Abstract: The system includes a sensor for each junction box in the building to be guarded, e.g., the residence, and a display panel showing the temperature of any junction box that is heated above the danger point. Another display panel shows the name of the resident and address of the residence, and the location of the heated junction box by room number and junction box number and the shape of the junction box. A plurality of residences are connected with a central station, such as a fire station, by a single telephone line to each residence. A single processing unit is located in each residence, and a single such unit is located in the central display station. A display panel is located in the central station identical with each display in a residence.