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Why Do LED Lights Flicker?

Lighting is a major factor in how we feel at home. It affects our mood, the way we see colors, and the overall ambiance of a room. That’s why it can be so frustrating to find out that your LED lights are flickering! We investigate just why do your LED lights flicker by examining potential common causes that you can observe yourself.

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Do LED Lights Flicker?

Did you know that LED lights are designed to always flicker!?

Their light output is pulsing on and off at a rate of 10,000 to 120,000 pulses per second. It is so fast that the human eye cannot detect it, which is why we can’t usually see the LED flicker.

You can check this out by holding your phone camera up to an LED light you will begin to see that flicker as your phone screen refresh rate is drastically different to your eyes.

This process is called “Pulse Width Modulation” (PWM) and it involves sending out short bursts of power or voltage on and off at a very rapid rate.

Why are My LED Lights Blinking?

So if you can see LED flicker then something somewhere is wrong. LED light should always look smooth and continuous to your eye.

There are many reasons that can cause LED lights to flicker, ranging from overloading circuits, incompatible dimmer switches and/or defective drivers inside LEDs themselves.

Your led light flickering problem may potentially be easily fixed yourself while others will require you to replace the affected hardware.

Are Your LED Bulbs Flickering Due to Loose or Incorrect Wiring?

The first thing to check is whether the wire connections are on the outside of the bulb or there are any loose or incorrect wiring inside the LED fixture. If you find any of these problems, then you will need to correct them before turning the lighting circuit back on.

Loose wiring can intermittently allow power through as the electricity arcs across small gaps where the wiring has freed itself. This will interrupt the smooth flow of power and cause LED flicker.

Arcing of power across terminals can lead to fire so be sure to thoroughly check all your wiring and consult a qualified electrician if it’s more than simply tightening its fixing.

LED Flicker With Incompatible Dimmer Switches

If you have an incompatible dimmer switch, it will cause the LEDs of your bulb to flicker because they do not follow this pulsing rate. This means that even though intermittent voltage pulses are sent out at a regular rate, they are not able to interact with the pulses sent out by your dimmers.

You will need to replace incompatible dimmers with dimmer switches that are compatible with your LED bulbs in order to fix this problem.

Use LED Sensitive Dimmer Switches

LED power loads are small, especially compared to the power hungry incandescent light. If you try to install LED lighting onto a standard dimmer switch designed for 400W loads, there may not be enough loading onto the dimmer module to smoothly reduce the light output, resulting in visible LED flicker.

LED sensitive dimmer switches are labeled as “compatible with LED” or “for use with LED bulbs.” These switches allow the user to adjust the power supplied to an LED bulb. The purpose is to regulate how much energy feeds into the light source because this will reduce the risk of flickering and premature LEDs failure.

Dimming can also extend your LED’s lifetime.

Flickering LED Light Bulb Due to a Defective LED Driver

LED lighting generally requires the AC power from your lighting circuit to be adapted. It runs the power either by a constant current or constant voltage, either way there must be a component to perform that function and it’s called an LED Driver

LED light bulbs have these drivers included within their base and if the management of heat is not running within the anticipated parameters ie the lighting fixture it is within is not ventilated sufficiently, the driver will become stressed and begin to show signs of imminent failure by strobing.

You will need to look at the warranty information for the specific product you have purchased and contact its manufacturer for assistance with troubleshooting it. Different products have different warranty periods, so it is best to check the warranty information before proceeding with your troubleshooting efforts.

Overheated Components Cause LED Flicker

Overheated components cause LED flicker and there are two possible causes of overheating – too much power and not enough ventilation

If the temperature rises above safe operating levels, the driver will start to show signs of imminent failure by strobing or flickering. It is important to check for any loose wiring around the bulb as this can cause overheating problems

Always make sure that there is proper ventilation in your room so that heat does not build up inside it enough to cause the LED to run outside of it’s designed parameters. Check with your manufacturer if you’re unsure about how best to maintain the temperature of your LED fixture.

