voltage between live and earth

[tommo1]

hi all
im currently doing some testing on a university the install is metal trunking and metal conduit used as the earth for the whole installation. when we disconect neutral and carry out isulation resistance test we are getting a 12v between live and the earth bar, and our metrel tester wont allow us to carry out the test. does any one have any ideas.
thanks in advance

 

[jeremy]

Are there any energised circuits at all in the installation?

 

[tommo1]

Yes wen we turn off other circuits it drops is this leakage from the computers

 

[Deleted member 26818]

It's induced voltage.

 

[telectrix]

as spin says, induced volts. need to isolate other circuits while testing.

 

[Deleted member 26818]

I would imagine, that your tester isn't allowing any tests, because the neutral has been disconnected, or you've altered the settings.
Should allow testing with voltage up to 50V, I believe.

 

[ExArmy]

long shot, but have you tried using an insulated screwdriver to press test? I had a metrel that would never carry out EFLI tests unless i did this, A symbol saying "phase voltage on PE terminal" came up and it beeped alot.

 

[tommo1]

Thanks for you help. The metrel won't let me megger with voltage over 10v

 

[Guitarist]

Are you not isolating the whole db when testing?

 

[tommo1]

We can't isolate the whole db because some of the circuits are in use so we do what we can there are 17 boards to do so just do what we can wen we can

 

[Guitarist]

We can't isolate the whole db because some of the circuits are in use so we do what we can there are 17 boards to do so just do what we can wen we can

Ah, lots of induced voltage then

 

[tommo1]

Seems to be I've just been having a read on Internet.do you know where I could find more info on this