Why Are Some LED Street Lights Purple? Unraveling the Mystery

The sky above Vancouver had an unusual twist – it resembled a colorful Prince concert on TV. Well, it's not the whole sky, but it's certainly a head-turner. Imagine strolling down the street and bam! Some of those ordinary white streetlights have decided to go all out with flashy blues, purples, and violets. What's the scoop, you ask? It's all thanks to a pretty intriguing phenomenon. It wasn't dangerous, just strange. Worried people got in touch with the city, so Vancouver promptly sent out maintenance trucks to swap these peculiar streetlights, even though they were relatively new.

This phenomenon wasn't exclusive to Vancouver; similar reports of LED streetlights changing colors had surfaced in numerous locations, including Wisconsin, North Carolina, Florida, New Mexico, California, and even Ireland. Speculations regarding the causes began to circulate, with some linking it to 5G radiation or government surveillance. However, the actual explanation behind these enigmatic purple lights is both less ominous and more profound than anyone could have guessed.

The Shift in Lighting Technology

Let's unravel the mystery behind those LED streetlights turning a shade of purple. Imagine we're on a time-traveling journey through the fascinating history of lighting. Picture this: we've gone from cozy candlelit nights and the warm glow of gas lamps to the electric revolution. And now, we've got the superstar of the show - LEDs, or Light Emitting Diodes, stealing the limelight. These little wonders are stealing hearts left and right with their energy-saving charm and lasting brilliance.

The majority of cities worldwide transitioned to modern, higher-tech LEDs for street lighting. These LEDs emit white light, but not all whites are the same. Scientists measure the color of white light in kelvins, and the choice of color temperature is subjective. Many cities settled on a color temperature of 4,000 K, which gives a bright, bluish-white light. This shift represented a significant change from the warm, orange glow of traditional sodium vapor lamps.
However, the color shift didn't stop at white; it turned purple for some LED streetlights. While the color shift affected only a small percentage of these lights, it still amounted to thousands of lights across the country. So what caused this shift?

The Role of Acuity Brands

Investigations revealed that Acuity Brands, a leading player in the LED lighting industry, played a pivotal role in the purpling of LED streetlights. Nearly every city with purple lights had purchased their LED lights from Acuity. Between 2017 and 2019, Acuity faced a problem related to LED technology and global manufacturing.

The Science Behind the Purpling

The cause of the color shift, it turns out, lies in the delicate LED packaging. LED streetlights typically consist of LED chips enclosed in a complex package of glass, sealant, solder, and wires. The issue seems to stem from a phenomenon called "phosphor displacement" that occurs years after initial installation. This displacement causes the laminate that gives the LED its white color to degrade, leading to a shift towards purple.
The most likely culprit behind this degradation is heat damage. The phosphor layer in an LED package is sensitive to temperature changes, and even minor errors in assembly or installation can cause LEDs to heat up. This can result in the edges of the phosphor coating curling away from the LED chip, allowing more native blue light to escape and altering the LED's color.

Quality Matters

While Acuity's LED lights aren't the most expensive on the market, their issues highlight the importance of quality in LED manufacturing. See, some companies chase after cost savings in their supply chain, and that could mean compromising on the quality of LED parts. Now, this situation has us pondering: can we really count on LEDs when they're such a big part of our world?

Conclusion

The purpling of LED streetlights, while seemingly a quirky and isolated issue, sheds light on the intricate relationship between technology and global manufacturing. The LED revolution, with its emphasis on cost-effective production, has brought us remarkable advancements in lighting technology. However, it has also revealed the potential vulnerabilities when manufacturers prioritize price over quality. As we journey ahead, let's pause for a moment to think about the stuff we count on in our ever-changing world. So, picture this: the next time you cruise beneath one of those oddly hued LED streetlights, remember it's not a government secret or some wild 5G theory – it's simply a little glimpse into the intricacies of our modern world.