LED Wall packs

[Sierrasparky]

I recenlty was looking at a job that called for LED wall paks by RAB. They are 70 watt /91 input watts lumens =5.4k lumens. RAB claims they will replace a 400w MH wall pak. OK fine.

So what I don't get is that the LED has a 60 lumens per watt (LPW) and the 400w MH has 89 LPW. OK
Then my question is how can the LED replace a 400 MH , and how can it do this when the total Lumens are substantial less than the 400w MH @40k lumens

SP

 

[Dennis Alwon]

My understandings is that the way the light is dispersed makes the actual effect the same as the 400 watt. I installed 64 watt LED in replace of 400MH and if the light output is less it is not significant.

 

[Dennis Alwon]

Here is a pdf of the Atlas I used. Go to page 10 and page 11 has the photometrics. Maybe that will help. Atlas Led

 

[ptonsparky]

We used some RAB 23 watt on a small convenience store addition instead of matching the existing 100 w MH wallpacks. I did a rather unscientific walk around the building with a light meter and found the LEDs did a far better job of getting the light to the ground around the store in the area of the walk and immediate parking.

 

[weressl]

I recenlty was looking at a job that called for LED wall paks by RAB. They are 70 watt /91 input watts lumens =5.4k lumens. RAB claims they will replace a 400w MH wall pak. OK fine.

So what I don't get is that the LED has a 60 lumens per watt (LPW) and the 400w MH has 89 LPW. OK
Then my question is how can the LED replace a 400 MH , and how can it do this when the total Lumens are substantial less than the 400w MH @40k lumens

SP

One of the fundamental difference from LED lightsources is how the disperse the light. Whereas an HID radiates light in a nearly 360* sphere must LED sources direct the light in a 120* or even less cone. So with HID lot of the light is utilized by reflectors at a loss or illuminates areas that do need illumination. Thus LEDs appear to provide better illumination WHERE it is needed.

 

[G._S._Ohm]

One of the fundamental difference from LED lightsources is how the disperse the light. Whereas an HID radiates light in a nearly 360* sphere must LED sources direct the light in a 120* or even less cone. So with HID lot of the light is utilized by reflectors at a loss or illuminates areas that do need illumination. Thus LEDs appear to provide better illumination WHERE it is needed.

Yes.

Somewhere I have a spreadsheet tying together watts, lamp efficacy, lumens, beam angle and beam throw. What's never mentioned in all this is "steradians". This is more for spotlights but will work for any light source.

Caveat emptor.

 

[Sierrasparky]

That is some great information. The one thing I don't understand If the LED puts the light where you need it and no wasted through reflectors and such then why do these LED's recieve such lower efficiency ratings than the appear to provide.
For example; if you are replacing a 75w HPS with a 35w LED and the has a lower Lumens and efficiency rating but puts out just as much light on the ground at 1/3 the power consumption I don'd get it.

 

[G._S._Ohm]

at 1/3 the power consumption

I've heard 1/4 or 1/5th.

 

[spark master]

Has anyone replaced a 400w HPS wall pack with LED ?

I'm not sold on LED's yet for replacement wall packs. Only new design.

 

[G._S._Ohm]

Some LEDs can put out 100 lumens/watt but the driver circuitry increases this watts-to-lumens ratio somewhat. I've heard sodium vapor can do 280 L/W of yellow light and a 40W incand. is about 13 L/W.

 

[weressl]

Some LEDs can put out 100 lumens/watt but the driver circuitry increases this watts-to-lumens ratio somewhat. I've heard sodium vapor can do 280 L/W of yellow light and a 40W incand. is about 13 L/W.

All these numbers are meaningless if the distribution efficacy is ignored. In other words: define the specific area you want to illuminate and see the fc levels, average it, hi/lo it ans see which fixture - not just lightsource - gives you more light.

 

[G._S._Ohm]

All these numbers are meaningless if the distribution efficacy is ignored. In other words: define the specific area you want to illuminate and see the fc levels, average it, hi/lo it ans see which fixture - not just lightsource - gives you more light.

And the fixture spacing will determine the uniformity of the illumination, so figuring the lux-to-dollar ratio for a given area at a given distance below the fixtures can be tricky.

 

[ptonsparky]

Trying to figure out LED vs, MH, HPS is easy.:roll:

Start sorting thru all the MFGs of LED fixtures and reading all the different BS most of them are throwing at you, makes a guy want to go back to candles.

