watts to lumens?

Merry Christmas
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Is there a way to calculate how many lumens are produced by a 100 watt halogen bulb. Wait....Scratch that......change "Is there a way to" into "Is anyone able to explain to me how to"


village planning board wants cut sheets, specs and lumens on luminaires to be wired and installed on an historic building prior to issuing the permit.

thanks in advance
 

480sparky

Senior Member
Location
Iowegia
Wattage is power consumption. Lumens is light output.

It's like converting an engine's horsepower to MPG in a car.

I'd contact the manufacturer for cut sheets. Specifically ask for photometrics.
 

james_mcquade

Senior Member
Page 173 of "conversion factors and tables" 3rd edition, says that you can convert
lumens (at 5 550 A and there is a small circle over the A) to Watts by multiplting the number of lumens by 0.001 470 588 2

i hope this helps.
regards,
james
 

mcclary's electrical

Senior Member
Location
VA
Page 173 of "conversion factors and tables" 3rd edition, says that you can convert
lumens (at 5 550 A and there is a small circle over the A) to Watts by multiplting the number of lumens by 0.001 470 588 2

i hope this helps.
regards,
james



There is simply no way this can apply to wide range of bulbs/voltages
 
Most Manufacturers have their Photometrics at their websites. If you know the lighting rep they can send you copies of submittal data with this information.
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
There is simply no way this can apply to wide range of bulbs/voltages

Sorry, James, but I have to agree with Mcclary. It sounds like that conversion is for how many watts a lumen of light at a certain wavelength carries. It wouldn't account at all for any of the inefficencies that happen in the process of converting electricity to light in a pratical lamp. Nor would it consider that the lumens we get are spread across a broad spectrum.

Kind of like the watts to BTU coversion we see posted about every other month. Those don't account for the fact that air conditioners just move BTU's from one place to another.

Steve
 

Cold Fusion

Senior Member
Location
way north
...Kind of like the watts to BTU coversion we see posted about every other month. ...
Yes, we do see those conversions regularly. The part that is mildly disconcerting isn't the efficiency/efficacy issue but rather the conversion. Watts has no conversion to BTUs:

watts btu/hour

steve -
I knew you already knew this, and were just speaking idomatically.

cf
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Yes, we do see those conversions regularly. The part that is mildly disconcerting isn't the efficiency/efficacy issue but rather the conversion. Watts has no conversion to BTUs:

watts btu/hour

Some folks won't let a little thing like mismatched dimensional units get in their way. When I was in the 9th grade, our algebra teacher quit unexpectedly in the middle of the school year, and one of the coaches had to fill in. On the first exam he gave, there was the following question: "How many feet are there in a square foot?" He adamantly claimed that the answer was 4. He didn't keep the job very long.
 
Returned to website!!

Returned to website!!

Gentlemen,

I revisited the lighting company website and found (was it lost?) the elusive spec sheets.... including the lumens ratings. How they managed to hide them from me :confused: on my first visit I'll never know..... there they were plain as day, and I looked!!.

As always, thanks for the replies.

Regards,
Mike
 

480sparky

Senior Member
Location
Iowegia
Page 173 of "conversion factors and tables" 3rd edition, says that you can convert
lumens (at 5 550 A and there is a small circle over the A) to Watts by multiplting the number of lumens by 0.001 470 588 2

i hope this helps.
regards,
james

The symbol you're referring to is for an ?ngstr?m (?), and is a measurement of length.
 

gndrod

Senior Member
Location
Ca and Wa
Lpw

Lpw

"Is anyone able to explain to me how to"

This is a real challenge due to the two different Surface Illuminance methods and Mfr luminaire cut-sheets needed to determine a reflective cavity or workplane surface for a required minimum footcandle (Fc) intensity. (I.e. Lux meter reading.)
Illuminance levels vary by task or mood lighting source distances and comprise a wide color spectrum from 'warm' incandescent to halide 'cool' illuminations that are also replicated by phosphor coatings in fluorescent tubing. (LED technology also has advanced with limited spectral color that almost match warm and cool color temp ranges.)

Photometric charts are needed to define each manufacturer's luminaire type for diffused or direct lighting reflective efficiency from the lamp output efficacy that is usually stated in rated lumens per watt.
Diffused (zonal) lighting is a radiated lighting source commonly found in fluorescent and frosted incandescent lamps.
Direct (point) lighting is a concentrated or focused lighting such as the IR Halogen MR16 and PAR lamps with narrow beam angles. LED's fall into the same narrow usually 10- 40 deg beam angles for distance effective illuminance.

So the challenge to illuminate a historic building depends on the lighting needed to replicate a mood of the era with upgrades that also comply to the minimum lighting codes required. A good start with what is acceptable with the planning board is the best bet before consulting with a lighting design subcontractor.
 
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K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
Some folks won't let a little thing like mismatched dimensional units get in their way. When I was in the 9th grade, our algebra teacher quit unexpectedly in the middle of the school year, and one of the coaches had to fill in. On the first exam he gave, there was the following question: "How many feet are there in a square foot?" He adamantly claimed that the answer was 4. He didn't keep the job very long.

A square square foot or a round square foot?
 
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