As a scam inspection piece I'm looking at a rewire of my folks garage.
Going to be a really simple job, just adding a few sockets and updating the CU to a 17th edition board.
The supply to the building is a 15ish metre run of SWA from the main CU, sheath earthed to the MET.
Oddly though, it appears there is also an earth spike in place (not yet verified, but there is a length of green and yellow from the garage DB earth terminal which goes into the concrete outside.
The local substation is actually the same building as the garage (everyone else in this area has a double, we have a single with the substation in the other half) so I'd assume that I'd find the earth impedance on the spike to be pretty decent.
What would everyone else do in this situation?
Isolating the SWA sheath from the installation and treating as a TT?
Disconnect the earth spike and treat as a TN-C-S?
Leave both in place and work on worst case scenario?
To me, all of those sound fairly reasonable, but being a potential NIC inspection piece I'm being extra-cautious!
Going to be a really simple job, just adding a few sockets and updating the CU to a 17th edition board.
The supply to the building is a 15ish metre run of SWA from the main CU, sheath earthed to the MET.
Oddly though, it appears there is also an earth spike in place (not yet verified, but there is a length of green and yellow from the garage DB earth terminal which goes into the concrete outside.
The local substation is actually the same building as the garage (everyone else in this area has a double, we have a single with the substation in the other half) so I'd assume that I'd find the earth impedance on the spike to be pretty decent.
What would everyone else do in this situation?
Isolating the SWA sheath from the installation and treating as a TT?
Disconnect the earth spike and treat as a TN-C-S?
Leave both in place and work on worst case scenario?
To me, all of those sound fairly reasonable, but being a potential NIC inspection piece I'm being extra-cautious!