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Dimmable LED Flash: How To Solve LED Dimming Issues

Older incandescent bulbs are being phased out thanks to the energy-efficient LED light bulbs. However, incandescent bulbs were very simple and reliable - after all, they are "just" a very thin tungsten (wolfram, W) filament with no electronics of any kind.

LED light bulbs, on the other hand, depend on the built-in electronic controller to run Light Emitting Diodes (LEDs) - if the controller doesn't work properly, the light provided by LEDs is anything but smooth and pleasant.

What causes flashing and flickering LED lights, and how can one fix it? We look at the causes and solutions for flickering LED lights.

Published: November 18, 2022.

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How Light Dimming Works

When the light switch is turned ON, power flows to the light bulb, and the light bulb starts to produce light. Simple as that.

In the era of incandescent and halogen lights, light dimmers had a rather simple job - limit the flow of electricity toward the light bulb, and that was it.

However, new LED lights are electronic devices whose proper operation depends entirely on the proper operation of the LED light built-in controller.

When the LED lights are connected to light dimmers intended for incandescent lights, LED lights don't work properly. Actually, they can be easily damaged by such dimmers for many reasons.

Leading-Edge Dimmers vs. Trailing-Edge Dimmers

Leading-Edge dimmers have been on the market for quite some time and are intended for incandescent and halogen lamps.

Note: leading-edge dimmers differ, and with so many models (still) available on the market, one MUST check the bulb type and power compatibility of each model.

Leading-Edge dimmers reduce the power sent to the load by shortening the sine wave leading edge - hence the name "leading-edge" dimmers.

As such, leading-edge dimmers are compatible with inductive and resistive loads, including incandescent light bulbs.

When leading-edge dimmers control LED light bulbs, at best, one can expect the LED bulb to start flashing, flickering, and even humming quietly. But, in many situations, such LED bulb gets destroyed.

Trailing-Edge dimmers are relatively new on the market, and as their name suggests, they shorten the sine wave cycle at the trailing edge, making them incompatible with inductive loads (current through the inductive loads cannot be abruptly stopped or increased).

But trailing-edge dimmers are compatible with dimmable LED light bulbs AND with incandescent lights.

Note: for every dimmable switch, be sure to check the supported light type and power.

In short, in order to dim the LED lights, You must have trailing-edge dimmers compatible with your dimmable LED lights.

Dimmable vs. Non-Dimmable LED Light Bulbs

Not all LED light bulbs are equal - some LED light bulbs are dimmable, and some are not. If You intend to use dimmers with your LED lighting, be sure to use dimmable LED bulbs that are compatible with your LED light dimmers.

As said before, most dimmable LED light bulbs are compatible with the most trailing-edge dimmers (also labeled as LED dimmers to avoid confusion with the users).

As one can see, the previous sentence used "most" twice - with so many models of dimmable LED bulbs and LED dimmers, one must be careful when checking if a certain dimmer supports a certain LED flashlight. In most cases, the answer is "Yes," but it better be safe than sorry.

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Smart Dimmable LED Light Bulbs

Smart dimmable LED light bulbs are a special type of dimmable LED bulbs that are controlled via a built-in Bluetooth and/or WiFi interface and the smartphone App.

In most cases, these bulbs can also be controlled using standard LED dimmers.

Smart dimmable LED lights have many advantages since the smartphone App allows the user to control the light intensity (usually between 10 and 100%, just like classic LED dimmers), but in many cases, App allows the user to change the light color and even the light temperature.

Also, You don't have to get up from the couch, for example, to change the light using a dimmer - just grab the phone and set it as you wish. Call me lazy, but these are excellent, very useful features.

Dimmable LED Flickr, Flash, And Even Buzz

So, You have a LED compatible dimmer, dimmable LEDs, or even smart dimmable LEDs paired with your smartphone App, and nonetheless, your LEDs are flickering, flashing, or even buzzing.

There are a few possible reasons for such behavior, including:

Non-Dimmable LEDs

Once again, check if your LED light bulbs are dimmable. If not, replace them with dimmable LEDs compatible with your LED dimmer.

Non-LED Bulb Compatible Dimmer

For the dimmer to dim the LED lights, it must be compatible with them.

If the dimmer is made for incandescent and halogen lights, it is not compatible with LED lights. Replace it with a compatible one.

Under-Loaded LED Dimmer

Light dimmers feature maximum and minimum load, with the leading edge dimmers being more suitable for incandescent, halogen, and similar lighting and are less complex and more powerful than the trailing-edge dimmers.

When the dimmer is underloaded, it can't operate properly, leading to light flashing and flickering. Also, it is possible that such a dimmer is going to damage the light bulbs.

Since trailing-edge dimmers are intended for LED lights, their maximum and minimum load are more suitable for LED light bulbs.

Loose Wiring

It is quite possible that everything is OK with your LED dimmer and dimmable LED light bulbs and that the issues are caused by loose wiring and bad connections.

This one is hard to locate, but if You have issues with dimmer and dimmable LED bulbs, connect them to another part of your home's electric system and test them.

Residual Electricity

Residual electricity or induced electricity is caused by wires and cables being very close to each other. When the current flows through the wire, it creates a magnetic field that can induce a current in the neighboring wires and cables.

This current and voltage are generally very low, but LEDs are very efficient light sources that need just a fraction of the energy needed by incandescent lights to start to produce at least a very faint light.

Residual electricity should not be a problem in homes with quality wiring and good earthing (potential is zero with respect to Earth)/grounding (potential is zero with respect to other points).

Faulty LED Bulb or LED Dimmer

LED bulbs and dimmers don't last forever - they tend to last for years but can fail at any given moment. Also, newly purchased parts can be faulty as well.

So, if You can't find the issue, try replacing the dimmable LED and LED dimmer with a new ones and check if they are working or not.

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Few Final Words

Replacing incandescent light bulbs with LED light bulbs can save plenty of energy in the long run, and thanks to the more and more acceptable prices of LED lights, it can also save some money.

However, not all LEDs are the same - if You have used dimmable incandescent lights and want to continue that practice with LED lights, consider replacing old dimmers with new ones compatible with the dimmable LEDs that You plan to use.

Or, just get smart dimmable LEDs and control them via your smartphone App - while dimmers can be used to adjust LED light brightness, smart dimmable LEDs have adjustable light brightness and often color and even a temperature.

Note: If unsure about dimmers, LED lights, grounding, residual electricity, etc., be sure to contact a professional electrician or company and let them do the job for you.