4.2.Cable insulation resistance test should refer to the standard GB 50150-2016 item 17.0.317.0.3 Insulation resistance shall be measured in accordance with the following provisions:1.There should be no obvious change in insulation resistance measurement before and after voltage withstand test.2.The insulation resistance of the outer sheath and inner lining of rubber and plastic cables shall not be lower than that of the cable 0.5MΩ/km;3.The rated voltage class of the megohm meter used for measuring insulation resistance shall comply with the following provisions:1)Cable insulation measurement should use 2500V megohm meter, 6/6kV and above cableIt can also be used as a 5000V megohm meter;2)500V megohm meter should be used for measuring the outer sheath and lining layer of rubber and plastic cables.4.3.Cable AC withstand voltage test should refer to the standard GB 50150-2016 item 17.0.517.0.5 Ac voltage withstand test shall comply with the following requirements1.Rubber and plastic cables should be given priority to 20Hz~300Hz AC voltage withstand test voltage and time shall be in accordance with table 17.0.5