Author Topic: Detroit LED streetlights already failing.  (Read 502 times)
mdcastle
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Re: Detroit LED streetlights already failing. « Reply #15 on: May 11, 2019, 10:08:26 AM » Author: mdcastle
People in the traffic signal business are not impressed with Leotek LED modules either, preferring GE or Dialights.

The old Detroit street lighting circuits were scrapped, replaced with parallel operation with predominantly above-ground wiring to keep people from stealing it.
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Re: Detroit LED streetlights already failing. « Reply #16 on: May 11, 2019, 10:15:26 AM » Author: mdcastle
The LEDs on the I-35W Mississippi River bridge were before the cheap junk era and they've been going since 2008 without noticeably dimming out or any failures.

One thing is that MnDOT is learning that LEDs are vulnerable to surges, or over-voltage conditions if a drunk driver takes out a neutral. New installations have better fasteners on the neutral wires and surge protectors in the cabinets.
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Lumex120
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Re: Detroit LED streetlights already failing. « Reply #17 on: May 11, 2019, 12:09:35 PM » Author: Lumex120
I'm pretty impressed with how long the I-35 lights have lasted. They aren't very bright  and have kind of an icky color but they are going on 12(?) years old this year and there hasn't been any big issues with them that I know of.
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Re: Detroit LED streetlights already failing. « Reply #18 on: May 11, 2019, 05:22:14 PM » Author: joseph_125
It is not that easy. The isolation transformers just provide circuitisolation and maybe current conversion, but still their output inherites the constant current nature of the main series system. And that does not work with the standard LED ballasts, you would need ones specifically desivned for that operation.
On the other hand it could be as simple as just a bridge rectifier and that isolation transformerbeing designed for the secondary current matching the LEDs, but it is definitely not a standard mains ballast plus a transformer.

In the site I linked you can see the specific isolation transformer is designed for exactly the purpose of allowing LED luminaires to operate on series systems. Of course any old isolation transformer won't work. Anyway I was more bringing up that there exists an off the shelf solution to run LED luminaires on a series system which Lumex120 was wondering about.

Then blame the municipalities for buying the cheapest products they can, and/or the state of your electrical network, and/or how the systems are used (e.g usage outside specified tolerances).

Yeah, the LEDs here that were installed in 2013-2015 still seem to be going strong aside from one or two early failures that got spot replaced. Same thing about the ones in another municipality that installed their LEDs in 2010. Of course they used mostly Philips luminaires which is one of the more decently made LED fixtures.

People in the traffic signal business are not impressed with Leotek LED modules either, preferring GE or Dialights.

Yeah, I believe GE and Dialight have much more of the market share of LED signal inserts too. I guess Leotek is more of a budget option just like their streetlights.
« Last Edit: May 11, 2019, 05:34:53 PM by joseph_125 » Logged
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Re: Detroit LED streetlights already failing. « Reply #19 on: May 12, 2019, 01:43:08 AM » Author: Silverliner
Caltrans had a big problem with the same Leotek fixtures yellowing and browning out. As a matter of fact they dumped Leotek. They now use a manufacturer called SolarMax, a local California manufacturer. They are yellowing somewhat after about two years but none of the problems the Leoteks have.
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Re: Detroit LED streetlights already failing. « Reply #20 on: May 14, 2019, 07:51:21 AM » Author: Prismatic
I've read, that not the LEDs and drivers are failing but the lenses are burnt reducing the light output extremely. Crazy  Huh?

Here it is:
https://www.gannett-cdn.com/presto/2019/05/06/PDTN/570da66a-bca2-4926-8ff3-893258dd3323-Burned-out-Lights-13.JPG?width=1080&quality=50
« Last Edit: May 14, 2019, 07:55:37 AM by Prismatic » Logged

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Re: Detroit LED streetlights already failing. « Reply #21 on: May 14, 2019, 09:13:37 AM » Author: dor123
The lens burned out because of the huge amount of blue light emitted by the blue emitters of the LEDs. And LEDs are considered "No UV"...
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Re: Detroit LED streetlights already failing. « Reply #22 on: May 14, 2019, 10:44:14 AM » Author: Medved
The lens burned out because of the huge amount of blue light emitted by the blue emitters of the LEDs. And LEDs are considered "No UV"...

I doubt the blue photon has enough energy to cause the problem. I would rather guess the cause is a bit different:
The LEDs do not emit any UV at all.
So someone decided the bowl does not need any UV hardening anymore, so cut costs on UV hardening of the used materials (using cheaper material, without UV resistance).
They maybe backed that decision up by "lab tests" with just the lanterns burning, but just inhouse.
But the problem is, when outdoors, the sun delivers A LOT of natural UV with the daylight (it mostly gets diffused by the atmosphere, but the overall intensity is high).
When the lens were designed with the lamp UV in mind so using UV resistant material, the same UV hardening had protected it from the daylight as well.
When the UV hardening was not used "because LEDs do not emit UV", it wasn't then protected against the natural daylight UV anymore and so had yellowed over time.
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Re: Detroit LED streetlights already failing. « Reply #23 on: May 14, 2019, 10:37:12 PM » Author: takemorepills
About 10 years ago, Leotek came sniffing around our traffic signal shop trying to sell us on LED signals. We were already happy with GE and Dialight.
I had noticed, in my road trips, that certain failing signals in California and Arizona looked like Leotek, so I asked the rep if they sold to those areas, they proudly said they did then I let them know that it was obvious, as a visitor to those areas, that their product is cheap garbage.
Even though I didn't have the "authority" to make a decision on behalf of the city, I told them to basically go pound sand, and I lobbied our management to blacklist Leotek. Sometimes, a contractor will install Leoteks, and our inspectors will have them remove the Leoteks and replace with Dialight or GE.

I had no say what City Light does, and City Light did end up buying Leotek street lights, but that's a whole other can of worms
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