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Fix Your Fluorescent Light Ballast

Two days before Thanksgiving I walked into our laundry to wash my underwear and noticed the light wasn’t working.

After a short three-word phrase (use your imagination) I started to have flashbacks about what led to this moment in time.

First, our laundry room light was struggling to turn on for several days prior to this.

Then it just stopped working altogether.

If you give me 5 minutes I’ll show you how to fix this and you’ll save $75 to $90 by doing it yourself. Let’s get started!!


Getting Started: How to Check that Your Fluorescent Light Ballast is Broken

You’ll only need three kinds of tools for this project:

One clue that your ballast is the reason for a non-working fluorescent light is the light bulbs struggle to turn on.

As I said in the intro, we noticed this happening over a 3-4 week period.

A good way to check that your ballast is the culprit is to turn on a voltage detector and hold it next to the wires supplying power to the ballast.

Test Ballast for Power

If power is going into the ballast and none is flowing to the fluorescent light bulbs this is an indicator the ballast is dead – unfortunately much like the cool old guy named Blue in Old School (for all you Will Ferrell fans, Blue the character dies while, ahem, wrestling!!)

RIP Blue

How to Remove Your Old Ballast and Light

Before doing anything further, turn off the circuit that supplies power to the light.

Then double-check that no electricity is running to the light by using your voltage detector. Many thanks to Mark for reminding me that I forgot to add this SUPER IMPORTANT tip.  But that’s why I have great fans like you who catch my absent-mindedness!!!!

There are only a few screws holding the ballast to the fluorescent light.

Remove these screws using a screwdriver but don’t toss them in the garbage. Primarily because you may not get news screws with the new ballast.

You can choose to remove the ballast before or after you remove the fluorescent light from the ceiling.

To avoid having shattered glass all over the floor I highly recommend removing the fluorescent light bulbs. They’re attached to the ballast and you’ll have to detach the plug.

Removing Fluorescent Light Bulb

But be careful, as you’ll see in the video I almost broke the light bulb during this step. I’m such a dummy sometimes.

Only two screws hold the fluorescent light to the junction box. Use a screwdriver to loosen these screws and just be aware that the light will drop slightly from the ceiling.

Junction Box Screws

Slide the light’s frame and pull it down off the junction box screws.

At this point take a picture of the existing wiring. This will give you a reference and help with wiring the new ballast.

Take a Picture of Wiring

If you’re not particularly strong or have weak shoulders get a friend or relative to help with this part.

Have them hold the light while you unwire the ballast from the junction box. Or, if you really don’t like electricity or your friend/relative (just kidding) you can hold the light instead and let someone else unwire it.

Loosen all the wire nuts. I like to take apart the black or hot wires, then the white or neutral wires, and lastly the ground. It just makes me feel better to do it in this order.

Pull the ballast wires out from the frame.

That’s how simple it is to remove a fluorescent light ballast.

Adding a New Ballast to Your Fluorescent Light

You’ll need to take your old ballast with you to the hardware store. It’s a good idea to call and see if they have the right ballast in stock.

I called around to several places that didn’t have the ballast I needed. And in fact, I still ran into a bit of trouble with the ballast I bought (I explain at the end of the video).

Place the new ballast on the fluorescent light’s frame and tighten it with the screws that you saved from the old ballast.

New Ballast

Fish the new ballast’s black, white, and green wires through the hole in the light.

Get your friend or relative to hold the light while you wire it to the junction box. Seriously, I had to call my wife into the laundry room to help. I felt bad that she had to hold the light up while I fiddled with the wires.

But, hey that’s what marriage is all about — helping each other through DIY sickness or health!!

If you have kinked wires like in the picture below cut them with your combination strippers and strip off 3/4 of an inch of the insulation.

Trim Kinked Wires

Wire the new ballast in the same fashion as the old one. This time around I recommend wiring the ground first, then neutral (white wire), and lastly the hot wire (black in color).

Twist the wire nut until the connection between the wires from the ceiling and the ballast are secure.

Push all the wires back into the junction box as neatly as possible.

