How Light Dimmers Work

Introduction:

Light dimmer switches can vary the brightness of a light to create a different type of atmosphere or mood. Light dimmer switches usually looks like a small dial that is turned to increase or decrease the brightness of lights by adjusting the power output from the switch.  Newer dimmers are sliding switches. Dining rooms, dens and bedrooms are where dimmer switches are usually used.

Older dimmer switches used a variable resistor to adjust the power. A variable resistor is an electrical device that you can vary the amount of power that passes through it.  It is made up of a resistive material, a moving contact and a non-moving contact. The resistive material is attached to the moving contact. When the moving contact is close to the stationary contact the electricity does not have to force its way through a lot of material because the resistance is low. When the movable contact is moved away, the material is extended and the electricity has much more difficulty to transfer through it. This extended travel dims the light because of a loss of energy that results in a loss of voltage.

Modern light dimmers today use a different method to vary the power output to dim the lights. They rapidly turn the power to the light on and off. In turn there is a lower amount of energy moving through the circuit to the light. Electric power running through the wires in your home switches direction approximately 60 times per second. Modern dimmer breaks up this current flow each time the direction is changed or at the point when the volts reach zero right before direction is reversed. This turns the power to the light off and on many times per second which lowers the energy going to the light. How quickly the power switches on after and off depends on where the dial is set. If it is close to full power, the on and off cycle of the current is very fast. If the switch is set to lower light, then the on and off cycle is slower.

That is how light dimmers work. If you use the modern light dimmer you can actually save power and money by running the lights at a low setting. However, if you are using the older light dimmer there is no energy saving from running the lights on low because the energy is consumed as heat at the dimmer switch.

Installing a light dimmer switch is an easy DIY task. Nearly all home improvement supply centers carry light dimmers ar very reasonable prices.

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