Im currently installing emergency lighting on the Eastenders set and the BBC are insisting that when a cable is drilled through a solid wall it must be protected with galv conduit. So Im allowed to clip direct but if I want to drill the cable outside I need to install conduit, only the length of the hole. (this is incase my 20mm hole weakens the wall and crushes the cable)
Is this a requirement of BS7671, good practice or just the BBC's requirement?
Is this a requirement of BS7671, good practice or just the BBC's requirement?