How to Troubleshoot a Fluorescent Tube

Updated February 21, 2017

Fluorescent lights are durable lighting options that last longer than traditional light bulbs. Although fluorescent lights come in a variety of bulb types, one of the most common is the tube light. There are many issues that can occur with fluorescent lights, including bad connections and flickering to name a few. Most of these problems are not difficult to solve. However, the first step to solving them is to troubleshoot the problem.

Stand on a step stool or ladder to access the fluorescent light.

Open the light cover to access the fluorescent tubes. The light cover usually opens by sliding small metal tabs located near the edge of the light.

Look at both ends of the fluorescent light tube that is exhibiting problems to see if the white part of the tube is dark. The darkness tends to look like a greying around the tube itself. Tubes that have grey colour at the ends need to be replaced since they are at the end of their life cycle.

Remove the troublesome tube from the light fixture by grasping it near both ends and pulling straight down out of the light fixture.

Remove one of the working fluorescent tubes from the light fixture in the same manner.

Place the troublesome tube into the light socket where the good tube was located. If the bad tube lights up, then you know the problem is with the ballast on the previous socket. If the tube does not light up, you know that you have a bad tube that should be replaced.

Replace the starter after performing the above steps to remedy any flickering problems that remain. Starters only exist in fluorescent lights that are older than 15 to 20 years old. The Resources section below provides a link to identifying and replacing starters.


If all of the above steps fail, the problem is probably with the fluorescent light ballast. Since the cost of repairing a ballast is extremely expensive, it makes more sense to replace the entire light fixture.

Things You'll Need

  • Step stool
  • Ladder
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About the Author

Kimberly Johnson is a freelance writer whose articles have appeared in various online publications including eHow, Suite101 and Examiner. She has a degree in journalism from the University of Georgia and began writing professionally in 2001.