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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

Electrical Wiring Video

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.

Recent Questions and Comments

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Complete Guide to Home Electrical Wiring
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Methods for Home Electrical Wiring
Types of Light Switches and Lighting Controls How They are Wired
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Wiring 3-Way Switches
Wiring 4-Way Switches
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Electrical Tips to Help You Wire it Right

The Safest Way to Test Electrical Devices and Identify Electric Wires!

The Non-Contact Electrical Tester
This is a testing tool that I have had in my personal electrical tool pouch for years, and is the first test tool I grab to help identify electrical wiring. It is a Non-contact tester that I use to easily Detect Voltage in Cables, Cords, Circuit Breakers, Lighting Fixtures, Switches, Outlets and Wires. Simply insert the end of the tester into an outlet, lamp socket, or hold the end of the tester against the wire you wish to test. Very handy and easy to use.

The Quickest Way to Check for Faulty Electrical Wiring!

The Plug-In Outlet Tester
This is the first tool I grab to troubleshoot a problem with outlet circuit wiring. This popular tester is also used by most inspectors to test for power and check the polarity of circuit wiring.
It detects probable improper wiring conditions in standard 110-125 VAC outlets Provides 6 probable wiring conditions that are quick and easy to read for ultimate efficiency Lights indicate if wiring is correct and indicator light chart is included Tests standard 3-wire outlets UL Listed Light indicates if wiring is incorrect Very handy and easy to use.

Strip Off Wire Insulation without Nicking and Damaging the Electric Wire!

The Wire Stripper and Wire Cutter
My absolute favorite wire stripping tool that I have had in my personal electrical tool pouch for years, and this is the tool I use to safely strip electrical wires.
This handy tool has multiple uses:
The wire gauges are shown on the side of the tool so you know which slot to use for stripping insulation.
The end of the tool can be used to grip and bend wire which is handy for attaching wire onto the screw terminals of switches and outlets..

The wire stripper will work on both solid and stranded wire. This tool is Very Handy and Easy to Use.


Electrical Question: 
Do I have to change both the dimmer switches?

Jim asks:
I am installing a dimmer switch on an existing 3way light switch. Do I have to change both the switches to dimmers or can I have one dimmer switch and leave the other original regular switch?

This electrical wiring question came from Jim, in St. Charles, Missouri.

Dave’s Reply:
If there are two existing 3way dimmer switches, the replacement dimmer switch must be the identical switch as the other to ensure total compatibility, otherwise two identical new switches should be installed.

More about 3 way dimmer switch

Wiring Connections when Adding Light Fixtures
I am adding more light fixtures, the new lights do not work, but the original light does work, what did I do wrong? Common Wiring Problems with Light Fixtures and Dimmer Switches and How to Fix Them.

Identifying The Cause Of a Dimming Light Circuit
What is causing my lights to be dim? How to Identify and Fix the Cause of Dim Lights, Dim Lights may be a Indication of an Electrical Problem, How to Check Electric Circuit Wiring.

Light Fixture Wiring and the Spare Red Wire
How to Connect the Red Wire for a Ceiling Light Fixture: The Red Wire in the Ceiling Fan or Light Fixture Wiring.

Ceiling Fan Wiring and Connections with Video
Where do the red and black wires connect on a ceiling fan? The Wires of a Ceiling Fan and How to Connect Them, Wiring at the Ceiling Electrical Box, Wiring of the Ceiling Fan.

Timers and Light Switch Wiring
Wiring a Light Switch - I'm trying to replace a single pole light switch with a timer light switch in a box that also has another single pole switch going to another light: How to Wire a Timer Switch for Lighting.

Installing Two 3 Way Dimmer Switches
Is it possible to have two three way dimmer switches? How to Make Two 3-Way Dimmer Switches Work Together.

Troubleshooting Light Switch Wiring
I just changed a light switch and lost power to my outlets, what did I do wrong? How to Check Light Switch Wiring Connections, Common Light Switch Wiring Problem and Solution.

GU24 Socket Lamps and Dimmer Switches
Can I use a standard incandescent dimmer on a fixtures that utilizes GU24 sockets?

3 way dimmer switch - 1562