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Fluorescent Lighting Problems and How To Fix Them

How to Fix Your Fluorescent Lighting Problems: The Most Common Problems with Fluorescent Lighting and How to Fix Them, Troubleshooting Problems with Fluorescent Light Fixtures.


Guide to Fluorescent Light Fixtures and How to Fix Them

Electrical Question: My Fluorescent kitchen light was not coming on quickly if at all.

Appreciate your help !
Background: Jim, a Homeowner from Southington, Connecticut.

Additional Comments: Great website.

Dave’s Reply:
Thanks for your electrical wiring question Jim.

How to Fix Your Fluorescent Lighting Problems

Application: Troubleshooting Problems with Fluorescent Light Fixtures.
Skill Level: Beginner to Intermediate – Best performed by a Licensed Electrician.
Tools Required: Basic Hand Tools, a Voltage Tester and Safe Ladder.
Estimated Time: Depends on personal experience, the light fixture and access to the light fixture.
Precaution: Identify the light fixture circuit, turn it OFF and Tag it with a Note before working with the wiring.
Notice: Replacement parts for the light fixture should be compatible with the type of fluorescent lamps that have been installed.

The Most Common Problems with Fluorescent Lighting and How to Fix Them

More about Installing Home Lighting

How to Install Kitchen Electrical Wiring
kitchen-electrical-wiring

Kitchen Electrical Wiring

Fully Explained Photos and Wiring Diagrams for Kitchen Electrical Wiring with Code Requirements for most new or remodel projects.

Using Testers to Identify Electrical Problems
digital-tester

Testers to Help Solve Electrical Problems

Troubleshooting Electrical Wiring
Types of Electrical Testers

Circuit Breakers for Light Fixture Circuits

Electrical Codes for Lighting Fixtures


» You Can Avoid Costly Mistakes! «

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Wire It Right with the help of my Illustrated Wiring Book

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Complete Guide to Home Electrical Wiring

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Includes:
Wiring GFCI Outlets
Wiring Home Electric Circuits
120 Volt and 240 Volt Outlet Circuits
Wiring Light Switches
Wiring 3-Wire and 4-Wire Electric Range
Wiring 3-Wire and 4-Wire Dryer Cord and Dryer Outlet
How to Troubleshoot and Repair Electrical Wiring
Wiring Methods for Upgrading Electrical Wiring
NEC Codes for Home Electrical Wiring
....and much more.




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107 Responses to “Fluorescent Lighting Problems and How To Fix Them”
  1. Allen says:

    We replace 2 T8 lights 4 bulbs total, in the kitchen, they are hooked up to to a double switch, wired them just like the old ones, had power, turned on top switch, all 4 lights came on, turn them off, turned on bottom switch, didn’t come on. Turned top back on no bulbs came on. We have power to all wiring, blallests are good. Can’t figure out the problem any help please!

    • Dave Rongey says:

      Hi Allen,
      Here are some items that may help get your fluorescent light fixture working:
      Make sure the lamps are fully compatible with the ballast, and the wiring of the switches should be checked very closely. To remove the fluorescent lights out of the equation, consider wiring up a temporary standard light fixture. This way you will be able to see if the switches are wires correctly. Once the switches have been checked out reconnect the fluorescent light and test it out. Make sure the fluorescent light fixture is properly grounded as well.
      I hope this helps you,
      Dave

  2. Don Bradman says:

    I have T5 high bay lighting, 4 bulbs in each fixture. The original ballast is a Advance ICN-4S54-2LS-H and I am replacing it with a Osram QTP 4x54T5HO/UNV PSN HT W. both are intellivolt. I have checked and re-checked wire colors and connections but no matter what I do only the two outside bulbs light up on the fixture once the ballast was changed. Both wiring diagrams match as well. Original problem was that all 4 bulbs went out at once. I have tried 4 new bulbs as well as moving current working bulbs from another fixture with no change. I have also tried another Osram ballast with the same results. Any ideas?

