EBME Forums Forums Maintenance Test Equipment Testing of earth resistance and potential voltages

I use the CROPICO earth bonding tester, which will measure down to micro-ohms. This can also be useful when checking switches and contactors. I carry a 10m and a 20m two core .75mm cable, and a clamp which is o modified spring clamp, and also a 2m length of cable which is soldered into the earth pin of a 13A plug to measure the bonding resistance of mains sockets.
The value of 100 milliohms has been considered a standard, ( in fact it was THE standard then) since 1989, as was the touch voltage of 10 millivolts.