Author Topic: Energy saving street lamps?  (Read 7792 times)

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Offline coppice

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Re: Energy saving street lamps?
« Reply #75 on: September 25, 2018, 10:31:20 am »
electronics can be made to last, but phosphor coatings still have a limited life.
Do you have any information about that? I looked recently, and couldn't find anything. Flourescent tube bombard the phosphor quit e hard with heavy ions, and the best lifetimes are something like 10k hours. Electron devices bombarding with electrons get a lot more life, but eventually fade. What sort of life do you get just bombarding with not too extreme photons?
 

Offline james_s

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Re: Energy saving street lamps?
« Reply #76 on: September 25, 2018, 10:32:07 am »
Well we already know that 10 years is achievable, the first LED streetlights I saw started going in around then and at least some of those are still in service. I think a 10 year lifespan is a pretty reasonable goal. When you figure most HID sources are relamped about once per 3 years and labor is the largest part of that cost, a 10 year LED luminaire is looking pretty reasonable. Claims much longer than that, well it may be doable but I wouldn't bank on it. There's s good chance whatever company sold them won't be around by then anyway.
 

Offline james_s

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Re: Energy saving street lamps?
« Reply #77 on: September 25, 2018, 10:37:37 am »
electronics can be made to last, but phosphor coatings still have a limited life.
Do you have any information about that? I looked recently, and couldn't find anything. Flourescent tube bombard the phosphor quit e hard with heavy ions, and the best lifetimes are something like 10k hours. Electron devices bombarding with electrons get a lot more life, but eventually fade. What sort of life do you get just bombarding with not too extreme photons?

That's not an easy question to answer. "Lifespan" is normally defined as time before L70, i.e. lumen output 70% of initial. The decay is roughly a halflife and depends heavily on how hard the phosphor is driven, chemical composition, quality, etc. If you use a good phosphor and don't pump it too hard, it can last a very long time. Use a cheap phosphor like low cost 5mm white LEDs and it will fade in just a few months.
 

Offline stj

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Re: Energy saving street lamps?
« Reply #78 on: September 25, 2018, 10:48:08 am »
the phosphor gets damaged by heat from the dye more than anything.
 

Offline SiliconWizard

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Re: Energy saving street lamps?
« Reply #79 on: November 10, 2018, 01:36:02 pm »
Speaking of surveillance cameras coupled to bright streetlights:

https://qz.com/1458475/the-dea-and-ice-are-hiding-surveillance-cameras-in-streetlights/
 

Offline Audioguru

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Re: Energy saving street lamps?
« Reply #80 on: November 26, 2018, 05:10:52 am »
In my city, we save energy on the new LED streetlights because some of them do not work (Chinese ones?).
The streets are still dark all night because most lights are shaded by trees.

Why do cars have headlights? Duh, to see the road at night? The streetlights are to light the road for little old lady drivers who do not know how to turn on the headlights and the car maker saved a few cents by not making headlights automatic.
 

Offline stj

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Re: Energy saving street lamps?
« Reply #81 on: November 26, 2018, 02:19:52 pm »
no, streetlamps are for people on foot. (and government camera's)
though obviously they let you see more road than your car will illuminate.
 

Offline coppice

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Re: Energy saving street lamps?
« Reply #82 on: November 26, 2018, 08:35:35 pm »
Why do cars have headlights? Duh, to see the road at night? The streetlights are to light the road for little old lady drivers who do not know how to turn on the headlights and the car maker saved a few cents by not making headlights automatic.
Most of the UK's motorways were built without street lights. The high death rate resulted in all the junctions being retrofitted with lights. The still not very good death rate resulting in the eventual lighting of the entire motorway network. Its not just about providing light for pedestrians. Before the motorways were lit they were OK to drive on in the middle on the night, when they were fairly quiet. In the winter rush hours they could be pretty scary.
 

Offline stj

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Re: Energy saving street lamps?
« Reply #83 on: November 27, 2018, 12:41:20 am »
i mostly used them in the night,
so just following the "cats eyes" like a 70's video game!  :-DD
 

Offline grumpydoc

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Re: Energy saving street lamps?
« Reply #84 on: November 27, 2018, 02:23:07 am »
The still not very good death rate resulting in the eventual lighting of the entire motorway network.
The whole of the UK motorway network is not lit, I don't even think all the junctions are, maybe all of the motorway-motorway intersections but certainly not all the junctions.

 

Offline coppice

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Re: Energy saving street lamps?
« Reply #85 on: November 27, 2018, 02:26:17 am »
The still not very good death rate resulting in the eventual lighting of the entire motorway network.
The whole of the UK motorway network is not lit, I don't even think all the junctions are, maybe all of the motorway-motorway intersections but certainly not all the junctions.
Perhaps. There is certainly a lot more lighting than there used to be. Even the M25, running through suburban London, was mostly unlit for years.
 

Offline grumpydoc

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Re: Energy saving street lamps?
« Reply #86 on: December 03, 2018, 12:29:44 am »
There is certainly a lot more lighting than there used to be.
M25, perhaps.

They've actually reduced lighting on the M5 Strensham to Birmingham stretch.
 

Offline james_s

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Re: Energy saving street lamps?
« Reply #87 on: December 08, 2018, 05:09:55 am »
You would need extremely bright headlamps to not be over-driving your lights at highway speed. Street lighting allows you to see further up ahead than you otherwise could, and also lets you see anything off to the side that could potentially become an obstacle, such as wild animals. Accident rates on unlit roads are much higher than lit roads, all else being equal. Street lighting done properly improves situational awareness.
 


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