We have a 27ft long dark wall, no road or adjoining lighting.
I would like to fit an external downlight & PIR.

Nearby exists a MK Masterseal socket outlet on a 20A
external radial to an outbuilding, RCBO protected. Above
ground it is HiTuf changing to SWA to enter ground.

I could fit an MK Masterseal SFCU 56410 alongside the
socket, creating a fused spur at 3A, w/double pole switch.

Q: Is that a legitimate usage of the SFCU 56410?

This would avoid running another cable alongside the existing.
I suspect it is considering likely popular for fountains & such.

Struggled in the dark for donkeys years and just stumbled
across the item in the MK catalog p206, guide #46 :-)
--
JSB.