Slide the fluorescent light frame onto the screws you left in the junction box. Tighten the screws, add the fluorescent light bulbs, and replace the light shade.

BAM!!!! You’re done.

Here’s my step-by-step video tutorial for your viewing enjoyment. It’ll show you just how easy it is to replace a ballast, or at least I hope so!!

If you can change out a light switch or outlet you can definitely replace an old ballast that doesn’t work.

As I said in the beginning, you’ll save yourself $75 to $90 doing this fix yourself. Years ago I paid our electrician to do a similar fix at a rental and this is how much the fee was.

Rightfully so, too!! But I like saving money for the grocery list that seems to grow every week.

What’s Next

If you’re installing other electrical devices we have several tutorials on how to wire a light switch, how to wire a dimmer switch, and how to install GFCI outlets in bathrooms.

If you’re doing a bathroom remodel and need help, join one of our online courses – they’ll make your bathroom renovation much easier!

Let me know if you have any questions and I’ll do my best to help.

Thanks as always for reading, watching, and being part of our awesome community.



Fix Fluorescent Light Ballasts

  1. Mark J says:

    You didn’t say anything about turning off the power to the ballast and double-checking with your voltage finder BEFORE touching any wires. But hopefully most people know this anyway 😉

    1. Thanks Mark, I should have made that clearer. I’ll add some clarification within the post.

      Yah, it’s not fun getting jolted by electricity. Been there!! The last thing I’d want is for anyone to get hurt.

      1. Sam says:

        Hey Mate, I’m an Electrician from Australia.

        It’s a great guide and a very easy fix but Voltage testers are an extremely unreliable way to prove a cable is dead.

        Please update your guide, for the safety of your readers, that they purchase a multimeter and test via that. Even then, if they don’t know what they’re doing hire an Electrician.

        Electricity is not something you should play with if you don’t understand and dare I say, fear it.

    2. Brian says:

      Mark J, you’d be surprised of just how many IDIOTS there are out there. Rofl

    3. John Wagner says:

      Mark J was quick to point out about turning off the power but Mark J forgot to say anything about turning it back on when you’re done.

  2. Good one Jeff! I like your focus on safety, using the breaker and not the switch. One whack from the secondary side of a ballast will wake you up in a hurry. I still remember hearing a guy screaming, only to realize it was me, when I got lit up by a commercial fixture, years ago. WAY more pain than a poke from a outlet or switch.

    1. Thanks John, getting electrocuted is no fun. I had it happen a just 2 times. Needless to say I don’t like the feeling.

      So even if I have to turn off the main switch in the panel to get electrical work done I’ll do it. Sure the kids get grumpy but for cryin out loud, they don’t need the TV all day long.

      1. Brian says:

        If you were electrocuted, you would not be alive to type this helpful tip.

  3. Julie says:

    Hi Jeff, your tutorial is greatly helpful. Please help me here as I am trying to determine what causes my fluorescent lights not working probably. Our laundry room has one of those four fluorescent tube lights. A few days ago, one of the light kept go off after few minutes. So we bought new light to replace that bad one. However, after replace the new one, those 4 lights would light up brightly but then they went off within a second. I would try to turn back and got the same result. Would that be a bad starter or ballast? Can it be ballast since it’s actually lighted up?

    1. It sounds like a bad ballast to me Julie since the light won’t stay on. So it could be worth it to change out the ballast. Just get an electronic one not a magnetic one, they kinda stink!!!

      1. Tim says:

        My light has trouble coming on some times could it be the starter

        1. Possibly, it wouldn’t hurt to test and see

  4. dale brown says:

    hope the light you or they are changing the ballast in is not sharing a nutral wire with another load thats turned on , like the one in my house. real reason im commenting is ive done the 4 thing ,replace bulbs, ballast, ends and ck power and still have to touch or rub the bulbs to make it work. why? cant find a awnser anywhere and it not just mine , my son and my mom have one too. different houses, location,and purchased at different stores

  5. Justin R. says:

    I have the same fixture you show in the pictures with two round bulbs. When it stopped turning on, I replaced the bulbs. Now, one works and one doesn’t. It’s the wires coming from the ballast, because when I switch them around, the other one works.
    Dumb question, but can I assume I need to replace the ballast?

