Failure of solid state fluorescent lamp elements plagues street lights

[Flicker Index]

I've seen blue lights in rest areas along the highway and at first, I thought it was injection drug use deterrent. I guess not. It was widely spread defects in LED elements.

So long, purple streetlights. Only a handful of the lights remain on Wisconsin interstates.

Less than 100 purple streetlights remain in Wisconsin after popping up around the country two years ago, during the spring of 2021.

www.jsonline.com

New installations of public street lighting these days consist of solid state fluorescent lamps employing lighting modules made up of solid state fluorescent elements consisting of blue activated yellow emitting phosphor blend and blue LED chips. https://www.nature.com/articles/srep24052

In traditional gas discharge fluorescent lamps, the final light was the result of mercury lines + visible lights emitted by an UV activated phosphor blend. In LED type solid state fluorescent lamps, the light is a mixture of yellow from the phosphor plus the blue from the LED chips. Either way, because they're both fundamentally a fluorescent lamp, they're both susceptible to functional failure due to a phosphor related failure.

 

[ActionDave]

Yawn. Old news.
https://forums.mikeholt.com/threads/purple-lights.2571600/

 

[ramsy]

Yawn. Old news.
https://forums.mikeholt.com/threads/purple-lights.2571600/

ActionDave should change his avatar to the Shrew rat.

 

[Joethemechanic]

Ok I gotta ask, what do blue lights have to do with injection drugs??

 

[winnie]

Old news, but something to be aware of.

Like any product, LED manufacturers are incentivized to make products as cheaply as possible while still meeting specification. LED lamps can be made brighter by running more current through them, getting more lumens per $ of lamp. But this makes the LEDs run hotter and puts them closer to failure.

Many of the apparent problems of LED streetlights simply go away if you use more LED emitters running at lower current, but that means more $$$$.

It is also important to keep in mind that, as @Flicker Index describes, white LEDs depend upon fluorescing phosphors. In addition to being subject to all of the possible phosphor failures, you have huge trade-offs in quality of light vs amount of light. If you search for (and pay) you can get LEDs with beautiful warm color temperature, high CRI, etc. Or you can get garbage.

-Jon

 

[Flicker Index]

Ok I gotta ask, what do blue lights have to do with injection drugs??

To make it harder for drug addicts to see their veins for the purpose of shooting up dope.

https://www.npr.org/2019/09/03/756976676/blue-lights-may-deter-intravenous-drug-use-in-public-spaces

 

[Flicker Index]

Old news, but something to be aware of.

Like any product, LED manufacturers are incentivized to make products as cheaply as possible while still meeting specification. LED lamps can be made brighter by running more current through them, getting more lumens per $ of lamp. But this makes the LEDs run hotter and puts them closer to failure.

Many of the apparent problems of LED streetlights simply go away if you use more LED emitters running at lower current, but that means more $$$$.

It is also important to keep in mind that, as @Flicker Index describes, white LEDs depend upon fluorescing phosphors. In addition to being subject to all of the possible phosphor failures, you have huge trade-offs in quality of light vs amount of light. If you search for (and pay) you can get LEDs with beautiful warm color temperature, high CRI, etc. Or you can get garbage.

-Jon

Another thing in common with traditional fluorescent lights is that while the elements themselves are fed DC/pulsed DC, LEDs need a ballast. Although, the interaction between LED modules and LED ballasts during a failure manifest themselves quite differently from traditional lighting.
LED system have a tendency to flash rapidly and deeply to the point of being a major distraction. Since this pattern of failure only plagues the LED type lighting, specifiers usually neglect to spec out the requirement to not flash upon failure.

 

[zbang]

Um, "traditional fluorescent lights" need a ballast. They also flash at 120Hz (each half cycle).

 

[gadfly56]

Another thing in common with traditional fluorescent lights is that while the elements themselves are fed DC/pulsed DC, LEDs need a ballast. Although, the interaction between LED modules and LED ballasts during a failure manifest themselves quite differently from traditional lighting.
LED system have a tendency to flash rapidly and deeply to the point of being a major distraction. Since this pattern of failure only plagues the LED type lighting, specifiers usually neglect to spec out the requirement to not flash upon failure.

I have an LED bulb in my basement that's starting to do that. I always write the installation date on the bulb base. I'll have to check and see how long it's been in there.

