On Mon, 19 Aug 2013 14:45:15 +0100, Toby wrote:

It then typically switches back soon after, but sometimes the RCBO
for
that circuit trips at the same time.

In my office, I had to change the 16A MCB for a type C, as that would
always trip on mains power restore if there was a power cut,

RCBO MCB ...

IT/electronic kit tends to leak rather a lot to earth because of the
filters on the mains input to keep all the nasty RF interference off
the mains cabling. IIRC it's not recomended to have more than 10 such
appliances on a single RCD.

Switching transients may well create enough earth leakage current to
push an RCBO that is already near its leakage limit past the leakage
trip point.

It could be a switching surge that a type C MCB would help with.

--
Cheers
Dave.