Does a dimmer switch (a rheostat) reduce power consumption?

In: Science.Physics Asked by: r56 Nov 29, 2007 - 88 Months Ago.  Viewed 9010 times

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Most household dimmer switches are not rheostats, they are triacs, which are solid-state devices. (Also known as SCR's, Silicon Controlled Rectifier) Triac dimmer switches consume very little power, so it does help reduce power consumption, and help reduce your electric bill.

A rheostat dimmer would be hard to find nowadays. It can also reduce your power consumption, but not as much as a modern triac-based dimmer.

How much money will you save with a dimmer switch? Not much, because with normal incincandescent bulbs, you can't lower the light too much without it being too dark. A better strategy is to change all the lightbulbs to the compact fluorescent type. Not only do you save energy, it last a lot longer so you wouldn't have to change it as much.

Note: Do not combine a compact flourescent and a dimmer switch.
Answered by: f4acre - 87 Months Ago.
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The term rheostat, tends to be an older expression that dates back to the days of using "windings" and a variable "wiper" to provide a variable resistance model between the supply and load, (light). With such a resistive device, the power consumption is actually increased slightly due to the additional component's presence in the circuit, but more importantly whatever power is not going to the bulb, is generated as "heat" at the windings.

In more recent years, we have moved to solid state devices which control the on/off time per each cycle of the AC current or a cyclic off time x times per second on DC current, but either way, the net result is a reduction of power consumption equal to the change in power factor, less a very slight amount of heat generated at the solid state device.

So yes, a solid state "dimmer" of recent and typical design can reduce the amount of overall wattage consumed for a given amount of light produced.

Keep in mind if you install a dimmer on the light over the stairwell and then fall down the stairs for not seeing the way, the medical bills may exceed the annual net savings from the dimmer. ;-)
Answered by: researchtermpapers - 58 Months Ago.
Nice post with awesome points! Can’t wait for the next one.

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Commented by: willie - 20 Months Ago.
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Does a dimmer switch (a rheostat) reduce power consumption? - HelpGlobe.Science.Physics

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