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How to Test Fluorescent Bulbs Download Article Co-authored by Daniel Stoescu and Hunter Rising
Last Updated: January 21, 2026
Download Article
Looking for Surface Issues
|
Checking the Electrical Components
|
Cleaning the Bulb
|
Video
|
Tips
|
Warnings
|Show more|Show less X
This article was co-authored by Daniel Stoescu and by wikiHow staff writer, Hunter Rising. Daniel Stoescu is a Master Electrician and the Owner and Operator of Home Tech Solutions, LLC in Hampton, Virginia. With over a decade of experience, Daniel specializes in wiring residential, commercial, and light industrial structures. The Home Tech Solutions team has over four decades of combined experience and offers comprehensive solutions for residential electrical needs. This article has been viewed 156,989 times.
A flickering or dead fluorescent bulb can be a nuisance and it may be time to replace it. Before going out to purchase a new bulb, ensure the bulb is the main problem. By checking for surface-level issues, cleaning the parts, and looking at the electronics, you can determine whether you have an easy fix or a trip to the hardware store.
Steps
Part 1 Part 1 of 3:
Looking for Surface Issues
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1 Look for dark areas at the base of the bulb. When bulbs age and have been used for a long time, brown spots will appear. If darkness begins to form at the ends of the tube, the bulb may be near its end. While they may still light, they are wearing out and will die soon.
If the darkness only forms on one end of a tube light, flip the tube so the darkened end is on the opposite side of the fixture.
If darkness forms on one side of the tube, rotate the tube by 180 degrees from how it used to sit.
2 Inspect the pins at the end of the bulbs. The pins of the electrode connect the light bulb to the power source. If the pins are bent or misaligned, use needle-nose pliers to straighten them before returning them to the fixture. Advertisement
3 Test the bulb in a working fixture. Remove the bulb from the fixture in question and test it in another lamp. If the problem lies within the lamp, the bulb should work in a separate fixture.[1]X Expert Source Daniel StoescuMaster ElectricianExpert Interview
If testing tube lights, be sure to test both bulbs even if only one is out. Currents travel between both tubes and either could be causing the problem.[2]XResearch source
Advertisement Part 2 Part 2 of 3:
Checking the Electrical Components
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1 Check your electrical panel box. Ensure the circuit is not broken. If the breaker has been tripped, push the switch entirely to the off position, and flip the switch back on. Test the lamp again to see if it lights.[3]XResearch source
2 Test the electrodes using a multimeter. Using a multimeter will determine if the electrodes still hold conductivity. If the electrodes are not intact, the bulb will not have a current running through it.[4]XResearch source Place the probes on both pins of the tube light to get an accurate reading.
If there is no reading on the multimeter, the bulbs should be replaced.
3 Replace the starter on the bulb if problems persist. Older fluorescent fixtures will have small metal cylinders called 'starters' on the ends. The starter ignites the gas within the bulb and is crucial for lighting the bulb.[5]XResearch source Many hardware stores will carry replacements for only a few dollars.
Note the wattage of the bulb to ensure the correct starter is purchased.
Old starters look no different than new starters, so throw away any starters that have gone bad.
Advertisement Part 3 Part 3 of 3:
Cleaning the Bulb
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1 Wiggle the bulb in its socket. Rocking the bulb back and forth in small motions can help loosen corrosion and dust that may have gathered near the socket. Clean any leftover residue with a fresh paper towel.[6]X Expert Source Daniel StoescuMaster ElectricianExpert Interview
Make sure the power is turned off to avoid any electrical damage.
2 Wipe the bulb with a cloth soaked in dish detergent. Some bulbs will not light if they are covered in dirt or dust. Remove the bulb and gently use a cloth on the surface. When finished, wipe the soap clean with another cloth soaked in water.
Be careful handling a fluorescent tube. They’re fragile and have potential to break into shards.
3 Scrub the pins of the electrode with a fine sandpaper. Clear away any corrosion or residue as you rub the pins. Small particles like these restrict the electric current and may be the source of your trouble. Use a cloth or paper towel to remove any loose particles before returning the bulb to the fixture.
