T12, 4ea 4ft lamps, 2 old ballasts in 20-year-old fixture. It appears two of the lamps aren't coming on. Sometimes the lamps flicker.

The wooden frame is attractive, so I don't want to replace the fixture. It's also a PITA to access the bulbs. Can't lower the frame, can't take off the clear plastic panel. To change bulbs, you have to remove a screw at each end of the frame, making it a 2-man job, and I hate to impose on my neighbor.

With two bad lamps (I suspect) and a ballast as well, would you buy two LED lamps and one electronic ballast to replace them? I've just been to HD and Lowes, and electronic ballasts is all they carry. My old ballast types are gone.

Or should I replace all the bulbs and ballasts and be done with it?

Can my fixture even use two different types of ballast? Can it use both conventional fluorescent AND LED tubes?

I saw some ballasts for four (4) tubes. Should I get one of these ballasts and replace all my tubes with LED? Will the one ballast work with the 4 LED tubes or should I get two ballasts?

Apologies for my elementary questions, but at 75 I want to do this right and do it once. I'm getting a little too old to fall off ladders anymore. (Eleven-foot ceiling, so it would be a more serious fall.)

Thanks for all advice.

  • 1
    Sometimes hiring people is the right choice. The amount you save via DIY .vs. the cost in quality-of-life if you take an unscheduled trip off a ladder may not look great. It's a call you have to make, and you probably have (or will have) friends on both sides of the "stopped driving without wrecking the car" and "stopped driving only after wrecking the car, or several cars" divide, for a similar choice. Depending on access for delivery, a platform lift might be a safer means of access.
    – Ecnerwal
    Mar 29, 2022 at 22:34

4 Answers 4


Skip "what you can find at HD/Lowes." I've looked there, it's awful, and overpriced.

Relamp with T8's and a nice 4-tube electronic ballast - programmed start by preference. You'll get longer tube life that way. Depending on your local scene and how friendly it may or may not be to end users, an electrical supply or an online electrical supplier. Not Amazon, where unlisted imported junk is the primary electrics they supply, an actual electrical supplier with a website, there are plenty, and you can find all sorts of ballasts there. And they will take your money if your local electrical supply won't.

If changing to LEDs, skip the ballast and get "direct wire" "LED-tubes" that don't need a separate ballast - one less part to fail.

  • "If changing to LEDs, skip the ballast and get "direct wire" "LED-tubes" that don't need a separate ballast - one less part to fail." Makes sense to me, too. Has to be a drawback, though; why are ballasts still being made and sold?
    – Steve Kohn
    Mar 31, 2022 at 3:52
  • Because there are still many florescent tubes being used.
    – Ecnerwal
    Mar 31, 2022 at 12:28
  • OP here. I think I asked too many questions earlier. Let me ask them one at a time. In a 4-tube fixture, can I replace one of the fluorescent tubes with an LED tube?
    – Steve Kohn
    Apr 1, 2022 at 0:37
  • OP here with another question. In a 4-tube fixture, can I use an old ballast with two (2) tubes and at the same time a new electronic ballast with two LED tubes?
    – Steve Kohn
    Apr 1, 2022 at 0:40
  • OP here with a last question. In a 4-tube fixture with one suspected bad ballast, is it hard to remove both ballasts and insert four (4) LED tubes, directly wired? If you have directions for this, would be much appreciated. This seems the best way to go, no?
    – Steve Kohn
    Apr 1, 2022 at 0:42

If you want to convert to LED

I personally find they are more efficient, but the reliability is hit-and-miss, and the light quality isn't naturally as high - many will cheerfully sell you sub-70 CRI LEDs with harsh light.

With an LED conversion, ask yourself - do you want the ability to rollback to real fluorescent? If "yes", then follow my "real fluorescent" answer and install a ballast, and then when you go to buy a fluorescent tube, instead buy "Plug-and-play" or "Universal" LED tube types. These are designed to work with a ballast.

Direct-wire: Get rid of ballasts for good.

If you are committed to LED, then rewire the fixture to bypass the ballasts altogether! Now you don't have to maintain them.

In this configuration, you use "Direct-Wire" or "Universal" LEDs. (note "Universal" can swing both ways)

But there is one more characteristic you need, which is "Double-ended". To cut costs some LED "tubes" are designed "single-ended"; these are fading from the marketplace but my point is to avoid them. They require fixture modification, as I discussed in "instant-start" ballasts in my other answer.

Re-wiring for LED only (single-ended)

Real simple: Don't. As discussed above.

Re-wiring for LED only (double-ended)

To fellow readers: this doesn't work for ALL fluorescent fixtures, but it does work for <=20 year old fixtures. If your wiring isn't like this, you'll need to study the diagrams closely.

Unplug the fixture. If it is hard-wired, then shut off circuit power, and install a "ballast disconnect" inline along the black and white wires. This is to allow you to turn the power back on while re-wiring the fixture. Obviously, do the wiring with the connector parted!

