What tests were done to prove that your water pipe was a good reference earth?
Otherwise you are trying to measure a suspect voltage on an unproven continuity CPC..
to a completely up-proven reference point?
Which I cannot see any sense or valid reason for doing?
In my book its either prove CPC continuity with dead tests first..
OR if you were trying to measure any suspect voltages..
get a long lead to use as a reference point back to the main-earth connection at the CU, or at suppliers connection point if accessible?
Any other methods of measuring random voltages are just pi55ing in the wind guessing at numbers for no practical purpose, to prove nothing!?
What are you trying to prove?
(a) Your meter can show random induced voltages?
(b) There is no continuous CPC connection back to the CU?
(c) Your CPC is good but the water pipe has an induced voltage?
(d) It's pointless trying to do random tests with the wrong meter because your other one was at home?
(e) Some unknown person in the past has connected "non-Class II" accessories onto pre 1966 lighting circuits?
(f) Other??