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Video
Tips
If the bulb still does not light, the gas may have leaked out and the bulb will need to be replaced. Thanks Helpful 0 Not Helpful 1
Submit a Tip All tip submissions are carefully reviewed before being published Name Please provide your name and last initial Submit Thanks for submitting a tip for review! Advertisement
Warnings
When working with electronics, make sure the power source is off to avoid electric shock. Thanks Helpful 4 Not Helpful 4
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References
↑ Daniel Stoescu. Master Electrician. Expert Interview
↑ Daniel Stoescu. Master Electrician. Expert Interview
About This Article
Co-authored by: Daniel Stoescu Master Electrician This article was co-authored by Daniel Stoescu and by wikiHow staff writer, Hunter Rising. Daniel Stoescu is a Master Electrician and the Owner and Operator of Home Tech Solutions, LLC in Hampton, Virginia. With over a decade of experience, Daniel specializes in wiring residential, commercial, and light industrial structures. The Home Tech Solutions team has over four decades of combined experience and offers comprehensive solutions for residential electrical needs. This article has been viewed 156,989 times. 55 votes - 65% Co-authors: 6Updated: January 21, 2026 Views: 156,989 Categories: Featured Articles | LightingArticle SummaryX
To test fluorescent bulbs, start by checking your electrical panel box to confirm the circuit isn't broken. If the breaker has been tripped, push the switch entirely to the off position, and flip the switch back on. You can also use a multimeter to determine if the electrodes still hold conductivity. Place the probes on both pins of the tube light to get an accurate reading. If there is no reading on the multimeter, the bulbs should be replaced. For tips on replacing the starter bulb, read on!Did this summary help you?YesNo
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Lester Wilder
Jan 9, 2021
"Im 58 and learning all about electrics. My job at AK Steel is to learn maintenance at the steel mill. This helped me a lot."..." more
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Yes No Advertisement Cookies make wikiHow better. By continuing to use our site, you agree to our cookie policy. Co-authored by: Daniel Stoescu Master Electrician 55 votes - 65% Click a star to vote Co-authors: 6Updated: January 21, 2026 Views: 156,989
Lester Wilder
Jan 9, 2021
"Im 58 and learning all about electrics. My job at AK Steel is to learn maintenance at the steel mill. This helped me a lot."..." more Share yours!
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Co-authored by: Daniel Stoescu Master Electrician This article was co-authored by Daniel Stoescu and by wikiHow staff writer, Hunter Rising. Daniel Stoescu is a Master Electrician and the Owner and Operator of Home Tech Solutions, LLC in Hampton, Virginia. With over a decade of experience, Daniel specializes in wiring residential, commercial, and light industrial structures. The Home Tech Solutions team has over four decades of combined experience and offers comprehensive solutions for residential electrical needs. This article has been viewed 156,989 times. 55 votes - 65% Co-authors: 6 Updated: January 21, 2026 Views: 156,989 Categories: Featured Articles | Lighting Article SummaryX
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1 Look for dark areas at the base of the bulb. When bulbs age and have been used for a long time, brown spots will appear. If darkness begins to form at the ends of the tube, the bulb may be near its end. While they may still light, they are wearing out and will die soon. 
2 Inspect the pins at the end of the bulbs. The pins of the electrode connect the light bulb to the power source. If the pins are bent or misaligned, use needle-nose pliers to straighten them before returning them to the fixture. Advertisement 
3 Test the bulb in a working fixture. Remove the bulb from the fixture in question and test it in another lamp. If the problem lies within the lamp, the bulb should work in a separate fixture.[1] 
1 Check your electrical panel box. Ensure the circuit is not broken. If the breaker has been tripped, push the switch entirely to the off position, and flip the switch back on. Test the lamp again to see if it lights.[3] 
2 Test the electrodes using a multimeter. Using a multimeter will determine if the electrodes still hold conductivity. If the electrodes are not intact, the bulb will not have a current running through it.[4] Place the probes on both pins of the tube light to get an accurate reading. 
3 Replace the starter on the bulb if problems persist. Older fluorescent fixtures will have small metal cylinders called 'starters' on the ends. The starter ignites the gas within the bulb and is crucial for lighting the bulb.[5] Many hardware stores will carry replacements for only a few dollars. 
1 Wiggle the bulb in its socket. Rocking the bulb back and forth in small motions can help loosen corrosion and dust that may have gathered near the socket. Clean any leftover residue with a fresh paper towel.[6] 
2 Wipe the bulb with a cloth soaked in dish detergent. Some bulbs will not light if they are covered in dirt or dust. Remove the bulb and gently use a cloth on the surface. When finished, wipe the soap clean with another cloth soaked in water. 
3 Scrub the pins of the electrode with a fine sandpaper. Clear away any corrosion or residue as you rub the pins. Small particles like these restrict the electric current and may be the source of your trouble. Use a cloth or paper towel to remove any loose particles before returning the bulb to the fixture. Advertisement 