Use a multimeter to measure whether there is a short circuit in the line
Use a multimeter to measure the line insulation to know if the line is short-circuited. For example, if the insulation of a single phase is measured, if the insulation value is zero (metallic grounding) or very low (non-metallic grounding), it can be judged that this phase line is grounded. If not grounded, the insulation value is high. Then measure the phase-to-phase insulation. If the phase-to-phase insulation is zero, it means that there is a short circuit between the two-phase lines.
