Dim Bulb....... Good or Bad?

Lisa writes:

"Your daughter sent me ... but I have an actual question! It's been bugging me for ages! Here you go: if you have a light on a dimmer, does it use less energy if it is dimmed? (One of our bathroom lights is on a dimmer and I leave it on as a nightlight, but I turn it way down - and every night I wonder if it is still sucking up electrticity as if it was on full bright ... )"
"Cheers!"

Thanks for checking out my blog.  And thanks for supporting Julie and Uncommon Misconceptions.   Up until a few years ago, I was absolutely convinced that electricity worked because little imp-like fairies ran back and forth in the wires.  Now that I've spent some time studying the matter, I know that it really works because of leprechauns.  

Dimmer switches.  There are two basic types of dimmer switches found in our homes these days.  The older of these is the rheostat-type dimmer.  They went out of common use about 20 years ago.  These dimmers worked by reducing the voltage that runs to a light fixture.  However, the voltage that wasn't needed to light the bulb was converted to heat.  Bottom line, the dim bulb still uses the same amount of electricity as the bright bulb.  If you're living in an older home or apartment you may still have this type of dimmer switch.  One way to find out if you've got the older rheostat dimmer is to turn the light fixture on, turn the light level way low, wait about 10 minutes or so, and then put your hand on the plastic cover plate.  If you've got the old type, the cover plate will be warm.  Not hot, just noticeably warm. 

The rheostat dimmers have been replaced by electronic dimmer switches.  These switches operate by rapidly turning the electricity on and off inside the switch. The on-off cycle happens so fast that our eyes can't perceive the changes and the light coming from the bulb appears dimmer.  I'm really convinced that those leprechauns are involved in this somehow.  The end result is that less electricity flows to the light and you actually do use less electricity.  Cool, huh?  A thorough and informative discussion of dimmer switches can be found here.

One other thing to keep in mind, though.  If you are like me and use CFL's (compact flourescent lights) wherever you can, dimmer switches may cause other problems, even with electronic dimmer switches.    However, if you put a CFL on a dimmer switch, after the light has been turned on for a while (20 minutes or so) you may notice the light level pulsating, rapidly going from bright to slightly dimmer and back.  If you have this problem, you should go to a simple on/off light switch.  These new fangled devices are changing almost daily, so they may have a solution to this problem that I don't know about.

Hope this helps.

Comments

[Julia]

I'm really impressed with the question! I never would have thought to wonder about the consumption of a dimmer. Good to know!

[Watch Basketball Online]

Terrific stuff! This is the type of stuff that should be spread around the web. Shame on the search engines for not positioning this post higher!