  6. LynneS says:

    Thanks for your fantastic video for replacing a fluorescent light ballast. I found it on youtube, watched carefully, headed to Home Depot, and got the job done myself. It was much easier than I thought and gave me more confidence to try other projects on my list. Keep up the great work!

    1. Great job Lynne!!!!

      You made my day and I’m so pumped that you’re inspired to do more projects 😀

  7. Jack Collins says:

    Hi…needed to replace an 18″ undercabinet fluorescent. Had to a drill new hole in fixture for incoming wires so I could place it at the same spot as old fixture. This necessitated having to move ballast. Would the moving of the ballast in the new fixture cause a safety problem?

  8. Sid says:

    I need help. i have a kitchen fixture that has 4 T8 bulbs. I have replaced the ballast a few years ago. None of the bulbs worked the other day when I flipped the switch. I removed a bulb and put it in my garage fixture and it worked. So I replaced the ballast again. I have juice going to a 4 sockets, but the light do not come on. Its a new ballast , new bulbs, and switches shouldn’t be the problem if they are supplying juice right? What else can it be? Thanks for any advice

    1. jeff says:


      Did u figure out the cause yet?

      I’m having the same problem!

  9. osu13 says:

    Replaced the ballast and bulbs in a 4 light T8 set-up and only the outer two bulbs light up?

    1. Alan Buchholz says:

      Only the 2 outer lights come on!

  10. Larry says:

    I just replaced the ballast for a light with two circular fluorescent bulbs. The old ballast had a ground wire. The new one doesn’t and only the inner bulb turns on now. Did I just get a bad ballast?

  11. HG says:

    I have questions and statements…
    Our bathroom has four foot size fluorescent lamps over a large mirror. I replaced all four with Home Depot matched bulbs. Three had worked before this exchange but colors weren’t identical.
    When I installed the lamps (while hot) some didn’t want to light up until I found a particular rotating location. All four had now lighted up. I turned them off for a few minutes to confirm all is well. They all started up again.
    The next day only one started up and that is now working consistently. The others are consistently dead.
    All lamps are using their own ballasts.
    Could there be a contact cleaner issue on the socket ends? The bulb’s pins are obviously new. Why would these work one day and then fail the next?
    This brings me to another issue. The cost of new ballasts vs substituting LED 4 ft bulbs in the same fixture (minus the ballasts).
    Are the LED bulbs as bright and at a COOL WHITE color of about 3000K temperature, anything higher and it would be unpleasantly going towards daylight.
    Now my statements….
    In our small laundry room we had a double Circline fluorescent fixture which worked okay, yet it needed periodic bulb replacement.
    Such bulbs aren’t cheap either and no fluorescent fixture appreciates constant ON-OFF usage.
    So I removed the complete fixture and replaced it with an inexpensive plain screw in porcelain type which holds a CFL of about 20 Watts. The bulb is completely exposed which don’t bother us the least because it’s a laundry room and on the ceiling. This has failed once in two years of usage. So in seconds I unscrewed it and replaced it with a new one.
    I also understand that regular fluorescent lamps don’t like high humidity which is to be expected in bathrooms, laundry rooms and obviously in FL. Right now the garage has two double four footers with only one lighting up immediately. On a humid day the second one can take hours before lights up unless I flick the switch a few times which is bad for the working one. The garage has a ten foot ceiling so Im considering doing the same thing as the laundry room…and as LED’s are coming down in cost these may be used too down the road.

    1. Mal says:

      For the color match on the bulbs look at the description on the bulb. There are CW ( cool white ) brighter bulbs and WW (warm whites ) duller bulbs

  12. Danny says:


    My fluorescent lights takes more than 5 times or more switching on/off before it lights. Both ends are dark and middle is dim everytime I turn the switch on. Sometimes I’m lucky after 5 tries it turns on completely. Thanks for any advice.

