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Neutral wire removed. Circuit still live.

Simon M

Hi all,

A customer has complained of rcd tripping on the garage circuit causing the garage alarm to sound. 

Garage is wired in 2.5mm SWA from house consumer unit split load board 20A mcb. 
A garage consumer unit is provided with one lighting circuit one socket circuit. Garage alarm is spurred from socket. 
There is an outside light attached to the garage. 

Something was causing the rcd in the house to trip.
Customer called an electrician to sort the problem. 

Electrician left without resolving problem. 

They call me. 

I go take a look. 

Socket tester says Live earth reversed. I call rubbish. 
Carried out some tests to find all circuits live but not functioning. 

I open the consumer unit in the house to find the neutral wire to the garage has been removed!

Live still connected MCB on. 

Now am I missing something magical and mystical?

My question is, why would he have done this. 

I carried out R1 + R2 test - all good, same reading as on the EIC. Installation new 6 months ago.

I replaced the neutral and energised to try replicate the tripping. Everything is fine.

it’s a good job the customer didn’t go poking around in the garage sockets believing they were dead when the line conductor was actually energised.

I am just trying to get my head round the removal of the neutral and why this NICEIC spark felt this was a good idea?

Thoughts  

  • Are you certain that the neutral was deliberately removed, rather than poorly connected and consequently dropped out of the terminal. 

  • My guess was it was removed to see if it stopped the tripping issue or to avoid compromising RCD tests or to allow an insulation test (together with the MCB switched off) - and (s)he simply forget to reconnect it.

       - Andy.


  • Here we see the neutral conductor removed. Poor photo sorry. 
    On further inspection we can see what appears to be two cut/broken neutral conductors still on neutral bar terminal 3. 
    Perhaps it just snapped off?

    Further investigation required.  

  • in reply to Simon M

    That hasn't just fallen out or snapped.

    Doesn't give you much confidence, does it?

  • in reply to Chris Pearson

    Hmm I can imagine a case where it may 'help' by masking a fault. Modern RCDs with electronics in need an L-N voltage to operate. If you can remove that LN difference by any means, the contacts will stay closed and not trip. So if a load side NE fault provides the return path, then with an RCD sans neutral, power will stay on and work, at least until the faulty device is unplugged. I agree it leaves a nasty taste not least as the ADS for earth faults has been borked. Did this chap or chapess arrive on a horse and wear spurs and a cowboy hat by any chance ?

    Mike.

  • Simon M said:
    I am just trying to get my head round the removal of the neutral and why this NICEIC spark felt this was a good idea?

    1. Proven NICEIC "spark"? 2. Circumstances causing "spark" to leave job "unfinished"? - "I replaced the neutral and energised to try replicate the tripping. Everything is fine." Customers sometimes speak with forked tongues.

    Jaymack 

  • in reply to Jaymack

    According to the EIC the spark is NICEIC. 

    I have further information. 
    a friend of the original installer came to look at the alarm and was told by the original installer to remove the neutral. Perhaps as mentioned above to aid testing. 
    the alarm was isolated. 
    perhaps just a case of forgetfulness. 
    but still.,

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