Caught out by mt own lazyness.....

[Doomed]

Did an EICR of a rented property, 2 up 2 down, old, one lighting circuit, cooker, ring and 2 radials (2 sockets in kitchenon one, hall socket on other).
All readings not to bad, not perfect I/R on kitchen radial, but damp walls so I wasn't surprised, end of line readings all good, realised that there must be loads of hidden joints on the lighting, so took readings at the furthest grond floor point and both ends of first floor.
Bonding up to date, but no RCD protection.
As rented recommended fitting RCD protection, gave landlord options and she went for a shiney new distribution board.
Came back, fitted it, retested all socket and cooker circuits and then got lazy..... as only the one lighting circuit checked the ground floor point I tested at last time as that had the highest reading last time and thoght jolly good, home time.
Silly me.
Two hours later called back when the tenant got home and tried to put the lights on upstairs - RCD trip!
After lots of hunting found a JB with the neutral and earth linked - AH HA I thought... - nope, take it out and no lights - upstairs missing the neutral - great, lifting boards and running a new feed 8pm at night with a moody tenant on my back.
Serves me right.

 

[Toneyz]

Like your drawing Anthony brag. Makes perfect sense, but...

In post one no mention of break in neutral. Just neutral and Earth connected.

In post 4 a bit more confusing, it says neutral was not connected where earth was linked. Not sure how to interpret that one.

Maybe wording not ideal.

Question to doomed, has anthonybragg got it right in his drawing. If so case cracked.

See post 7

 

[Deleted account]

Post 7 as I said neutral was broken prior to join.

I saw no mention of this being said in post 1 or4.

My reply was in post 5.

 

[Baddegg]

See rough drawing

Thanks for the drawing Anthony made things much clearer,I know I’m missing something here but why would the rcd only trip once the upstairs lights were switched?

 

[Deleted account]

Thanks for the drawing Anthony made things much clearer,I know I’m missing something here but why would the rcd only trip once the upstairs lights were switched?

When any switch is in the on position there would be Current through the residual current devices live, but no return feed through neutral as the return path would be via the cpc. I balance trip.

If all lights switched off no current through live and no current through neutral. Also non of the lights neutrals are actually connected to the neutral bar in the earth. No imbalance no trip.

 

[Baddegg]

Thanks Pete that makes sense, What’s confusing me is it only tripped with the upstairs lights when there is only a single lighting circuit? Not doubting anyone here just trying to keep up ha ha

 

[Deleted account]

Anthony brags picture shows the break before any lights. If the break was half way into the circuit the down stairs lights would have a return path through neutral, so no trip.

This is provided I've understood anthonybrag, And Anthonybrag has understood doomed correctly

 

[Toneyz]

Could be a possibility that the lighting circuits were both together before and has now split up to upstairs and downstairs could also be that they switched on one of the upstairs lights first.

 

[Baddegg]

Thanks Anthony I was toying with the second option myself but convinced myself it couldn’t be that simple ha ha

 

[Doomed]

There was only one lighting circuit, the ground floor was fine, the link to upstairs had the break in the neutral and the upstairs was as per the drawing.
As I said, if I had gone upstairs and checked a light I would of found it after the DB change, but I was lazy.

 

[a-z electrics]

Interesting post.. thanks for sharing it.