A real electrical Question
 

The mains is 230V.

If you find a voltage on a length of 2.5 t&e, and this voltage is on the earth lead, measuring 51 volts ac. you then disconnect all points of contact at both ends of the cable apart from the active and the voltage is still there, then you decide to megger it and find the cable is correct, what is the problem,

I'd like to have your thougths on this.

Ps all test equip is good

Regards

Kevin

Re: A real electrical Question
 

is it possible to trace the whole length of the cable??? perhaps its chaffed /beared somwhere along the lenght and touching another ciciut cable and picking up some voltage from that????? have you switched off all the other mcb`s 1 by 1 with the test kit still connected reading the 51 v???? and wiating till it diisapears? what sort of install are we talking about here? domestic /industrial???

Re: A real electrical Question
 

Sounds like inductance to me. The voltage is being induced by another circuit or circuits. Switch off all the breakers and one by one switch them on. It should indicate the circuit or circuits causing the problem. Most houses have some kind of inductance. Thats why you should never bunch single cables in their colour grouping only. ie. if you group phase cables without neutrals then you can cause problems. I had the same problem when i ran a bunch of switchlines down a wall with an earth. The voltage from the sw lines had induced a voltage into earth with a similar reading.

Re: A real electrical Question
 

;)i agree sounds like inductance check if the earth is actually attached to the earth bar, if its off then you would definatly get a voltage on theearth cable whilst the active is active ;)

Re: A real electrical Question
 

Hello All,

Thanks for all the info and suggestions, i chased the entire length and found the main supply cables running within mm's of the run, the earth is correct and everything else appears to be correct. Have moved the run away and problem has gone, once again thanks all.

Regards

Kevin