On 28/07/2019 12:01, charles wrote:
Or were you
referring to shared neutrals which might still have caused the RCD to
trip even if the live was disconnected via the MCB? Or is there another
explanation?
while the master breaker would be double pole, the ones on subicircuits
would almost certainly be single pole.
Correct. Neutrals all come back to a big busbar and an earth neutral
short will cause anything on wiring close to it to trip.

Its a matter of whether the return conductancee via the earth short is a
reasonable fraction of the true neutral return: If it is it will divert
enough current to trip the RCD



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