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.
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.
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.
