Lighting circuit tripping on 17th edition board

[wee_ron]

I've been called to look at a lighting circuit which is tripping the rcd when one particular light is switched. I've disconnected the light and circuit stays on even when switched and getting voltage at connectors but when I add a bulb to the light it blows the trip instantly. Any suggestions on how to solve this fault???

 

[Rockingit]

Is this light on a landing by any chance? Sound to me like you've got a shared neutral between the upstairs and downstairs lighting circuits, which will then make whichever RCD on that side of the board trip.

Good hunting!

 

[Octopus]

Sounds to me as if somebody has been fiddling around. Is the light new? the CU new?

 

[telectrix]

soundsd very much like a shared neutral. usually both RCDs will trip when a load is switched on.

 

[lofty84]

how can 2 lights share a neautral? how do u go about finding out if yes that is the problem and whys it not tripping both RCDS

 

[sparky692]

Gotta be a shared neutral without doubt. 2 way stairs landing hallway .. had it so many times ...

 

[Octopus]

Gotta be a shared neutral without doubt. 2 way stairs landing hallway .. had it so many times ...

Could be but what caused it???????? Such issues don't suddenly appear out of nowhere!!

 

[lofty84]

I would like to know this to