Author Topic: Street Lights turning Purple  (Read 20194 times)

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Offline rgaritoTopic starter

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Street Lights turning Purple
« on: March 26, 2022, 01:01:38 am »
All over America (at least), there are numerous reports of street lights turning purple.

The issue is caused by some sort of "manufacturing defect" of the LED bulbs that many cities have used to replace their old lamps.

Here's an example:
https://www.fox13news.com/news/failing-street-lights-in-tampa-emit-bright-purple-hue

A simple Google search reveals 1000's of hits.

Sounds like some LED manufacturer(s) gonna be replacing a lot of LEDs!!!   :palm:
 

Offline Whales

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Re: Street Lights turning Purple
« Reply #1 on: March 26, 2022, 01:11:10 am »
Almost all commercial white LEDs are blue LEDs with phosphors ontop.  These street lights sound like they're losing their phosphor layers.

Temperature x hours too much for them?  Or maybe something more creative like the phosphors flaking off due to moisture and cycling?
« Last Edit: March 26, 2022, 01:13:12 am by Whales »
 

Offline sleemanj

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Re: Street Lights turning Purple
« Reply #2 on: March 26, 2022, 01:17:55 am »
I think I recently saw somebody look at this sort of failure where the phosphor detached... maybe it was BigClive.

Edit: ahh it was the lg tv thread below I was thinking of
« Last Edit: March 26, 2022, 03:56:47 am by sleemanj »
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Offline floobydust

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Re: Street Lights turning Purple
« Reply #3 on: March 26, 2022, 01:31:12 am »
It's been attributed to phosphor failure. I thought it's the same problem affecting LCD TV backlights https://www.eevblog.com/forum/chat/why-do-backlight-leds-burn-out-and-go-blue/

The debacle of Detroit's streetlight failures- over 20,000 "prematurely dimming and burning out" cost almost $7M to replace them. They failed melting the lens.
Detroit Sues Lighting Manufacturer Over Failed Street Lights The City sued Leotek Electronics, got only $4M in settlement.

Point is it's very expensive labour-wise to swap out defective streetlights, about 1,500 a week were done and the City of Detroit contracted out all streetlight work, they didn't have their own crews.
 

Offline james_s

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Re: Street Lights turning Purple
« Reply #4 on: March 26, 2022, 02:24:28 am »
My friend who works in the streetlighting industry was just talking about this the other day when I was hanging out with him. He said it is a particular brand and model of luminaire that is having this problem, he's been working on getting me a defective one to do a failure analysis on.
 
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Offline jonpaul

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Re: Street Lights turning Purple
« Reply #5 on: March 26, 2022, 11:00:23 am »
the cities purchase the cheapest Chinese junk.

Buy EuropĂ©en or American not  China
j
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Offline james_s

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Re: Street Lights turning Purple
« Reply #6 on: March 26, 2022, 05:32:57 pm »
IIRC it is an American company's products that are doing this, I think he said it was Cooper Lighting but I'll check.
 

Offline AVGresponding

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Re: Street Lights turning Purple
« Reply #7 on: March 26, 2022, 05:58:13 pm »
Regardless of the nationality of the manufacturer the LEDs themselves are likely made in China nowadays.

My main gripe with LED lights is that you have to replace the entire fitting when they go poof, rather than just a lamp or ballast. Any organisation looking at reducing their overall costs by installing low energy LED lighting is going to be in for a nasty surprise a few years from now.
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Offline floobydust

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Re: Street Lights turning Purple
« Reply #8 on: March 26, 2022, 06:21:33 pm »
Cobra head LED light fixtures fail for many reasons - overheating, water ingress, cheap/overstressed components like the LED's, electrolytic capacitors etc. and thermal cycling, bad driver design, lightning/transients, loose bolts falling down and many more reasons.

For the purple/blue streetlights, "American Electric Lighting (AEL) a division of Acuity Brands Lighting products" seems to be just a middleman, a dealer of numerous lighting brands.
Their warranty is the usual 1 year, liability limited to the purchase price of the product. A few warranties went to 6 years on select components.
Our municipality's tax dollars pay for these failures but it's always hush hush and swept under the rug because it's very expensive to replace streetlights, labour-wise.

For Detroit, LEOTEK is part of Lite-On Group.
So is their melting LED "cheap" or driven at the datasheet maximum? You want the highest lumens number in order to make the sale, who cares about lifetime- by then you will have bought your Lambo and can blame someone else.

 

Offline SiliconWizard

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Re: Street Lights turning Purple
« Reply #9 on: March 26, 2022, 07:12:47 pm »
That's funny, especially when you think about the gigantic cost behind the replacement of all street lights by LED-based ones, allegedly to draw less power and/or require less maintenance.

