This paper is purposed to analyze the thermal characteristics of wiring according to the number of electric fans in operation for 10 fans over 10 year old and 10 fans less than 1 year old in livestock barn. In order to achieve the goal in the paper, it selected VCTFK, VFF, HIV, and CV wiring that were used most at 64 livestock barns in Cheongwon location through the research on the field investigation. Finally, it also analyzed the dangers by deducing the thermal characteristic data of 4 wiring. In addition, this paper suggested the mode of load current (the most frequently measured load current) of both over 10 years old and less than 1 year old electric fans. The data of this paper could be used for the maintenance and management of wiring and fire investigation of livestock barn as well as for materials of safe designs of wiring of electric fans.