# Question about light bulbs **URL:** \ **Category:** Factual Questions\ **Created:** [February 12, 2004, 9:39pm UTC](https://boards.straightdope.com/t/question-about-light-bulbs/228921 "2004-02-12T21:39:15Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Carol\_the\_Impaler](https://avatars.discourse-cdn.com/v4/letter/c/6a8cbe/32.png) [@Carol\_the\_Impaler](https://boards.straightdope.com/u/Carol_the_Impaler)\ **Post date:** [February 12, 2004, 9:39pm UTC](https://boards.straightdope.com/t/question-about-light-bulbs/228921/1 "2004-02-12T21:39:15Z")
Just ordered some 3-way lightbulbs for my office. They are too tall to replace the 70w bulb in the lamp! They are 50-100-150. If I order 30-100’s, will they be shorter, and thus fit in the lamp? ---
**Author:** ![Carol\_the\_Impaler](https://avatars.discourse-cdn.com/v4/letter/c/6a8cbe/32.png) [@Carol\_the\_Impaler](https://boards.straightdope.com/u/Carol_the_Impaler)\ **Post date:** [February 12, 2004, 9:50pm UTC](https://boards.straightdope.com/t/question-about-light-bulbs/228921/2 "2004-02-12T21:50:12Z")
Oh, for the love of Jehovah. I just found “short” 3-ways on the web. (And no, not the porn.) Nevermind. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 12, 2004, 9:56pm UTC](https://boards.straightdope.com/t/question-about-light-bulbs/228921/3 "2004-02-12T21:56:13Z")
Pardon me, but what exactly _is_ a 3-way light bulb? ---
**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:** [February 12, 2004, 10:35pm UTC](https://boards.straightdope.com/t/question-about-light-bulbs/228921/4 "2004-02-12T22:35:20Z")
> [@Mangetout](#): > > Pardon me, but what exactly _is_ a 3-way light bulb? A three-way light bulb has two filaments inside. The lamp has a switch which can turn on one filament or the other or both. The 50-100-150 bulb mentioned in the OP has a 50-watt and a 100-watt filament, and when both are on the total draw is 150 watts. ---
**Author:** ![Carol\_the\_Impaler](https://avatars.discourse-cdn.com/v4/letter/c/6a8cbe/32.png) [@Carol\_the\_Impaler](https://boards.straightdope.com/u/Carol_the_Impaler)\ **Post date:** [February 12, 2004, 10:41pm UTC](https://boards.straightdope.com/t/question-about-light-bulbs/228921/5 "2004-02-12T22:41:57Z")
Well, at least my ill-thought-out post has done some good towards the fight against ignorance!!! 😉 ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 12, 2004, 10:43pm UTC](https://boards.straightdope.com/t/question-about-light-bulbs/228921/6 "2004-02-12T22:43:59Z")
Intertesting… what fitting are they and how are the (presumably multiple) contacts arranged? ---
**Author:** ![CurtC](https://avatars.discourse-cdn.com/v4/letter/c/ce73a5/32.png) [@CurtC](https://boards.straightdope.com/u/CurtC)\ **Post date:** [February 12, 2004, 10:49pm UTC](https://boards.straightdope.com/t/question-about-light-bulbs/228921/7 "2004-02-12T22:49:16Z")
I guess they should be called four-way bulbs though: 00 01 10 11 ---
**Author:** ![moriah](https://avatars.discourse-cdn.com/v4/letter/m/b2d939/32.png) [@moriah](https://boards.straightdope.com/u/moriah)\ **Post date:** [February 12, 2004, 10:52pm UTC](https://boards.straightdope.com/t/question-about-light-bulbs/228921/8 "2004-02-12T22:52:15Z")
> [@niblet\_head](#): > > Just ordered some 3-way lightbulbs for my office. > > They are too tall to replace the 70w bulb in the lamp! > > They are 50-100-150. If I order 30-100’s, will they be shorter, and thus fit in the lamp? Ummm… you’re jumping from 70W to 150W. That’s a lot of extra heat. Make sure the lamp is rated for 150W. Peace. ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [February 12, 2004, 11:03pm UTC](https://boards.straightdope.com/t/question-about-light-bulbs/228921/9 "2004-02-12T23:03:54Z")
Three way bulbs add a ring contact between the threaded shell and the center tip. ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [February 12, 2004, 11:12pm UTC](https://boards.straightdope.com/t/question-about-light-bulbs/228921/10 "2004-02-12T23:12:30Z")
Does Europe still use primarily bayonet-style sockets? (Push straight in and engage the pins with a slight twist) If so, you’re probably unfamiliar with our screw-in bulbs. [Here’s a picture of a North American 3-way bulb.](http://bulbmuseum.net/bulbs/verilux.htm) ---
**Author:** ![Popup](https://avatars.discourse-cdn.com/v4/letter/p/94ad74/32.png) [@Popup](https://boards.straightdope.com/u/Popup)\ **Post date:** [February 13, 2004, 10:51am UTC](https://boards.straightdope.com/t/question-about-light-bulbs/228921/11 "2004-02-13T10:51:15Z")
> [@gotpasswords](#): > > Does Europe still use primarily bayonet-style sockets? No, although they still exist. (They might still be popular in UK. I think I’ve seen some there.) In continental Europe (at least Germany, Switzerland, Sweden and Norway) **E27** bulbs are the norm. I’ve never seen three-way ones though. Pity, it seems like a neat idea. ---
**Author:** ![Xerxes](https://avatars.discourse-cdn.com/v4/letter/x/d2c977/32.png) [@Xerxes](https://boards.straightdope.com/u/Xerxes)\ **Post date:** [February 13, 2004, 10:57am UTC](https://boards.straightdope.com/t/question-about-light-bulbs/228921/12 "2004-02-13T10:57:15Z")
Bayonets are still by far the norm in the UK; they come in normal and small (SBC) varieties. Screw-type lamps (they’re known as Edison Screw - hence ES and SES (small Edison Screw) are available, and some table lamps take these, but they’re not the norm… ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [February 13, 2004, 12:02pm UTC](https://boards.straightdope.com/t/question-about-light-bulbs/228921/13 "2004-02-13T12:02:15Z")
> [@CurtC](#): > > I guess they should be called four-way bulbs though: 00 01 10 11 Then you have to refer to normal bulbs as 2-way bulbs… I’ve never seen a 3-way bulb in Japan either, though the same E26 socket as the US. (I think E26 is the 100V version of E27?)