Excellent article [“Type B TLEDs,” LD+A, October 2024]! It’s unfortunate, six years after others found—and revealed—the issue, that flickering Type B TLEDs are still available.
In 2018, for a New York State Research and Development Authoritysponsored lighting project in the town hall of Croton-on-Hudson, NY, I had the opportunity to compare a dozen types of LED conversions, including Types A, B and C TLEDs from several manufacturers and a pair of LED retrofit kits. We produced a booklet on the project that features a table of LED characteristics that includes data on flicker percent and frequency of the tested options.
One of the surprising findings of the project was the intense flicker from Type B TLEDs. Another was that one of the LED retrofit kits also flickered due to the low quality of its driver. Upon notifying the latter’s manufacturer, he immediately switched to a better driver that caused very little flicker.
To quantify the flicker percent and frequency range, we used a Fauser LiFli light flicker meter and miniature oscilloscope. But the flicker was obvious even when using either a primitive flicker wheel or a handheld “ballast discriminator” used to find magnetically ballasted fluorescent lamps in the 1990s.
Among the PNNL authors of the LD+A article, I was surprised to not see Naomi Miller of PNNL, the acknowledged “Queen of Flicker” for her work and presentations on the issue. Her July 11, 2019, webinar on LED flicker was the best I’ve ever seen.
The issue of Type B TLEDs in schools is significant. The New York State Department of Education still provides funding of LED lighting conversions solely for Type B TLEDs, despite flicker issues.
Lindsay Audin, CEM, LEED AP Chair, Croton Sustainability Committee
Croton-on-Hudson, NY
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