But in hindsight, with real figures, have they really lowered cost, energy included - or will they ever during their lifetime - compared to sodium vapor lights? Actually, efficiency is on par, or was even in favor of sodium vapor until recently. As to lifetime, as we all know, this is just mostly a lie. LEDs as built and used in most street light are not made to last. Yes, I've also witnessed changes of brand new (like one-year old) street lights due to early failure. It seems common.

So, where are the real figures, and independent analysis of that? This is our tax money.

The two real "benefits" of LEDs for street lights are that they can be almost instantly turned on, while the sodium vapor ones take a few minutes of warm-up time. The other is that they have a much broader spectrum. Useful in particular for surveillance cameras. ::)
 
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Offline james_s

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Re: Street Lights turning Purple
« Reply #10 on: March 26, 2022, 08:00:53 pm »
I asked my friend, he said it's American Electric ATB0 and ATB2 luminaires that have been turning blue.

The melting Leotek lights are another common problem, it isn't the LEDs in those but the optics. They get dirty and it absorbs heat and causes them to darken which of course absorbs more heat and eventually the lens melts completely. Apparently they're pushing a lot of optical power through a relatively small lens.
 
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Offline james_s

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Re: Street Lights turning Purple
« Reply #11 on: March 26, 2022, 08:03:27 pm »

The two real "benefits" of LEDs for street lights are that they can be almost instantly turned on, while the sodium vapor ones take a few minutes of warm-up time. The other is that they have a much broader spectrum. Useful in particular for surveillance cameras. ::)

The major benefits of LED is that they are about half the wattage of the HPS lamps they replace, and they produce nice white light. The latter is huge IMO, at least to me. Personally my favorite is still the old mercury vapor lights that were common up into the 80s. They are less efficient on paper but they do a better job of lighting things up than HPS, the orange light is absorbed by so much and just makes greenery look brown and gross. The spectral lines of a mercury lamp make plants practically glow.
 

Offline Ben321

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Re: Street Lights turning Purple
« Reply #12 on: April 08, 2022, 10:24:23 am »
Almost all commercial white LEDs are blue LEDs with phosphors ontop.  These street lights sound like they're losing their phosphor layers.

Temperature x hours too much for them?  Or maybe something more creative like the phosphors flaking off due to moisture and cycling?

The phosphors are inside of the LED component itself. There's the blue gallium nitride blue emitter chip itself, which is then coated with a layer of yellow fluorescent material. This entire structure then is fully encapsulated inside the dome shaped piece of clear plastic. And by encapsulated I mean that liquid plastic is poured over the chip+phosphor structure that's sitting in a dome shaped mold so that the chip+phosphor structure is completely potted. There's absolutely no way for it to flake off. Overheating could burn out LED or even explode it, but the phosphor can't flake off while the LED is operational because it's physically sealed by the surrounding plastic. And of course if it burns out or blows up, the LED stops emitting all light.


I have a hypothesis about the ones turning purple or blue. I think that there's those are using tri-color non-phosphor LEDs. These are the same type that are used in RGB LED advertising signs that can display bright full color pictures on billboards. Except here they are being used not for image display, but rather for illumination. My guess is that the drivers for green LED chips and red LED chips are failing faster than the ones powering the blue LEDs, resulting in the blue color you see from them when they fail. While most LED streetlights use the normal white phosphor design, I think a few are using tri-color LEDs and these are the ones that turn blue when they fail.
 

Online wraper

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Re: Street Lights turning Purple
« Reply #13 on: April 08, 2022, 10:38:19 am »
The phosphors are inside of the LED component itself. There's the blue gallium nitride blue emitter chip itself, which is then coated with a layer of yellow fluorescent material. This entire structure then is fully encapsulated inside the dome shaped piece of clear plastic. And by encapsulated I mean that liquid plastic is poured over the chip+phosphor structure that's sitting in a dome shaped mold so that the chip+phosphor structure is completely potted. There's absolutely no way for it to flake off. Overheating could burn out LED or even explode it, but the phosphor can't flake off while the LED is operational because it's physically sealed by the surrounding plastic. And of course if it burns out or blows up, the LED stops emitting all light.
Have you ever seen an SMD LED? I have never seen any lighting solution with outdated through-hole LEDs.

« Last Edit: April 08, 2022, 11:50:10 am by wraper »
 

Online themadhippy

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Re: Street Lights turning Purple
« Reply #14 on: April 08, 2022, 11:37:06 am »
Will the traffic lights be turning blue tomorrow?
 

Offline Zero999

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Re: Street Lights turning Purple
« Reply #15 on: April 08, 2022, 12:19:34 pm »
Almost all commercial white LEDs are blue LEDs with phosphors ontop.  These street lights sound like they're losing their phosphor layers.

