1

I'm wondering if running the ballast at its maximum rated output is safe. Is it necessary to provide it with some overhead by using a higher wattage ballast? Should I get, say, a 40W ballast for my 32W bulbs?

Robert M.
  • 111
  • 3
  • Do you mean "driver" rather than ballast? But "bulbs" usually have built in drivers. I'm interested in the question but don't understand it. – jay613 Oct 08 '22 at 20:53
  • 2
    If you are (I'm guessing) installing LED tubes in ballasted fluorescent fixtures, the best way is to buy bypass bulbs and bypass the ballast, then its wattage is irrelevant. – jay613 Oct 08 '22 at 21:19
  • Pretty sure he was asking if he could use an actual 32 watt LED bulb (60W equivalent - that creates double the lumens) for the added brightness in a 32 Watt rated fixture originally for fluorescent bulbs. – Eric Mar 29 '23 at 14:02

1 Answers1

6

First let's correct a misconception. Consider a normal screw-in Edison bulb that is 800 lumens. 800 what??? Exactly. What we care about is the brightness, which is 800 lumens. But for historical reasons we call it a "60 watt bulb" because old incandescent bulbs that bright were 60 watts. When we switched to CFLs those 800-lumen bulbs were actually 12 watts, and the LEDs are 8 watts, but we kept calling them a 60-watt bulb. See how that's wrong?

OK. So here you are calling this LED tube a "32 watt tube". Not likely. That would be too much light, too many LEDs and would make the tube too expensive, and then you wouldn't buy it lol.

So what you really have there is a 22-28 watt thing, which emits around 2600 lumens, same as a 32-watt F32T8 fluorescent. Get it?

Now, that whole thing of 32 vs 40 watts actually has nothing to do with power rating. The older fatter fluorescent tubes were sized F40T12. (40 = watts. 12 = 12 eighths of an inch, so 1-1/2" diameter). The newer, more efficient real fluorescent tubes are called F32T8 (32W, 1" diameter).

with real fluorescents, the ballast needs to match the tube, so a 32-watt fluorescent ballast is made for F32T8 tubes and not older,fatter F40T12.

The LEDs generally don't care.

So for your "Plug-n-play" or "Universal" type LED retrofit tube, that will simply work if the ballast is working.

Now, if you've tried new real fluorescent tubes of the correct type to match the ballast (i.e. F32T8 versus F40T12), and that's not working, the ballast is burned out and LEDs won't work either.

If that's the case, you should convert the fixture to ballast-bypass aka direct-wire in which the ballast is bypassed entirely. This takes some rewiring in the fixture, and by the way you'll want the small "blue color" wire nuts for that. If your LED "tube" is Universal type, that means it can work that way also. So follow its instructions.

Harper - Reinstate Monica
  • 276,940
  • 24
  • 257
  • 671