OP
Sparkz123
It may or may not be relevant here, but I recently installed an MK Sentry dual RCD board, where one RCD failed to trip on test. I had to leave the installation covered by the one good one as it was getting dark.
That seems a bit of a coincidence, what was the outcome? Was it a faulty RCD or something else?
I'm confident that there are no shared neutrals, I have tested between the 2 neutral blocks and the readings were clear. It's not a new installation, I've just replaced an old board covered by a voltage operated trip. I'll disconnect all the circuits tomorrow and see what happens but I can't think of a wiring fault that could cause this. If it fails to work properly once the circuits are disconnected it's got to be a fault on the boards internal wiring, but God knows what.
Thanks everyone for the input.