The ballast will have black, white and some other wires. If those other wires are

  • Red and 2 blues: Then wire the black to red. Wire the white to both blues.

  • 2 yellow, 2 red, 2 blue: Then wire black to both yellows. And wire white to the four remaining wires (2 red and 2 blue).

Now the fixture should accept double-ended, direct-wire or universal LEDs.

  • I also like the idea of not using ballasts at all, but am not about to rewire the fixture until it's perfectly clear how to do it. Off to YouTube! Thanks for confirming my intent can work.
    – Steve Kohn
    Mar 31, 2022 at 3:46

If you want to stay with real fluorescent

This answer is about staying with fluorescent. I do hundreds of fluorescent upgrades. You have good prospects any way you want to go. In most cases electronic ballasts will fit right up where the old ballast was.

Yes, all new ballasts are electronic, but that is an overall "win" as they are vastly superior. They do not hum, they do not shimmer, and they do not start badly in the cold. The best ones have a momentary hesitation on startup, but so do many LEDs. You have some things to decide.

Older F40T12 tubes, vs newer F32T8 tubes

First, do you want to switch to the more modern and efficient "T8" type tubes? You probably do, but that will require keeping tubes straight inner vs outer, since T8 tubes won't work on a T12 ballast or vice versa. You could also switch both ballasts (I advise one at a time). The T8 type is F32T8, the T12 type is F40T12.

Ballast types and wiring

"Instant-start" seems like a better feature, right? However to start the tube without use of pre-heaters, it shocks the tube with a very high voltage, and that shortens tube life somewhat. Something to think about for a difficult-to-access fixture.

Wires: Your old ballasts will have black+white, + some other wires.

  • If it is 1 red and 2 blue, your only choice will be an "instant-start" ballast. Modifying the fixture for the other kind will be too much work to do from a ladder.
  • If it is 2 yellow, 2 red and 2 blue, then your best bet is a "rapid-start" or "programmed-start" ballast, since it will wire up exactly the same - paint by numbers, can't get it wrong lol. The "programmed-start" ballast gives a very gentle start that extends tube life further. It's my preference.

When counting wires, look at the text of website listings, not the photos. They often use the same photo for all ballasts.


Different fluorescent ballasts have different brightness on purpose; this feature is provided to help lighting architects get the light intensity correct. The brightness is decided by a figure called "Ballast Factor" (not to be confused with Power Factor, which you won't need to worry about). A Ballast Factor of 1.00 means you get exactly the watts and lumens advertised.

"Low" (L) or "Extra Low" (2L) ballasts have a 0.7 to 0.9 ballast factor, or 70-90% of normal brightness.

"High" (H) or "Extra high" (2H) ballasts have 1.1 to 1.3 BF, or 110-130% brightness.

Go shopping

So you look at a) "F32T8 vs F40T12", b) wiring, and c) ballast factor, and go shopping for a ballast.

It wires right up, and then you install the tube type that matches the ballast.

On the tube types, you get to choose your color temperature (2700K vs 3500K vs 4100K vs 5000K, 4100K being traditional fluorescent). That decides how yellow or blue the light will look, and will be apparent when looking at the fixture. (and how it matches other lights).

You can also choose your color rendering index (CRI) or how color-pure the light is. 80 CRI being the realistic minimum you'll find in real fluorescent, and many tubes being 90 CRI or larger - 100 is perfect.

I myself prefer T8 ballasts made by GE, Sylvania or Philips/Advance... with Sylvania 22438 T8 tubes, 4100K and 90 CRI. Menards stocks those at sane cost.

The great news is top quality ballasts are readily available cheap. One fellow on eBay has thousands of beautiful GE programmed-start ballasts on sale for $2 each, but they are "2L" (0.71 ballast factor). Great if you want that. But if you don't, watch out - many resellers buy them for $2 and resell for $7-12.

Wiring it up

Unplug the fixture. If it is hard-wired, then shut off circuit power, and install a "ballast disconnect" inline along the black and white wires. This is a Code requirement and allows you to turn the power back on while re-wiring the fixture (so any other fixtures in the room can illuminate your work - it's the first thing I do). Obviously, do the wiring with the connector parted!

After that, cut the wires where they enter the ballast (no one ever said "Oh no, I have too much slack!").

Then just match up wires, like for like color, assuming you got the correctly matching type of ballast. Wires of the same color CAN be interchanged.

  • Lot to digest. Just wanted to thank you for the feedback.
    – Steve Kohn
    Mar 31, 2022 at 3:50

All my questions (except one: are LED and fluorescent bulbs interchangeable, and we all know yes they are) are answered in this excellent YouTube video: https://youtu.be/zLScPdm82M4

Now I know I can replace the two ballasts with one 4-tuber.

So easy.

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