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Electrical Wire and Cable

Wiring a 3 Way Dimmer Switch

wiring-a-dimmer-switch Summary: Fully Explained Wiring for 3 Way Dimmer Switches with Wiring Diagrams and Pictures - Instructions about How to Wire 3 Way Dimmer Switches.
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3-Way Dimmer Wiring Diagrams for Lighting Control and Energy Savings

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How to Wire a 3Way and 4Way Light Switches

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Basic 3-Way Dimmers Switches
A 3-way dimmer switch is very similar to a regular 3-way toggle switch except for the electronic unit which performs the actual dimming function.

Pre wire Dimmer Switches
Most 3-Way dimmers come with pre-wired leads that are color coded and explained below. These dimmers are also known as wall dimmers and light dimmers.

If you are replacing an existing 3-way switch: When replacing an existing 3-way switch take note of how the existing switch is wired BEFORE you remove the wiring, then refer to your notes to help you wire the new 3-way dimmer switch.

Many manufacturers are now producing dimmer switches that can be used for either Single Pole or 3-Way Switches. For the Single Pole application the instruction sheet will have you cap off one of the wires which will not be used.

Care should be taken in selecting your dimmer switch.
Most dimmers are rated for 600 watts of power consumption, so if you have several light fixtures which will be controlled by the 3-way dimmer switch you will need to count the number of fixtures, the number of lamps per fixture and the watts per lamp. Calculate the total watts which will be controlled by your 3-way dimmer switch. A good rule of thumb with any electrical load calculation is to never exceed 80% of the rated load for any electrical component or device.

Never wire a regular dimmer to an older fluorescent light fixture that is not rated for dimming or a fixture which has CFL - Compact Fluorescent Lamp adapters.

Dimming non-compatible fixtures or lamps will cause the fluorescent lamps to over heat and burn out prematurely.

Newer specially designed fluorescent fixtures and dimmers are available which are are compatible and work well together.

  • Wiring Dimmer Switches

  • Residential Dimmer Switches used for several types of lighting fixtures.

These wiring connections are for:
  • Dimmer Switch Sizes
  1. 600 Watt Dimmer Switch
  2. 800 Watt Dimmer Switch
  3. 1000 Watt Dimmer Switch
  • Dimmer Switch Types
  1. Single Pole Dimmer Switch
  2. 3-Way Dimmer Switch
  3. Knob Style Dimmer Switch
  4. Slide Dimmer Switch
Dimmer Switch Applications
  1. Incandescent Light Fixtures
  2. Dimmable Fluorescent Lamps
  3. Dimmable CFL Lamps
  4. Dimmable LED Lamps
  5. Dimmable Quartz Light Fixtures
Dimmer Switch and Light Fixture Compatibility
  • Check to make sure your dimmer switch is compatible with your lamp or light fixture.
  • Check to make sure your lamp or light fixture is compatible with your dimmer switch.

Dimmer Switch Basics

Dimmer Switch Watt Ratings

Residential dimmer switches are available for several load requirements including 600, 800 and 1000 watts. If you do not size your dimmer properly the dimmer could overheat and cause internal damage. Regular 3-way dimmer switches are designed for incandescent lamps unless otherwise stated.

Dimming Low Voltage Lighting fixtures

Consult the instruction sheet that accompanies the low voltage lighting fixture for the correct dimmer to use. Some fixtures allow you to use regular dimmers, however some do not.

Wiring a Standard 3-Way Dimmer Switch

3-Way Dimmer Switches typically come with the following pre-wired leads

Green wire: Attach to the bonded ground wire(s) in the switch box.

Two Red wires: These wires attach to the "travelers" which are the pair of wires attached to the two screws at one end of the regular 3-way-switch.

One Black wire: Attach to the wire commonly found on the screw by itself on the regular 3-way switch, typically the Power or the Switch Leg leaving to the fixture(s).

Dimmer Switches will help you Save Energy
Installing Dimmer Switches can help reduce your electrical consumption as shown in the chart below.

Dimming lights this much

Reduces your energy bill

And extends bulb life


2 times longer
4 times longer
20 times longer
More than 20 times longer

Electrical Safety

As with all electrical projects
Always positively identify the circuit and turn off the power before performing wiring of any kind.

Never work on an energized circuit!

Below you will see some photos that I have selected to help you with your project.
Take a look at a typical 3-Way Dimmer Switch installation
[Click on the images to Enlarge]

Instructions for Dimmer Switch Wiring

The typical 3-Way switch wiring has two screw terminals at one end of the switch. This is where the "travelers" are connected.
The opposite end of the switch has one screw terminal which may be a different color as seen here in this photo. Depending on your wiring configuration, this single terminal will have attached either the Power Line or the Switched Leg that leads to the fixture.

This wired 3-Way dimmer switch has the Red and White "travelers" attached to the set of screw terminals at one end of the switch. The screw at the other end of the switch has either the Power or Switch Leg wire attached to it.

Here a 600 watt Knob Style 3-way dimmer switch has pre-wired leads: Green, two Red and a Black Lead ready for installation.

This 3-Way Dimmer Switch is wired as follows:
The Green Ground Lead attaches to the switch box ground wire, the Red and White "travelers" are attached to the pair of Red Leads and the Black Lead is connected to the Power or Switch Leg connected at the fixture(s).


More about How to Wire Dimmer Switches


Replacing a Switch with a Dimmer Switch

Hi i'm trying to wire in a dimmer switch.

The dimmer has a turn switch and a normal switch.
There are 2 loads and 2 lines with in this switch.
The old dimmer only has 1 line and 1 load on it and there are only 2 wires in the wall red and blue.

The new dimmer wont work properly when i connect and use jumpers, what am I doing wrong?

Dave's reply:
The switch that you purchased is really two switches in one, and it appears that this switch has a dimmer for lights and a speed control.
This combo type switch is normally used to control a ceiling fan and light.
It would be best to purchase a single dimmer switch that will have the same wiring as found with the original switch.
Make sure the dimmer switch will be compatible with the lamps that are in the light fixture.

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