In article , Gareth Davies
writes
The people who lived here before me wired outside security/night lights
not to the lighting circuit but to a socket ring. Although controlled by
a wall switch the lights actually plug in to a socket inside.

It's not the best job in the world.

I've been using the lights with my old style fuse box and a plug in RCD
which does trip every now and again - probably three times a week.

I'm having the fuse box replaced with a consumer unit and I am
pre-empting nuisance tripping from these lights.

The only way to do this without the risk of nuisance tripping is to use
a dedicated circuit on an RCBO in the consumer unit.

Outdoor circuits are the most at risk from physical damage and moisture
ingress so you don't really want to risk them causing problems with
internal circuits.

You will need to properly check the complete outdoor run and junction
boxes but bear in mind that plug in RCDs are really intended for task
related (reset, plug in, cut grass remove) use rather than long term
installations so although rather to frequent, those trips may be
spurious. Plug in RCDs are often cheap junk and can trip on mains
transients (or sometimes, it seems, changes in wind direction) so while
you may have a problem with that circuit, you may not.

I found this after exporting power to a greenhouse over SWA (armoured)
cable and made a temporary hook up with an RCD plug. After a few
unexplained trips I was suspecting my installation skills but when I
swapped the lash up for a mini-CU with a proper RCD, the tripping
problems disappeared.

--
fred
it's a ba-na-na . . . .