I have just done some tests on electronic kit on which I used the 100mA earth bond test. I had a load of failures. On a couple of items I was not able to get the test within spec (0.1 + lead resistance). On these I "risked" a 25A test and the resistance was 0.04 so WELL within spec for a 3 metre cable. Re test at 100mA - fail at 4.30 at best.
I have not had this type of problem before.
Any clues as to why?? Machine only just passed cal - this month. Do I take it back to the cal lab??