    • Dave Rongey says:

      Hi Don,
      Double check the wiring from the ballast to the sockets for the inside set of lamps, and that the sockets are not cracked or damaged. If you spliced the wires then make sure the original wires to the sockets are secure and are making a good connection. After checking specs for both ballasts the Osram ballast should work fine if you are using the FP54T5HO lamps. Also, make sure the fixture is well grounded.
      I hope this helps, let us know how what you find,
      Dave

  3. J. D. Richmond says:

    I wired two 2 tube 36 inch fixtures with new ballasts and new tubes. Only 1 tube will burn in each fixture. I followed the diagram on the new ballast and even took one in to the electrical supply store to let them see that I had wired it properly. Any suggestions on what to try next?

    • Dave Rongey says:

      Hi JD,
      Go through the checklist described in the article above, and make sure the light fixture is well grounded and the metal reflector is in place and within one half inch of the lamps.
      I hope this helps,
      Dave

  4. Mike says:

    I put a ballast in for duel 8′ bulbs at the end of a row of lights. When I turned the power on, half of both bulbs are dark toward the next fixture. The next fixture is humming. Could the bad ballast in that fixture cause the problem in the one on the end?

    • Dave Rongey says:

      Hi Mike,
      The ballast of one fluorescent light fixture should not affect a different light fixture unless the wiring has been modified. Keep in mind that when a new ballast is installed it is best to replace the lamps as well.
      I hope this helps,
      Dave

  5. Tim says:

    I just bought a house and one of my florescent T12 lights had bulbs that both were dim. So I changed the ballast to a t8 and put in 32 Watt LED lights. I am now getting one light that is dim and one that is bright. I jumped one tombstone light socket to the other. I thought that might of been the issue so I switched to a 3 wire connection and I still have the same problem. Also the breaker keeps tripping when I turn it back on. When I turn the electricity back on to test. I takes 5 or 6 times of resetting the breaker to get it to not fault.

    • Dave Rongey says:

      Hi Tim,
      Here are some things to consider about your fluorescent light fixture problem:
      You should always make sure that the LED lamps you have are compatible with the ballast that is installed.
      If the lamps are not compatible then obtain the type of lamps as listed on the information label on the ballast.
      Be sure the wiring connections for the ballast and the sockets is the same as shown on the wiring diagram that is attached to the ballast.
      Please note that since the circuit breaker has tripped so often it is possible that the ballast and lamps have been damaged and will need to be replaced.
      I hope this helps you,
      Dave

  6. Nathan says:

    I have 2 u-tube fixture in our kitchen where I recently changed the ballast. Now only 1 side is working, please help. Thanks

    • Dave Rongey says:

      Hi Nathan,
      When replacing the ballast it is always best to replace the lamps as well. Often the lamps burn out and this causes the ballast to go bad, therefore new lamps will most likely get the fixture working again.
      I hope this helps,
      Dave

  7. Frank says:

    While installing a new 15W T12 18 inch fluorescent bulb into an under counter fixture, there was a bright flash at one end of the bulb and then it did not work.

  8. Marc says:

    In my finished basement I have three rows of fluorescent fixtures with four 4 standard 2pin bulbs they are controlled by 3 rocker switches in one wall plate. One rocker controls one row of fixtures and the stairway light leading upstairs. The other two rocker switches are on a different breaker and control the other two rows of lights. My problem is one of the rows is out and it’s one of the ones that are a set of two on one breaker but the other rocker switch turns on its row but not the other. So I assumed it was a bad rocker switch so I replaced it myself and to no avail. One row is still out. In review 3 switches, two on one breaker one on another breaker. One of the two on one breaker not working the other is and not the switch. Hope this makes sense, Tia.

  9. Norm Hulse says:

    My daughter recently purchased her first house. The fluorescent fixture in the garage works fine. It’s a two lamp (4 feet) dual pin fixture. Problem is the lamps remain lit and slowly fade and flicker for a couple of minutes every time the switch turned off. Is this an issue or not? Never seen anything like it before. Thanks for your time and trouble.

    • Dave Rongey says:

      Hi Norm,
      I would have the wiring to the switch and the light fixture checked. Sometimes there may be a slight glow after a fluorescent or LED light is turned off, however this would only last a few seconds.
      I hope this helps you,
      Dave

  10. Pete says:

    When I took the switch out and replaced it with a timer, the lights don’t come on all the way. One bulb pulsates. It is like it is not getting enough juice and the timer gets hot.

