hob lights trip

[fog]

Hi fitted new 17th edition board in house partial re-wire have 2 rcbo's for the lighting circuits.1 for upstairs and 1 for the downstairs lights
2 downstairs lighting wires one old one new, when the old wire is fitted to rcbo all works ok until the hob, is taking load/power i.e a ring turned on then it makes the rcbo trip on the lighting circuit?
If the lighting circuit wire is fitted to the 6 amp MCB for the smoke alarms there is no problem.
What would be causing the 30ma rcbo to trip, any ideas ? and is it ok to leave this on the smoke MCB?
never had this sort of problem before any ideas welcome thanks

 

[baldsparkies]

Always a pain in the proverbial, my guess would be a shared neutral somewhere in the old install, Would be worth doing some continuity checks between circuits, disconnect from the board first to prevent false readings.
Just a thought . Your new board should be high integrity, if it has two rcd's you should have three neutral bars, with rcbo neutrals on the non protected neutral bar

 

[fog]

Hi BS
you are probably right need to do more checks
Yes it is high integrity board with seperate neutral bars , 3 off
could understand if it was all lighting circuits but cables are 1.0mm for lighting and 6/2.5cpc for the hob circuit.
builder has been in the loft adding extra bracing he may have disturbed something, but more likely to be neutral sharing typical after all is plastered next time will do checks on old circuits before changing board

 

[baldsparkies]

What if you put the problem circuits on one of the rcd's Fog.Just to see if it cures the tripping problem.

 

[fog]

will give it a try back in a couple of days