How many lumens do fluorescent lights produce? I don't understand why it's so hard to find a STRAIGHT answer?

Question

I've got 2 ft. tubes. Box says 17w but equal to 75w output. Color temp's 7600k. How many lumens do they produce or how do I calculate this?

Answer 1

Best Answer - Chosen by Voters

Your best shot is to go to the manufacturer and get the data. Efficiency of the bulb, gas mixture, color rendering index, all should be available for the individual bulb. So different for so many manufacturers.
The color temperature is very hot, true. 735 is 3500ºK, 741 is 4100ºK, 750 is 5000ºK, daylight lamps are 6500ºK, A Phosfor Major is 7500ºk with a CRI of 92 in a 48" bulb. That is the highest temperature that my supplier sells commonly. 1950 lumens.

Answer 2

The quickest answer is, depending on the diameter of your tube, between about 60 and 90 lumens per watt, so approx. 1275 lumens. Different diameters of tubes will be higher or lower than this (see first two sources).

The reason that this is a hard question to give a straight answer to is twofold. First, lumens are a measure of perceived light, whereas wattage is a measure of power, which is work over time. Since fluorescent bulbs are more efficient than incandescent, they don't use as much power to generate a lumen, and so can achieve similar levels of luminous intensity with fewer watts. Also, since all light sources work at different levels of efficiency, there is no easy conversion between wattage and lumens. There is, however, a handy chart in source two, the luminous efficacy one, with the units for that being in lm/W (lumens generated per watt)

Source(s):

http://en.wikipedia.org/wiki/Fluorescent_lamp#Tube_designations
http://en.wikipedia.org/wiki/Wall-plug_luminous_efficacy#Lighting_efficiency
http://en.wikipedia.org/wiki/Lumen_(unit)

Answer 3

Here are some Mathematical Formulas for Lighting. Hope this helps

Source(s):

http://www.controlbooth.com/forums/colla…

Answer 4

normally the lumens output is shown on the box. generally the efficiency of that 2ft fluorescent is 60-65 lum/watt, no formula is used to calculate the efficiency. the product is tested and the lumens output for each catalogue is shown to the consumers.

looking at the mfg data sheet, typical 2ft tube cat F20T12/W lumens output is 1220. other catalogue slightly different

Answer 5

There are lots of 17W. 2 foot fluorescents.
Initial Lumen Outputs range from 900 to 1350.
Are you sure you don't mean 3600 K. that's about average.
7600 would be bluish.
For comparison, a 75 W -19 incandescent out-puts 750 Lumens.

Source(s):

Retired Electrical Consultant
with Large Lamp Catalogue