I tried Home Depot, Batteries and Bulbs, Amazon, and just Googling it and I found nowhere that sells this kind of florescent bulb anymore:

Sorry for the blurriness!

4' Sylvania Super Saver Cool White F40CW/SS. Rapid Start 34W

I've found other Sylvania bulbs that are close, but none that are F40CW/SS.

Now I don't care about any of that Rapidstart Cool White stuff, I just want some light. Will another bulb of another wattage/style work?

  • Any F40 bulb with the correct end connections should work. The rest of the code is proprietary (Cool White, Super Saver).
    – isherwood
    Jun 26, 2017 at 13:09
  • 1
    The current number for that same lamp is sylvania F34cw/ss/eco the change from F40 to F34 is the result of federal energy regulations.
    – Tyson
    Jun 26, 2017 at 14:31
  • I should've said "F40-compatible". A simple search results in a great many options.
    – isherwood
    Jun 26, 2017 at 15:53

2 Answers 2


Any common T12 bulb is what you need.

You surely have the most common 4' T12 bi-pin type. They are everywhere.

You have a wide choice of color temperature (4100k is standard fluorescent color, 5100k is more LED color, 2700K is incandescent color).

And CRI (color rendering index), nobody will sell you less than 80 anymore, but you can get as high as 98. Your old tubes were probably 50-60 CRI, the difference will blow you away.

Tube sizes

The 4-foot bi-pin type bulb is far-and-away the most common. They come in two primary types that you'll spot in an instant:

  • T12 (literally 12/8 inch or 1.5" diameter) - what you have in your hand.
  • T8 - notably smaller (8/8" or 1" diam.), will physically fit, but won't work properly.
  • T5 - a very small Euro bulb which is an inch too short with too-narrow pins. This is definitely the wrong thing.

Base types

It's rare, but on occasion you will run into an oddball base type. The 8-foot fluorescent tubes use different styles of base, and some idiot made a 4‘ long version of that - complicating everything. Most of these critters are T12. Just for the record, here are the three base types that are possible:

  • normal bi-pin: two plain pins 1/2" apart. Universal on any tube shorter than 4‘.
  • monopin: one little nub maybe 1/4” across. Universal on 8’ style tubes.
  • High-Output dual-pin: an odd plastic casing about 1/2" wide shielding two little pins. Used on exotic high-output 8' tubes mostly.

Consider LED

You can now get "tubes" which are in fact a row of LED lights. They come in a variety of color temperatures and CRIs (not as good as you can buy in real fluorescent). Don't just throw a pair in the cart, they take some wiring.

  • "Plug-n-Play" types use an existing ballast. The problem is, it may not be your type of ballast (there are several). Which will leave you in the painful position of having to change ballasts for a technology that shouldn't even use them.
  • "Direct wire" definitely require rewiring the fixture. But then you get the old ballast out of there for good.
  • FYI - For years the industry has been phasing out T-12 type lamps by eliminating certain types and should eventually take them off the market. They are not as efficient as other fluorescents. So I recommend you upgrade to a T-8 with an electronic ballasts or an LED as recommended by @Harper. Jun 27, 2017 at 16:25
  • Different countries can be pretty bloodthirsty about how they ban things. But in the USA, they nibble at the margins. They banned all T12s with less than 80 CRI thinking that would price them off the market. That didn't work, but LED retrofits are doing the job naturally, so they have stopped nibbling. Jun 27, 2017 at 16:49
  • I ended up finding these on Amazon and they worked: Sylvania 22462 - F34CWX/SS/2PK CP Straight T12 Fluorescent Tube Light Bulb
    – LCIII
    Dec 11, 2017 at 19:26

Look up specs for a F40/ADV841 and a F32T8/841 both have cri of 85. F40 is 3600 lumens F32T8 is 2900 lumens. That's 90 lpw for T12 and 90.625 lpw for T8. Most comparisons between T12 and T8 were done with low end T12 compared to high end T8. F40/CW/WM which is 2650 lumens and 62 cri is what they used to compare with the high end T8 of 2900 lumens and 85 cri. Notice that they never compared high end T12 to low end T8. Wal mart sells an 1800 lumen F32T8 and a 2200 lumen T12. These have been gimped down to make led appear better than they really are. Since magnetic ballast are now banned why do they still rate T12 and T8 on them. Electronic ballast have a 10% gain over magnetic. If they rated the advantage series T12 and T8 on electronic ballast the T12 would make 3600 lumens at 36 watts and the T8 would make 2900 lumens at 28.8 watts. That's 100 lpw and 100.694 lpw respectively. T5 is already rated on electronic ballast, that's why they appear better than T12 or T8. Please search this information if you don't believe what I have written.

  • They make T8 vs T12 ballasts because the two types have different electrical characteristics. As far as overdriving or underdriving tubes, that’s what ballast factor is all about. You can get ballasts with a variety of BFs from .62 to 1.35. Jun 24, 2020 at 3:49

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