# Streetlamp Candlepower?



## Go Go Gadget Flashlight (Sep 25, 2001)

Don't know the candlepower, but the last one I worked on was 400W. Metal-halide, I think...


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## **DONOTDELETE** (Sep 26, 2001)

Whats an average candlepower of a typical
sodium or mercury vapor streetlight?

And for that matter, typical power usage.


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## Brock (Sep 26, 2001)

My brother just put up a 175w Metal-halide and I believe my parents are using a 140w low-pressure sodium. I just have a couple of 13w compact flourescents. I couldn't tell you the CP ratings, but I can say it would take about a 750 halogen to match the 175w MH, or the 140w LPS. Of course the color temps are way differnt.


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## **DONOTDELETE** (Sep 26, 2001)

I'm asking solely to see if it would be feasible to replace a streetlamp with a LED alternative while maintaining or increasing the candlepower and maintaining or reducing the power usage.


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## Brock (Sep 26, 2001)

As far as I know the most efficient light is the low-pressure sodium, the orange ones. They are more then twice as efficient as some of the better LED's, right now anyway. So if you want a lot of light for not a lot of power that is the way to go. Of course you get that lovely orange glow.


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## busbar (Sep 27, 2001)

http://www.darksky.org/~ida/infoshts/is004.html lists 150-watt high-pressure sodium (a fairly common lamp) at 14,400 mean lumens (over the life of the lamp) and 75 lumnes/watt.


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## PeLu (Oct 8, 2001)

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Brock:
*As far as I know the most efficient light is the low-pressure sodium, the orange ones. They are more then twice as efficient as some of the better LEDs*<HR></BLOCKQUOTE>

The larger ones come to 150lm/W, thats about 5-6 times what the best amber LEDs will do. 
A 180W low pressure sodium will come to about 3-5,000 cd


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## LightingGeek (Feb 9, 2007)

Most streetlights are between 70 and 150 watt HID, although you could see some 400 watt streetlights on major intersections in a downtown. Lumen output of these lamps generally run in the neighborhood of 100 lumens per watt, so just do the math.

Candlepower depends on where you are in the "beam", which generally focuses light up and down the street, and between the curbs. 10,000 to 20,000 candlepower (candelas) are not uncommon "in the beam".

LED streetlamps are out there, but the power of LED's is not yet of an intensity to do much unless you pack a WHOLE BUNCH of them in there. There is an intersection in Chicago that's undergoing a test with LED streetlights, but they're really not yet ready for prime-time.


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## petrolux (Mar 7, 2007)

Hi,

Gas streetlamps in the past had 4000 CP and more!

Juergen


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## 2xTrinity (Mar 7, 2007)

> I'm asking solely to see if it would be feasible to replace a streetlamp with a LED alternative while maintaining or increasing the candlepower and maintaining or reducing the power usage.


The advntage of LEDs, which probably won't come until we have one more generation of emitters that can put more light out of a single LED, or maintain the 100 lumen per watt seen at lower power, at higher outputs. The LEDs can potentially be more efficient by using separate optics on each emitter to have greater contorl over the light distribution than with a single point source and reflector. While a lot of HID lamps put out 100 lumens per watt or more, the optics/fixture losses are typically greater, and regularly I see at least half of the lumens coming out of the fixture completely wasted by throwing them over unused/unoccupied land, or up into space. 

A fixture with several adjustable LED lenses that could be pointed/adjusted would be much cheaper than trying to machine a custom reflector for each applicatoin. Another potential advantage is improved color rendering/spectral output, which would make it possible to have the same sort of visibility with less overall light, I know this is a potential advantage of the metal halide compared to the high pressure sodium -- low levels of white light is still useful as your eyes adapt to it, but I find orange light only works if you have ridiculously large armounts of it, which defeats the purpose of the efficiency in many cases. 



> The larger ones come to 150lm/W, thats about 5-6 times what the best amber LEDs will do.
> A 180W low pressure sodium will come to about 3-5,000 cd


There are white LEDs that have 3x the efficiency of amber LEDs, and in the case of the white, you're not stuck with monochromatic amber light. I don't know why anyone woudl explicitly want to reproduce a low pressure sodium spectral output.


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## tenfour (Mar 7, 2007)

http://www.lithonia.com/Energy/EnergyCalculators/PulseStart/default.asp
400w metal halide = ~32000 lumens.

I have one as a grow light in my office =)


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