# Turning off lights at night does not conserve electricity? **URL:** \ **Category:** Factual Questions\ **Created:** [July 29, 2004, 5:46pm UTC](https://boards.straightdope.com/t/turning-off-lights-at-night-does-not-conserve-electricity/257461 "2004-07-29T17:46:52Z")\ **Posts on this page:** 10\ **Page:** 2
**Author:** ![Una\_Persson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/una_persson/32/346_2.png) [@Una\_Persson](https://boards.straightdope.com/u/Una_Persson)\ **Post date:** [July 30, 2004, 2:55pm UTC](https://boards.straightdope.com/t/turning-off-lights-at-night-does-not-conserve-electricity/257461/21 "2004-07-30T14:55:47Z")
> [@Q.E.D.](#): > > That’s what I _said_. 😛 > > Only I wasn’t so polite about it. 😉 Tell you what - in this thread I’ll be the iron fist of information in the velvet glove of diplomacy; you can be the cricket bat of enlightenment whanging on the groin of ignorance. 😉 ---
**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:** [July 30, 2004, 3:11pm UTC](https://boards.straightdope.com/t/turning-off-lights-at-night-does-not-conserve-electricity/257461/22 "2004-07-30T15:11:38Z")
> [@Una Persson](#): > > Tell you what - in this thread I’ll be the iron fist of information in the velvet glove of diplomacy; you can be the cricket bat of enlightenment whanging on the groin of ignorance. 😉 Heh. And thanks for the additional info. I hadn’t though about additional factors in maintaining a minimum operating energy expenditure other than electrical loading. My _Electrical Engineer’s Reference Book_ doesn’t cover the mechanical aspects of power generation so much. ---
**Author:** ![Futile\_Gesture](https://avatars.discourse-cdn.com/v4/letter/f/f05b48/32.png) [@Futile\_Gesture](https://boards.straightdope.com/u/Futile_Gesture)\ **Post date:** [July 30, 2004, 3:30pm UTC](https://boards.straightdope.com/t/turning-off-lights-at-night-does-not-conserve-electricity/257461/23 "2004-07-30T15:30:59Z")
> [@Shade](#): > > If we don’t that energy is LOST!! 😮 And matter is just energy. Turning lights off mean the universe is decreasing constantly, as this energy is just deleted. \ It’s far worse than that. If you don’t leave all your lights and appliances running all night all the electricity gets backed up on the lines. One day it’s going to overflow all the way back to the generators and all the power workers consoles will explode, like on Star Trek, and the power station will be knee deep in electricity. So just think about the lives you’re putting at risk next time you selfishly switch your lights out. This thread has now reach its terminus, having called at OP, Unenlighted Speculation, Expert Analysis and finally Flippant Sarcasm. Would all dopers make sure they have their luggage with them when they disembark. ---
**Author:** ![hammos1](https://avatars.discourse-cdn.com/v4/letter/h/ba8739/32.png) [@hammos1](https://boards.straightdope.com/u/hammos1)\ **Post date:** [July 30, 2004, 3:44pm UTC](https://boards.straightdope.com/t/turning-off-lights-at-night-does-not-conserve-electricity/257461/24 "2004-07-30T15:44:25Z")
I have no expertise to add. But this reminds me of a story a friend told me. There was a sign in his university physics department corridor that said : **Conserve energy- please switch off light bulbs when not in use** Under which some wag had written: \*\*First Law of Thermodynamics: Energy is always conserved. \*\* ---
**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:** [July 30, 2004, 7:44pm UTC](https://boards.straightdope.com/t/turning-off-lights-at-night-does-not-conserve-electricity/257461/25 "2004-07-30T19:44:01Z")
> [@LSLGuy](#): > > It’s also impressive, in a sad way, how often you get reasonable-sounding statements of “fact” up near the top of a thread that are conclusively debunked when the real pros check in a few hours later. Oh well … Eh? > [@Q.E.D.](#): > > While it’s true that the generators turn at a constant rate (usually 3600 RPM for a 60 Hz system), the power production varies with load demand. > [@Una Persson](#): > > Most combustion power plants vary their load fairly considerably according to demand… Seems to me the OP was correctly answered early on, and that **Una** and I are substantially in agreement on this point (though I don’t wish to speak for her). I see nothing in **Una** ’s excellent post that “debunks” anything in my initial post, but if you do, would you be so kind as to point it out to me? I’ve conceded to a misunderstanding of minimum load conditions, but this has no real bearing on the OP’s question; it only means that fuel usage is not necessarily linear to demand. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [July 31, 2004, 2:35pm UTC](https://boards.straightdope.com/t/turning-off-lights-at-night-does-not-conserve-electricity/257461/26 "2004-07-31T14:35:44Z")
