Getting the Flicker Issue Behind Us Requires Action – Beyond Whinging on Social Media

Posted: September 17, 2018 in Uncategorized

Flicker is a persistent and frustrating issue, and has been since the first fluorescent and HID lamps were put in service. Complaints of headache, migraine, feelings of ill health, and eye strain are the most common complaints. For some, flicker at 100Hz (Europe/Asia) or 120Hz (North America) is debilitating. Studies have shown that flicker creates reading errors from rapid eye movement changes under sources flickering at under 200Hz – NCBI The effects of flicker on eye movement control, Energy Focus Presentation ‘Lighting Flicker: Effects of Flicker in the Classroom’, including roadway effects – Lux ‘Street light flicker is a new hazard, says watchdog’, CBC – ‘Calgary seizure sufferer worries flickering LED street light will break down again‘.

I will not go into a great deal of detail here on the effects of flicker on human health or the environment. There are hundreds of articles on this topic, by experts in human visual sciences and non-visual physiology. I will say that the science is still somewhat soft on pointing to specific characteristics of flicker that can be pointed to that will carry a lot of weight in a legal sense – other than the well established low frequency (<40Hz) issues with seizure and other serious health effects. I will say that the issues of lighting, including flicker and color content, are being addressed by thousands of concerned professionals and responsible manufacturers, every day of the week.

There are literally dozens of articles pointing out issues with modulating light sources, and their effect on human visual and non visual responses. One of the most comprehensive reviews of the topic of flicker and human health is the IEEE Standard PAR1789 ‘LED Lighting Flicker and Potential Health Concerns’, with the most current version available for purchase from the IEEE directly. In this paper,. there are numerous references that support the conclusions of this work, which provide anyone truly interested in making the case for mitigating flicker, or eliminating flickering lighting products the supporting data they need. In addition to this, the LRC/Assist has created a paper ‘Flicker Parameters for Reducing Stroboscopic Effects from Solid-State Lighting Systems’,  and ‘Minimizing Flicker from SSL Systems’. ‘DOE has published ‘Characterization of Photometric Flicker’, to provide insight into how flicker is defined using known metrics. Naomi Miller presents a PNNL summation in ‘Flicker: How to avoid it, test for it, and fix it’, which includes reference to CIE 17.443 e-ILV, which is also referenced in Energy Focus – Fighting Flicker, The Causes and Effects of Flicker in Lighting’.  California’s JA10 also addressed flicker and acceptability in energy efficient products, outlined in ‘Measuring Flicker: California’s JA10 Test Method and Its Uses’. The IES is expected to issue its own recommendations on flicker soon.

Further information on flicker can be found here: ‘Flicker: Understanding the New IEEE Recommended Practice’, ‘Flicker’, eere ‘Flicker’ with references, ‘Optical Flicker in Light’, ‘Flicker: Strandards and Test Methods’,

A review of the topic of AC driven LEDs and Flicker effects can be found in ‘Understanding a new flicker metric and its application to AC-LED light engines’.  Further, the issue of whether flicker has any impact at frequencies greater than 1KHz, Wilkens has written a paper titled ‘Flicker can be percieved during saccades at frequencies in excess of 1KHz’.

On this blog, I have described a task light I developed ‘Zero Flicker Task Light’,  a review of flicker and sources in ‘More on the Flickering of Things’, and described my simple ‘Flicker Indicator Machine’. My early experiences with AC LEDs were posted in ‘Seoul Semiconductor Acriche 120V AC LED’, ‘Molex Electronics Launches 120VAC LED Modules’, and ‘More 120VAC LED Experimentation – The Frankenstein PAR20’.  Note that the early articles date back to 2009, before we began to question whether this was such a great idea. Even back then, we were seeing that using AC to drive LEDs presented some visual effects that were not desirable, leading to the later blog entries and the creation of the flicker indicator machine and critique of the emerging lot of retrofit lamps exhibiting poor quality, including flicker in ‘Without Quality – LED Retrofits Will Fail’. In one of my earliest posts (2008), I mentioned flicker in ‘Want Solid State Satisfaction?’.

I have lived under AC LEDs for a significant period of time, and understand intimately what the impact of them is. I will offer that at this time, I have replaced or removed all AC driven LED products from my personal environments and at home, with the exception of a couple of task lights for occasional use.

Measuring and Defining Issues

There are issues in defining and measuring flicker that have yet to be resolved. The IES has created a solid paper on this titled ‘Flicker Frustration: Measuring What You Can’t See’. The work of creating a solid metric and definition of what is acceptable and unacceptable modulation is ongoing. This is not a simple issue, nor will solutions to remaining outstanding questions and problems come the immediate future.

