1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Light Switch Dimmers

Discussion in 'General Discussion' started by sunama, 29 May 2006.

  1. sunama

    Capodecina

    Joined: 18 Oct 2002

    Posts: 15,968

    Location: NW London

    So, I'm in the process of re-wiring my property and im deciding on whether to use dimmers or ordinary light switches. I just wanted to know: Do dimmers (that allow you to change the intensity of your lights in your home) help save on electricity?
     
  2. PureAppleJuice

    Wise Guy

    Joined: 18 Dec 2005

    Posts: 1,419

    Location: Londontown

    Think they use a bit more actually, though i'm probably wrong.
     
  3. ste_bla

    Sgarrista

    Joined: 9 Aug 2004

    Posts: 7,794

    Location: Milton Keynes

    Surely the dimmer puts up resistance reducing light and therefor the amount of juice going to it?

    Thats what common sense says to me..
     
  4. Minto

    Hitman

    Joined: 15 Jun 2004

    Posts: 756

    the variable resistor in the dimmer just dissipates any of the power that isn't used in the light bulb as heat and sound (the slight buzzing you hear from them)
     
  5. PureAppleJuice

    Wise Guy

    Joined: 18 Dec 2005

    Posts: 1,419

    Location: Londontown

    Yeah, thought there was little difference in efficiency, as it still draws the same amount. Meh, i'm no electrician :)
     
  6. Chasser

    Mobster

    Joined: 18 Oct 2002

    Posts: 3,023

    Location: West Oxon

    You can't use energy saving bulbs with dimmer switches.
     
  7. whitecrook

    Sgarrista

    Joined: 22 Aug 2005

    Posts: 8,367

    Location: Clydebank

    Have 2 or three lighting circuits in the room and put a dimmer on one of them.
     
  8. Trigger

    Mobster

    Joined: 15 Dec 2004

    Posts: 3,822

    *cough* PART P *cough* :p

    In answer to your question, there will be very little difference in effeciency.
     
  9. [SKR]Phoenix

    Wise Guy

    Joined: 12 Feb 2003

    Posts: 2,441

    Can't be used with ceiling fans either. Well, thats not strictly true because Hunter Ceiling fans can and do work, but they are remote control and have internal dimmers.

    Would like to say that they are the best you can get, we have them in every room! VERY quiet (providing they are mounted correctly) and complete with dimmer fuctions.

    Check out their website, they are from the US, but there are dealers here.
     
  10. Adam_151

    Mobster

    Joined: 18 May 2004

    Posts: 2,711

    Location: Lincoln, Uk

    No, thats not how they work at all (well not these days, old theatre dimmers from days gone by did), if they worked like that then they'd get a lot hotter than they do, and be a lot bigger than they are

    They work by phase cutting... switch on at the beginning of the the half cycle and bright light, switch on towards the end and dimmer, everything resets at the end of the half cycle to start again

    Also, it should be noted that adding series resistance would reduce the power taken anyway, just not in a very efficient way becuase of the power that remains, some goes into the load and some into the series resistance


    Anyway to answer the OPs question... yes they do save money (at least assuming a domestic meter that measures true power, rather than apparent power, whether they save money on a meter that measures apparent power is a question that its two late to thing about, though its irrelevant to this thread), but not as much as you imagine, if you dim the lights to 50% you are using about 75% of full power. If you are using many downlights, split them off into separate banks and switch them individually (oh, side point, derate dimmers by 50% when using with halogen lamps if thats what you are doing... the transisants are greater than with normal lamps :) )
     
  11. phykell

    Mobster

    Joined: 18 Oct 2002

    Posts: 4,410

    Agreed ^^^ dimmers do save power but if you find you're needing them, consider changing the bulbs to a lower wattage anyway. There's not really much difference in light output between a 60W and a 100W bulb (or a 40W and a 60W, etc.).

    Good link here if you're interested:

    http://home.howstuffworks.com/dimmer-switch.htm
     
  12. sunama

    Capodecina

    Joined: 18 Oct 2002

    Posts: 15,968

    Location: NW London

    I was thinking about having 7 (halogen) spotlights in the lounge, in 3 banks, controlled by a triple light switch. So this would enable me to switch on only the lights that i want. This should enable me to save power.

    It was just a thought about the dimmer lights. I read some adverts stating that dimmer switches allow savings to be made in electricity and ive always held the idea that this is not the case.

    Of course if u really want to save money then energy saving light bulbs are the answer, though they dont look particularly nice.