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Topic Title: induced voltage???
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Created On: 25 November 2010 04:41 PM
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 25 November 2010 04:41 PM
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tothetop

Posts: 41
Joined: 04 November 2010

even chap
have 2nd fixed some exteran lighting today wired 3 plate
all insulation resistance >299 L-E L-N N-E
polarity ok

when testing E loop found 15V on switch line and neutral/earth
disconected again to test again >299
broke down circuit sw/line >299
2way strappers >299
loop in/out >299
this is a property that is a new build so i thought may be some tracking through damp switches tested acroos an open switch >299

when circuit is disconected voltage disapears

in short my question is whould a damp atmospear improve the chance of induced voltages

strapppers and sw/line total length about 20m but i cant say i think this length is would induce a voltage.
tested live out of breaker and there if no current flowing and circuit is protected by a RCBO which is operating fine.

sorry so long but im at a loss on this one

cheers in advance
 26 November 2010 06:57 AM
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normcall

Posts: 8122
Joined: 15 January 2005

Is the earth actually connected to earth?
Maybe the RCBO has a small leakage?
"found 15V on switch line and neutral/earth " - only on the one circuit?

That should point you in the right direction.

-------------------------
Norman
 26 November 2010 01:09 PM
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tothetop

Posts: 41
Joined: 04 November 2010

yes earth loop good reading
r!+R2 1.57

RCBO leakage would not show on sw line with switch open would it ??

im at a loss
 26 November 2010 01:43 PM
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ectophile

Posts: 544
Joined: 17 September 2001

Are you seeing capacitive coupling? If the wire that has the unexpected voltage is disconnected at both ends and is running parallel to a live conductor, then capacitive coupling between the two can introduce a voltage.

The voltage you see will depend on the impedance of your tester, but a floating wire between a live and neutral can rise to half the supply voltage.

-------------------------
S P Barker BSc PhD MIET
 26 November 2010 07:36 PM
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tothetop

Posts: 41
Joined: 04 November 2010

OH this sound about right
thinking about it at this point in time there is no load on this circuit.if there was the voltage would bleed away through the load to neutral

cheers
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