plaster boarding an existing ceiling and locating pipes and electrics
Find the joist at each end and snap a chalk line so you know where to put your screws. The national electric code requires wires to be 1-1/4 away from the edges so you should be fine putting screws in along the line. If you hit a spot the screw wont go in there may be a metal plate protecting the wires that are two close and sheetrock screws will not punch through the plates if there or metal pipe.