    • Dave Rongey says:

      Hi Pete,
      From what you have described, the timer is not compatible with fluorescent lights. The timer should be removed to avoid damage to the timer switch and the light fixture. You will need to locate a timer that is compatible with fluorescent lights. When selecting a light fixture timer you may notice that some timers require a separate neutral wire in the switch box, therefore the switch box will need to be examined to see if there is a neutral wire available for the required wiring connections.
      Thank you for sharing your lighting question with us,
      Dave

  11. Cedric Martin says:

    In my garage I have four, two tube fluorescent fixtures. During winter months these fixtures work perfectly, however, in the summer heat they won’t come on completely. In other words, they start to light at each end of the tube, but will not come on completely. They have done this for the last two years. There are two double receptacles in my garage ceiling and two of the fixtures plug into one of these receptacles, and two into the other. All four fixtures work in unison, e.g, either all four are lit (as in the winter months), or all four will not light fully (as in the summer months).
    Surely, if it were the tubes that were faulty they wouldn’t work at all, winter or summer. And, if it were a ballast problem, would you expect all four ballasts to go bad simultaneously? This problem has frustrated me for two years now, I do hope you can help me solve this issue.

    • Dave Rongey says:

      Hi Cedric,
      I admit I have had similar problems with some fluorescent light fixtures. Therefore, after checking to make sure all of the other fixture components are satisfactory I typically find that by replacing the lamps with a new set of quality lamps of the same type the problem will be solved. Over time the lamps will wear down and get sluggish to start, and two years of general use is typically the lifespan of these lamps.
      Thank you for sharing your fluorescent light fixture question,
      Dave

  12. Sallyann Evans says:

    I know the problem is my ballast. I have had 4 new ones as they had faults. This has worked well for 6 months now but it has started again. I have to change fuse in plug to get it to light. It will stay lit until I turn it off but then it won’t work again unless I replace with a new 3 amp fuse. I would also like to point out that the fuse hasn’t blown. I tested it with multimeter so I know they are still good. But still have to replace with new one to get lamps to work. I have been told it’s like an automated light sensor system and won’t come back on until it’s ready. Is this correct? I don’t know if I’m explaining myself properly as I’m not an electrician. The example given by customer services was its like walking into offices and the tubes automatically light as you walk through but sometimes think you are gone and won’t relight until sensor is reset. By changing the fuse I’m kind of pressing the reset button.. Is this information accurate? Well even if it isn’t I’m still stuck with an aquarium I can illuminate when I need to unless I change fuse. The warranty is now expired on my aquarium and I can’t afford to buy new ballasts, can you help of advise me please of what to do.

  13. Rick says:

    My laundry room florescent light has two bulbs, and is four foot long. Then fixture will come on quickly about half the time. The other times I must flip the switch multiple times before the light comes on. I have noticed recently that when turning the switch on, the end of the bulb shows a little light. I leave it on for a little while, then go back and flip the switch again and the light comes on. Bad ballast?

  14. Scott says:

    I have a 22 watt circular fluorescent with a 22 watt starter. It is installed in a 60’s vintage clock. The bulb flashes and burns out. Not sure what to do. Gone through 3 bulbs.

    • Dave Rongey says:

      Hi Scott,
      From what you have described I would suspect a bad ballast. A replacement ballast should be available from a local hardware store or electrical distributor. Be sure to get the correct ballast for your fixture.
      Thanks for sharing your fluorescent light fixture question,
      Dave

  15. Bruce says:

    I replaced both of my fluorescent lights when they didn’t come on. When I put the new ones in the lights were bright, but soon became very dull. Could this be a bad ballast? Thanks for any help.

  16. Larry says:

    I have an old magnifying fluorescent workbench light that has a 22w circline bulb. I finally found a new starter switch after having the light tore apart for along time and now I don’t remember how to wire the new switch. The switch has a spinner mechanism in it and you have to push and hold the button for 3-5 seconds and then the bulb lights, push the button again and the light goes out. The switch has 4 contacts, the bulb socket has 2 white and 2 black wires and of course a hot and neutral feed coming in. I need a wiring diagram to save this awesome old light. Thanks, Larry.

    • Mike says:

      Larry,

      Were you ever able to get a solution to the switch with 4 leads for your magnifying work lamp? I am in the same situaton

  17. Rich Federici says:

    I have 2 fluorescent fixtures with single F14T12CW tubes. The ends of the lamps are blackened so I am changing them. They still work. Upon replacement, the new tubes will not light, but if you put the old ones back in they will light. What am I doing wrong?

