Thank you all for the clarification, very informative as always.
I can now clearly see that my installation is TN-C-S/PME. As I know you love em, I've attached the pictures.
Lectrician the bottom of the service head looks to be complete, at least in the sense that there is no copper showing from the live!
RF, thanks for the link to the wiki. I now know what concentric cables are having seem them mentioned many times. As with many things electrical, a very clever design.
Incidentally, the tails disappear into the cavity wall running sideways before emerging near the base of the garage wall then running up to the consumer unit. Probably around 5 meters. In mitigation, it’s possible that the tails may run just below the floor level – I won’t know until we replace the kitchen which shares the wall with the cutout.
On this picture of the TN-S cable with it’s sheathing stripped back:
//wiki.diynot.com/_detail/elec...bles_straight_concentric_and_split_concentric
It looks like there is a single green wire? Presumably part of the earth, does it have a special significance?
Wider shot of cutout.
Closeup of concentric cable splitting off into the live and neutral terminals.