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Unusual voltage measurements

Hi, 

Just moved into a new build and have 2 questions which have me scratching my head. 

The electrician has used through crimps (so he says on the phone), to join a 25mm armoured and meter tails in a metal junction box. He stated this was inside of the meter cupboard on the outside wall, but it isn‘t. I think this is OK as a setup, however the builder has whacked the joint into the cavity of the wall behind the built in meter cupboard so it isn’t accessible - this of course isn’t acceptable. 

The second finding is that, if the main switch in the DB is turned off, I can measure 230V between L&N and L&E (as expected, PME system) on the input side of the isolator. 

What i am unsure of, is that a measurement between the live side of the isolator and the Neutral (output side of the isolator), shows a voltage of 230V. This neutral output, should be isolated by the main switch. My thought is that perhaps voltage is flowing back to earth through electronic devices that naturally leak to earth?  

The isolator is absolutely working as it should, so no issues there. The voltage must be running back somewhere else . 

I haven’t seen this before, so before I call the original installer i wanted to raise it here first. 

Thanks. 

Parents
  • The reported voltage readings may be fine. With a 2 pole switch turned off, there should be no significant voltage between any conductors downstream of this switch. This is as reported.

    Testing between the still live INPUT terminal of the switch, and the isolated downstream neutral, should in theory and in a perfect world, show no voltage.

    Back in the real world, there will be capacitive coupling and a little leakage between the isolated downstream conductors and true earth. A sensitive test meter will show this.

     

Reply
  • The reported voltage readings may be fine. With a 2 pole switch turned off, there should be no significant voltage between any conductors downstream of this switch. This is as reported.

    Testing between the still live INPUT terminal of the switch, and the isolated downstream neutral, should in theory and in a perfect world, show no voltage.

    Back in the real world, there will be capacitive coupling and a little leakage between the isolated downstream conductors and true earth. A sensitive test meter will show this.

     

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