Measure Insulation Resistance Cable

[Flatronssssss]

Why do we need to measure insulation resistance of cable both + and - in DC system and L1 L2 L3 N in AC system

Is it important to use equipment to measure and put inside
Distribution Board

How is it involved with Earth Fault
please describe step by step

any idea are welcome

 

[BSEE1980]

Generally it is best to measure each cable separately, disconnecting both ends, not as a system. You megger could damage connected equipment, especially in a distribution board!

Now if you have a Y connected xmfr rated at 480V, you can lift the neutral and 500V or even 1000V meg between it and ground, checking all the cables at once. If it is good, you just saved a lot of time. If not, you will need to go step by step.

So know your test equipment and your system. There is not one answer for all situations. If you really want one answer, lift each cable, both ends, and test just the cable.

I suggest you read the instruction books that came with your megger.

Steve