Abstract: Fires caused by overhead line faults have occurred frequently in recent years. Because it involves the power supply principle of the power system, high technical requirements are placed for fire investigator. This paper introduces the investigation process of a 10 kV overhead line ground fault fire. When the fire scene was severely damaged and the fire location was identified as ambiguity in the preliminary investigation, the investigators comprehensively analyzed the cause of the fire through video analysis, investigation and inquiry, on-site inspection and other methods, combined with power data analysis, ground fault principles and models, restore the process of fire spread and development, and provide reference for fire investigation and identification of 10 kV overhead line ground fault.

Key words: overhead line, earth fault, fire investigation, fire scene inspection