Temperature x hours too much for them?  Or maybe something more creative like the phosphors flaking off due to moisture and cycling?

The phosphors are inside of the LED component itself. There's the blue gallium nitride blue emitter chip itself, which is then coated with a layer of yellow fluorescent material. This entire structure then is fully encapsulated inside the dome shaped piece of clear plastic. And by encapsulated I mean that liquid plastic is poured over the chip+phosphor structure that's sitting in a dome shaped mold so that the chip+phosphor structure is completely potted. There's absolutely no way for it to flake off. Overheating could burn out LED or even explode it, but the phosphor can't flake off while the LED is operational because it's physically sealed by the surrounding plastic. And of course if it burns out or blows up, the LED stops emitting all light.


I have a hypothesis about the ones turning purple or blue. I think that there's those are using tri-color non-phosphor LEDs. These are the same type that are used in RGB LED advertising signs that can display bright full color pictures on billboards. Except here they are being used not for image display, but rather for illumination. My guess is that the drivers for green LED chips and red LED chips are failing faster than the ones powering the blue LEDs, resulting in the blue color you see from them when they fail. While most LED streetlights use the normal white phosphor design, I think a few are using tri-color LEDs and these are the ones that turn blue when they fail.
Why would the green and red LEDs fail first? If they were RGB then a good number of them would turn yellow, or cyan, rather than purple.

It's phosphor failure. The reason why some change purple is because violet, rather than blue LEDs are often used to excite the phosphor.
Cobra head LED light fixtures fail for many reasons - overheating, water ingress, cheap/overstressed components like the LED's, electrolytic capacitors etc. and thermal cycling, bad driver design, lightning/transients, loose bolts falling down and many more reasons.

For the purple/blue streetlights, "American Electric Lighting (AEL) a division of Acuity Brands Lighting products" seems to be just a middleman, a dealer of numerous lighting brands.
Their warranty is the usual 1 year, liability limited to the purchase price of the product. A few warranties went to 6 years on select components.
Our municipality's tax dollars pay for these failures but it's always hush hush and swept under the rug because it's very expensive to replace streetlights, labour-wise.

For Detroit, LEOTEK is part of Lite-On Group.
So is their melting LED "cheap" or driven at the datasheet maximum? You want the highest lumens number in order to make the sale, who cares about lifetime- by then you will have bought your Lambo and can blame someone else.
Laws vary. In some countries the manufacturer still has a statuary obligation to the customer, beyond a year, or whatever the warranty states. If a large number are failing too soon, they still might be able to get some money from the manufacturer to replace the failed luminaries.
 

Online Gyro

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Re: Street Lights turning Purple
« Reply #16 on: April 08, 2022, 12:41:35 pm »
Will the traffic lights be turning blue tomorrow?

No, they use dedicated colour LEDs.
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Offline james_s

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Re: Street Lights turning Purple
« Reply #17 on: April 08, 2022, 05:52:59 pm »
I have a hypothesis about the ones turning purple or blue. I think that there's those are using tri-color non-phosphor LEDs. These are the same type that are used in RGB LED advertising signs that can display bright full color pictures on billboards. Except here they are being used not for image display, but rather for illumination. My guess is that the drivers for green LED chips and red LED chips are failing faster than the ones powering the blue LEDs, resulting in the blue color you see from them when they fail. While most LED streetlights use the normal white phosphor design, I think a few are using tri-color LEDs and these are the ones that turn blue when they fail.

Your hypothesis is wrong. I have worked as a consultant in the street lighting industry, a close friend of mine has spent his career in it. I've seen many different examples of LED street lighting luminaires up close and absolutely every single one of them uses phosphor based white LEDs in surface mount packages. The lights that are turning blue are having the phosphor flake off, the same has happened with some LED backlit TVs.
 
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Offline Ground_Loop

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Re: Street Lights turning Purple
« Reply #18 on: April 13, 2022, 11:56:53 am »
I just drove into Atlanta airport and saw literally dozens of the street lights that had gone purple. Sorry no pics, but it looked to be around 25% had the problem.
There's no point getting old if you don't have stories.
 

Offline Stray Electron

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Re: Street Lights turning Purple
« Reply #19 on: April 13, 2022, 12:18:47 pm »
  They put a new street light in front of my house about a year ago and it was a brilliant, glaring white! About two weeks ago I came home and it had suddenly changed to pinkish purple color and wasn't nearly as bright. This week they came out and repaired or replaced it (I wasn't here and didn't see what they did).  IMO it didn't last very long! The old mercury vapor lights would run for years!

