Thought this might interest some. Doing a CU change. Took a quick look at the supply head, saw the earth terminal on the side and assumed TN-C-S. When the chap from EDF turned up to change the meter and connect to my isolator, it turned out to be TN-S. It looks like the underground supply cable is split concentric; you can see the black insulated strands to the neutral terminal and bare copper to the earth terminal.
Ze was 0.17ohm, Z line was 0.18ohm, so testing wouldn't really have revealed what the earthing arangement was. By the way, does anyone know if there's a standard symbol for the line impedance, line to neutral?
Ze was 0.17ohm, Z line was 0.18ohm, so testing wouldn't really have revealed what the earthing arangement was. By the way, does anyone know if there's a standard symbol for the line impedance, line to neutral?