Can a earth fault on a lighting circuit effect another circuit , this being ring main , only two circuits in flat, After changing a light fitting i came across an earth fault on the lighting circuit , I thought i had sorted earth fault out but the other circuit in the flat started tripping , when the lighting circuit cpc is removed from earth bar , nothing trips both circuits power up. With lighting cpc in earth bar ring main trips, not on rcbos.
Have you undertaken an insulation resistance test of both circuits ? - particularly N-E
Depending on the age of the flat it wasn't unusual to have a single earth conductor doing "everything" as it allowed smaller conduits etc to be installed in the structure
If you remove the lighting circuit CPC, do you have an "earth" at socket outlets.
Well, if IR really is 200 Ohms, then the installation is leaking over 1 amp - which may well be lethal. Have you tried breaking the sections down to find out why so low (and as above a few continuity tests
What was the lighting circuit fault - what was the repair
Can a earth fault on a lighting circuit effect another circuit , this being ring main , only two circuits in flat, After changing a light fitting i came across an earth fault on the lighting circuit , I thought i had sorted earth fault out but the other circuit in the flat started tripping , when the lighting circuit cpc is removed from earth bar , nothing trips both circuits power up. With lighting cpc in earth bar ring main trips, not on rcbos.
Hi Thomas Ward, could you describe the earth fault that you came across initially and how it was rectified? Any pictures you have of the fuse box etc may help :)
Look for places where the two circuits come together - wall lights perhaps, or fire alarm circuits, or really anything that looks like a late addition. Can you clarify what device is tripping ? is it a 32A MCB, or an RCD / RCBO at 30ma or whatever ? In the first case a 32A sort of fault should show up with a meter or even a battery and a test buzzer, while an earth leakage type trip may be more subtle and involve shared neutrals, as we should then only be looking for 30mA more down L than N to cause enough imbalance to fire it.
Its a 32amp mcb thats tripping and a 40 amp rcbo which is in the main board , I was working on a lighting circuit but this has somehow caused the ring main 32 amp mcb which is in the flats cu to start tripping and also the 40 amp rcbo which is in the main board . Its a flat with its own cu which is fed from a main board .