  I see LED signs and stop lights all over town that have large numbers of failed LEDs in them and I'm also noticing a lot of very new cars and trucks with LED lights that have failed.

  IMO the poor quality of the mass produced LED lights vastly exceeds any theoretical improvements in longevity or energy efficiency.
 

Offline SeanB

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Re: Street Lights turning Purple
« Reply #20 on: April 13, 2022, 12:58:28 pm »
Down the road from me is a street with LED lamps that were fitted around 2008, and, due to the usual competence of the council electrician contractors, they all have shorting caps, and the group relay was disconnected, and each was wired to the phase wiring of the overhead line. Now on 27/7/365 they are still sort of functional, as in they still emit some light at night, even though more than half the dies in the head are failed, and these obviously have failed led detection in the optical head, and a really good power supply. Lumen output is down by more than half, they used to be impossible to look at during the day, but now they are a lot dimmer.

The other ones in the street had to be replaced within a year, as they all failed, so the supplier, Beka, replaced them, and then the metro also put in a lot more additional fixtures to supplement the light, replacing the 400W HPS fixtures with an 80W fixture on the street side, and an 18W fixture on the pavement side.

Still a few 400W HPS and MH units left though, and the rear alley by me got a relamp with a new 80W MV fixture, as the ballast had rotted away. I kind of wanted that old Phillips lamp, but it fell to pieces when they touched it, so in went a Beka GRP fixture, complete with 80W Osram lamp. I did get the old shorting plug though, to use on my other 80W fixture instead of the photocontrol.

Typically the LED is between 80W and 135W, replacing a 400W fixture, and for residential 18W or 36W, you place either one lamp assembly in, or two, and set the power supply accordingly.
 

Offline james_s

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Re: Street Lights turning Purple
« Reply #21 on: April 13, 2022, 07:15:18 pm »
  They put a new street light in front of my house about a year ago and it was a brilliant, glaring white! About two weeks ago I came home and it had suddenly changed to pinkish purple color and wasn't nearly as bright. This week they came out and repaired or replaced it (I wasn't here and didn't see what they did).  IMO it didn't last very long! The old mercury vapor lights would run for years!

  I see LED signs and stop lights all over town that have large numbers of failed LEDs in them and I'm also noticing a lot of very new cars and trucks with LED lights that have failed.

  IMO the poor quality of the mass produced LED lights vastly exceeds any theoretical improvements in longevity or energy efficiency.

It's really hard to beat the old mercury lamps in terms of longevity, at least the good quality American and European lamps. My grandparents house had a 175W mercury yard light on the front of the workshop in the back yard and it had been running dusk till dawn for around 35 years when the house was sold, still on the original lamp and it still looked about as bright as a new one. It had one of the GE Bonus Line lamps they made for a few years that had electrodes formulated to make white deposits instead of black.

That old mercury light consumed about 200W though with ballast losses, and a modern LED replacement would probably be around 30-50 watts for roughly the same light output so the LEDs do probably ultimately save money, especially when you consider the mercury lamps made more recently are mostly cheap crap. The last producer of good quality mercury lamps is/was probably Iwasaki in Japan.
 
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Offline CCitizenTO

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Re: Street Lights turning Purple
« Reply #22 on: April 18, 2022, 06:28:47 pm »
IIRC it is an American company's products that are doing this, I think he said it was Cooper Lighting but I'll check.

Just because it's an American Company doesn't mean they aren't using cheap Chinese parts. Remember the cheaper they are to produce something the more profit they make...
 

Offline james_s

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Re: Street Lights turning Purple
« Reply #23 on: April 18, 2022, 06:30:49 pm »
Just because it's an American Company doesn't mean they aren't using cheap Chinese parts. Remember the cheaper they are to produce something the more profit they make...

Sure but almost everyone is using Chinese parts. Some Chinese parts are quite good, what matters is the specifics.
 

Offline floobydust

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Re: Street Lights turning Purple
« Reply #24 on: April 18, 2022, 07:09:37 pm »
I think the supporting design is also important, as far as not driving the LED's so hard that they have a short lifetime. Unfortunately this is commonplace, just to get a bigger lumens number and be cost-competitive. Then, the city's engineers use the exaggerated light numbers and design to their own cheapness. My city's LED streetlighting has so many dark areas where some CivE thought the cheap cobra head would cover many 100m, space them faaaaar apart, it's kind of pathetic. Easy to bust into cars in total darkness. If I were a woman walking at night, I would be terrified it's just creepy.

There is also contract manufacturing of LED's, rather than use something in a product line, specify your own to get advantage. But numbers can get exaggerated twice (by the LED component manufacturer and the product designer) and the result is short lifetime, a failed product.
 


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