  13. Kris says:

    I have a recessed fluorescent fixture in my bathroom over the mirror. Two 48″ tubes. The fixture is at least 29 years old. It’s very diffficult to change the bulbs as the housing is tight and you have to get the tubes in just right before you can twist them into place. Sometime in the past, while attempting to change the bulbs, one of the plastic bulb retainers broke making it precarious to get the bulb to stay in place. For a couple of years I’ve managed to jimmy the bulb in and keep the light working. Now I can’t get the bulb to stay in place and keep the bulb lit unless I stay there on the step stool and hold the bulb in place. Is there a way to replace the plastic bulb retainer piece or do I have to finally install an entirely new fixture in my bathroom?

    1. You know Kris, I’d say replace the entire light. As long as you have a junction box it’ll be pretty easy and you’ll likely enjoy the new light better than the old one.

      Let us know if you have any questions along the way, we’d be happy to help

  14. Raman says:

    Hi Jeff,

    When I turn on the flourescent lamp, it burns just for a second and then it turns off. Not sure what to do. Could you please suggest?


  15. Mo says:

    Hi Jeff,
    Thanks for the post.
    I have a question. I have in my kitchen 4 fluorescent tubes ( 48″). All of a sudden the light did not work anymore, no previous signs something was getting old, (the light was not struggling like in your case). The light fixture and light bulbs are no older than 6 years. What do you think is the causing the problem? Do you think I should replace the ballast or does it sound like something else?

  16. sheryl says:

    I am totally lost. I have a small light that my grandfather used for his Big Band. Its probably 1940’s. I used it about 30 years ago for a night light in my sons room. It worked fine. Now it wont stay lit. I’m afraid it could be the ballast. A few people have said there is nothing I can do. I feel like I can’t give up on such a wonderful piece.

  17. George Albitz says:

    The ground makes the connection work. You should ALWAYS disconnect the ground wire FIRST and install Last.

  18. warren c. roosen says:

    Two fluorescent lights on same switch. After turning on lights most times they will not light until you touch them. new bulbs in each fixture.

  19. Dana says:

    Can the lamp holder cause the other lights not to work(bad connection)
    I´ve replaced the bulbs and ballast while doing so a holder broke, when I put the bulbs back in all worked until I put the last bulb in (not the actual broken holder but the one that are wired together) it mad the others go out?

    Any suggestions..


  20. Bert Savage says:

    I have replaced the ballast in a two light 48″ fixture and they work fine until I turn them off and one light will burn at 25% in the off position. I have tried different bulbs and still have the problem. I also replaced the ballast a second time and that did not cure the problem. Where else should I look for the problem.

  21. Wendy says:

    Hi, Jeff,
    I just replaced all 4 tubes in the kitchen light fixture. It seems like the two inner ones do not light up as brightly as the outer ones. When I remove the outer ones, they seem to light up just fine. I’m not sure if it’s an optical illusion when all 4 tubes are in or if there’s an actual loss of illumination. Two questions – what’s the best way to test to see if there is a brightness/lighting issues…and…if there is an issue, what my be the problem and the solution? Thanks!

  22. Kate says:

    Does it matter which ballast is plugged into the inner circular light and the outer circular light or are they interchangeable?

    1. James Lumpkins says:

      Yes, I replaced a ballet a week ago. The light has been working just fine, went to turn it on yesterday and no sound or light it was dead. What should I look for

  23. Richard Pettigrew says:

    Thanks for your very clear instructions for the DIY project. I have a 4 ft. light and I replaced the ballast. The new bulbs worked or 2 days and then went out. No fluttering, just went out. When I replaced the ballast, the lights seemed dimmer that before, but I did not think anything of it. Now what should I do?

  24. Yaso says:

    I have a different problem.
    The Fluorescent batten seams to be defect.
    I changed the ballast. But still not working.
    I have changed the starter – still not working.
    What else could I replace more?

    The Tube works in an other batten.