    • Dave Rongey says:

      Hi Rich,
      Make sure the replacement lamps are the same as the originals, and double check to make sure both of the pins at each end of the lamps are inserted into each socket.
      I hope this helps,
      Dave

  18. John says:

    Installed a new ballast in my fluorescent light fixture one side works and one side does not.
    Please help

  19. Doug says:

    Thanks for your great service on this site! I’m replacing the ballast on an 8′ single bulb fixture from T12 to T8. The fixture has 1 blue wire at one end and 2 white wires at the other end. Ballast has 2 blue and 1 red. How do I connect them? Thanks!

    • Dave Rongey says:

      Hi Doug,
      Make sure you have the correct ballast to match the circuit voltage and the lamp of the light fixture. Please refer to the wiring diagram that is included on the new ballast, and transfer the new wiring as described. Keep in mind that when connecting the wires from the ballast to the lamp sockets the wire colors of the original fixture sockets do not matter as long as you are following the wiring diagram, however the circuit wire colors do matter and should conform the same as the original ballast.
      I hope this helps,
      Dave

  20. Landon says:

    I changed my old 4 lamp t12 to a new 2 lamp t8 fixture. It worked great for a few days, but now it won’t turn on. I changed the wall switch and it came back on for a few minutes, then cut back off. Could it have anything to do with too much power sent to the smaller fixture, or is it more likely a bad ballast?

    • Dave Rongey says:

      Hi Landon,
      The electrical circuit power should not be an issue. I would go through the checklist as outlined above, and be sure the pins of the lamps are making full contact with the sockets. If the sockets become arced this can cause a bad connection which is enough to cause intermittent lamp performance and erratic light fixture starts.
      I hope this helps,
      Dave

  21. David says:

    I recently replaced a 8″ circline 22 Watt bulb. New bulb will not come on. I checked power at the plug from the ballast. I have 120 volts so ballast is good. I tried a few different bulbs to make sure it was not an issue with bulbs. Do you have any thoughts on this problem? I don’t know what else to check. Thanks.

    • Dave Rongey says:

      Hi David,
      If the previous Circline lamp burnt out while still in the socket then most likely the ballast will need to be replaced. Even though the socket of the ballast appears to have 120 volts the ballast may still be bad. Also, make sure the socket connector is configured properly where it plugs into the lamp. Some of these types of socket plugs can be tricky to connect.
      Replacement ballast can be a little pricey, you may want to consider replacing the light fixture with a new round LED fixture which will be much more energy efficient.
      I hope this helps,
      Dave

  22. Bobby says:

    I have a row of old T12 8′ light fixtures. I replaced the ballast in one of the fixtures (SM-2E75-S-1-TP) with the replacement B260IUNVHP ballast. It has a extra blue wire so I wired the two together and it worked for about 2 hours and then it went out again. What am I doing wrong?

    • Dave Rongey says:

      Hi Bobby,
      Double check the wiring diagram on the ballast compared to how you have the wiring connected in the light fixture. You will notice that the wiring diagram for this ballast shows that there is one blue wire for each lamp socket at one end of the light fixture, and if there is only one lamp in the fixture then the extra blue wire should be capped off. The single red wire of the ballast is connected to the lamp socket(s) at the opposite end of the light fixture, and shared if there are two lamps.
      I hope the helps,
      Dave

  23. Jim says:

    I have five 8 bulb T5 light fixtures. They all seem to have the same problem of dim light output. All of the fixtures are less than 2 years old. I checked everything you suggested. Is it possible for a ballast to read good but still make the bulb produce dim lighting?

    • Dave Rongey says:

      Hi Jim,
      Sorry to hear about the dim light problem with all of your fluorescent fixtures. Note the brand of the lamps and contact a representative to see how many hours the lamps should be warranted for and then compare that to the number of hours the lamps have been used. A quality brand name standard T5 fluorescent lamp is rated up to 30,000 hours of life based on 12 hours of usage after a single start. Keep in mind that all lamps are not the same, and an off brand lamp of lesser quality may have a lower life span, and the same goes for the ballasts.
      I hope this helps brighten up you day,
      Dave

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