Just to add...
the convention used on some electrical certs, EG NICEIC, is that..
r1 is the measured end to end line(phase/live) conductor of a ring.
rn is the measured end to end neutral conductor of a ring.
r2 is the measured end to end CPC conductor of a ring.
{**lower case letters**}
R1+R2 is the loop resistance up the line(phase/live) and back down the CPC.
when the Line & CPC are strapped together at the CU. as used with Zs calculations.
{**upper case letters**}
Where Zs= Ze+(R1+R2).
and with a ring circuit R1+R2 = (r1+r2)/4
that is Lives & Cpc's {i hate calling it "LINE" phtt!} strapped at CU..
meter continuity at furthest point on the ring AND assuming the ring has NO spurs off it.
If there was a spur the R1+R2 value would be ((r1+r2)/4)+the resistance of R1 & R2 of the longest spur!!
HOWEVER..
Part 2 of wiring regs.. page 36, makes NO differentiation between 'R' and 'r'...
whereas it does between 'C' and 'c' ????
Also the model EIC form schedule of test results.. pg 341..
only specifies an R1+R2 to be noted... (no r1,r2 or rn!)...
so there you go..
Think that is most combinations and permutations of RrRrRrRrRrRr whatever!!!
; )