Had a small job today, just install an outside socket, when I went to price the job all looked good, split load CU, main bonding in place, lovely. Upon testing the CU seemed to be a fairly pro install, even numbering on the neutral and line conductors, although two sets of 1,2&3 as they had counted from #1 from the main switch and #1 on the rcd instead of continuing the numbering right through (hope that makes sense) although all the CPC's were bunched into about 4 terminals instead of spread out in corresponding terminals. Anywho, insulation resistance was good, RFC loop readings all good, r1r2 readings all good, Ze out... strange, had a reading of 53 odd ohms, very strange as all the properties in the area are TNS, on poking my head around the corner to where the main supply cable comes in I notice that the 16mm main earth cable doesnt go to the earth clamp on the main cable but goes down some trunking that is housing the main supply cable and then pops out through the wall to an earth rod. Someone has wired the installation to be compliant to the 16th ed but TT'd a TNS supply. With a test on the suppliers earth I get a good reading of 0.13 ohms.
Why oh why has someone done this? I cant for the life of me begin to understand.
Why oh why has someone done this? I cant for the life of me begin to understand.