I'm mulling over replacing the old tubes in the garage with LEDs. However, I'm learning that if I want to do that without doing some re-wiring, it might depend on what type of ballast I have. I have this clearly labelled rapid start ballast. However, it's unclear to me if this is compatible with the LED tubes that are ballast-compatible. I'm not even sure if this ballast is electronic or magnetic, as I've seen websites that suggest that rapid start ballasts could be either. I'm wondering what type of ballast this is, and whether I should expect it to be compatible with any of the LED tubes on the market that are compatible with ballasts.

rapid start ballast

  • Why don't you want to rewire? Getting out the ladder and removing the cover is 3/4 of the work and you've done that to take the picture! :)
    – jay613
    Commented Jun 13, 2021 at 20:32
  • 1
    I actually ended up rewiring after all after I realized how quick it would be. And yes, it was easy :)
    – gammapoint
    Commented Jun 14, 2021 at 1:43

2 Answers 2


From the bulk of it, it's definitely magnetic. It has a balky transformer, and will do all "that 70's Fluorescent" behavior: flicker, hum, start hard in the cold, etc.

It uses the "rapid" or "programmed-start" wiring method, NOT "instant-start", so if you replace with an electronic ballast, select rapid or programmed.

I buy competent GE, Advance or Sylvania electronic ballasts on eBay.

One guy sells beautiful GE programmed-start ballasts for $4 each. Why? They are "2L" with a 71% ballast factor; they are designed to under-drive the tubes to give only 71% normal light. (This is intended to give lighting architects a way to fine-tune lighting intensity without changing number of fixtures). However an LED might not care.

That said, LED "tubes" are very confusing, which is bad, but good if you can sort through it. There are at least 4 kinds:

  • Plug-and-play: These require the ballast to be present. Downside, you must maintain the ballast; upside, you can change back to real fluorescent, which are fantastic these days.
  • Direct-wire (opposite ends): These require the fixture to be rewired and the ballast removed. You remove the ballast and wire 120V hotshot to each end of the fixture (hot on one end, neutral on the other).
  • Direct-wire (same end): Same, except both hot and neutral are on one end of the fixture.
  • Universal: This can auto-switch between being Plug-and-play, and direct-wire (opposite ends).

Obviously, there's big advantage in bypassing the ballast altogether; though rolling back to real fluorescent will be impossible at that point.

Also, you can never quite tell whether a tube will be single-ended or double-ended, the box will sometimes will say one kind and there'll be a note inside saying "Hup, we shipped you the other, just rewire". They don't think anything of telling you to rewire the fixture for their tube, since "they're supposed to last forever, right?" Well, in my observation the supply chain is so glutted with cheap Chinese that they don't last like they should.

So, while real fluorescents are not simple, they are not full of complications and surprises: the wiring is "exactly what it says on the tin". And a modern ballast for and with T8 tubes will beat an LED any day of the week IMO. Not for efficiency, but certainly for quality.

  • Thanks for all the detail. I ended up rewiring with a direct wire (same end), although I thought I was getting a direct wire (opposite end), just like you said might happen.
    – gammapoint
    Commented Jun 14, 2021 at 1:44

I had the same question, and it turns out, some LEDs are electronic but not magnetic compatible, and some claim to be magnetic but not electronic compatible. It looks like yours is magnetic, though.

I ended up bypassing the ballast in my fixtures. It's really not that much extra work, and it was worth it to me.

  • 1
    I ended up bypassing them as well, and I like the end result. Thanks for sharing your experience.
    – gammapoint
    Commented Jun 14, 2021 at 1:44

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.