Research on ways to Improve Safety Standards through Electric Blanket Accident Cases

The rapid spread of heating mats combined with Korea"s ondol-style housing culture has led to more than 200 fire incidents annually. In particular, incidents related to overheating caused by non-metallic sheathed wire (NM cable) used in electric blankets are reported to the Consumer Protection Information Center and compiled by the National Fire Agency"s Fire Statistics Center each year. NM cable consists of a heating element wound in a spiral pattern on synthetic fibers (PE), insulated with nylon, and further wound with detection wires in a spiral pattern. The impedance of the nylon thermistor, which changes with temperature, is used to control the electrical signal flowing from the heating element to the detection wires based on temperature. This paper verifies the uniformity of impedance changes in NM cable based on temperature for different electric blanket products. Specifically, it confirms the temperature increase in electric blankets through heating experiments and its correlation with the impedance changes in NM cable. The experimental results showed variations in impedance changes even for the same product, and in cases where the rate of impedance change is not consistent, it was confirmed that overheating of over 100°C can occur due to excessive heating.