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Thread: LED Street lights - getting better

  1. #1

    Default LED Street lights - getting better

    I noticed lately that a new style of LED street light was popping up in a local town, and these were quite a bit different than the ones I've seen deployed in other areas. It's also the first large scale roll-out I've seen of the LED fixtures used for several miles of roadway.

    First thing I noticed about the new lights was the color. My camera balanced in RAW at about 4500k, and visually I'd put them aroudn there. You can see in the picture the oncoming halogen headlamps aren't an extreme difference in color showing how warm these lamps are. No cool-white 'blues' here. What's also interesting is each fixture only has 36 heads - Obviously I can't tell what brand of emitters are, but that is certainly the lowest number of discrete emitters I've seen in such a fixture. Pretty obvious were aren't dealing with under-driven XP-E's.

    The only negative was oddly the color. Something was 'off' in regards to the color rendition, and I have a suspicion these LED's are the infamous 'ANSI' spec'd versions which sacrifice CRI for increased efficiency. I have all brands of neutral white emitters laying around and none are as 'flat' as these lamps were with the exception of a ANSI spec'd neutral white rebel.

    These lights were used to replace mostly mercury vapor fixtures, and the corresponding intensity is very similiar, although they have a far more even spread. In that respect, somebody did their homework. I posted some shots awhile back of some much brighter fixtures used down-town for evaluation, and although much brighter the color was around 6500-7000k and far more annoying.


  2. #2

    Default Re: LED Street lights - getting better

    Is this a complete replacement or a retrofit head? Location?

  3. #3

    Default Re: LED Street lights - getting better

    Quote Originally Posted by blasterman View Post
    These lights were used to replace mostly mercury vapor fixtures, and the corresponding intensity is very similiar, although they have a far more even spread. In that respect, somebody did their homework.
    Almost any "neutral" white LED on the market today from a quality manufacturer would be an improvement over the blue-green spectrum of mercury-vapor lamps.
    I apologize that this letter is so long; I did not have time to write a short letter

  4. #4

    Default Re: LED Street lights - getting better

    Retrofits - West Michigan. I'm trying to find the exact heads being used.

  5. #5

    Default Re: LED Street lights - getting better

    West Michigan?! I'm in GR (home that is, business is just South).

  6. #6
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    Default Re: LED Street lights - getting better

    http://www.designlights.org/solidsta...t_Publicv2.php has an excel spreadsheet of lighting. I'd wager its one on the list. The more fancy certifications you get, the easier it is to get that gov't or grid contract.

    http://www.relume.com/ seems to have grabbed a bunch of contracts.

  7. #7
    Flashaholic* yuandrew's Avatar
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    Default Re: LED Street lights - getting better

    Do you have any daytime shots of the fixtures ?

    I hang out on a streetlight forum/gallery as well so you could try to match it to some of the pictures we have

    http://www.galleryoflights.org/mb/ga....php?album=445

  8. #8

    Default Re: LED Street lights - getting better

    Nope - not on the list. I took a close look at the lights in the daytime and they are unique interms of thermal management. There are two rows of 18 LEDs, and in between them is a rather finely spaced radiator grill. On top of the light there appears to be a cap, which likely protects the fins from debris, bird crap, etc., but still allows air to flow. Looks like somebody took vertical convection seriously. When I have a chance I'll take a picture and post them to that site.

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    Blasterman, do these LED streetlights have a resemblance to flip-flop shoes in daylight? The ones I'm seeing in several neighborhoods around Las Vegas (northwest area of town) look like that, and have very consistent 4500K look about them, almost no variance between examples. I'm 99% sure they are LED because of the spectral shape when checked using a CD.

    These have the fins on top too. At some point I have to get some shots of them.

  10. #10
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    Default Re: LED Street lights - getting better

    Quote Originally Posted by blasterman View Post
    ...There are two rows of 18 LEDs, and in between them is a rather finely spaced radiator grill. On top of the light there appears to be a cap,...
    That would be a fair description of the Relume lights. http://www.relume.com/htm/products_street.htm

  11. #11

    Default Re: LED Street lights - getting better

    bingo

  12. #12

    Default Re: LED Street lights - getting better

    Where in W.MI?

  13. #13
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    The orange sodiums just got swapped out in front of my house today, for what seems like blasterman's LED units. I'm in northwest Las Vegas. They appear to be swapping these out together with street repaving.

    These are not the same units as the sandal-looking things I mentioned earlier; those are in a different subdivision nearby, and have a concentrated spot source within which I cannot discern individual emitters.

    The new ones are wider and have what looks like 2 rows of discrete emitters. The newer units are also a bit warmer/yellower in color than the "sandals".

    I'm going to try and get some daylight pics of these tomorrow.

  14. #14

    Default Re: LED Street lights - getting better

    Where in W.MI?
    In Wyoming, along Michael and 36th Street.

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    *Flashaholic* PhotonWrangler's Avatar
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    Default Re: LED Street lights - getting better

    A month ago I saw some LED parking lot lights show up in my area, and in the last two weeks I noticed a couple of LED streetlights along the freeway near a rest stop. They appear to be test units as there are only two or three of them. I haven't gotten a close look at them yet but they seem ok-ish in terms of brightness.

  16. #16

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    We have a ton of these in Seattle, they've been deploying them slowly for a couple years now.

  17. #17

    Default Re: LED Street lights - getting better

    Michael and 36th. Got it. Thanks blasterman. Time for a ride!

