Min Cable Insulation Value

Have a look in Google or search this forum!

What does the specification say? You DO have a specification, right? Why else would you know that you are supposed to test? And if you know that you are supposed to test, you should know why and what the requirements are, right?

The OP wants to fail the cable. By failing this cable, he'll prove to his boss that he's a knowledgeable employee doing his job. The problem is he doesn't have a specification or requirement to show off his capabilities. That's why he came to us.

Well I'll give some numbers to suit the goal.

The minimum insulation resistance at 1000V is nothing less than 10¹² ohms for a one meter length of cable. Now if you wish to really show off, you can also measure the cable's capacitance per meter which should not be more that 10^-12 farads.

This might be a partial answer: http://forums.mikeholt.com/showthread.php?t=51861

1000 ohms per volt--general rule .

If that were the case, then no residual current device would ever do anything other than trip! So the answer is inctredible.

Identify what type of cable your testing (should be marking on outside sheath) and, search for cable spec. or speak to the manufacturer.

Thumb rule which is applied in field for Insulation Resistance ( IR ) testing of cable is :

Rated Voltage of cable ( in KV )* 10/ Length of cable ( in KM ) in Meg. Ohms.

As a thumb rule for for 415V motors, minimum acceptable cable insulation should be 1 Megaohm. There is a formula:

Safe Minimum IR value = Rated Voltage/ (Rated output in KVA) +100.

In your case it comes as 1.14 Mohms.

BB Raina