I came across this one yesterday. Not touched it yet, but got any idea what's going on here?
It kind of looks like the upper bare Earthing Conductor to MET might be Earth/Neutral from inside the head, meaning TNCS. (or it might be from a wrap to the sheath inside the head, making it TNS?). The cut-down diameter in the cable before the head implies any sheath is possibly removed above the oiled paper wrap, meaning TNCS more likely.
..But then there is the old lower Earthing conductor which appears to be a wrap/clamp which I assume must therfore come off a TNS sheath which disappears into the wall. (Perhaps it goes to defunct Cu water pipe). The old lower one is solid copper and quite substantial. I have no idea where it goes to, there is nothing visible.
Zs sockets measures 0.3R.
Quality of that Earthing conductor:
I will probably verify Earthing conductor with Adiabatic eq'n once I get on site. Doing this backwards shows I could get away with 6mm^2 for Ze down to 0.1 (I have not yet measured Ze). I have six strands here, so we'll probably have at least 6mm^2 (a vernier job). Mechanical protection of earthing conductor is another matter - I would need to add a cover to comply with 542.3.1. So I can't argue necessarily this earth is non compliant, and I assume DNO wouldn't then take any responsibility to improve this for free? - Or is it worth getting them in?) .
It kind of looks like the upper bare Earthing Conductor to MET might be Earth/Neutral from inside the head, meaning TNCS. (or it might be from a wrap to the sheath inside the head, making it TNS?). The cut-down diameter in the cable before the head implies any sheath is possibly removed above the oiled paper wrap, meaning TNCS more likely.
..But then there is the old lower Earthing conductor which appears to be a wrap/clamp which I assume must therfore come off a TNS sheath which disappears into the wall. (Perhaps it goes to defunct Cu water pipe). The old lower one is solid copper and quite substantial. I have no idea where it goes to, there is nothing visible.
Zs sockets measures 0.3R.
Quality of that Earthing conductor:
I will probably verify Earthing conductor with Adiabatic eq'n once I get on site. Doing this backwards shows I could get away with 6mm^2 for Ze down to 0.1 (I have not yet measured Ze). I have six strands here, so we'll probably have at least 6mm^2 (a vernier job). Mechanical protection of earthing conductor is another matter - I would need to add a cover to comply with 542.3.1. So I can't argue necessarily this earth is non compliant, and I assume DNO wouldn't then take any responsibility to improve this for free? - Or is it worth getting them in?) .