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Figuring out the 3 way dimmer switch wiring is one of the first steps of any DIY project. Installing a dimmer with any light fixture has multiple benefits. You’ll economize on power bills and get the right amount of brightness you need at a given time after installing a three way dimmer switch. Improving the room’s ambiance and longevity of your bulbs are only some of the added positives.

Before you get started, remember to try a DIY project only if you have some experience in doing electrical work. If you haven’t done this before, consider calling an expert professional to take care of your wiring. But, if you’re sure you can handle it, here’s how to get started. 

3 Way Dimmer Switch Wiring - Guide with diagram

Some Safety Precautions for 3 Way Dimmer Switch Wiring

When you’re ready to install a three way dimmer switch, start with these safety precautions:

  1. Make sure to get a pair of safety glasses when handling sharp wires. You must also get safety gloves to protect your hands.
  2. Go to the main circuit box and locate the power switch for the room where you’re working. Switch it off.
  3. Go back to the worksite and turn on the lights to check if they work. If the lights don’t come on, you can be sure that the power is off. It’s now safe to get started.
  4. Use your voltage tester to tap each wire to confirm that there is no power in them. 
  5. Chances are that when you open the wall socket, you find that the wire colors vary from what you expected. Stop right away if you can’t identify the grounding, hot, and traveler wires. Contact a trained electrician to come by and complete the task for you. 

With the safety precautions taken care of, you are ready to begin working on the 3 way dimmer switch installation.

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How do I know if I have a 2 way or 3-way switch?

If your light fixture is connected to a single switch for turning on and off, that’s a two-way switch. You can also call it a single-pole switch. However, if you have two switches controlling a single or multiple light fixtures, that’s a 3-way switch.

If you wish to install a dimmer, you’ll make sure to get a device with 3 way dimmer switch wiring for proper installation. 

When installing the dimmer, remember that you can only install a single device to control the brightness. You cannot have two dimmers for a single set of light fixtures. While your dimmer can also have an off-and-on button, the other switch will have to be a standard on-off switch. 

Before buying the appropriate dimmer, you’ll also check for the total wattage the switch will handle. To do that, make a list of the light fixtures the switch controls. Add the maximum wattage for each.

For instance, if the total is 600 or 800 Watts, you must get a dimmer compatible with this number. Getting a higher wattage controller is always preferable. Anything less than that risks overheating or a fire. Also, get a dimmer switch that matches the kind of bulbs you have, like incandescent, halogen, CFL, or LED.

Do you need special wiring for a dimmer switch?

Most dimmer switches use a 12/2 wire with 3 cables that connect with the light fixture. They also have a 12/3 wire with 4 cables that runs between the dimmer and on-off switch. Newer brands come with a green grounding wire or a green screw.

This is where you’ll connect the grounding wire from the wall socket. Chances are that the wall has bare copper wires. You must connect these wires to the 3 way dimmer switch. Here’s a quick overview of the typical wire colors and how to use them.

  • White wires are neutral wires
  • Grounding wires can be green, brown, or bare copper
  • Black wires are the hot wires
  • Red wires are traveler wires

Understand that 3 way dimmer switch wiring running from the light fixture to the dimmer will likely have three cables. They are a copper grounding wire, a hotwire, and a neutral wire. The same goes for the wires connecting the power source to the on-off switch.

However, the cables running between the dimmer and regular switch typically have a neutral, a grounding, and two traveler wires. Check out the 3 way switch with dimmer wiring diagram below to understand how it works. 

How to Attach the Wiring for the 3 Way Dimmer Switch

3 Way Dimmer Switch Wiring diagram
3 Way Dimmer Switch Wiring diagram

Examine the dimmer you’ve purchased. Some devices come with wires that you must attach to the corresponding wiring in the wall socket. Others come with terminals and screws. You’ll connect the ends of the wires in the wall with the appropriate terminals on the dimmer. Next, you’ll screw them securely in place. Read ahead for some step-by-step directions:

Procedure for Connecting the 3-Way Dimmer Switch Wiring

  1. Start by sorting the wires in the wall socket. You will set two sets of cables, one from the light fixture and the other running from the on-off switch. 
  2. Examine each wire and ensure that a ⅝” section is bare. If needed, use the wire stripper to remove a section of the plastic covering.
  3. Whether you’re replacing an old dimmer or installing a new one, start by identifying the copper grounding wires. Using a copper crimping sleeve, connect the grounding wires and twist to fasten them properly. Clip off the end of one of the wires, leaving you with a single grounding wire. 
  4. Identify the neutral wires and connect them together by twisting and fastening securely. You can cap off the ends with a wire nut. Push back these wires into the wall socket. You won’t be needing them. 
  5. You’re now left with two traveler wires, one hot wire, and one copper grounding wire.
  6. Examine your dimmer switch. It will either have wires that you can connect with the proper wires from the wall socket. Or, the dimmer will have terminals with screws. Some dimmers are designed to have the cables looped around the screw and tightened. Others have a small gap below the screw. You must insert the ends of the wires under the screw and tighten it to hold it in place. 
  7. Depending on the dimmer switch design, curve the ends of the wires to create tight loops. Or, trim the ends to ensure that they fit under the screw entirely. Make sure there aren’t any loose ends that might touch and create a short circuit.
  8. Typically, the traveler wires attach to the bottom two terminals on either side of the dimmer switch. The remaining grounding and hot wire connect with the terminals on the dimmer top.

Completing the 3-Way Dimmer Switch Circuit

Now that the 3 way dimmer switch wiring circuit is complete, check that the wires are securely fixed. Replace the dimmer switch into the wall socket and screw it in place. You might want to go back to the circuit box and restore the power.

Before affixing the face-plate, test the dimmer for proper functionality. Now that you know how to handle the installation, let’s address some FAQs you might have.

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Can you have 2 dimmers on a 3 way switch?

You can have a maximum of 1 dimmer for every set of light fixtures controlled by a single on-off switch.

Can I use a 3-way dimmer switch as a single pole?

Yes, you can make it work. Most 3 way switches are single pole double throw or spdf having 3 screw terminals. You can safely attach them to a single-pole wiring circuit.

Why does my 3-way dimmer switch not work?

Several reasons can result in the dimmer switch not working. The primary cause can be that the 3 way dimmer switch wiring is not installed correctly in the appropriate terminals. You might also want to check if you turned on the power. If nothing works, contact an electrician. Or check the troubleshooting tips in the user manual that comes with the dimmer switch.

Can I use a 3-way dimmer on a 4-way circuit?

Yes, you can install a 3 way dimmer switch in a 4-way circuit. But make sure to check that the voltage and amperage of the dimmer are compatible with the circuit.

What is the difference between a 3-way and 4-way switch?

A 3 way switch has three terminals and controls lighting from two locations. However, the four-way switch has four terminals and controls the room lights from two or three spots.

While this guide gives you an overview of how 3 way dimmer switch wiring works, do keep in mind that circuits sometimes vary. You might open the wall socket and find unfamiliar wires, or the dimmer might not work as expected. If that happens, call in a professional electrician to deal with the installation. Since you’re dealing with hazardous electrical wiring, exercising extreme caution is advised. 

References:

  1. https://www.cnet.com/
  2. https://www.tomsguide.com/ 

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