Earth Fault Loop Impedance Test - 3 Lead Low or 2 Lead High - Test Explained In this video Marcus explains what happens when we would set our MFT tester to 3 lead low, 2 lead high and even 2 lead low in order to carryout an earth fault loop impedance on a circuit that has RCD protection. So we can carryout a earth fault loop impedance test it is important to select the correct setting on an MFT tester but do you understand why we often select 3 lead low setting when testing for earth fault loop

Total Earth Fault Loop Impedance Zs = Ze R1 R2 for TN-S and TN-C-S Earthing Arrangements How to calculate or measure total earth fault loop impedance for an installation connected to a TN-S and TN-C-S earthing arrangements. In this video I show drawings to aid with City and Guilds and EAL electrical exams at level 1, 2 and 3. The total earth fault loop impedance Zs of a circuit is made up for the impedance of the supply authorities cable Ze and the circuit impedance of the line conductor R1 and