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    Default Re: LED Street lights - getting better

    Finally, here are my shots of the "sandal" LED street lights going in around my neighborhood. Only now do I notice that they are helpfully labelled "LED"

    The wider unit is the one right outside my front door; the longer and narrower units are older by about a year, and are in a neighboring subdivision. Both are definitely using Crees, as you can see from the detail crops; they appear to be XP-E's in the older units, and XP-G's in the newer ones to me. Color temps are cooler in the older units, and seem a bit more appealing to my eye than the new ones.

    The new units look like they have 18 emitters in a spread out pattern (except for 2 pairs of 3 off to one side, not sure what's up there), whereas the older ones have 27 in two tight rows.
    Last edited by Canuke; 04-13-2012 at 05:59 PM. Reason: more details

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    *Flashaholic* PhotonWrangler's Avatar
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    Default Re: LED Street lights - getting better

    Thanks for the great pictures, Canuke! How does the brightness compare between the newer, warmer units and the older cooler ones?

  20. #20

    Default Re: LED Street lights - getting better

    The "Sandal" lights are apparently trying to mimic the footprint of standard "cobra" heads for MH/sodium-vapor streetlights.
    I apologize that this letter is so long; I did not have time to write a short letter

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    PhotonWrangler, the brightness is comparable between them. Together with the possibly better heat dissipation of the spread-out pattern, it seems about right for 18 XP-G's versus 27 XP-E's.

  22. #22

    Default Re: LED Street lights - getting better

    I would almost lean towards XP-G and XM-L purely on the need to achieve a reasonable output to behave as a streetlight. I have my serious doubts about the optical implementation achieving an effective distribution. Can you find out the brand and could see if there is IES files.

    Semiman

  23. #23
    Flashaholic* yuandrew's Avatar
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    Default Re: LED Street lights - getting better

    Canuke: Finally, here are my shots of the "sandal" LED street lights going in around my neighborhood. Only now do I notice that they are helpfully labelled "LED"
    First four is the GE Evolve II Scalable Cobrahead which was just released last summer. The LED and optics assembly can be interchanged/stacked to suit various applications

    http://www.gelightingsolutions.com/R...able_Cobrahead

    The last three with concentric optics is the original GE Evolve

    http://www.gelightingsolutions.com/R...dium_Cobrahead

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    Default Re: LED Street lights - getting better

    Thank you yuandrew. The info there matches what I see, including that the older units are a bit cooler color temps, 4300K versus 4000K for the scalable cobrahead. The newer units also show less color consistency, which makes me think that Semiman is right about the likely emitters; AFAIK there's more of a tint lottery with the XM-L's versus XP-G's, if 4sevens' experience isn't unique.

    The specs for both units say 70 CRI.

    Regarding the light distribution, it seems subjectively "logical" to me, a good compromise between coverage and spill onto nearby buildings, relatively minimal artifacts.

  25. #25

    Default Re: LED Street lights - getting better

    I remember seeing the Evolve in a comparison test and it did rather poorly. I am not surprised. The data sheet ISO plots for the Evolve II on the data sheet look good, but I ran some quick simulations and I am not that impressed. They are rather peaky under the light. The total area is tolerable, but I think a lot of light is being lost by over illumination under the light. No doubt the design is a lot cheaper than some more optically sophisticated designs, but not only is the lumens/watt so-so, but the placement of the light is so-so too.

    Semiman

  26. #26
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    Default Re: LED Street lights - getting better

    Last night I compared two of the nearby Evolve II units with the output from the XR-E 5A and 5B Dereelights I have; the nearest one looked like the 5A (but a bit cooler) while the next one over looked like the yellower 5B. This is as seen from directly underneath; they do get a bit yellower at (directly viewed) angles, as expected from Cree emitters.

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    I just found out that it's a city-wide effort to convert all of Las Vegas to LED lighting, and they just got to my area.

    http://news.yahoo.com/las-vegas-conv...195500084.html

    They just completed my subdivision. In addition to the 4000k units on the side streets, the main roads in the subdivision have the 6000k Evolves with 2 sections.

  28. #28
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    Default Re: LED Street lights - getting better

    Quote Originally Posted by yuandrew View Post
    Do you have any daytime shots of the fixtures ?

    I hang out on a streetlight forum/gallery as well so you could try to match it to some of the pictures we have

    http://www.galleryoflights.org/mb/ga....php?album=445
    That looks like a great resource, and seeing a streetlight forum makes me feel very main stream with my flashlight addiction

  29. #29
    Flashaholic* Kilovolt's Avatar
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    Default Re: LED Street lights - getting better

    About two years ago all the street lamps around my home have been replaced with LED lights of this type:





    they have a total of 49 LED's each (7 rows of 7 LED's) with an estimated power of 150 W each light. Only the complete heads were exchanged while the poles remained the same.

    The change was obviously welcome from an energy saving point of view while actually because the LED's are pointing downwards the illuminated area was significantly reduced in comparison with the previous halogen lights.

    Yesterday night I was dropped by friends at some distance from home and walked down the street, something I seldom do at night, and had an opportunity to check the lights, a total of 12 of them. Well, an average of more than 10% of the LED's are already off, say 5/6 LED's per lamp. Considering that these lights have been on for less than 9,000 hours (12 hours per day x 2 years) I consider this result rather disappointing.

    Any similar experience?

  30. #30
    Flashaholic* Steve K's Avatar
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    Default Re: LED Street lights - getting better

    The lamp is attractive and traditional in appearance, but my first thought upon seeing it was "how do they get the heat out of that??" Poor heatsinking could easily be the cause for early failure. It might also be something more mundane like poor solder joints.

    This reminds me of the LED traffic lights that had segments of dead LEDs. Has there been any public info on why they failed? My assumption was poor heatsinking, since the lights were originally designed for incandescent bulbs, but it would be nice to see the results of a failure analysis.

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