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Hot talk of the LED lights flicker standard published by Institute of Electrical and Electronic Engineers (IEEE)

22-07-2015

The Institute of Electrical and Electronic Engineers (IEEE) has published a new standard that talkes about flicker in LED lights — essentially mentioning safe levels of flicker by percentage relative to the operating frequency of a light source powered by the AC line. Presumably, IEEE Standard 1789-2015, "Recommended Practice for Modulating Current in High-Brightness LEDs for Mitigating Health Risks to Viewers," was developed with good purposes intending to help guide developers of LED lighting products in delivering products that are safe for consumers. But once again we are reminded that nothing about LED light is simple, and there are strong opinions that the IEEE standard is completely strict in its recommendations.

 

The National Electrical Manufacturers Association (NEMA) has already announced a press release questioning the recommendations in the new standard. NEMA has previously published a position paper on what it calls temporary lighting artifacts (TLAs) that discuss what are more typically called flicker and stroboscopic effects. The NEMA paper calls for better metrics to quantify TLAs and states that current work, including the IEEE standard, does not work for the fact that human impact depends on both frequency and the wave shape of a light source.

 

What is the big deal, you ask? What would be wrong with a flicker standard that is perhaps very strict and therefore perhaps came with margins that ensure no impact of LED light on humans? NEMA and others believe that the IEEE flicker standard will result in unnecessary costs being added into LED driver ics. And upfront cost remains the biggest problem to broad application of LED lights and broader global energy savings.

 

Zdenko Grajcar, CTO of Once Innovations and a former executive with AC-LED advocate Seoul Semiconductor, said the IEEE standard fails to talk about AC-LED technology proven in the field and even would eliminate traditional lighting as safe for humans. Grajcar said incandescent and high-pressure sodium (HPS) lighting would not qualify as safe under the guidelines set by the new standard. NEMA coincides on the point about incandescent lighting. Many AC-LED products would also fail to meet the requirements.

 

Of course, there are fundamental differences between incandescent and other traditional sources and LED lights. LED lights have no insistence when there is no power and quit producing light instantaneously. Incandescent and other traditional lighting sources produce light through the zero crossing of the AC input. And the new standard was aimed to apply to LED lights as the title clearly indicates.

 

Still, should the authors of the IEEE flicker standard have been less conservative? Should the authors have directly discussed AC-LED technology? Grajcar said he has seen no reasonable evidence that any danger exists for flicker above 75 Hz. He further has accused the IEEE 1789 committee of bias against AC-LED technology and is attempting to organize a legal challenge to the conclusions reached in the standard.

 

The controversy over the new standard was just heating up. We fully support the concept of standards as a vehicle that can enable ecosystems that both allow for profitable deployment of LED lights and related technologies such as networks and controls. And a standard that mentions the flicker risk is a good thing because flicker can be a serious problem. Clearly, however, such standards must be accurate and be talked about without bias to specific technologies. Its not clear that any bias existed in the IEEE committee and the guidelines may truly be focused on conservative bounds to ensure health. But clearly the subject of flicker will require more work.

 

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