Correct way to run wires in a domestic context

Carlow52

Setup is as follows:
have 6.5m extention with A roof with sloped ceiling up to apex.
insulation in place between rafters and vapour membrane in place.

client wants a number of cable drops for lights along underside of ridge board.

Suggestion is to run cable vertically up gable wall and along underside of ridge board

Builder wants to remove insulation in rafters and run cable up behind insulation // to rafters and out at each point at ridge board.

His view is that that cables cannot run along underside of ridge board: poses danger of electcution when fixing lights

What about putting them in a steel conduit?
Thanks

bertie1

What about getting the builder to put in grounds at the ridge board where the fittings are going . If you are going to clip them to the ridge board you want to make sure they are well out of the way of any slab nails. The slab is probably 12.5 mm which means that it will be hit & miss to get the ridge board & the light fitting base will not be flush. You could also suggest grounds pround of the slabs ( in a decorative timber )again to get the base of the light fitting flush to finish