There are several manufacturers investing a great deal into the elimination of drivers to produce “Direct Drive” LED systems. Lynk Labs is one in the USA, Seoul Semiconductor with its Acrich Line, both working on various approaches to reduce undesirable flicker effects. My own tests show them to be effective, to some degree. There are also others offering direct drive LED products, like that from INDO (UK), that supposedly mitigate flicker without the use of drivers. Others, like Solid State Luminaires have developed driver-less products with zero flicker, even when dimmed. Many others are working on similar technologies, which are likely not to be identified as AC LED products at all, as their lack of the typical low frequency flicker, or zero flicker performance simply does not demand they differentiate them from other offerings.  Driver-less and direct drive LED products are going to continue to be more common, as engineers innovate methods for mitigating AC line induced modulation.

Concerns about driver-less products

The primary concern over eliminating drivers, is the propensity of the resulting products to flicker. This ignores the fact that many products with drivers also flicker. The presence of a driver does not indicate that flicker has been resolved. In many retrofit lamps, flicker remains a serious issue, yet most incorporate drivers – this is particularly troublesome when they are dimmed. Other concerns include the failure mode flicker. Should the rectified circuit inside fail in a way that allows the LEDs to operate at line frequency (60Hz or 50Hz), the results can be far more damaging and noticeable than when they operate at the typical twice line frequency (120Hz or 100Hz). If this failure mode also include failure of the flicker mitigation circuit components in any way, then flicker can become obnoxious and even threatening to the health of some of those exposed to it. However, this is not unique to driver-less LED products. Drivers can also fail in a manner in which AC modulation occurs at the LED. Products (driver-less and driver-included), should include circuiting to shut the product off should the product exhibit such failure mode.

Other Modulation Sources that Flicker

Pulse Width Modulation (PWM) driving of LED circuits has been used for many years. This may be within a driver, where the PWM output is then converted to DC prior to powering the LED, and through circuits that drive the LEDs at PWM circuit frequencies. These can be anywhere from 1KHz to 20KHz. For the majority of applications, driving the LED with PWM (a Phillips patent BTW), is not going to be an issue at full light output. However, when dimmed to low levels, it is possible for some to be sensitive to the modulation of those driven at 1KHz, and be effected physiologically to the effects of this.

Why the pressure to get rid of drivers?

These are the three primary reasons why manufacturers want to get rid of drivers:

  1. Drivers fail faster and more frequently than the LEDs they are powering.  This is particularly true for  high power products and compact designs that expose drivers to high temperatures, either due to ambient conditions, operating conditions, or both. This applies to street/roadway lighting, cove lighting, and compact decorative lighting, as well as retrofit lamps. In my experience, the vast majority of all failed LED products we have tested, have perfectly functioning LEDs, with failed drivers.
  2. Drivers are space hogs. Converting voltage from line to LED, converting AC to DC, and adding in dimming features, minimum UL creep-age and clearance requirements, thermal separation, etc.. all results in driver case sizes that are cumbersome on top of the additional wiring involved.
  3. Cost and Complexity. Drivers add more cost and increase complexity of assemblies more than integrating components to reduce or eliminate flicker into AC line powered products.

My Personal Take

I personally do not like seeing LEDs driven from any sort of modulating at all. When asked, I offer the following recommendation, based on what I have read and witnessed personally, in order of selection preference:

  1. Use products that deliver regulated DC current to the LEDs, that use current control for dimming.
  2. If the product utilizes any driver component that modulates current/energy to the LED, such as PWM driven products, select those that modulate at no less than 2KHz, favoring those with the highest frequency modulation available (20KHz is ideal).
  3. If the only choice is between products that utilizes AC driver-less technology, select those that include circuiting to mitigate flicker completely, with protection circuits to insure that any failure does not result in mains frequency flicker being evident.
  4. If the only choice is a product driven from AC circuits with measurable flicker, demand they produce a maximum of no more than 25% modulation depth, no greater than 10% flicker percent, and no greater than 0.05 flicker index, with protection circuits to ensure that any failure does not result in mains frequency flicker being evident.
  5. If none of these choices are available, select another manufacturer, another option, or another product direction, as any other choice is unacceptable.

For my own environments, I use only products covered in 1.) above.

Action Plan

This all said and covered, I offer that anyone experiencing an environment (indoor or out) where they suspect flickering light sources (LED or otherwise) are present and causing them harm or discomfort, needs to do the following:

