Abstract: In this paper, a 10 kV distribution network grounding short circuit fault, coupled with the cable copper braid threading zero sequence TA error caused by the self-healing system misjudgment, a typical case of override trip occurred. First of all, the fault was studied and analyzed in depth and the maintenance work was carried out, and the wiring rectification and acceptance of the copper braided belt crossing TA were completed. Then, in order to eliminate the impact of poor grounding of the grounding grid, the acceptance and detection of the grounding resistance of the grounding grid in the relevant distribution room are carried out. Finally, in order to avoid unnecessary power outage maintenance, this paper innovatively carries out the research on live detection of copper braid TA wiring based on cable endoscope, and the experimental results verify the effectiveness of the proposed method, which ensures the stable and reliable operation of distribution network equipment.