LED bulbs are used in lieu of traditional incandescent light bulbs because they emit less heat, use less electricity, and last longer than that type of bulb. However, even though LED lights are more energy efficient, that does not mean that they are immune to problems related to overheating.

Some dimmers have been known to cause LED lights to flicker due to a faulty driver. If your LED light bulbs are flickering, it may be time for you to replace the drivers inside them.

LED Flicker By Mixing of Light Types on the Same Circuit

This is one of the main causes of LED light flicker when turned on is when different types of lighting source type are combined on the same lighting circuit, as this will cause the power factor to decrease.

The power factor is an important number that shows how many volts are drawn on your circuit line to produce a unit of electricity. This number must always be above 0.8 to ensure that there is enough power for all components- including LEDs- to function correctly.

LED lighting is very efficient and draws comparatively much lower amounts of energy than other traditional sources. For example, if you combine incandescent or even fluorescent lighting on the same circuit, the higher wattage sources will draw most of the power, potentially leaving not enough of the LEDs to function normally without LED flicker.

LED Flickering Due to Age of Bulb

LEDs have a limited life span and if the device has reached that limit then this could also be causing the flickering problem. The best solution in this regard is to replace the LED driver or a new LED bulb.

LED Lights Flash When Turned On

Flashing and flickering are different. Some LED dimmer switches deliberately flash all the LEDs when turned on to demonstrate the dimmer module behind the face plate is in a listening mode and ready for you to interact with it. This programmable mode can be switched off which should stop led lights flashing.

LED Driver & Dimmer Compatibility

LED drivers can be leading edge or trailing edge in their design and specification. Leading edge has become the predominant choice for it’s more universal compatibility with popular LED dimmer switches.

LED lamp flickering can result from a dimmer switch trying to reduce the power to an incompatible driver type.

LED Flicker From Low Frequency Power

Your led light flickering problem may be due to the building’s AC power.

The power in your home or business runs with an alternating current or AC power. The electricity reaching your LED lights is also pulsing between on and off at a cycle rate of 60 hz.

If your home’s AC current fluctuates or is running below 50hz, the PWM of your LED is compromised revealing a strobing of on and off that the eye can see.

This will cause the LED light to appear as though it is flickering.

LED Lights Flickering in the House

Usually, if the LED lights are flickering in the house it is because the overall voltage has dropped. It could be because of large appliances like an electric fan being turned on or even an EV car charger draining resources. The power can be too much for the circuit to take, so when these appliances turn on, the light bulbs might start to flicker.

Before calling an electrician, try turning any potential culprit off to hopefully isolate the issue.

If the LED house lights are flickering you need to run some basic visual checks on where the power enters your building and the distribution board that divides that power into the individual circuits around your home.

Any ingress of moisture from a potential leak within the home from a slow escape of water from a hidden pipe or bad weather pushing rain into the building, can tamper with the efficient delivery of power to your lighting circuits and frankly become very dangerous. Call in your qualified contractors if you are ever in any doubt.

Conclusion

So you have learnt that all LED flicker all the time anyway, it’s the rate that they strobe that is important to hide the pulsing from the human eye. Any interference in the combination of components between dimmer switch or LED driver will reveal this flicker to the eye.

Stick to the same type of LED light on a single circuit, so not mix lighting types for fear of power factor issues that starve LEDs from adequate power to run as designed.

Loose wiring and poor quality LED bulbs and equipment will have short lifespans before showing signs of imminent failure, sometimes flickering as a result.

Always buy good quality LED lighting to ensure the best performance.

Andrew Orange , the owner of Orange Lighting qualified and worked as an interior designer in 1993 before specialising in lighting working on high profile projects based in London. Since starting Orange Lighting Ltd in 2003 he has been sharing his knowledge and unique teaching style mostly to his designer clients, offering practical real life advice born from running a busy consultancy and lighting supply business. Launching in 2020, his blog has evolved into Quick & Easy Lighting, curating some 25 years design experience into making the lighting choice and design process achievable and easy to understand for all.