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Topic Title: new circuit
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Created On: 12 January 2015 08:54 PM
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 13 January 2015 04:49 PM
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Phillron

Posts: 1411
Joined: 18 January 2007

Given that you are testing both the cable and the accessories connected to them
Have you assured yourself its not just these accessories playing a game with you
 13 January 2015 05:17 PM
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Manxie

Posts: 246
Joined: 08 January 2015

Maybe your tester needs calibrating
 13 January 2015 05:23 PM
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JZN

Posts: 787
Joined: 16 November 2006

If the reading keeps rising when you keep your finger on the test button then that's a good signal that it's damp from the plastering. The reading trickles up because the 500 volts applied "dries" the moisture.

I would expect it to shoot off scale if it's properly dry.

Another thing it could be is minor cable damage at one of the accessories while it was away from the wall.

John
 14 January 2015 06:39 AM
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spinlondon

Posts: 5494
Joined: 10 December 2004

When you conduct the testing, if you hold the test button down for a few seconds the reading should rise if there is damp.
 14 January 2015 11:07 AM
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IronFreely

Posts: 322
Joined: 06 November 2014

I'll just point out that although a new circuit should have a much higher result for insulation resistance, 50Mholms is still a pass, so strictly speaking you could leave that.
 14 January 2015 11:07 AM
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goldenboy1818

Posts: 809
Joined: 22 February 2011

Yea reading was slowly increasing, and plaster was very wet so all makes sense. Thanks for the advice guys
 14 January 2015 11:16 AM
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potential

Posts: 1630
Joined: 01 February 2007

When I was taught how to test the insulation resistance of cable many, many years ago it was assumed you'd test cables several times.
Tests would be over a period of days/weeks dependant on weather to get an accurate picture of the insulation.
 14 January 2015 07:16 PM
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Zoomup

Posts: 3265
Joined: 20 February 2014

We used to use an analogue "Megger" insulation resistance tester. If the reading gradually improved over a few seconds, shown by the needle moving into the higher regions of the scale, then that indicated condensation / moisture. Usually after drying out the circuits then proved to be ready for connection. Sometimes actually connecting the new circuits up actually improved the insulation resistance. (Did I just say that?).

Bye,

Z.
IET » Wiring and the regulations » new circuit

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