  • Do not begin by blasting some angry tweet away on your favorite forum or SM outlet. Your objective opinion has no value in causing any change to occur, any resolution to be undertaken, or activating the world to come to your rescue. What you must do is the work of collecting appropriate data, identifying the actual problem, in detail and taking real action in the real world:
  • Obtain, rent, borrow, or call on a lighting expert to help collect data on the lighting condition in question with a calibrated flicker meter. This includes products like the  UPRTek MF250N Flicker Meter or Lighting Passport meter. Others include the BTS256-EF from Gigahertz-Optik, Everfine LFA-2000 Light Flicker Analyzer, and Admesy Asteria SC-ASTR-10 Illuminance Photometer (could not find a link to product). Also see the article on DOE Meter Tests. or the DOE Report itself.)
    • Do not presume that any  smart phone based flicker meter app, like that offered by Viso Systems will give you the accuracy you require to make the case against anyone to have the problem resolved. The App based flicker meter is fine for doing a quick preliminary test before going any further, but the results are simply not reliable enough to base a strong claim on.
  • With the data in hand, review the IEEE Standard 1789, as well as California’s JA10, and the other articles and papers linked above.
  • Assemble a summary report of findings, concerns – backed by and citing the objective information found in the papers – why you feel the lighting condition is a hazard, unhealthful, unattractive, uncomfortable, or requiring address.
  • Include a brief summary of recommendations for resolving or correcting the issue, including reference to each specification line item as it relates to the issue itself. Do not confuse details of light levels, color and flicker as inter-related. If all of these are involved, separate them as specific items, and address each individually, with equal clarity and backing by cited reference papers or data. Include copies of the most applicable and important papers or articles.
  • The report should include a brief introduction, statement of the problem identified, and executive summary of the content of the report itself.
  • Keep the entire document to less than 2-4 pages, plus cover letter, reference page, and reference documents.
  • Keep the report crystal clear and on topic. Do not include any accusations or threats, or conspiracy theories, or statements of opinion about the state of lighting and/or government, or why you feel personally offended, or elevations of the issue beyond the facts and actual findings.
  • If at all possible, use a known white paper format for the report, such as the APA guide.
  • If possible, recruit the assistance of a lighting professional or medical professional to assist in evaluating the findings, reviewing the summary, and possibly offering a written letter of support and validation of the case being made.
  • Communicate your results and concerns to others in your area that are impacted by the condition of concern, and ask them to support your findings, sign the cover letter directed at those targeted to receive the finished report and documentation. Perhaps with enough support for the concerns addressed, money can be made available to secure the assistance of a paid professional to assist in developing the final report.
  • Direct the report and summary of findings to those who installed, operate, and/or in charge of making the product purchasing decisions. Include all of the above when possible, sending one letter to one person is rarely effective. Send a copy of all correspondence to local leadership (Mayor, Governor, Constable, etc..). This should not be through email, it should be on paper, with an appropriate, professionally written cover letter, sent registered post or mail with a receipt request.
  • If there is a City Council meeting available, ask for time to present the summary, case, and recommendation for correction. Keep the brief to 10 minutes or less. This means no B.S., just the facts, the supporting facts, and an actionable suggestion for correcting the problem.

If you wish to engage Social Media for the purposes of building support, then do so as follows:

  • Place the summary and all of its supporting documentation in a location that can be readily linked to messages. This includes Facebook and WordPress, which can be created quickly, for free.
  • Write a post that describes what the issue is, and what has been done, and what you are asking those receiving the SM message to do.
  • Ask for comments and shares of the lined summary and its content, and ask for comments as to its accuracy and voracity.
  • Once established and responses have been received, now is the time to follow-up with all those who received a written copy of the report, via email, with a link to the summary, and links to pertinent comments received.

The power of social media is not to insight a feeling of discord and airing/venting one’s spleen in a public venue. The real power of social media is found in the building of a call to action, based on solidly written, well-defined issues.  This is how politicians use SM, this is how corporations build their image with SM, this is how individuals get things done using SM.

Bottom Line

If you don’t feel up to the effort of addressing the issue, or organizing a group to do the actual real work involved. You obviously do not feel the issue is very important.  If doing the work of making a legitimate case is too much to ask, then live with the result of that lazy approach. Those who have something to gain from selling products or services, at your detriment, will have no such relaxed passive approach. Most likely, the reason you are having a problem, is that someone with a great deal of energy and a strong case for their own recommendations succeeded. To defeat such action requires, at a minimum, a force equal to that.

In my past, I have belonged to several local organizations for the purpose of making change happen. My very first was in Boise, Idaho, in the Near North End Neighborhood Association (1982-1984). Our goal was to direct the city away from plans to destroy older neighborhoods to widen streets and convert homes to commercial use. We succeeded, after some effort, in changing the direction of city planners, that today still stands. The neighborhood (a large residential area north of the city center) remains strong and healthy. We had no twitter, no web site, no internet. The game has not changed. City councils do not respond to anonymous or hysterical SM posts, they respond to strength, which comes from making a solid case, drawing supporters into forwarding the cause, and presenting the issues in terms they can deal with, including responding to recommendations for resolving the problem.

In a more recent example, I was asked to review the complaints of employees who claimed to be suffering migraine and eye strain, as well as feeling of sickness, they claimed was caused by the lighting. It took less than an hour to discern that a magnetic ballasted HID lighting system with clear lamps, was creating flicker at 60Hz well outside the acceptable parameters described in the IEEE 1789 standard report. The employer read the one page summary with graphs of measured results, an a recommendation that the lighting be changed to a DC driven LED source. The employer responded immediately, the folks effected were thrilled, problem solved. Had this been handled as an indictment of the designer who specified the original lighting, or the industry in its irresponsible approach to humans, etc., or rushed back to blast the company on some SM platform for exposing their people to such horrible conditions – I do not doubt nothing would have changed, and I would have been shown the door without payment for my time.

SM is not a solution to anything. SM is a tool for change, when it is utilized as a tool. Everything else is just noise, easily ignored.




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