Lighting fault

Spent all day today changing consumer unit powerd back up and one set of lights in kitchen extension tripping RCD on Neutral.

Thought about borrowed neutral but supply comes from board into switch and feeds two lights neutrals also connected through back box any one give me some quick tips how I can trace if definetly borroed neutral fault as have to go back in the morning to sort out these two lights.

What do you mean by 'tripping RCD on neutral'?

Hi Bryn

Is this a duel RCD board?

Are these two lights a seperate circuit to the other lights?

Have you got the nuetral in the correct N bar?

Have You done an Insulation Resis. test on the circuit?

If N goes to switch with Live feed then maybe not a borrowed N but perhaps a N-E fault.

Try disconnecting Ns at switch and then trying them one at a time