Fluorescent Light Bulbs Troubleshooting

Troubleshooting a fluorescent lighting fixture means being aware of things such as flickering lights or how long it takes for the bulb to kick on. Special care must be used when using overhead fluorescent light tubes. Allow the light to stay on for a while after it has been turned on, as repeatedly switching on and off can limit the life of the bulb. Your problem with illumination may be that the tubes have become dirty so take care to clean your fluorescent lights periodically.

Check the power source if the light won't come on at all. Make sure the light switch is actually on. Go to the main service panel to check for a blown fuse or tripped circuit breaker.

Remove and look at the ends of the lighting tube. If the ends are black, the tube is worn and needs replacing. If the tubes are not black, check that the pins are straight and clean. Make sure that the socket in the lamp fixture is not damaged.

Turn off the circuit breaker to the fixture and locate the starter on the fixture and give it a quarter-turn counterclockwise and then pull it out. Take the starter mechanism to the store and purchase a new starter with matching wattage. Push the new starter in until you feel the pins entering the slots. Give it a quarter turn clockwise until it clicks into place.

Remove a flickering fluorescent tube by turning it a quarter of the way around and pulling straight down. Use a rag to wipe the pins at each end. Try to get these pins as clean as possible, but make sure you don't bend them. A flickering light is often caused by a poor connection at the socket, and wiping the pins will provide a cleaner connection.

Twist the tube back and forth if the light continues to flicker. If twisting the light doesn't stop the flickering, it probably needs to be replaced.

Listen for a vibrating or humming sound in the fluorescent lighting fixture. This is almost always an indication that a part known as the ballast is not properly secured or is of the wrong type. Turn off the circuit breaker to the unit. Remove the tubes and then remove the cover from the housing. Tighten the mounting screws on the ballast. Check that all electrical connections are right. If this does not resolve the vibration and humming, replace the ballast with a new one.

Replace the ballast with one that is rated for use in cold temperatures if your fluorescent fixture takes longer to kick on when then temperature in the room is below 10 degrees C. A faulty ballast that is rated for cold temperatures may also result in the fixture taking longer to come on than normal.


Always turn off power to the fixture before removing or testing the ballast or starter.

Things You'll Need

  • Replacement tube if needed
  • New starter if needed
  • New ballast if needed
  • Screwdriver
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Timothy Sexton's more than 10,000 articles have been published on sites ranging from USA Today to CareerAddict, from PopEater to His writing has been referenced in books ranging from "The Reckless Life...of Marlon Brando" to "Brand New China: Advertising, Media and Commercial and from Scarface Nation to Incentive!"