That s because running a fluorescent fixture with a burned out bulb will damage the ballast. Install the new tube the same way insert the tube s prongs into the socket and twist the tube to lock it into place. Unique Light Fixture Wire Diagram Diagram Wiringdiagram Does your fluorescent light flicker or only come on dimly. How to install fluorescent light bulb . You can either install a new one or if you re not sure the tube is burned out test the old tube in another fluorescent fixture. Remove the old tube by twisting it out of its sockets in the fixture. Start with the fluorescent tube or bulb. There could be a problem with the bulbs. Otherwise an existing fluorescent light might have cable running directly into it with no electrical junction box. Replace a fluorescent lightbulb taking care not to break the bulb. This video will show you how to change a fluorescent light bulb. Lift the new fluorescent tube into place. That s ok usually the fixture s housing is c