# Compact fluorescent bulbs: what's T2, T3, T4, T5? **URL:** \ **Category:** Factual Questions\ **Created:** [April 4, 2009, 4:31pm UTC](https://boards.straightdope.com/t/compact-fluorescent-bulbs-whats-t2-t3-t4-t5/491980 "2009-04-04T16:31:35Z")\ **Posts on this page:** 6\ **Page:** 2
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [April 5, 2009, 6:03pm UTC](https://boards.straightdope.com/t/compact-fluorescent-bulbs-whats-t2-t3-t4-t5/491980/21 "2009-04-05T18:03:34Z")
> [@emmaliminal](#): > > Any recommendations? Any of the major players: Sylvania, Philips, GE, etc. ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [April 6, 2009, 3:23am UTC](https://boards.straightdope.com/t/compact-fluorescent-bulbs-whats-t2-t3-t4-t5/491980/22 "2009-04-06T03:23:25Z")
> [@Q.E.D](#): > > Any of the major players: Sylvania, Philips, GE, etc. I agree. And I avoid Lights of America (LoA) – I’ve had bad luck with that brand’s products. I think Consumer Reports rates them pretty low, also. ---
**Author:** ![Alex\_Dubinsky](https://avatars.discourse-cdn.com/v4/letter/a/dbc845/32.png) [@Alex\_Dubinsky](https://boards.straightdope.com/u/Alex_Dubinsky)\ **Post date:** [April 6, 2009, 3:31am UTC](https://boards.straightdope.com/t/compact-fluorescent-bulbs-whats-t2-t3-t4-t5/491980/23 "2009-04-06T03:31:15Z")
The thing to care about with a CFL is the _color of its output_. ---
**Author:** ![Jeff\_Lichtman](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jeff_lichtman/32/1531_2.png) [@Jeff\_Lichtman](https://boards.straightdope.com/u/Jeff_Lichtman)\ **Post date:** [April 6, 2009, 3:35am UTC](https://boards.straightdope.com/t/compact-fluorescent-bulbs-whats-t2-t3-t4-t5/491980/24 "2009-04-06T03:35:46Z")
> [@Snnipe\_70E](#): > > The screw in type of CFL are not dimmable. For a florance to be dimmable requires a dimmable ballast. [Here](http://www.dimmablecfls.com/products.html) are some screw-in dimmable CFLs. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [April 6, 2009, 3:42am UTC](https://boards.straightdope.com/t/compact-fluorescent-bulbs-whats-t2-t3-t4-t5/491980/25 "2009-04-06T03:42:20Z")
> [@Alex\_Dubinsky](#): > > The thing to care about with a CFL is the _color of its output_. That’s _a_ thing to care about, but it’s hardly _the_ thing or sometimes even the main thing. Form factor, dimmability, base type, light output, startup time, reliability, shock/vibration resistance, operating temperature range and, yes, spectrum are all things to consider, along with several others, depending on the specific application and personal preferences. ---
**Author:** ![Alex\_Dubinsky](https://avatars.discourse-cdn.com/v4/letter/a/dbc845/32.png) [@Alex\_Dubinsky](https://boards.straightdope.com/u/Alex_Dubinsky)\ **Post date:** [April 7, 2009, 3:37am UTC](https://boards.straightdope.com/t/compact-fluorescent-bulbs-whats-t2-t3-t4-t5/491980/26 "2009-04-07T03:37:20Z")
> [@Q.E.D](#): > > That’s _a_ thing to care about, but it’s hardly _the_ thing or sometimes even the main thing. Form factor, dimmability, base type, light output, startup time, reliability, shock/vibration resistance, operating temperature range and, yes, spectrum are all things to consider, along with several others, depending on the specific application and personal preferences. Well, if you don’t care that your bedroom is lit with a sickly pale blue hue, then sure. [Previous page](https://boards.straightdope.com/t/compact-fluorescent-bulbs-whats-t2-t3-t4-t5/491980.md?page=1)