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Flicker: A Hazard of LED Lighting

Flicker: A Hazard of LED Lighting

LEDs (or light emitting diodes) have taken over the conventional lighting marketplace and rightfully so. LED lighting is energy efficient, LEDs offer better light quality, LED bulbs are more durable and offer longer lifespans than other types of lighting, and LEDs have lower maintenance requirements. In the United States, the greatest potential for widespread energy savings is the use of LED lighting – with projected savings of more than $30 billion (at current electricity prices) by 2027. As with every emerging technology, however, there are disadvantages to using LED lighting.

LEDs and Flicker

Flicker is exactly what it sounds like – light output from a given source changing repetitively over time – similar to flicking the light switch on and off except the light output is fluctuating on its own and at a much quicker pace. There are two types of flickering with lights: visible flicker and invisible flicker.

Visible flicker (considered anything below a frequency of 100Hz) is observable by the human eye and is typically undesirable except in special applications such as stroboscopic lighting. Invisible flicker is flickering that is present but not perceived by the naked eye. If left uncontrolled, lighting flicker can cause an abundance of biological and health issues that can ruin an otherwise well-designed space. Neurological problems (including epileptic seizures), dizziness, headaches, fatigue, increased autistic behavior (especially in children), eyestrain, impaired thought, and migraines are some potential flicker-induced impairments.

What Causes Flicker?

For LED lighting to perform optimality, it should be run on direct current (DC), since there is a constant stream of current through the circuit. But because electricity in the U.S. is delivered through alternating current (AC), voltage delivered to a source fluctuates between on and off as it bounces off the positive and negative poles of the sine wave (unless the current is maintained in some way). A source without quality electronic circuitry – such as a ballast, driver, or capacitor — will flicker.

Another cause for flicker is with dimming and control circuitry that uses a method called PWM (pulse width modulation). PWM cycles the LED from the maximum current to zero current, essentially switching the current on and off very fast, and repeats this process at a fixed rate. Dimming is controlled by the driver, so choosing the proper driver is crucial to getting the desired lighting effect. Drivers that use PWM at a low enough frequency have a high potential to introduce undesirable flicker.

How to Reduce LED Flicker

The key to reducing flicker lies in a well-designed driver. The right driver can eliminate the problem of flicker by providing the LED with a constant, non-oscillating current. The issue here is that manufacturers must weigh several factors—such as size, efficiency, cost, and reliability—when deciding which driver to include in their products.

Capacitors are typically used in LED drivers to smooth and reduce the ripple that comes from the power supply. Selecting a quality capacitor for an LED lighting system can help to avoid flicker, eliminate excessive heat, and ensure the longevity of the LED lights. Even lamps with capacitors may flicker; it is a matter of the quality of the lamps and their components. Lower cost lights/lamps have lower quality capacitors.

It is also important to verify that the LED lighting product is compatible with the dimmers or other control circuits used in the lighting system. A faulty photosensor or timer can cause flicker issues. Moreover, random flickering may be an indication of another problem in the lighting system, such as loose wiring and interconnections. The quality of the electrical supply can also result in problems with power fluctuations.

Energy Performance Lighting Gets Lighting Right

Energy Performance Lighting focuses on lighting because lighting is all we do. We can update your current lighting system to a quality lighting that works for your space. Our technicians are informed and inspect all products to ensure we are installing proper performance lighting products. We are happy to work with you, and provide information on lighting, to protect the health of your business and employees.