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Your lights might be flashing with LED dimmer light flicker for any number of reasons, the most likely of which we’ll explore with possible remedies.
We asked Andrew Orange, who as an established lighting consultant has a successful history of fixing this issue for clients, projects, and even in his own home.
Here are his top 20 quick tips to investigate and solve dimmable LED flash, accompanied by his quick fire video guide.
We start with the most common causes for flickering LED lights.
Table of Contents
When your LED lights flash when dimmed it’s most likely to be one of these top 5 reasons for dimmable lights flickering.
Intermittent flickering LED lights could be a simple installation fault. Loose wiring is one of the most common problems we see. If there are any loose wires, they will need to be reconnected and/or tightened.
It’s advisable to have a professional check your wiring as they will be able to spot any potential loose connection issues that result in flashing LED lights and fix any potentially dangerous issues.
Not all LEDs are dimmable.
A common reason of why do my dimmable lights flicker and LED bulbs flash when dimmed, is that the LED itself isn’t actually dimmable.
If you try and dim an LED product that hasn’t been designed to be dimmable it will flicker, which is also a common reason for buzzing LED lights.
So LED light bulb flickering is usually the result of trying to dim a non dimmable blub.
Be aware that manufacturers give you the choice to create a dimmable LED lighting circuit or pay a little less and buy products that are non dimmable.
Look for ‘dimmable’ on the packaging or specification for light bulbs to be compatible with a dimmer and avoid problems like led bulb strobing.
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| GE Relax 100W Equiv. Dimmable Soft White LED Bulb |
| Soft white 2700K all frosted glass A21 shaped E26 base. 100 Watt replacement 13.5 Watts (1600 lumens). Branded quality for good dimming with most dimmer switches. |
| Check Current Price |
GE Brand Quality Dimming |
If it is one light bulb or light fixture flashing, then before investigating further swap it for one you know is working and see if you can isolate the problem down to a faulty product.
If they are all flashing then it’s unlikely down to them all being faulty at the same time.
Just because an LED is dimmable, doesn’t mean it will work with every kind of dimming system.
Dimmable light flickers on a dimmer switch that contains the wrong dimmer module in it. There are specific dimmer switches for LED lights, so when you are changing your lights to LED buy new and compatible controls.
Using old dimmer switches with new LED lamps is also likely to be incompatible.
Dimming lighting can be a complicated business so there are many reasons why dimmed LED lights flash. From our experience here are some more in depth solutions.
LED light sources almost always use a transformer power supply called a driver, which by design can be dimmable or non dimmable. Drivers can be internal within a product or external on the lighting circuit.
Using a non dimmable driver with a dimmer will cause your LED lights to flicker.
Pulse width modulation (PWM) is a process that allows an LED to be dimmed by rapidly turning it on and off at a rate that is too fast for the human eye to see. They offer very smooth dimming but if not done correctly, it can reveal the dimmable led flicker and flashing led lights.
Check to see if you are using a PWM power supply if your dimmer switches uses adaptive dimming.
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| Lutron Diva LED Dimmer Switch |
| Paddle switch turns lights on/off and returns light to preset level. Convenient slider dims and brightens. Provides the best dimming performance for dimmable LED bulbs. DIY Friendly. |
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Highly Compatible Dimming |
LED lights flicker when dimmed with the wrong type of control.
You need to know how the dimmer and light relate to each other to avoid LED dimmer flicker.
So another tip to see why your dimmable light flickers is to check if your light bulb or lighting circuit is a “leading-edge” or “trailing-edge” type and make sure it is compatible with the dimmer switch itself.
We look deeper into what is dimming, explaining the methods you will need to know and why some led lights flicker on dimmer switches.
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| Lutron Skylark LED Dimmer Switch |
| Tested on 1,000s of bulbs and dozens of brands for flicker-free dimming. Provides over 250 lighting levels so you can create the perfect light for any activity Works with up to 150 Watts of dimmable LED/CFL bulbs. Click for list of compatible bulbs. |
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Budget Smooth Dimming |
Another common reason for flashing is using a non-compatible or non-reputable source.
A suitable dimmer switch for LED bulbs are those that have ‘RC’ labelled on them.
LED lights flicker on dimmer switches that are not sensitive enough to handle a low power loading on the lighting circuit, so buy a dimmer switch designed specifically for LEDs.
