Been to look at a consumer unit replacement and when I checked the service head found the following. PME service head with no 16mm from the neutral link to MET, just the main protective bonds, 6mm earth from MET to fusebox and a 16mm black cable going down the hockey stick to god knows where. No PME warning lables. Got a ze of 0.21, so assumed it was PME as no signs of TT anywhere. Am I correct in my assumption, is this black cable the earth supplied by the DNO and the neutral linked somewhere I can't see. Should I run a 16mm earth from neutral link to the MET, no seals on the fuse so able to get inside the head. This is a new one for my first year in domestic.
TIA for help.
TIA for help.