Flickering lights explained

Why the light bulbs flicker?

Following the trends and new, better technology nowadays the traditional incandescent and halogen lighting are being replaced with the new energy-saving LED lighting. That's not only because LED lighting is cheaper to run and last longer but they are also environment-friendly. However, in some cases, LED lighting may have an unpleasant effect. The LED light bulbs may flicker and in this article, we will explain the effects and causes of flickering lights and how to fix the issue. In order to explain that first, we need to understand how electrical power and current works.

Alternating Current

An Alternating Current (AC) runs in all mains sockets. The AC constantly changing directions and the benefit of it is that it is easy to use a transformer to increase or decrease the potential difference of AC. In the UK the Alternating Current has a potential difference of around 230V and changes the direction 50 times per second. The current moves 50 times a second towards the positive side and 50 times per second towards the negative side. This is called the mains frequency in Hertz. In the UK the mains frequency is 50Hz. So the alternating current is ON and OFF all the time (due to changing directions), so are the lights that are connected. The direction change is 50 times per second so in most cases, this is not visible.

Direct Current

A Direct Current (DC) is a type of current which travels only in one direction counterpart Alternating Current. The Direct Current can be found in all battery-powered devices such as remote controls. Worth to know there is no frequency associated with the DC as it does not change directions. However, you also need to know that with the DC there will be a voltage drop on longer runs. This may be seen on LED strip installations. The beginning of the strip will be brighter than the end if it is longer than 5m.

Why does LED lighting flicker?

Have you ever noticed the incandescent flickering lights? I'm pretty sure you haven't and that is because in the incandescent light bulbs the filament is heated until it gives off light. A filament needs time to cool down so it continues to glow when the alternating current is at 0. However, the LED light bulbs do not have a cooling down period and the source of the white light (phosphorus) no longer emits light when the AC is temporarily set to 0. Because LED lighting reacts more quickly to changes in power output than incandescent light bulbs the LED light bulbs need a Direct Current. Each LED light bulb needs a driver that converts alternating current to direct current. Some LED lights already have a driver built-in (mainly these bulbs with E14, E27, B22, B15, GU10 bases). For other LED lighting, an external driver needs to be installed.

We can distinguish two types of flicker:

- Visible flicker

- Invisible flicker

Visible flicker can be spotted with our own eyes. This occurs when the light output of the light changes rapidly. Invisible flicker cannot be detected with the bare eye. However, they do have an adverse effect on the state of mind and health. In most cases, invisible flicker can be detected by pointing the camera on your mobile phone at the light source.

The effect of flickering lights - LED lighting

Visible and invisible flicker may be perceived as uncomfortable. However, this can also cause health problems. The most common symptoms are fatigued eyes, headaches and migraines. In traditional lighting, the flicker usually consists of bright and dark light. With LED light sources, the flicker consists of bright light and no light. This can cause a stroboscopic effect. This means that people can sometimes see a trace of the same image of a light that repeats itself one by one, each time their eyes move over it. This can also cause a moving object to appear to be standing still or to move in slow motion. This can be very dangerous in an industrial working environment, for example.

Flickering LED lighting - causes and solutions

LED lighting can flicker when the power supply is not constant. Do you have flickering LED lights? Below we have listed the 7 most common causes and solutions for you.

1. Use a dimmable LED light for dimming.

When dimming LED lights, you definitely need dimmable LED lighting. Not every LED light is dimmable. Connecting a non-dimmable LED light to a dimmer will definitely end in a flickering light that functions as a strobe.

2. When dimming LED lights, use an LED dimmer.

In order to dim LED lights, it is not sufficient to connect them to the dimmer you use for incandescent and halogen lights. Incandescent and halogen lights use considerably more power to achieve the same light output as LED lighting. Dimmers for these types of lights have a high minimum output. The minimum power of these dimmers is then greater than the general power of the LED light. This causes a LED light to flicker. Always use the LED dimmer to dim your LED lighting. This will prevent the lights from flickering.

3. LED Light isn't connected to the right type of LED dimmer.

LED dimmers are available in different kinds. As an example, there are the following 2 sorts of dimmers:

- Leading edge

- Trailing edge

These dimmers both use a specific way of dimming. Not every dimmable LED light works in both ways. It's often difficult to know what type of dimmer you need because this is usually poorly indicated on the packaging of LED lighting. If you have any questions about which dimmer you should use, you can always contact our customer service.

4. Settings of the LED dimmer aren't set correctly

Do you have the proper type of LED dimmer? Then also take into consideration the dimming position of the dimmer itself. Many dimmers now have adjustment options. This enables you to dim your LED lights further, but also to work more stable. Adjustable dimmers usually have a COARSE and sometimes a FINE button. Turn it back so that the LED light is dimmed as far as possible without flickering. This is the best dimming position.

5. LED light isn't connected to the right driver

LED lighting needs a driver to convert the power to the specified output. If the wattage of the light isn't within the minimum and maximum power range of the driver, it will flicker. Make sure you have connected the right light to the right driver. 

6. Large spikes in the power grid

LED lighting is extremely sensitive to changes within the power supply. It may occur that the light does not blink constantly, but only when other heavy devices are switched ON or OFF. Think of your washing machine, refrigerator and dishwasher. In this case, the heavy appliances are on the same circuit as the LED lighting. Because the LED lights only flicker when the appliances are switched on, this is not a big problem. Do you still want to solve this problem? Then connect the heavy devices to a different power group than the LED lighting. This can solve the matter.

7. Defective LED driver

Is there a LED light that has suddenly flickered after having always worked well? In this case, there's a chance that the driver is broken. A driver can be broken by overheating or by physical damage. LED lights and drivers can break down if they are located in an environment of 50⁰C or higher. Do you have a light with an external driver? Then you can simply replace your driver with a brand new one. Does your lamp have an internal driver? Then you, unfortunately, will need to purchase a brand new light.

Hopefully, after reading the above steps, you may now not be bothered by flickering lights. Has your problem not yet been solved otherwise you found a different example which you would like to share with us? Please comment below we are happy to help you with all your questions about your LED lighting. We also would like to offer you LED lighting from LED line® brand which are built in a Flicker-Free technology.