The electrical fires were the most happening events in the all fire accidents which ratio arrives to 30%. The main reason is that the most houses in Taiwan are over twenty years, and most of them didn’t change the old power lines, and the house only has a few outlets. Therefore,people would like to use the extended power line in the home.More electronic products are used in homes which increase the loading of extendedpower line, now. These reasons all belong to the potential risk of fire accident. The purpose of this study is using infrared thermal imager to detect abnormal heating location and its temperature of the extended power line when the extended power line was tied up by the different types, according to this studied results, we could give some suggestions to the manufactures. These extended power line have a danger marker to explain how to use the extended power line. We hope this study could reduce the fire accident.