Light Dimmer Efficiency
Name: Jonathan N.
Date: June 2003
Somebody told me that common light dimmers use as much electrical
energy if they are turned up to 100% as they do when they are turned down... to 25%
(for instance). Is this true? I do not know too much about electricity, but it seemed
to me that it would be more like a water faucet...
They do not use as much energy when turned down. You would know if they did, because the
energy that did not go to the light would have to go somewhere, and you could hardly fail
to notice it. The dimmer would get hot, for example.
Common light dimmers are more like a pulsating shower head than a faucet. They allow
current though for a fraction of each cycle (of 60 Hz), and then they stop the current
for the remainder of the cycle.
"Old time" dimmer switches were just series resistors that dropped the voltage across a
light bulb, but technology has long since replaced these relics. Dimmer switches are
really pretty sophisticated now, and a detailed discussion here would not do the topic
justice. Better that you look at the interesting web site "How Things Work" for the
answer to this and many other "How Things Work" topics:
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Update: June 2012