Bob Watkinson wrote:

314-01-01 states that 'Every installation shall be divided into circuits as
necessary to

1) avoid danger in the event of a fault, and
2)facilitate safe operation, inspection, testing and maintenance.

The On Site Guide does not give specific reference to RCD's and this reg
either and indeed the subject has regularly come up for debate on other
forums.

Section 3.6.2 gives advice on the application of RCDs and cites
314-01-01 & -02. That seems to me to be fairly "specific."

What you have to consider is each installation and what is needed to
comply with the regs. For example in a large multifloor Victorian house
there would be considerable risk of a person falling down the stairs if
because of a fault on another circuit the RCD tripped. On the other hand in
a small ground floor office it is difficult to imagine how danger could be
caused by an RCD trip. In any case if emergency lighting were used the
problem again disappears. In short, the use in itself of a single RCD does
not necessarily breach 314-01-01.

True, but it does not necessarily comply either.

My view is that 314-01-01 is primarily aimed at considerations for
overcurrent protection

It doesn't actually say that, though.

314-01-02 requires that other circuits remain energised when a circuit is
faulty. Again, I interpret this as for overcurrent protection. If you
interpret it as being for earth faults then you would not even be able to
use a split board, unless there were a separate rcd for each protected
circuit

"Circuit" doesn't necessarily mean "final circuit" (see definitions).
The arrangements feeding the supply to (say) the two halves of a
split-load CU are "circuits" so far as this reg. is concerned. The key
words in 314-01-02 are in the final sentence "... and due account shall
be taken of the consequences of operation of any single protective device."

--
Andy