wrote:

We have three electrically opened garage doors, currently they are
simply plugged into sockets in the garage which are fed by the RCD
protected side of a split load CU.

Since our garden electrics are also fed from the same side of the
split load unit it means that anything that goes awry in the garden
and trips the RCD also stops the garage doors working which can be a
bit of a nuisance (especially since the CU is in one of the garages!).
It's not a disaster because there's a alternative access to the garage
but it would be good if we could split the garage doors off the RCD
protected circuits - or at least split them off the same circuit as
the garden, pond, etc.

So what are the allowed/correct ways of doing this?

Can I used a dedicated, non-RCD protected circuit for the garage
doors? The existing sockets are mounted on the rafters adjacent
to the door opening gear so are hardly likely to be used for
'portable equipment out of doors'. Is it OK to have these three
dedicated sockets non-RCD protected even though they're in a
garage? This is the cheapest way to fix the problem, I have
spare circuits on the non-RCD side of the CU.

Similar to the above I could dedicate a circuit to the garage door
openers and not have them on sockets at all but I suspect that
this then requires a double pole switch for each to allow it to
be isolated. A bit more expensive but not much.

The most expensive solution is to dedicate an RCBO (combined RCD
and MCB in other words) to either the garden/pond or the garage
doors and add this to the CU on the non-RCD side. I suppose it's
the ideal solution but will cost thirty or forty pounds. It is
also the simplest solution in that it only involves moving some
wires in the CU.

.... and yes, I know it's probably part P'able.

--
For me changing the existing sockets to the non RCD side of the CU
would be adequate provided you put a notice next to the other sockets
say something like "Sockets must not be used for outdoor equipment".
After all the regs speak of sockets that might reasonably be expected
to be used for outdoor equipment and to my mind it is not reasonable to
use a socket with such a notice on it. But he part P inspector might
have differnat views. But I wouldn't be bothering to notify :-)

I think that the most cost effective way to satisfy every jobsworth
would be to run a new non RCD circuit to a fused/switched connection
unit near the unit. Cost about a tenner to do that yourself

Of course if you are going th inspected route the cost of the job is
trivial compared with the cost of inspection so you might as fell fit a
dedicated RCD.