I am aware of some investigation into false tripping of RCDs when there is a high transient fault L to N current and no apparent earth path to create earth leakage and un-balance.
That doesn't surprise me, particularly with electronically-tripped RCDs. However, in the OP's case, that would still require that both lighting and sockets loads were (by fault or design) drawing enough current to trip the corresponding MCBs (or 'switched L-E faults', such as you have mentioned, being present in both circuits) and, also (I would have thought unlikely) an RCD which operated every time an excessive (but not imbalanced) current flowed through it. ... seemingly pretty (extremely?) unlikely combinations of circumstances.
Well, yes, but that requires multiple simultaneous coincidental faults - and when one starts multiplying very small probabilities together ......! I think I'll stick with:
My assumption was that you are not competent to do the work you decided to do.
Nothing which has been posted since has given me reason to revise that assumption.
Will that be testing, as in proper testing, or switching it on and not having something trip?
Well, yes - but as I asked in response your your above suggestion at the time, and as Simon has just re-iterated, although that is a common mistake that would have explained the RCD operating, how can you explain the MCBs also operating as a result of that wiring error?
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