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Why Do LED Lights Flicker — and How to Stop It?

Why Do LED Lights Flicker — and How to Stop It?

Have you replaced old incandescent bulbs with LED light bulbs only to have them flickering on and off?

If so, you are certainly not the first or the last one to experience this issue. This is a common problem, and more often than not the bulb in question is not the real culprit.

Since a flickering bulb can instantly make a space go from splendor to squalor, this is something you may want to fix right away.

LED light bulbs function much like a computer. That is, they have a binary on and off status. Unlike traditional light bulbs, they don’t have any persistence.

If this on and off cycle, which is powered by mains AC (alternating current), is functioning improperly, you see the LED light bulb flickering (that is, it rapidly turns on and off).

So why do this happen? There is more than one reason, but generally:

LED light bulbs flicker when the frequency is lower than 50Hz. LED light bulbs may also flicker if the wiring is incorrect or loose. Another reason is incompatible dimmer switches. Last but not the least, a problem with one or more LED bulb components, like a faulty LED driver, may also cause flickering.

LED Light Bulbs Flickering Without Dimmer

If the dimmer isn’t at fault, the flickering problem usually occurs because of one of these three reasons:

  • there’s some fault in the LED light bulb
  • the fault lies in the wiring
  • the fault is in the current regulation

At times, the problem occurs because of a short wire length in the light fixture. All wires should be 6’’ long at the least. If the wires connecting the bulb, switch, and fixture is loose, then also you can experience the flickering issue.

Another culprit could be a faulty LED driver component. If the driver is not of high-quality, it might not be able to withstand sustained heat from other LED components. If you are someone who likes opening electric components for checking what is wrong, then you should look for a bulgy or swollen capacitor.

Apart from your light fixtures, check the electrical panel as well. If the circuit breaker has loose wiring, then also you can experience the flickering issue.

You also can’t discount the power factor, which is also known to cause the flickering problem. For instance, if you connect LED light bulbs and incandescent bulbs to same circuit, LED light bulbs might flicker. That’s because incandescent bulbs use hundred percent of required energy — in most cases this is 60W — leaving the remaining supply for LED light bulbs and other appliances.

Two or three traditional bulbs may quickly consume all the power, as a result of which almost nothing will be left for LED light bulbs. This in turn will cause them to flicker on account of lack of available power.

Why Do LED Light Bulbs Flicker on Dimmer Switches?

As said earlier, LED light bulbs function in binary on and off state. On the other hand, old dimmers, which were designed for incandescent light bulbs, evenly change the current level being provided to the light bulb. And that’s why LED bulbs might not function as desired when you use them with old dimmers.

If you use an LED light bulb with an incompatible dimmer switch, flickering may occur. In such a situation, the best thing to do is upgrade your dimmer switch. Buy a new dimmer switch that’s made specifically for LED light bulbs. 

While dimmable LED light bulbs are becoming more common than ever, not all LEDs are dimmable. Using non-dimmable LEDs with dimmer switches can also lead to flickering. If that is causing the problem, the solution is simple. All you have to do is replace the non-dimmable LED light bulb with a dimmable one.

Why LEDs Are Flickering When Lights Are Off?

You may see switched-off LED light bulbs flickering. We’re not talking about a faintish after-glow which lasts just for 20-30 seconds or even a minute or two but rather about a full flicker effect or dimmed light which stays on even after you close the switch.

What’s happening here? Is this some kind of trick?

First things first: this is a common issue and there’s no trickery involved. Nearly always in such cases a smart switch is involved.

These switches come with a bundle of additional features such as WiFi control, a dimmer, a night light, and more.

Such fancy switches always require some standby power for these smart features to properly work. And this is where the fault usually lies.

We will not go into a lot of technical detail here, but some technical explanation is needed here. If the circuitry is incorrect, the smart switch might fail to utilize the neutral wire. Since your LED light bulbs are on the negative wire, capacitive coupling may occur, which in turn, leaves residual power in your capacitor.

Because of the current leakage and stray capacitance, enough voltage builds up in the circuit, which cases the LED light bulbs to flicker or glow.

A simple way to test this is by using a one-touch tester. Turn the switch off and touch the tester to any one connection in the LED lamp socket. If there’s stray capacitance and current leakage, the light will flicker.

How to Prevent or Stop LED Lights from Flickering?

The first thing you should do is make sure the bulb is connected properly. Give it a little twist to ensure it is not loose.

If that doesn’t fix the problem, try another LED light bulb in its place. If everything seems fine, then you can safely conclude that there was some issue with the previous bulb.

As said above, a swollen capacitor often causes the flickering issue. So instead of throwing out the older people, replace the broken capacitor. This will not only add a few more years to your LED light bulb but may also fix the flickering issue.

But if you experience the flickering issue with a new LED light bulb as well, check your dimmer. Is it compatible with your LED light bulb?

You can look up compatibility online by entering the existing dimmer switch and the model number of your bulb. If you have an old, incompatible dimmer, we suggest you get a new one. Buy a dimmer that is compatible with LED bulbs and you may never again experience the flickering issue.

If the problem is not with the dimmer, perhaps you should call in an electrician.