Running lighting cables where no access from above

I have seen someone doing this and wondered if it was right?

New cable to be run to ceiling light, no access from above, so make a run of holes in ceiling, locate joists and run cable - clipping to underside of joists where encountered. Replaster.

Now I thought that cables had to be run through a hole in the centre of the joist - to avoid anyone putting a nail/screw through them?? Would one way round this be to put a protective metal plate (not sure of the technical term) over the cable/joist bits to give them protection?

SB

Its not ''right'' but its not uncommon on refurishment of bedsit flats etc, and in practice, ceilings are much less often nailed through than floors (carpets and all that) so problems of cable damage are rare. If the joist is not being notched significanltly then the building strength is not being compromised. The other way is with a very long drill bit to angle drill the joist though the ceileing, but patch up can be a pain, as the hole mid-joist to get the drill in is a great oval gash, particularly with lath and plaster. protector plates, also as used for rewiring older housee with notched joists from above, would seem to be a better way, if really worried. I suspect there are those who would say even that's not really acceptable. If in doubt note the departure on the paperwork and leave a copy by the fuseboard(s).

If you are replacing an existing cable it is sometimes possible to tape on a new cable to the old one and pull it in from the other end. But admittedly you have to be lucky