formation in heating systems.