How to Install a Dimmer Switch

Most traditional homes have what is called a single pole light switch on most of the controls used for lighting. These types of switches have only two choices: on or off. However, replacing single pole controls with a dimmer can give you many more options for controlling the ambiance in your home.

Dimmers typically use a sliding lever or a turn dial to increase or decrease the voltage going to the circuit which allows only a portion of the bulb’s energy to be used.  This can provide a number of benefits.

Advantages of Light Dimmers in the Home

Dimmer switches have many advantages over their single pole counterparts.

  •  Environmentally friendly:  saves on average between 4-9% off your monthly electric bill[1]
  • Allows you to set the mood in a room to meet whatever is happening at the time, whether children are playing or you are watching a movie
  • The light bulbs used with dimmers last longer: lights dimmed by at least 25% will save approximately 1/5 of the electricity required[1]
  • Fluorescent bulbs  that are used with a dimmer will have a softer, cooler color
  • Bulbs can last 3 to 4 years longer when used with dimming features

Before You Begin

  • Dimmer switch
  • Wire nuts
  • Electrician’s tape
  • Screwdriver
  • Wire strippers
  • Pliers

Tips for Buying the Right Dimmer

  • Make sure the dimmer switch you purchase is rated for the total wattage of the fixture it will be controlling.  For example, a light over a kitchen table with 10 – 100 watt bulbs is too much for a standard 600-watt dimmer.
  • Rotary dimmers look like standard switches that slide up or down to control the light
  • Rotary model dimmers have their own on and off switch so you can turn on the light at the level you choose

Dimmers for Ceiling Fans

Additionally, if you will be using the dimmer to control a ceiling fan, do not use a standard How to Install a Dimmer Switchdimmer because it will burn out the fan and significantly shorten its life. Here are some of the typical types of dimmers that can be used with ceiling fans

  • Fully Variable Fan Speed - Used for controlling paddle fans or exhaust fans
  • Quiet 3-speed plus off – no fan motor hum; used for controlling one ceiling paddle only
  • Quiet 7-speed plus off - no fan motor hum; Controls up to 4 ceiling paddle fans with 1 canopy module for each fan

Dimmers for LED Bulbs

LED lights are becoming more and more common in residential homes so it is worth taking a moment to discuss some issues you will be dealing with if you are trying to dim those types of bulbs.

Buying a dimming switch that will control LED light bulbs requires more research than for an incandescent bulb because most are not compatible with most of those types of switches. You will need a special dimmer that is designed to send power and control signals to each type of electronic LED driver. However, certain LED bulbs are not designed to be dimmed at all and can never be connected to a dimming device.

Before you install any dimming switch, make sure you have the right bulb in the fixture. Whether it is an LED, incandescent or fluorescent, you have to make sure that it physically fits in the fixture. It must have the right shape, size and socket type. The amount of voltage is critical because LEDs operate on low voltage direct current. Each LED bulb contains a driver that converts the high voltage AC from the power company into the low voltage DC required.

One of the most important things to look for when buying any type of bulb is the brightness. LEDs are measured in terms of lumens, not watts. The higher the lumens, the brighter the light.

LED bulbs come in many different variations of white, such as warm white and neutral white. Warm white is more commonly used in home settings whereas neutral white is the type you would traditionally see in high light commercial areas like offices and any type of displays.

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(price as of Jan 6, 2015)

Installing a Standard Dimmer Switch

Before you begin the process of replacing or installing a new dimmer, make sure you are usingHow to Install a Dimmer Switch the right dimmer for the right setting.  Only install one 3-way dimmer per receptacle. For this discussion, we are installing a new standard dimmer switch.

  1. Shut off the power to the circuit at the breaker box.
  2. Remove the existing plate cover and place to the side make sure not to lose the screws.
  3. Once the plate is removed, remove the mounting screws that hold the electrical box in place.
  4. Carefully pull out the switch body.
  5. Some dimmer switches do not correspond to the traditional black and white wiring. If you purchase a new dimmer, it may only have two black wires plus a green one for a ground. However, the black wires from a standard dimmer are interchangeable.
  6. Remove the existing wire nuts from the connections. Strip away any electrician’s tape if necessary.
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Allows you to set and recall 7 light levels and fan speeds
  1. Attach the ground wire from the new receptacle.
  2. Strip ¾ inch of insulation from each existing house wire and 1inch from each new dimmer lead.
  3. Wrap a lead around a wire with your fingers so that the lead protrudes past the wire about 1/8 of an inch.
  4. Slip on a wire nut and it until it stops turning.
  5. Place electrician’s tape around the wire nut to hold it in place.
  6. While you have the assembly out, go to the breaker box and flip the power back on and check your connections. If everything works as desired, continue.
  7. Push the assembly back into the wall being careful not to twist and bend the wires too much. Some bunching is inevitable however in tight spaces. If you put electrical tape around the wire nut tight, your connection should remain.
  8. Secure the mounting box to the wall, then reinstall the mounting plate.

One important point to remember

If you are installing a dual dimmer with a fan controller, be sure to adhere to the manufacturer’s recommendations for wiring the two together because it can be tricky. Additionally, the dimming switch you purchase will also have wiring diagrams for various situations so if you are uncomfortable working with electricity, it is probably best to hire a qualified person.

How to Install a Dimmer Switch

Installing a Three-Way Dimmer

If you are replacing and existing three-way dimmer, tag the existing lead wires to connect the new on in the same way as the old one. If only one cable enters the box from behind, attach the black wire to the common terminal and the other two wires to the traveler terminals.

If you replace a three-way toggle switch dimmer, tag the wire that leads to the common terminal. The other two wires are interchangeable.


The right light can set the mood for any occasion. Lower light allows you to control the ambiance of any room for any occasion. Whether you have traditional incandescent bulbs, florescent or LED bulbs, you can find the right dimmer switch to create the mood you desire and save between 5 – 10% a month on your energy bill.[2]

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(price as of Jan 6, 2015)