Mystery Voltage!!

new_spark · Nov 18, 2010

Evening Everyone,

Got a problem with a mystery voltage showing on a domestic lighting circuit.

Job initially started as a CCU change 1970s house old rewirable board with only 5 ways. Upstairs and downstairs were on same fuse both wired in 1.5 T&E so after installing new 17th dual RCd board, seperated the 2 circuits only to suffer from borrowed neutral for the landing light, light was powered by d/stairs circuit, a single and earth cable which ran from back of living room switch to landing switch, and borrowed N from U/stairs, any how I seperated the light from d/stairs circuit and ran a new 1.5 T&E from the ceiling rose in bedroom to landing light and put new strappers in for the 2way landing light. All of the other bedrooms are ceiling rose method, however when I came to do continuity test for upstairs lighting, MFT wouldnt perform the test as it is reading a voltage of 65V bet L-E on all of the ceiling roses??? I performed an insulation resistance test which was fine, and without getting into the extremely tight loft and manually tracing all of the wiring I am totally stumped!!

Any ideas would be hugely appreciated.

Cheers

pushrod · Nov 18, 2010

You isolated the circuit to do a continuity test and you found 65 volts??

Isolate the other circuits one at a time until the voltage disappears,
some interconnection somewhere - or am i not reading this right?

new_spark · Nov 18, 2010

pushrod said:
You isolated the circuit to do a continuity test and you found 65 volts??

Isolate the other circuits one at a time until the voltage disappears,
some interconnection somewhere - or am i not reading this right?

Yep you're reading it right!! I'll try doing that tomorrow, thanks.

andekoch · Nov 18, 2010

had that problem before. mine was water in a switch.

Jonesy83 · Nov 18, 2010

how did that create a voltage

Sparky Ninja · Nov 18, 2010

I've had 230V on a towel rail before, it was from a damaged switch drop which had been there many years. It was conducting through part of the blockwork in the wall (about 1.5 feet I think). The fault had always been there, and the RCD's never operated due to there being no CPC's in the switch drops. It was only when Mr Bathroom fitter replaced plastic rail for metal that it became apparent.