Gee, as if nobody saw this coming... 

https://www.detroitnews.com/story/news/local/detroit-city/2019/05/07/detroits-led-streetlights-going-dark-after-few-years/3650465002/

they should have just installed HPS lights to replace the nonworking ones.

Here's the issue.  The manufacturers didn't do long term mass testing.  Long term as in 5+ years of testing.  They all rushed to get things to the market to beat out everyone else and to satisfy the tree huggers.  That being said, these LEDs are here to stay.  Detroit will just go with another manufacturer.  Don't expect them to return to HPS or MH or MV lighting.  But it might keep some municipalities from rushing to switch to LED. 

I think they're also suing Leotek over this.

These LED stories gets me very angry. Why Detroit didn't expected from these LEDs to EOLED fast? 4 years is the average life of LED lighting in extreme cases.

I agree. They should have just replaced the fixtures that didn't work with new HPS ones. Or even PSMH. The money they would have saved from switching to LED in the long run, well that's long gone now. They're gonna have to invest more money and time in going back out and replacing all those failing LED's, and hope that those last their expected life. What a waste, and a joke. One more reason LED doesn't belong in streetlights.

IIRC their problem with the original series MV system was more with people stealing the wiring for scrap than the actual lighting equipment going bad. Unfortunately I'm not sure if enough series equipment is still made to restore the old system to working order and a conversion to 120/240v multiple would have meant reballasting all the luminaires and MV ballasts were already banned at the time. I guess you can reballast with probe start MH gear and continue running the MV lights on a multiple system.

Do those LED lights run on series circuits? Never heard of series LED but it's possible I guess.

Also, probe start metal halide would be a pretty bad choice for streetlighting there. The lamps dim out quickly and don't last very long.

I don't think any LED fixtures come with native support for series but you can run them on a series system with an external isolation transformer. As far as I know, series systems are long gone here so I haven't seen one of those transformers in use.

Heh, I was joking about keeping them MV but running the lamps off a MH ballast since you can't get that quantity of MV ballasts anymore.

...you can run them on a series system with an external isolation transformer.

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.

The Detroit municipality is also to blame for choosing cheap products over the more expensive and reliable luminaires from reputable manufacturers... in the best case we could just say that they were gullible and believed the claims from Leotek (who the heck is this company anyway? what's their legacy on the lighting market?).

There's no question that LEDs are here to stay. Nowadays the efficiency of good LED fixtures (the keyword is "good", not "cheap junk") is much better than that of the best HPS systems out there. Also, saying that "4 years is the average life of LED lighting in extreme cases" is plainly ignorant of the state of the art in LED technology - I know of some actual LED installations here which are more than 10 years old and that are still going strong.

I never seen LED installation that don't lasts more than 4 years. Even the Schreder Teceo 2 at HaDeshanim Road/Kiryat Ata Junction, flashing or not working, and they began to do this month after their installation, and they have Philips made drivers.

I never seen LED installation that don't lasts more than 4 years. Even the Schreder Teceo 2 at HaDeshanim Road/Kiryat Ata Junction, flashing or not working, and they began to do this month after their installation, and they have Philips made drivers.

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). The fact that the "Schreder Teceo 2 at HaDeshanim Road/Kiryat Ata Junction" (just one specific case, seriously?) fail so early in life (just one month after installation) is a clear indication of improper use of the equipment (voltage outside tolerances, faulty neutral or ground, spurious voltage spike in the network causing driver failure, etc...). In the very unlikely case of early failure due to improper product design (this must be a really bad design for failure to occur naturally just one month in), then if the luminaires are from serious and reputable companies, municipalities will get replacements as per the warranty, so no harm done.

It's not because the situation with LEDs is crappy in your country that it is the same everywhere, so please don't generalize like you always do, that only reveals your ignorance in this matter. Here is Northern Europe (except UK, apparently) the situation is far better with LEDs because we have the sense of installing proper quality luminaires (well, in most cases - there still are the occasional poorly-specified installation here and there; that was true back then, it is still true now). We know that it pays in the long term... going for the cheapest stuff always ends up costing you more in the long run, and Detroit is proof of that.

The Detroit municipality is also to blame for choosing cheap products over the more expensive and reliable luminaires from reputable manufacturers... in the best case we could just say that they were gullible and believed the claims from Leotek (who the heck is this company anyway? what's their legacy on the lighting market?).

There's no question that LEDs are here to stay. Nowadays the efficiency of good LED fixtures (the keyword is "good", not "cheap junk") is much better than that of the best HPS systems out there. Also, saying that "4 years is the average life of LED lighting in extreme cases" is plainly ignorant of the state of the art in LED technology - I know of some actual LED installations here which are more than 10 years old and that are still going strong.

Leotek was founded in 1992, and are one of the early companies behind the push for LED light. They started with LED traffic signals, but only entered the streetlight market in 2007. They never produced HID lighting, only starting with LED type. Their fixtures seem to me more techy and don't have the same form factor, of those companies such as AEL or Cooper that were in the market decades before they produced LED lights.

OK, so it's a very young lighting company with experience primarily in low-power LED systems (traffic lights)... that doesn't amount to much compared to GE, Philips and Ledvance/Osram, especially since the thermal design of high-power LED systems is completely different from that of traffic lights. That's no wonder that their streetlight luminaires show some severe thermal degradations; they did not have decades of experience with high-temperature lighting systems (e.g. HID streetlights) when they began assembling their first LED streetlight luminaires. This is still a major problem nowadays judging the observations of Detroit's maintenance engineers.  

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.