Q.E.D., In no way was I intending to refer to any post of yours, in this thread or any other. I apologize if you interpreted my post that way. I have great respect for the expertise and clarity of explanation you demonstrate in every post I’ve seen. The poster I quoted, threemae, was making the general observation that the SDMB has a lot of expertise in amazingly diverse areas, incidentally including electrical plant engineering, the topic of this particular thread. I seconded that motion, while offering a corresponding lament that there are also a lot of non-experts who don’t realize where their expertise fades from real knowledge to assumptions and “common sense”, to speculation, even to downright fantasy. And that, human nature being what it is, those folks often are among the first to jump into the fray with authoritative sounding posts. It was meant as a general comment about the overall SDMB GQ and IMHO experience. Again I apologize if my post appeared to be aimed in your direction. It wasn’t meant that way at all. ---
**Author:** ![legion](https://avatars.discourse-cdn.com/v4/letter/l/838e76/32.png) [@legion](https://boards.straightdope.com/u/legion)\ **Post date:** [July 31, 2004, 3:06pm UTC](https://boards.straightdope.com/t/turning-off-lights-at-night-does-not-conserve-electricity/257461/27 "2004-07-31T15:06:25Z")
Won’t somebody please **think of the light bulbs?** ---
**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:** [July 31, 2004, 3:14pm UTC](https://boards.straightdope.com/t/turning-off-lights-at-night-does-not-conserve-electricity/257461/28 "2004-07-31T15:14:13Z")
> [@LSLGuy](#): > > It was meant as a general comment about the overall SDMB GQ and IMHO experience. Again I apologize if my post appeared to be aimed in your direction. It wasn’t meant that way at all. Fair enough. No hard feelings. Your post gave the the impression that you felt that this particular OP wasn’t answered until **Una** showed up. You can see how one could make that interpretation, but no matter. 🙂 ---
**Author:** ![InvidiousCourgette](https://avatars.discourse-cdn.com/v4/letter/i/e47c2d/32.png) [@InvidiousCourgette](https://boards.straightdope.com/u/InvidiousCourgette)\ **Post date:** [July 31, 2004, 3:53pm UTC](https://boards.straightdope.com/t/turning-off-lights-at-night-does-not-conserve-electricity/257461/29 "2004-07-31T15:53:31Z")
> [@Q.E.D.](#): > > Fair enough. No hard feelings. Your post gave the the impression that you felt that this particular OP wasn’t answered until **Una** showed up. You can see how one could make that interpretation, but no matter. 🙂 I am glad I was not the only poster who felt slightly slighted by LSLGuy’s comment. 🙂 ---
**Author:** ![Fish](https://avatars.discourse-cdn.com/v4/letter/f/bc8723/32.png) [@Fish](https://boards.straightdope.com/u/Fish)\ **Post date:** [July 31, 2004, 3:58pm UTC](https://boards.straightdope.com/t/turning-off-lights-at-night-does-not-conserve-electricity/257461/30 "2004-07-31T15:58:18Z")
> [@Shade](#): > > You use SO much more power. And you’ve probably turned your car ignition off at night. SAVWE OUR PLANETT RUN LEAVE CAR IDLINGING in UR GARIDDGE OKOKOKOK??? ViTal!! now. > > \ All one, all one! Dilute! Dilute! Though the OP has been answered, when I saw the thread title I thought it sounded like a mutation of the canard that turning off and on your lights used more power than to simply leave them running all night, that somehow you would “save power” by leaving them on. It was [one of the first questions I asked](http://boards.straightdope.com/sdmb/showthread.php?t=133180&highlight=sylvania) on the SDMB, even. (A discussion of the answer can be found in the thread, but as it is two years old, it oughtn’t be bumped.) [Previous page](https://boards.straightdope.com/t/turning-off-lights-at-night-does-not-conserve-electricity/257461.md?page=1)