Abstract: By analyzing a repeated grounding fault of 10 kV line, the company immediately organized personnel to inspect all poles and towers of the line. It is found that the A phase post insulator is inclined, and the post insulator fixing nut is not fixed firmly during line construction. Due to the terrain, pole 13 is lower than the poles on both sides. Under the influence of thermal expansion and cold contraction of conductor, when the temperature is high, the sag of conductor increases, the insulator tilts, and the safe distance between conductor and cross arm is not enough. Find out the causes of faults, eliminate potential accidents, and put forward preventive measures such as strictly controlling construction quality and strengthening construction project quality management.