Minimum discharge time recommended at the end of cable testing

[epenland]

What is the minimum discharge time recommended at the end of cable testing?

[gchoquette]

What is the minimum discharge time recommended at the end of cable testing?

I faintly remember 10 minutes, but I think this is incorrect. I believe that you are supposed to use a grounding stick and discharge the cable that way.

Please correct me if I am wrong.

[michaellabeit]

What is the minimum discharge time recommended at the end of cable testing?

If I remember correctly, DC and AC tests charge cables differently so the discharging time will depend on the type of test conducted. Megger states the following with regard to DC insulation resistance testing: "It is very important that capacitance be discharged, both before and after an insulation resistance test. It should be discharged for a period about four times as long as test voltage was applied in a previous test." In their DC hipot testing slides NETA states the same thing: discharging should last 4 times the test interval.

However, if you're conducting AC hipot testing, either at 50/60 Hz or VLF the discharging shouldn't take nearly as long.