Quick Tips for Installing Your Ceiling Fixtures
You should mount all recessed ceiling fixtures to joists. Your first step in mounting a ceiling fixture, then, is to locate the joists.
Joists in ceilings are usually located exactly 16" apart. Use a magnetic or electronic stud finder to locate these joists. If you are using a nail-on box, the joist location is very important. Even with the bar, if the hole is too close to the joist, it will make installation difficult, if not impossible.
If you do not have a stud finder, you can tap on the ceiling. As you get closer to the joists the sound becomes more deadened. Another way is to drill a small hole and use a piece of wire to help locate the joist.
Once you've located the joist, saw out a hole in the ceiling to the correct size and in a location which permits the recessed fixture to be mounted where it can be screwed or bolted to the ceiling joist.
Turn off the current at the main switch. Attach the electrical wiring to the ceiling fixture, then mount the fixture in the proper location.