It has always been common practice by the testing branch of my company that when doing a IR test on a cable, the +ve terminal of the IR tester (megger) is connected to the screen and the -ve terminal to the cable core conductor. the accepted reasoning (since the 'olden days' it seems) was connected with water absorption during the test....but the exact logic behind this is absent. i'd be grateful if anyone could give an explanation for this method of connection. many thx in advance,
Daniel