5 years and counting.

 

[G._S._Ohm]

...reading all the different BS most of them are throwing at you,...

I'm surprised it took me this long to think of this but I have your post to thank.

You don't need to know steradians, lux, beam angle and all that.

Just pick a similar fixture made by at least five makers. Ask them standard questions, like: cost, lux at 4' directly below and lux at a 45 degree angle from the fixture, power input & PF, etc..

The person who asks the questions controls the conversation and this will put you in control of the conversation.

Repeating this for several fixture types and many makers and then ranking them on Excel will give you a base of 'good choices'. Different makers may be better choices for different fixtures.

If they object to answering your questions by e-mail and insist on calling you, cross them off. Maybe half the makers will cooperate with you.

 

[TNBaer]

All these numbers are meaningless if the distribution efficacy is ignored. In other words: define the specific area you want to illuminate and see the fc levels, average it, hi/lo it ans see which fixture - not just lightsource - gives you more light.

Without question this is fantastic advice.

I am a huge fan of replacing HID wallpacks with LED. It's the one situation where LED is my go-to solution. In this case, don't even pay attention to lumens, it's all a candela game. I've found that I can frequently use 20% of the lumens with a good quality pack and be fine.

However, the 400 watter is a tough nut to crack. RAB's product offering, at this point, really suffers from its early entry into the game. LPW and efficacy are really lacking compared to some of the newer products on hand.

Among reputable manufacturers, Hubbell's Cimmaron Area light with a wall mount may be your best bet: http://www.spauldinglighting.com/products/cimarron_led/

There are other guys saying they can hit this mark. Maxlite says they can hit it with 150 watts: http://www.maxlite.com/products/led-area-light-fixtures (Don't ask for distribution types, though.)

Companies like Duraguard or Tech-D play well in this market with induction. You can also take a look at digital HID with Metrolight or Accendo.

 

[Electric-Light]

All these numbers are meaningless if the distribution efficacy is ignored. In other words: define the specific area you want to illuminate and see the fc levels, average it, hi/lo it ans see which fixture - not just lightsource - gives you more light.

Right, but the sales literature are based on selective interpretation using non-standard methods.

I could say my 3W LED flashlight is comparable to 400W MH if I arbitrarily choose a distance and spot that makes my numbers look good.

i.e. shine the light at a spot on a sign that needs to be lit up at say 15'. I mess with the optics.
I choose a generic metal halide flood light. I then only then take measurement at where the flashlight's hot spot lands, then write up a conclusion that "it's equivalent" and answer "fc level was the same" to inquiries.

LEDs are often pre-fitted with optics at individual chip.


The classic 175W metal halide looks like an AA battery sized arc tube approximately positioned within a 20oz coke bottle. This doesn't give much room for effective optics sized to fit within a 175W wall pack. The optics within wall packs are fairly primitive. These days we have smaller ceramic metal halides and more efficient solid state control gears to go with them.

That's not a reason to credit LED technology as being superior to HID.
Brand new best available HID source with best optics will be superior to 30 year old HID wall pack.

http://www.luminairetesting.com/Files/Roadway.pdf

Don't let sales people decide the equivalency. Get a copy of relevant report, like the one above.

 

[Sierrasparky]

Looks like some better standards are needed.

 

[Electric-Light]

Looks like some better standards are needed.

They like to obfuscate things by hiding behind "its 150W equivalent, because we said so" while refusing to publish or not even having relevant reports.

It's not fully substitutable unless the photometry is identical. Once there's a light distribution report from a reputable source, we can then discuss if the source is carbon arc, plasma ball, wrath of god, LED, MH, whatever. The report should be made from industry accepted data.

 

[Electric-Light]

...

 

[TNBaer]

They like to obfuscate things by hiding behind "its 150W equivalent, because we said so" while refusing to publish or not even having relevant reports.

It's not fully substitutable unless the photometry is identical. Once there's a light distribution report from a reputable source, we can then discuss if the source is carbon arc, plasma ball, wrath of god, LED, MH, whatever. The report should be made from industry accepted data.

I think we're getting there with the Lighting Facts label. Given, the label doesn't address photometry but it's a huge, HUGE step in the right direction. Photometry is so important on a case by case basis I don't know if some sort of standardization is ever possible, and even if it is, will contractors know how or bother to use it?