Confused ...IR readings

[Octopus]

^^ you should always do IR tests on a cable with the cpc connected to the cu, along with the other circuits.....

 

[Hellmooth]

If you carry out IR testing like that then you have to expect to get readings like this on long cables.
The cable forms a capacitor and you need to apply the test voltage for long enough to fully charge this capacitor, otherwise you will not be measuring the resistance of the insulation but will just get a slightly random number.

re-test the cable, but this time make sure you allow long enough to overcome the effect of the capacitance of the cable.

Don't forget to safely discharge the stored energy in the cable.

Is this why my Megger will give a low reading when button is first pressed but increases pretty rapidly as button is held down?