Why Does LED Light Flicker?

why does led light flicker

No matter which type of light bulbs you’re using, it seems like some form of flickering is inevitable. Incandescent lights dim with every voltage fluctuation and fluorescent lights visibly flicker all the time. Not even modern LED lights are flicker-free. And to understand why LED light flickers, you first have to understand the difference between visible and invisible flickering.

Visible vs. Invisible Flickering

If the light flickers more than 100 times per second (100Hz), the human eye can’t notice the flickering. To your eyes, it would look like the light is on all the time. Because LEDs operate on direct current, but your mains power supply is alternating current, your light bulb needs to convert the current before passing it on. However, converting the AC to a stable DC power supply can get tricky at times.

To get around that, some LED light manufacturers produce LED light bulbs that flicker at double the frequency of your mains power, which is around 100–120Hz. On the other hand, some manufacturers use a technology called PWM to control LED light brightness with precisely controlled flickering. Both of these technologies’ effects are invisible to the human eye, and they’re not the cause of noticeable LED flickering.

However, flickering lights slower than 100Hz can cause a multitude of harmful effects, such as headaches, blurred vision, and eye strain. In fact, this light might induce seizures in people suffering from photosensitive epilepsy. If you notice your LED starting to flicker, you should replace the bulb immediately. Still, the problem might not even be with the bulb. In fact, chances are that the current leading to the bulb is causing the problems.

Why LED Light Flickers

If your LED light keeps flickering even after you’ve replaced the bulb, you probably have a problem with the current leading to it. Depending on the issue, fixing the problem can be as simple as changing a fixture, or as complex as rewiring the entire power line. Listed below, you can find the three most common reasons why LED light flickers:

Dimmers and Photocells

In the majority of cases, the light flickers because it is connected to a dimmer switch or a photocell. Since both of them change the alternating current leading to the light, the bulb can’t convert it to DC properly. In addition to flickering, the light will also get considerably dimmer. Fortunately, simply disconnecting the dimmer and replacing it with a regular switch will solve the problem. However, if you want to use LED light bulbs with a photocell without flickering, you need a LED-compatible photocell.

Voltage Fluctuation

If you live in a house with older wiring, you might experience voltage drops when you draw too much current. For instance, you might notice your light flickering when you turn on the microwave or the washing machine. If so, you should call an electrician to inspect your mains voltage. Even though it might be due to old wiring, you should check if there are any further electrical issues.

Loose Connection

The reason why LED light flickers may be that your light fixture is old and used, and thus the contact has been worn out. In addition, the connection leading to the fixture might have dislodged. Either way, simply replacing and rewiring the fixture should do the trick. However, make sure you disconnect the fuse before handling the wires. In fact, if you’re not skilled with wiring, you should call an electrician to properly and safely replace your fixture.

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