To wire a mounted fixture into a ceiling, follow these Installation Steps: First, turn off all power to the existing light or fixture Remove your old ceiling light Inspect your old wiring to make sure there are not any exposed wires Mount the crossbar of your new fixture Connect the new wires of your fixture as they were to the old fixture Make sure all the new wires are safely secured behind the drywall Secure the new fixture’s base Make sure you have the correct bulb with the correct wattage for the fixture Turn the power back on Finished