It is more likely that the LCM involves solid state switching or at least he/ she  thinks it does, - perhaps rather like the triac lamp dimmers of old., and attempts to measure the live path though it, either with a low voltage DC (for R1) or mains AC (for Zs) are doomed to give fruit machine answers.

A reasonable regs complaint compromise may be an R2 only wander lead test to anything that can be touched and should be earthed downstream of the offending box of magic- after all if R2 is OK, and R1 is a bit high/indeterminate, then the voltage it reaches during fault  is still safe - and if there are RCD/RCBO upstream , then exact numerical result, apart from 'not actually earthed'  of course is not especially critical, more of a 'cpc present?' check..

Mike.

mapj1 said:

A reasonable regs complaint compromise may be an R2 only wander lead test to anything that can be touched and should be earthed downstream of the offending box of magic- after all if R2 is OK

Agreed, R2 (wander lead) is acceptable ... but where ADS is used, still might require knowledge of the earth fault loop impedance?

Alternatively, Guidance Note 3 Issue 9 (2022) advocates (Rn+R2) as an option where electronic switching prevents (R1+R2) - although again, would only provide knowledge of the loop impedance if Rn=R1 (i.e. no reduced neutrals)

mapj1 said:

A reasonable regs complaint compromise may be an R2 only wander lead test to anything that can be touched and should be earthed downstream of the offending box of magic- after all if R2 is OK

Agreed, R2 (wander lead) is acceptable ... but where ADS is used, still might require knowledge of the earth fault loop impedance?

Alternatively, Guidance Note 3 Issue 9 (2022) advocates (Rn+R2) as an option where electronic switching prevents (R1+R2) - although again, would only provide knowledge of the loop impedance if Rn=R1 (i.e. no reduced neutrals)