  25. Stephanie says:

    Thanks every one for the information, especially Jeff. Ok, so duh, but I guess I have a ballast problem? I have 2 sets of florescent lights on my third floor — attic converted to bedrooms in the 70’s.. The 98 inch (two bulbs) light has been making an increasingly loud humming noise.for a while now. After a few days of acting oddly both bulbs blinked out. Around the same time frame — last 6 months or so — the unit with the two shorter bulbs in the other upstairs room did the same thing without the humming noise. I bought replacement bulbs for both lights. Neither light works. There is a faint blinky glow from one of the tubes in each of the lights. Humm? New ballasts? I am not sure I can do the electric master thing. What to do? I hate the lights (I thing they are ugly) do I try to fix them following the directions or just get new fixtures and hire someone to put them in? Would that be Way More Expensive?

  26. Victor Loar says:

    I’m sorry if somebody’s already posted this but I am just replace the ballast on my light it’s for a four tube light system but only half of my lights are working do I have a bad ballast or did I miss something

  27. Jais says:

    Hey Jeff
    I need help
    I have kind of the same light, the voltmeter shows juice coming all the way to the end into the 4 pin. But for some reason the lamp dosent light up. I tried with 4 new lamps and it’s still that way. Give me some suggestion on what would be the issue

  28. Ian says:

    Hi can you help? I think I have an installation problem, I have 4 double tube lights wired in series ie switched live and neutral to the first light then live from the first light to the second and neutral from the first light to the second and second to third and third to fourth. The first fitting both tubes light the other three only one tube lights and it’s the same tube on all three. Any ideas?

  29. phil says:

    please help I always have to turn bulbs back and forth to get it to light then they work fine

  30. K. says:

    I have a vintage Circline ceiling fixture in my kitchen with 2 round fluorescent tube bulbs, 12″ & 8″. Finally removed both bad bulbs. How do I get the new bulbs past the 3 curved metal clips holding each bulb up? Seems impossible. Wearing safety glasses & gloves! Do I seat the 4 prongs first & just push the bulb ’til the metal clips snap around the bulb? Seems like the glass would shatter. Do I get the bulb situated in the 3 clips & then seat the 4 prongs? Seems impossible, too. Any expertise would be greatly appreciated! Thanks very much.

  31. Douglas Allen says:

    My kitchen light is a 4 ft florescent light. It never flickers. And I don’t hear it humming/ buzzing. When I flip light switch it comes on sometimes and sometimes not. When it doesn’t, I just turn switch off and directly back on and it comes on then… any suggestions??? Thanks!!!

  32. Chris Malone says:

    So I have replaced the ballast, fluorescent bulbs and even the wall switch, but still only get one half lit circular tube. Any ideas?

  33. MARY McNEAL says:

    I purchased a Phillips Natural Light, 32 watt, 48in fluorescent bulb to replace one of my kitchen lights and when I turn the light switch on the new light is purple. Is it defective?

  34. Flustered says:

    Jeff, HELP PLZ!!! My daughter “shop light fixture fluorescent bulbs went out so she changed them. They worked fine for a week or so, then all of a sudden they wouldn’t come on at all but the bulbs are new so she didn’t know what to do. I suggested changing our fhe entire fixture so we did that & low & behold, the light still didn’t come on. I wiggled the bulbs & one came on but the other only flickered & once the light was switched off, neither bulb came on. What do u thinknis going on here? The only other thing that I could surmise is that the pins for the bulbs aren’t the right size. Could that be the problem?

  35. Bryan says:

    I have a light that has 4 48 inch bulbs. I replaced all of them with new ones and 1 comes on and is dim and flickers. Please help???????

  36. Kevin says:

    I followed the instructions and replaced my ballast. It worked great! For about three hours… about three hours after I replaced it, the lights flickered and again went out. It seems like the ballast again is the problem. But I just replaced it with a brand new one but I just bought at Home Depot. What gives? What should I do now?

  37. B. says:

    Hello: I just had my T8 florescent light fixture (ballast) changed to use with LED bulbs. However, I had a constant hot attached to the previous wiring so the light would remain on 24/7. The electrician installed the new ballast and capped off the constant hot and just made the light work with the switch that controls the other lights in the room. I want the constant hot to be reattached. I don’t know where to do it. I thought I found the wires (black) to switch, but I got a spark when I just touched the constant to what I thought was the right wire. YES! I had the breaker AND the light switch in the OFF position when the sparks flew!!! HELP!

