You're meant to do the testing with the conductors isolated from the supply!
End to end resistance of each core - r1 = end to end phase conductor resistance, r2 = cpc end to end resistance and rn = neutral end to end resistance. Then do the interconnect with r1 and rn, check at each socket. Then do r1 and r2 interconnect, check at each socket. The highest value is your R1+R2 value - if you have spurs it will likely be on one of these. The R1+R2 at each socket on the ring should be roughly (r1+r2)/4. Notice the difference in small case r1, r2, rn and caps R1 R2.