Triac Dimmers Explained: Complete Guide

Light Dimmer On Rock Lg

Are you looking for the best dimmer for your lighting control? Triac dimmers are the best match for you. Anyway, don’t be scared off by its technical name. In this guide, we will help you understand everything as far as TRIAC dimmers are concerned. Continue reading this article to the end.

A triode for Alternating Current (TRIAC) dimmer is an electronic device used to handle voltages and currents at high levels to brighten and dim lights. You can use TRIAC dimmers throughout your home to control incandescent lights.

Inside this device, you will find a circuit that translates high electrical voltages to lower outputs and releases only the energy required by the switch.

How Do TRIAC Dimmers Work?

Triac dimming is a physical dimming that starts from alternating current phase 0 and reducing the input voltage until the TRIAC dimmer goes on. The primary working technique is to control the conducting angle between each half-wave of the alternating current and transform it into a sinusoidal waveform. It also adjusts the correct value of alternating current to realize the dimming objective.

The TRIAC dimmer regulators work like fast-speed switches to control the energy flowing across the light-emitting diode light. A trigger determines where the device is supposed to start conducting the power by dividing the voltage waveform. It, therefore, prevents the voltage from being supplied with a full load. For LED lights, a TRIAC controller works by regulating the light strength.

How to Install a TRIAC Dimmer Switch

Here is a rough list of the tools and equipment that you’ll need for installing a TRIAC dimmer:

  • Screwdriver
  • Neon circuit tester
  • Combination tool
  • Wire nuts
  • Electrical tape
  • New TRIAC dimmer switch

1. Disconnect and Remove the Existing Switch

Switch the power off to safely remove the old TRIAC dimmer switch. Loosen the screws fixing the switch, and disconnect the wires. Straighten the cables and check if they are in good condition. If badly nicked, clip them off to have a bare wire for connecting to the dimmer. You need two or three wires to connect the switch. One wire should be black, the other one can be white for carrying hot current, and the last one is a bare copper wire for grounding.

2. Connect the Ground Wire to the Dimmer

Connect the ground wire in your switch box. If the wire is insulated, strip away about 4/7 inches using a combination too. Hold the TRIAC dimmer wire together with the circuit ground wire, then fix the two together using a nut.

3. Connect the Load Wire to the Dimmer

TRIAC dimmers are a bit particular on which wire is connected where. You will likely see two colored wires at the back of the dimmer. One wire is black, and the other can be red or blue. If there is a cut in the insulation on the switch, remove it and expose about 4/7 inches of it. Hold the dimmer’s exposed end together with the circuit load cable, then join them using a wire nut. Make sure the connection is tight enough.

4. Connect the Hot Wire to the Dimmer

Fix the remaining wire (black). This wire supplies power to the switch and connects the witch and the power source.

5. Test the Dimmer for Proper Operation

Since all the wires are connected, test your dimmer to check if it is working correctly. Begin by switching the power on at the main switch. If the device is not working, troubleshoot your connection.

6. Install the Dimmer Cover plate

After everything is as required, fold the wires carefully into the switch box. Fix the two dimmer plate fixing screws. Place the cover over the device and fix it using the two finish screws.

What is the Difference Between TRIAC and ELV Dimming?

The distinction between these two devices is in their definitions. ELV is an acronym for Electronic Low Voltage. It has other names that originate from how this device transitions your light-emitting diode’s luminosity. The Electronic Low Voltage works by turning off an electric load at the end of the AC (Alternating Current) waveform. 

On the other hand, TRIAC works by allowing current to flow in both directions—the current changes with the gate voltage polarity. The gate voltage alternates current passing through the load terminals of the TRIAC.

Are Lutron Dimmers TRIAC?

A Lutron dimmer has a TRIAC dimmer in its Diva product line. However, the Caseta line of dimmers is not TRIAC.

What are Different Types of Dimmers?

Light Dimmer Switch Lg

Choosing the correct dimmer for your bulb is essential and sometimes can be daunting if you are not well equipped with such knowledge. Dimmers regulate the level of brightness of a bulb. The device extends the life of your bulb and helps you save energy. Below are different types of dimming.

Single Pole

Single pole dimmers control the light from one point. You can use these dimmers to switch your light on and off as well as dimming your lights. Single pole dimmers are easy to install and considered the best for overhead lights in a room.

