You don't have to be a journeyman electrician to install a flush mount ceiling fixture. Follow these steps to install the fixture.
Step 1 - Be Sure the Power is Turned Off at the Fixture
The best place to turn it off is at your circuit breaker box. Turn on the light that is screwed into the fixture. Once you turn off the breaker switch, the light should turn off. Of course, the best and safest way to be sure the power to the fixture is off is to use a voltage tester.
Step 2 - Measure the Height of the Globe from the Ceiling
If you're replacing the old globe with a new one — but using the old threaded tube — make sure the new globe fits the existing tube. The best way to do that is to measure both the tube and the globe depth. The tube should be long enough to allow the nut to be screwed onto the tube when the globe is in place.
Step 3 - Tighten Nuts
Tighten the nut to hold the threaded tube in place in the strap without turning it. Otherwise, when you install the final nut holding the globe in place, the tube might move and prevent you from tightening the nut.
Step 4 - Remove Screws
If the new fixture came with junction box screws, remove old screws and use the new ones.
Step 5 - Screw Tube
Screw the threaded tube in place in the junction box.
Step 6 - Secure Wire
Secure the ground wire on the green mounting strap ground screw. Twist the fixture's stranded wires together with the supply wires, and screw a twist-on wire connector over them.
Step 7 - Screw the Nut
Hold the fixture in place against the ceiling and screw the nut onto the threaded tube until the nut is tight enough that the fixture and globe will not wobble when in place.
Step 8 - Screw Light Bulbs
Screw light bulbs into the sockets. They should not be more than 40 Watts each. Bulbs with higher Wattage can produce excessive heat.
Step 9 - Turn on Power
Turn the breaker switch on again. The light should come on.