Single phase spur from 3 phase breaker

[Ringo]

Quick one - been asked to take a single-phase feed to a switched fused spur in an industrial premises, ready for another team to connect power to a simple single CCTV camera. The spur is to come from a nearby 3-phase breaker which feeds only one roller door, on its own fuse back at the board. The spur will only be a matter of a couple of feet away, fed by 3-core 2.5 SWA clipped to the wall. Is it ok / safe / legal / the done thing to take the live conductor for this spur out from the brown phase IN on the top of the 3-phase breaker? It seems ok to me, especially as it's an SFS I'm running to. I can't find anything ruling against it but as usual I know the various voices of experience here on the forum can shed light on anything I may have overlooked.

Ta.

 

[Darkwood]

Read REG 314.1 AND 314.2 (Red book may have changed in green but not got to hand), this should highlight that you shouldn't employ this method for the reasons stated, but electrically it would work ok its just you have to consider maintenance/testing confusion and and in the event of a fault say of roller shutter you would loose your cctv system if fuse operated.