Three-Way Dimming

A three-Way dimmer allows you to regulate a single light from distinction areas and have two switches. Generally, you can use a single button to switch the light on and off and control the bulb’s brightness. The other switch is a three-way switch that turns on the light. This type of connection works best when placing switches at both ends of a large room.


This kind of dimming offers you the best dimming regulation. With multi-location dimming, you can regulate your lights from many different locations with the help of companion dimmer switches. This type of dimming works best for big rooms such as kitchens, living rooms, and dining rooms. 

The dimmer can be positioned everywhere in the room to make it easy to access the dimmer anywhere. Additionally, the multi-location dimmer has a remote control that allows you to adjust the lights to your comfort from the closest switch.

Smart Dimmers

Smart dimmers are operated using a smart speaker with your voice or using a compatible app. You can configure some of these dimmers with a double-wire circuit without a neutral wire. You can even operate Smart dimmers manually when there is no internet connection. 

Smart dimmers are convenient to use since they allow you to set when your lights should be on or off. They are the best for living rooms, bedrooms, and halfways.

Slide Dimmers

Slide dimmers come in a modern design. Instead of using a traditional switch, slide dimmers use a sliding bar with a small switch on the lower part. You can slide the bar down on these switches to dim the lights or up to increase their brightness. When you switch off the light, the bulb remains at the dimming point that the bar initially was when you turned on the light.

Rotary Dimmers

With rotary dimmers, just like slide dimmers, you can adjust the intensity of your lights accurately. Nevertheless, instead of using a slide bar, the lights are regulated using a rotary dial. You can increase the brightness of your light by turning the dial one way and dim them by turning the dial the other way. 

Depending on the dimmers design, you can switch the light on or off by rotating the dial to the left or right completely. You can also push the knob in to switch the light on or off.

Digital Dimmers

This type of dimmer uses the latest technology to regulate light. You can activate digital dimmers by tapping the switch. Usually, digital dimmers have a toggle switch for adjusting the brightness of your light. 

Most of these dimmers have select models that offer excellent features such as ‘fade out. This feature slowly turns the lights off, allowing you to see as you walk out of the room. Additionally, digital dimmers have sensors that switch the lights on when a person is in the house and turn them off when they sense no one in the room.

Plug-In Dimmers

Contrary to other types of dimmers that regulate hardwired lights, these types of dimmers can dim light fixtures like lamps. Plug-in dimmers do not require installation. You need to plug the dimmer into the wall then fix the lamp you would wish to regulate into the dimmer. 

You can use the dimmer’s controls to regulate the brightness of your lamp. Depending on the model, plug-in dimmers can be adjusted using buttons, a rotary knob, or a touchpad.

Common Questions About TRIAC Dimmers

Below are a few of the most commonly asked questions about TRIAC dimmers and all the answers to them!

What is the Primary Function of TRIAC Dimmers?

The primary function of a TRIAC dimmer is to allow an electric current to flow in both directions. The current’s flow changes directions with the polarity of the gate voltage. This gate voltage derives from the alternating current voltage that flows through the TRIAC’s load terminals.

Is TRIAC Dimming the Same as Phase Dimming?

Dimmers help you set the level of brightness of your lamp and save energy. When a dimmer is connected with a light-emitting diode light source, the amount of energy saved is quite significant. Therefore, phase-cut dimmers are the common dimmers and are also known as TRIAC dimmers.

Is Triac Dimming Forward or Reverse Phase?

Triac-based dimming is the most common technique employed when designing forward phase controls. In forward phase dimming, a semiconductor is used as a switch to control both the negative and the positive half cycles.

Is a TRIAC Dimmer Leading Edge?

The leading edge is a switch used to dim incandescent and halogen bulbs. Leading-edge dimmers are also known as TRIAC dimmers and are used in dimming controls.

Final Words

As stated in the above guide, a TRIAC dimmer is an essential component for your home lighting. They will solve all your dimming needs and let you have the required amount of light around you. Therefore, having gone through this piece, you have all that it takes as far as lighting jargon is concerned. Finally, do not hesitate to share this guide with your friends on social media.



Hubert Miles | Licensed Home Inspector, CMI, CPI

Hubert Miles is a licensed home inspector (RBI# 2556) with more than two decades of experience in inspection and construction. Since 2008, he has been serving South Carolina through his company, Patriot Home Inspections LLC. As a Certified Master Inspector, Hubert is dedicated to providing his expertise in home inspections, repairs, maintenance, and DIY projects.