which brings me back to my post... why not nominate in line with lights as safe zones similar to walls? the method would then comply.
cost being a factor, it's way less expensive than cutting and repairing huge holes, and eliminates the risk of drilling blind through joists, trying to miss any cables etc.that can't be seen.
apart from which, it's farless likely to be screwed or nailed than a cable in a wall.not many customers want to hang pictures or fit shelves on a ceiling.
My approach, for what its worth, is,
1, Find a joist, look for popped nails, sags, split joints. IDEALLY close to the existing rose, this will allow you to relocate/extend existing cables to first new light position.
2, cut in a 100-150mm hole on one side of the joist. To allow access for angle drill. Number the balnk and ceiling and draw a line across the cut to to aid with relocating.
3, use a fish rod to gauge distance between joists, use phone camera to have a scan round.
4, repeat alongside all joists that need drilling. This will give you all the visuals you need. Only now can you make a reasonable stab of planning the locations and and should avoid hitting any snags.
5, using these holes, often upto 4/5, you can see both sides of any joists that need drilling, so you can now drill your routing holes in the joists.
6, drill out the light holes, fish in cables, test and energise.
7, to fill the routing holes I use any suitable timber on site to make battens, fix two across the hole. Use the numbers and marks from earlier to fix the correct blank back in its hole.
8, Use easifill and a small filling knife to fill the deeper parts then a large (150-200mm) filling knife to skim over, let dry and sand. If the holes are still visible after sanding give them another skim. Should be invisible after painting.
If its lath and plaster make your excuses and leave..
If artex, new ceiling. Its awful stuff and should be illegal.
www.themetalstore.co.uk
www.discount-electrical.co.uk
