Fluorescent lights are commonly used because of their low operating cost. Like other lighting fixtures, fluorescent light fixtures sometimes work improperly. Aside from a burnt tube, other factors, such as a worn starter and loose or oxidized electrical contacts, can contribute to a fluorescent light not working properly. Troubleshooting fluorescent lights is typically not complicated, but involves the inspection of several parts of the light.
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Inspect the Fluorescent Tube
If the fluorescent tube is flickering or dead when you turn the light switch on, remove the light diffuser, if any. The light diffuser is the plastic piece that covers the light fixture. To remove, press on the clips or detach the screws holding the diffuser. Once removed, look at the fluorescent tube for dark spots near either end of the bulb. Replace the tube if spots are present, as this condition indicates that the tube is close to failure or defective. The dark spots are created by the mercury emissions under high voltage during start ups.
Check the Light Sockets
Gently push the fluorescent tube in its socket. The tube must be tight in the socket for it work correctly. If the tube moves, the sockets might be loose. Turn off electricity at the main circuit breaker. Remove the fluorescent tube to access the sockets inside the light fixture. Turn on the voltage tester and point toward the sockets, one at a time, to make sure there is no current in the socket. Wiggle the sockets to test if they are loose. If they are, tighten the screws on the sockets using a Philips screwdriver.
Damaged or Oxidized Contacts
Check the prongs of the sockets. If they are damaged or oxidized, replace them. Use a screwdriver to loosen the screws holding the prongs in place. Inspect the contacts at the end of the wiring inside the socket after removing the prongs. Wipe off any green or white oxidized material on the wire contacts with a cotton swab dipped in cleaning alcohol. Bring the old prongs to the store so you will know which size to buy. Insert the new prongs in the socket and tighten with the original screws.
Replace the Starter
Old fluorescent light fixtures use starters, also called ballasts, for lighting the tube. These are usually cylindrical, silver in color and screwed onto the fixture near the tube. Each fluorescent tube has its own starter. Press the starter in, then turn it counter clockwise to unscrew. Take the old starter to the store. The fluorescent starter size is not universal. Different makes of fluorescent light fixtures have their own dedicated starter sizes and voltages. Look for the model, size and voltage rating imprinted on the old starter to match the new one that you wish to buy. Press the new starter into the starter seat and turn clockwise until tight. Do not over-tighten the starter when installing it.