What is a TRIAC Dimmer

TRIAC Dimmer

In this article, we’ll discuss a TRIAC dimmer, how it works, and how to test a Triac dimmer with a multimeter.

A TRIAC dimmer works as a high-speed switch that controls the current supply of a light bulb or fan. It contains the speed of a fan and the light intensity of a bulb. Triac dimmers are used for AC-powered devices.

What is a TRIAC dimmer?

When we rotate the dimmer toward the low side, less current is released to light the bulb that glows with low intensity. Different resistors are used to control voltage from entering the circuit.

It is also essential that your bulb or fan is compatible with a TRIAC dimmer and can work at low and high voltage.

TRIAC stands for triode for alternating current. A triode is a device that has three electrodes or connections. 

A TRIAC dimmer works by cutting down the power supply according to the dimmer’s speed and then passing it to the bulb. It detects the rotation angle of the dimmer and regulates the amount of current to pass through the circuit.

A Triac dimmer only changes the primary supply voltage. It can’t be used in other circuits, such as speakers and AC switches.

How to test the dimmer switch with a multimeter?

If you have removed the dimmer switch from the circuit, you can test resistance in its terminals. You can determine if the course is damaged or broken by measuring resistance. The dimer switch circuit is damaged if the multimeter reads relatively high resistance.

If the multimeter reads OL in any terminals. It means that the circuit is incomplete.

You must connect your switch to the circuit to check the voltage. After the power supply is on, connect the red probe to the live wire terminal and the black probe to the ground terminal.

Now you check the voltage reading after rotating the knob on the dim and high sides. The multimeter will read 240 or 120 V when you turn the dimmer switch to high and decreases as you rotate the dimmer switch in the low direction.

The dimmer switch reduces (cuts) the voltage supply converted into a low bright light by the LED bulb.

How to install a dimmer switch?

The most important thing is to check which wire is hot neutral and which ground. To install a dimmer switch, screw the live wire of your outlet in the COM terminal. 

Connect the dimmer switch’s green wire to the circuit’s ground wire. If the ground wire is unavailable in your outlet, then connect the dimmer switch ground wire to the plastic case of your box.

A dimmer switch reduces the average voltage being supplied to the bulb.

Does a dimmer switch reduce voltage or amperage?

A dier switch changes voltage by turning it off quickly, which results in a low average current. Changing the voltage waveform dimmer controls the current and intensity of light. Also, when you rotate the dimmer, the resistance increases, and the resistor stops current from passing through the circuit.


So we’ve learned what a TRIAC dimmer is and its function. A Triac dimmer controls the voltage supply to a bulb that results in low or high-intensity light.

Hopefully, you have learned what a Triac dier is and how it works. If you still have any ask in the comments.

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