# Am I missing something here (leds)



## HARRY304E (Sep 15, 2010)

farlsincharge said:


> I keep seeing company's advertising new led fixtures that are "a direct replacement for 400w metal halide".
> 
> The leds put out somewhere in the neighborhood of 8000 lumens, whereas a 400w metal halide is 36000 lumens.
> 
> What am I missing here?


They have decided *for you* that you do not need 36.000 lumen,s..:blink:


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## 10492 (Jan 4, 2010)

farlsincharge said:


> I keep seeing company's advertising new led fixtures that are "a direct replacement for 400w metal halide".
> 
> The leds put out somewhere in the neighborhood of 8000 lumens, whereas a 400w metal halide is 36000 lumens.
> 
> What am I missing here?


 
36,000 is the initial lumens. 

21,000 is the mean lumens

15,000 is EOL.

LED's are directional, meaning all lumens are headed towards the target area.
MH bulb with 21,000 lumens sends light in all directions. Only 10,500 heads towards the target, the other 10,500 has to be reflected around and steered towards the target, if you will. The amount/angle of reflection, type of bulb, and reflector properties all add loses to the reflected light.

FWIW.


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## Runion Energy (Aug 17, 2011)

Wow somebody that actually understand the new Leds and how they can compare to higher lumen HID system , lay the numbers out on a LM-79 study and see were you end up, Ive seen in some layouts were a 110 watt led will replace a 400 watt HID system you cannot compare apples to apples to different technoliges.


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## 10492 (Jan 4, 2010)

Runion Energy said:


> Wow somebody that actually understand the new Leds and how they can compare to higher lumen HID system , lay the numbers out on a LM-79 study and see were you end up, Ive seen in some layouts were a 110 watt led will replace a 400 watt HID system you cannot compare apples to apples to different technoliges.


Me and electricwhiz went to a job he was doing. He was pulling down HID wallpacks and 400W flood lights from around buildings and replacing them with 100W Induction wallpacks. 

It would appear at one time, someone decided that the orginal wallpacks weren't lighting up the lot enough. 

Someone hung a 400W HPS flood, 12' off the ground, and pointed it at a 65 degree down angle. The hood of the van parked there was 80 FC.
It seems as if when lumen depreciation was happening at this place, someone just kept adding lights. 

Anyway, whiz tore out all of them, and installed 100W Induction WP.

Came out beautiful.

I suppose you could say a 100W (I) could replace a 400W (HPS), once you consider the conditions.


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## electrictim510 (Sep 9, 2008)

LED's are also brighter that your typical fixture of the same lumen output also because of the type of light output it provides. The lumen output that you read on fixture info does not take into account the contribution of Scotopic vision that LED's provide to the sensitivity of the eye. Most info on lumen output only considers Photopic vision which is not the way we see all light, we see light through mesopic vision (a combination of scotopic and photopic vision). More and more we should be seeing more s/p ratios on lights once the industry catches up with current technology.


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## Electric_Light (Apr 6, 2010)

These are some photos and write ups from sites I personally visited:

Arco BP gas station. I'm not sure if this project makes economic sense, but for the purpose of lighting a gas station, subjectively, I found the performance acceptable. 

If the existing MH fixtures are in a poor shape, like yellowed cover, dirty, etc. and compared against brand new, fresh LED fixtures, this improvement can't be credited to LED. 

http://www.electriciantalk.com/f8/l...-case-review-british-petroleum-project-24449/

Pilot project for street lighting. I was less than impressed with the performance. 
http://www.electriciantalk.com/f8/my-impression-led-street-light-field-visit-photos-16716/

Scotopic lumens is not a universally recognized measurement. It is not something unique to LEDs. A 6500K fluorescent lamp has a higher S/P ratio than a 3000K fluorescent lamp, because the blue-rich spectrum has a higher perceived luminous output. For the sake of standardization, scotopic lumens is not used. LEDs are usually 6,500K. For interior lighting, this was one of the major hurdle in acceptance. Warmer color LEDs didn't really come into play in the last 2-3 years.


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## electrictim510 (Sep 9, 2008)

Electric_Light said:


> These are some photos and write ups from sites I personally visited:
> 
> Arco BP gas station. I'm not sure if this project makes economic sense, but for the purpose of lighting a gas station, subjectively, I found the performance acceptable.
> 
> ...


Thanks for the links, I am going to read them immediately. I am semi-new to the lighting side of the business so the more I can soak in the better.

I know that LED's aren't as great as they're hyped up to be, but I think they make for one of the better light types and theyre pretty efficient. Again, I think the numbers are off like all newer technologies but I don't think that disqualifies them as a better option. I am hoping as technology advances abroad and more competition starts kicking in then the cost of LED's drop.


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