Insulation resistance testing

[Sparks321]

456megaohms on a 25m 3core swa is acceptable as its more than 1megaohms. Correct.

 

[Carl S]

At 456MΩ I wouldn’t be worried. When you test a cable of any length keep your finger on the test button for a while as the cable acts as a capacitor and needs charging. A word of warning, short the cores out before touching them, 1000V up your arm hurts.

The old way was to calculate the minimum IR resistance as a maximum leakage of 1/10,000th of the full load current. Using this calculation I’ve put old PILC cables back in service at below 1MΩ, after 6 months they were >10MΩ.