Looks like a TT system 'upgraded' to a DIY PME where the Neutral Henly block is being doubled up as the MET.. Although its unclear whether the service fuse seals have been cut.
When I pulled up to park outside of the bungalow there were two DNO linesmen parking up to work on another supply cable off the same pole that supplies this intake. After looking at it for a couple of minutes I went back out and to ask them what the earthing arrangement is, but when I saw the overhead cables the penny dropped and I realised what it is, the linesmen laughed when I said I have traveled the length and breadth of the country but never actually worked on an installation with this earthing arrangement before on overhead supply cables.
The jobs a good one and in theory is quite acceptable, though may be due an upgrade.
3 wires come into the building.from the outside, and so I would have said TN-S overhead or TT split phases but mostly I think TNS.
Though maybe not clear as it looks like either something odd has been done with the earths and neutral at the cut-out, or more likely that all 3 wires LNE duck down behind the board to supply another cut-out on the other side of the wall as a loop through supply.
Hopefully there is not an un-needed NE link or an NE transposition, unless this is an odd way of implementing a double fault to failure on TNS upgraded to PEN.
Now the pole will be L1/L2/L3/N /E and presumably the 'spare' is a street lighting timed live, so that supports a TN-S assuming it has not been retrospectively PME'd.
The indoor run in the loft leaves something to be desired and as Mike spotted it is a looped supply feeding next door as well .
It is the first time I have seen a TNS overhead supply wired in three singles, it probably dates from the late 1950's, so has been in use for around sixty years.
Ah that loft looping is really sweet, I presume it was installed by candle light or something. If the cable is really from the '50s I'd be checking to see if the rubber is brittle enough to rub off the incoming singles between finger and thumb yet ? The metal Saren clips can become live if it is which would be, shall we say, disappointing.
I agree this sort of line-up is getting pretty rare, if it was round here it would probably have become ABC (Aerial bundled cable) by now, they are actively trying to eliminate the overhead bare singles , especially ones with flying crimps like that pole has on the 6 wires that leave to the right. I am pretty sure those 6 bumps are crimp tubes with no strain relief - as it is now, really a new PME feed should not be taken from such a pole, as the single flying crimp in the neutral acting as a PEN is not adequate (not being a double fault to danger.).
Ide say the installation is PME you can clearly see the house green/yellow going into the neutral block.
It looks to me that the block with the G/Y wires isn't a N block, but a simple PE block - there are three incoming cables, two go to the cutout- the third to this extra block I agree with Mike, it looks like TN-S to me. I have seen similar (although single phase) in a very quiet backwater of West Wales some time ago where the main run of overheads had three conductors - the bottom two only joined at the transformer.