  38. Bill Litz says:

    Two of twelve flourescents bulbs are controlled by a wall switch. When the switch is on, two bulbs will not light unless I turn them slightly. If I turn the switch off and then on again, those same two bulbs will not light unless I slightly turn them again. I replaced the ‘tombstones’ but that didn’t make a difference. I guess I am left with a ballast issue?

    1. It couldn’t hurt to replace the ballast. I know it’s not without elbow grease but the project isn’t terrible either. You can definitely do it. And Home Depot might have the ballasts in stock. Just take the old ones to the store!

      1. Stephen says:

        Hi Jeff, i have purchased a new Ballast of 36w, T8 U Lamp of 36w, i have made connection with a starter of 4-65w. and the U light keeps flickering. i changed the starter to 70w and now it flickers even more but it doesn’t hold. Do you know what maybe the problem? i have brought everything brand new

  39. Kenneth Martin says:

    And where do you buy the ballasts? Hard to find most older models!

    1. Good question Kenneth. I got mine from Home Depot but you could also try a local light company. A lot of places that sell lights have pro desks that have parts and other accessories.

  40. Cecil Hensley says:

    I replaced a 4tube, lights & ballast in kitchen. Two tubes not working (2 blue wires) but power is there. Not sure what volt should read from a ballast. Can you advise?

  41. David says:

    Lots of unanswered posts here. Many with varying questions to which it would be very helpful to know the answer. Is this site no longer being maintained?

  42. Will says:

    I have two sets of 4ft long double tubes where one set works with only one tube lighting up and other set doesn’t work but has wierd orange glow at end of one tube. I tried replacing all bulbs but makes no difference. Any ideas of what I am doing wrong? This gets really annoying.

  43. Gary says:

    Question, if you shut off the circuit breaker how can you get an accurate reading with that dohickey to know that the ballast is bad if the circuit breaker is off? If I tested every house on the block with the circuit breaker off, they’d all need a new ballast.

  44. Shruti says:

    I just love the way you write. Thank you for the info 😊

  45. Chris Smith says:

    Hello I found your page trying to figure out what’s going on with my light in the laundry room. One day the lights stopped working. I changed the bulbs to what I thought were the correct ones but the light still didn’t come on. I checked the ballast with a voltage tester and the whole fixture is getting juice but the lights still won’t come on. Does the bulb have to be the exact same to work in a fluorescent light?

  46. John Friedel says:

    Hello, great video but you didn’t fix anything. all you did was replace a ballast .fixed, means to take it apart and repair the ballast.

  47. grey says:

    I thought the idea here was to FIX the ballast. This is just replacing it. Most ppl already know that and this is pretty misleading.

  48. Mike says:

    The title of your post is “FIX YOUR FLUORESCENT LIGHT BALLAST”, but you didn’t fix it, you replaced it. I’m specifically looking for how to fix a ballast that is not working. The blog post title is misleading.

  49. Darlene says:

    Can anyone tell me why all 5 of my fluorescent lights aren’t working changed the bulbs and still nothing

  50. Jerry Guinn says:

    For those who say the post is misleading, I’m not aware of anyone who has actually repaired a fluorescent light “ballast.” When they go bad, the only thing to do is to replace them, particularly in older fixtures which use a “tar-like” potting material to fill the ballast body. No way to repair them, so the actual “fix” is to replace the ballast.

  51. Ricky Mac. says:

    The title states “fix a ballast” …. I believe it should say replace! I actually read this thinking hmmm…. is there a way to fix these things and not have to replace? Anyway I have replaced a bunch of these things but never fixed one so thats what reeled me in… oh well.

  52. Daniel Yongue says:

    I have a 4 bulb florescent light fixture in the kitchen. When I turn on the light first am
    the lights try to come on but do not. I have to open the fixture and in many cases run
    my fingers over the bulbs and they come on. Worse case I have to turn a few to get them to come on. Rarely happens the rest of the day turning them off an on.
    What could be the issue?

  53. Steve says:

    I have a 4′, 4 light fluorescent tube fixture, 1 light works, 3 do not, even with new bulbs. What can be the problem?

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