The best led dimmer switch’s use a microprocessor that helps to smooth out the current, which in turn prevents dimmer bulbs flickering and flashing.
LED bulbs flicker on modern dimmer switches that are left in a programming mode.
Manufacturers help you see which lights are on a particular circuit by giving them a group flash, so you know it’s in a listening mode and ready for instruction. Left in that mode and there is pulsing LED light instead of a constant light.
Some dimmer models can accidentally be triggered by pressing a button or rotary knob in quick repetition, either because you have leaned on it or children love to play with switches!
Check to see if the switch is in the right mode by following the manufacturer’s instructions.
The answer to why do led lights flicker, can be found in the type of LED you have. Your dimmable LED is flashing because you may be trying to dim the wrong type of LED light source with your choice of dimmer switch.
LED lights use one of these 3 types of power:
You need the correct setup of equipment to avoid flicker. For example, an LED strip needs the correct constant voltage driver (power supply) with a suitable dimmer module. If your equipment combinations are wrong, you can create flashing.
We look at how to dim LED strip lights for smooth LED dimming.
What causes LED lights to flicker is there are too many LED bulbs or products on the circuit.
Dimmer switches have a load range and if you try to use more LEDs than it’s designed parameters the switch will overload and cause flickering and flashing.
The minimum and maximum power of the dimmer switch is always stated on the packaging or at the back of the fixture itself.
To solve this, simply remove some of the LED lamps from the circuit or install a new dimmer switch that can handle the increased load.
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| Philips LED Dimmable Warm Glow Effect A19 Bulb |
| Warm Glow Effect provide 800 lumens of soft white light. Warm Glow dimming offers flicker free, silent dimming that works with more dimmer switches than any other LED on the market; The more you dim, the warmer the light from 2200 to 2700 kelvin just like traditional incandescent light bulbs. |
| Check Current Price |
Warms Color as Dimmed |
You may need more than one dimmer switch to handle the load and avoid flickering LED lights or a failure to light up at all.
Some LED dimmers need their loading capacity de-rated, possibly as much as 70% not used to avoid complications. So although not overloaded beyond the recommendations, the circuit may not start properly or stutter with visible flashing if there is not enough spare capacity allowed for.
Dimmable LED drivers vary in capacity size, they must always be larger than the loading on the lighting circuit.
The recommendation is the total wattage of all the LED lights should not be more than 80% of the driver’s wattage for a longer product lifespan.
For example, if you are using four 4W MR16 LED bulbs, then you will need a 20W driver.
If the pulsing LED lights are still flashing, it might be that your particular brand or model of dimmer switch has a built-in minimum load that must be met.
Check to see if your switch has been designed specifically for LEDs and can handle very low wattages. The Varilight V-Pro range has no minimum load, which means it can dim a single low wattage GU10 LED or LED downlight.
Legacy dimmer switches intended for incandescant and halogen light sources work well with a load of at least 40 watts. LED bulbs flicker on these switches as their cumulative loading is too low and particularly noticeable when dimmed to below 50%.
One way to solve this problem is to use a resistive (or dummy) load that creates more load on the circuit, solving the problem.
You could also think about using wireless lighting controls where all the lights are on a programmable network connected using low frequency radio waves or bluetooth mesh, such as Casambi or Philips Hue systems.
A professional solution usually solves the issue provided the install is supervised by the manufacturer or a consultant.
What is the quality of your dimmer switch and LED lights?
Largely speaking, the better the quality of your dimmer switch and LED lights themsleves, the less likely you are to have problems. Reputable brands need to protect their reputation with thorough testing and after sales advice, so buy well.
Overheating electronic devices causes them to run outside of tested ambient temperatures, potentially triggering unusual behaviour like intermittent LED flashing and strobing.
Check the dimmer switch is not running hot from overloading by dimming too much wattage, or overheating from other electronic devices installed near the switch plate.
You can work out any potential problems before they become a costly reality by creating a mock-up first. Test all the different components together and get an idea of how they will interact with one another, consulting with an experienced installer or lighting specialist to help you iron out incompatibilities.
There are many different reasons to why do LED lights flicker and why dimmable LED lights might flash, but fortunately, there are just as many solutions on how to fix flickering led lights. By understanding the causes and knowing which solutions to try, you should be able to fix the problem quickly and easily.
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