My builder states he will be using 8 inches of "rockwool" type insulation -
four inches running with the beams four running over.

I had thought it was good practice to

a: Cleat the cable to the ceiling joists for support, and
b. Ensure the cable runs over the insulation to prevent overheating of the
cable (related to fault current calculations).

In my situation above the two (a and b) seem to be contradictory as four
inches of insulation will be over all the joists. What do you guys do in
this situation???????

Many thanks for all your help

Laurie