Installing a Two-Way Dimmer Switch: A Step-by-Step Guide

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To install a two-way dimmer switch, follow these steps:

1. Turn off the power: Locate the circuit breaker that controls the switch and turn it off to ensure safety.

2. Remove the old switch: Unscrew the cover plate and remove the screws holding the switch in place. Disconnect the wires from the old switch.

3. Prepare the new switch: Connect the wires to the new dimmer switch according to the manufacturer’s instructions. Make sure to match the wire colors correctly.

4. Install the new switch: Attach the new switch to the electrical box and secure it with screws. Replace the cover plate.

5. Test the dimmer switch: Turn on the power and test the dimmer switch to ensure it is working properly.

Remember to always follow safety precautions and consult a professional if you are unsure about any step of the installation process.


If you’re looking to enhance the ambiance of a room and save energy, installing a double light switch with a dimmer is a simple and effective solution. You don’t need to be an electrician to tackle this project; all you need is a little DIY enthusiasm and some basic knowledge about dimmer switches.

What You’ll Need

A standard light switch is a single pole switch with an “on” and “off” label, allowing you to control the light from one location in your home. However, when you want to control a light from two different switches, you’ll need a three-way switch. This type of switch has three terminals and doesn’t have an “on” or “off” label.

There are various types of dimmer switches available, so make sure you purchase the correct one for your needs. If you’re installing a dimmer switch on a three-way circuit, be sure to carefully read the packaging label and instructions. Additionally, gather the necessary tools for the project, including a flathead and Phillips screwdriver, a voltage tester, and a drill.

Step-by-Step Installation Guide

Traditionally, it was not possible to dim a light from two different switches without causing circuitry conflicts. Electricians would tell you that a regular double switch three-way circuit cannot accommodate this. However, you can install specialized two-way dimmers using a primary and standby switch.

A primary and standby switch allows you to control dimmers from multiple locations in your home. The primary switch operates as a one-way circuit and can only work with a standby switch. You can set up multiple standby switches throughout your home, all controlled by the primary switch.

Keep in mind that primary and standby switches are equipped with digital mechanisms, making them more expensive than regular dimmers. Some even come with remote controls. It’s important to purchase a compatible primary and standby switch from the same brand, as using switches from different brands will likely result in compatibility issues.

Installing the Switch

Once you have all the necessary components, installing the primary and standby switch is relatively straightforward. However, it’s crucial to refer to the circuit diagram provided in the packaging of your specific primary and standby switch, as installation steps may vary between brands.

Start by deciding which switch you want to replace and designate it as the primary switch. Then, turn off the main power from the circuit breaker. Remove the switch cover plate and unscrew the switch from the wall box. Gently pull the switch out to expose the wires. Use a voltage tester or toggle the switch on and off to ensure that there is no power running to it.

Next, you’ll need to wire the three-way dimmer switch. You’ll notice four colored wires: red, white, black, and green. In some systems, the green wire may be copper. If you don’t have this specific wiring configuration, you’ll need to rewire the switch using the standard red, white, black, and green wires.

If you have the correct wiring configuration, start by loosening the wires from the old switch, but make note of the marks on the terminals. If you see two or more wires connected together, ensure that you keep these wires connected together when installing the dimmers.

When you disconnect the wires, replace the new switch in the same position and match the colors of the old switch. Remember to secure it with a wire nut before reattaching it to the wall. Turn on the circuit breaker to check if the dimmer lights are working properly. Once you are satisfied, screw and mount the new switch in place.

Follow the same procedure when installing standby switches in different areas of the house.

Combined Fan and Light Switch

Some houses have dimmer switches that control the ceiling fans. However, this method is not very efficient as it can result in a noisy fan. Improper speed control can also damage the fan motor, causing it to overheat and potentially start a fire. To ensure safety, it is recommended to install separate wiring and a switch specifically for the ceiling fan.

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