A blue LED light against a dark background

Flickering LED Lights: Why It Happens (and How to Fix It)

Efficient, eco-friendly, durable, affordable—LED lights seem to be all positives, without anything to dim their appeal.

Except that they tend to start flickering. But is there more to it than just being obnoxious?

In fact, flickering LED lights are so common that you wouldn’t be wrong to say that wherever there are LED light bulbs, they’ll eventually start to flicker.

But the problem is, it’s not just annoying. It can be harmful too.

So let’s explore and lay out the reasons behind flickering LED lights, and what to do about it.

Common Causes of LED Lights Flickering

Light Emitting Diodes
Ingo Dierking, CC BY-SA 4.0, via Wikimedia Commons

So, where is this flicker coming from?

To answer that, we need to understand how LED lights work. LED is short for Light Emitting Diode that converts electrical energy into light by using a semiconductor device. The electricity passes through a microchip and through the diode to generate light.

The first reason behind the flicker is the most common-sense one: fluctuations in the AC power source. Since LEDs run on DC or direct current input, the AC is getting converted to DC by using electronic components. Unless the light is labelled “flicker-free”, the conversion will not produce a truly stable DC, and will generate flicker.

Another reason behind the flicker can be pulse-width modulation or PWM. Sounds complicated?

There’s no reason to delve into any details apart from saying that all PWM LED dimmers and controllers generate flicker. It’s just how they work! However, high-end dimmers generate flickering that’s less noticeable to our eyes.

Here’s several more causes of flickering in day-to-day scenarios:

  • Cheap LED bulbs with sub-standard components that don’t meet the standards
  • Faulty drivers in the LED
  • Dimmable LED lights when paired with incompatible dimmers
  • Voltage fluctuation in the circuit
  • Insufficient power supply to the LED light bulb
  • The LED bulb generating excessive heat, or there’s a lack of proper heat dissipation or heat sinks in poor-quality bulbs
  • Faults in the electrical wiring and improper installation of the LED bulbs.

Are Flickering LED Lights Dangerous?

A man squinting and rubbing his eyes with eyeglasses in one hand

Short answer: they aren’t outright dangerous. But harmful, they are!

So your LED light shows no flicker and you think it’s working fine. Well, not really. The problem is that LED flickers can be visible—or invisible.

Flickers with frequencies between 3 and 80 Hertz are visible and can have the worst effect on humans. Take it from Naomi Miller, a lighting scientist. “[Such flickering] is producing this very jerky square waveform that is the kind of waveform that your brain was not designed to handle,” she told the NPR.

Generally, a flicker that is above the frequency range of 90 Hertz remains invisible to the naked eye. But our brain has a way of detecting more than our eyes can see, it seems. This flicker can go as high as 2,000 Hertz and even when you can’t see it, it can still affect your neurological system.

In reality, even incandescent and halogen lights flicker.

However, their filaments have a slower response to current fluctuations. The quicker response in the LEDs automatically means—more noticeability!

But what’s the big deal with flicker if it’s not outright dangerous?

The thing is, it can cause eyesight problems like eye strain, blurred vision, and can even trigger migraines. Children who study under LED lights for hours can be more affected by the negative effects of flicker.

With kids on the autism spectrum, the impact is potentially even worse. Flicker can cause sensory overload and trigger behavioural problems, a study has showed. Individuals with special sensitivities are at risk too. Miller quotes people affected by photosensitive epilepsy as an example. But any of us will remember how strobe lights make us dizzy. Of course, it takes a much more powerful lighting to cause the so-called flicker vertigo, but you get the point.

But even the much more moderate flickering that’s invisible can cause trouble. Many of us will feel distraction and annoyance from invisible flickers. That’s all relatively manageable in your kitchen (unless you’re handling a knife). But in some industrial settings, such distractions can lead to serious accidents.

Another occasion when flicker can bother you is during driving at night behind a vehicle with LED tail lights. Since the light source is moving, it can create a “ghosting effect” that can affect visibility.

Note, however, that the effects depend on the flicker characteristics, ambient light conditions, and also on the individual. Also, the tolerance and sensitivity to LED flicker is just not the same in all people.

How to Fix LED Light Flickering

PHILIPS G9 light bulb as an example of flickering LED lights
Dmitry G, CC BY-SA 3.0, via Wikimedia Commons

When it comes to fighting the invisible enemy, you have a weapon ready at hand—your very own phone camera.

Switch to slo-mo video mode and capture a video of the light for 3-4 seconds, then play it. Any high-frequency flicker present will be clearly visible in the form of a distortion in the video.

At times, LED flicker can happen because of multiple issues combined. The easiest thing you can do is…

Check If the Bulb Is Well Connected

If it’s not, screwing it properly will deal with the problem.

But if it is, try replacing it with another bulb. The old one might just be faulty or worn out.

Now, what if you’ve done it all but the flickering is still there?

Hold on. There are other things you can try.

Is the Dimmer Switch Compatible?

Make sure that the LED light is not paired with an incompatible dimmer switch. For flicker-free dimming, choose a LED-compatible dimmer switch.

The load range of the dimmer switch should be able to support the LED lighting.

Get High-Quality Light

Investing in LED bulbs and fixtures could be just what you need. And let’s face it, it’s not all that expensive considering the durability! Quality products not only have superior components but are also designed to dissipate heat more effectively. As a result, there is less flickering.

Low-quality LEDs also come with cheap driver components that cause flickering. At times, a swollen capacitor in these components can be a sign that there are issues with the driver. So replacing the light with a more rugged or sophisticated product will help the driver deliver a steady current flow to the LED.

Talk to a Professional

If the issue persists, the reason can be voltage fluctuations or faults in the wiring. But there’s not much you can (or should) do alone on that account. So talk to a pro! They’ll suggest if you need additional electrical work or maybe even an upgrade of your switchboard to get rid of the problem.

They’ll also be able to detect any underlying issues with your connections and circuits. Exactly the things that could cause more serious problems than LED flicker!

Flickering LED Lights: FAQs

How do I stop my LED lights from flickering?

To stop LED lights from flickering, start by checking if the bulb is properly connected. Then check if the bulb is in working condition and the dimmer switch. If nothing works, call a certified electrician to check the voltage and circuit.

What causes LED lights to flicker?

The reasons for LED light flicker include a fault in the light bulb components, loose connections, voltage fluctuations, or problems in the circuit. As we said above, an old dimmer switch connected to the bulb can also cause flicker.

Do LED lights flicker when burning out?

Generally, the flicker won’t be caused by burning out. Some LED lights can get dimmer as they age. Flickering is a separate issue and is not connected with the life of the bulb.

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