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A little.

First off, most modern dimmer switches aren't rheostats. Those have been supplanted by TRIACs (triode for AC), and later, IGBTs (insulated gate bipolar transistors). For both of these, their mode of action is to change the duty cycle of the AC wave (duty cycle is time on versus cycle time) such that less power per cycle is put through the bulb. This is more efficient than a rheostat, in that, there isnt as much resistive loss across the dimmer.

The resistive loss is where the "a little" comes in. For all three types, a small amount of the power put through the dimmer is dissipated as heat - however, this is significantly less than the reduction in output power to the bulb, whatever the type.

An ideal dimmer would have 100% efficiency - that is, for a given setting, it would dissipate no heat, and the bulb would be the only thing on the circuit consuming power. However, no component is ideal, and modern dimmers typically consume under 1% of their power throughput (so if it's passing a total of 1W, it'll consume less than 10 milliWatts).

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โˆ™ 2015-07-15 21:41:03
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Q: Does a dimmer switch rheostat consume the electricity that the light fixture is not receiving?
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Does a down light consume less electricity?

The fixture construction has nothing to do with the amount of energy that the fixture uses. It is the lamp in the fixture that draws the amperage. This amperage times the fixtures voltage is what gives you the fixtures wattage. W = A x V. Watts = Amps x Volts.

Buzzing noise from light fixture?

A buzzing noise from a standard incandescent lighting fixture can be caused by a short in the lighting circuit (which is dangerous), or in some cases it can happen using a rheostat that is not all the way on or all the way off. The larger the physical size (not necessarily wattage) of the filament, the more likely it is to buzz using a dimmer -- these bulbs are designed for 120 volts, and using a rheostat gives less voltage to the lamp.A tube fluorescent fixture can make a buzzing noise if the ballast (small electrical box inside the fixture) is beginning to fail.Some outdoor fixtures are inherently noisy, such as a sodium arc lamp. In this case, there is really nothing to be done about it.

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