Flickering LED

A friend’s ​apartment building has recently been refurbished with warm white LED downlights in the entrance hall and corridors. Being of higher quality than the usual mediocre LED bulbs sold in shops, these lamps gave a more pleasant light and ambiance than the tired old fluorescent tubes. The change also included motion sensors which would turn the lights off when not in use, which is smart and energy saving. All in all, a definite upgrade.

However, last time I went to visit, one of the downlights had gone completely crazy and flickered in regular bursts like a strobe light! Even though I’m not prone to seizures, I found it extremely disturbing and could hardly walk past it with my eyes open. After making sure the super would come and fix it a s a p, I managed to film a few seconds of this horror. (Do NOT watch if you’re epileptic!)

I don’t know if this is common behaviour in failing LEDs. These were less than a year old and should not be failing so soon. Oh, and it turned out the super couldn’t do anything as these LED downlights required specialist help from the company that installed them. No longer a matter of just replacing a burned-out bulb or tube.

Even though annoying enough, I’ve never seen a failing fluorescent tube flicker with such a sharp and piercing strobe effect. This seems like a rather serious issue.

For instance, photosensitive epilepsy is more common than one might think, affecting “about one in 4000 individuals,” according to the group. Factors that may combine to affect the likelihood of seizures include flash frequency in the range of 3 to 65 Hz, and especially in the range from 15 to 20 Hz. That’s why line frequency fundamentals (50 or 60 Hz, depending on country) are important and why asymmetric behavior of the external triac controller is significant.”

http://electronicdesign.com/lighting/do-leds-have-dark-side
More to read on LED flicker:

http://www.ledsmagazine.com/articles/print/volume-11/issue-4/features/developer-forum/proper-driver-design-eliminates-led-light-strobe-flicker.html

Update: The year after, another LED downlight in that same apartment building started flickering in exactly the same way. It kept doing so for weeks before it got fixed.