 

[GoldDigger]

Um, "traditional fluorescent lights" need a ballast. They also flash at 120Hz (each half cycle).

Technically, there is a "flash" at the level of the arc current and the resulting light output. But because of the smoothing effect of the phosphors it is more generally considered to be a "flicker".
Add that to the averaging effect of the eyes, with a threshold around 30 Hz, and you get near unnoticeable.
Early LED Christmas light strings with half-wave rectification, on the other hand, was really obnoxious. Especially in terms of the motion strobe effect.

Sent from my Pixel 4a using Tapatalk

 

[Flicker Index]

I have an LED bulb in my basement that's starting to do that. I always write the installation date on the bulb base. I'll have to check and see how long it's been in there.

A dead lamp amongst a group of lamps that has failed in a reasonably non annoying way can be ignored for quite some time. Cycling HPS or even glow bottle start fluorescent flashing is not even close to the distraction hazard of a flashing solid state type lighting caused by LED ballast failure. Some LED system designs fail in a way that make them blink in a way that mimics the flashing rate and depth of a fire tuck strobe requiring immediate repairs or deactivation at potentially significant expenses due to the need to service something outside of expected scheduled interval in remote or difficulty to access locations.

Technically, there is a "flash" at the level of the arc current and the resulting light output. But because of the smoothing effect of the phosphors it is more generally considered to be a "flicker".
Add that to the averaging effect of the eyes, with a threshold around 30 Hz, and you get near unnoticeable.
Early LED Christmas light strings with half-wave rectification, on the other hand, was really obnoxious. Especially in terms of the motion strobe effect.

Sent from my Pixel 4a using Tapatalk

In the context of LED ballast failure symptoms, this would not be considered flashing.

 

[Flicker Index]

Um, "traditional fluorescent lights" need a ballast. They also flash at 120Hz (each half cycle).

I don't know of fluorescent lights that don't. "ballast bypass" LED based solid state fluorescent lamps are no more ballast-less than CFLs. They're both integral ballast lamps.

Flicker contents of a line frequency fed LED based lamps (rectified AC fed straight into LEDs through a resistive linear ballast) are similar to that of a clear neon lamp. On the other hand, tri-phosphor or old school cool white traditional fluorescent lamps flicker less, because, at 120 Hz rate, (twice per line cycle) the phosphor blend used provides much more ride-through than blue light activated yellow phosphors used with solid state fluorescent lamps.

 

[AlbertL57]

A photographer in Tampa, FL has been putting them to good use: https://petapixel.com/2022/12/28/ph...lights-that-shine-purple-for-ethereal-photos/ and https://selinaroman.com/section/505171-A Bad Batch.html .

 

[Flicker Index]

High viz is glowing yellow, because, the raw 450nm is causing it to fluoresce. High proportion of this light in significant quantity isn't good for you either. The blue light used by dentists to cure light cured resin is the same wavelength as the exciter in LED based solid state fluorescent lamp sans the phosphor blend. Dentists and hygienists use an orange shield protect their eyes from blue light while working with the device.

 

[AlbertL57]

Apparently there's a collector's market for those lights - see this post on the manufacturer's website: https://acuitybrands.my.site.com/s/article/Purchasing-Fixtures-with-Blue-or-Purple-Color-Temperature

 

[synchro]

Apparently there's a collector's market for those lights - see this post on the manufacturer's website: https://acuitybrands.my.site.com/s/article/Purchasing-Fixtures-with-Blue-or-Purple-Color-Temperature

They're Blue Light Specials.

 

[Flicker Index]

I have an LED bulb in my basement that's starting to do that. I always write the installation date on the bulb base. I'll have to check and see how long it's been in there.

It's annoying but it's not a big deal for a lamp that can be serviced easily. If they're cycling on and off the way HPS do, they can often be ignored until next planned service if there are other luminaires nearby to prevent major dark spot in that area.

However, LED ballast failure often causes the load to flash from zero to full brightness in a rate that can vary anything from an aircraft beacon to police strobe and they become a serious nuisance or even a safety issue necessitating a service call specifically to address that pole to disable it from the hand hole until aerial work can be done. LED light is the only commercially sold lighting products that suffer from disco strobing failure. Perhaps pre-heat fluorescent with glow bottles do as well, but not in the flashing rate and depth that is anywhere near as annoying that goes along with LED ballast failure.