Such a phenomenon may occur when the withstand voltage test is performed with AC voltage. There is a capacitance between the wires of the wire harness. When AC voltage is applied to a capacitor, current flows according to the capacitive reactance. The capacitance of a wire is proportional to its length. Also, the more circuits, the larger the capacitance. Generally, a high-voltage tester detects a leak current and judges it as NG in that case. Therefore, it is not possible to distinguish between the current flowing by the capacitance and the current flowing by the withstand voltage NG. If the wire harness is long, it may be judged as NG regardless of the withstand voltage performance of the product. To avoid this situation, you can set the threshold higher. However, if you set it too high, you may miss NG caused by high voltage. The best method is to withstand voltage testing using DC (direct current) voltage. Inspection used DC can cancel the effect of capacitance.