Lumens per watt - do they vary within a given bulb type?


A simple question from a simple mind. You have two lights, both fluorescent and both 40 watts. On light is 36" long, the other is the spiral type that fits in a regular incandescent socket. Do they both give off the same amount of light?
And, do different 40 watt 36" bulbs give off different amounts of light, or does it just seem that way based on the "Temperature" of the color?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 13 Oct 2006 19:59:40 -0400, Bret Miller

They do differ, since watts is a measure of what energy is consumed, while lumins is a measure of light emitted.
Check the markings on the packages.
later,
tom
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Tube flourescents go from apx 60-110 Lpw, T8 and electronic ballast would be the best. CFLs are less efficient overall.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I agree for ones 3 feet or longer and ones with electronic ballasts (which includes most 17 watt T8 (1 inch diameter) 2-footers - although 110 sounds awfully high to me, I would say don't count on more than 100.
Lower wattage linear fluorescents (less than 15 watts) tend to underperform compact fluorescents in my experience. It gets to be a close call for 15 and 20 watt linear fluorescents, but my experience tends to slightly favor compacts. 15 watt linear ones achieve 60 lumens per watt when all is well, except the wattage figure does not count ballast losses of typically 3 watts. Ballast losses are included in the power consumption for compact fluorescents with integral ballasts, as in the screw-in types.
Many compacts now achieve 60 lumens/watt, and I have seen 70.
- Don Klipstein ( snipped-for-privacy@misty.com)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Bret Miller writes:

Yes, things like various phosphors affect luminous efficiency. Gets worse as the tube ages. Your eyes are more sensitive to the middle of the light spectrum than the ends.
Color "temperature" is used of fluorescents, but they don't really have a temperature, they just evoke a perception of approximating one, typically not very well. It's an illusion to the eye, which is why your digital camera photos don't look right under fluorescent lighting.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Bret Miller wrote:

Yes, but not always by type. Different brands and different lines of the same brand can be far different. Fixtures also can make a difference. Check the specs on the lamps.
--
Joseph Meehan

Dia duit
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Are you sure you have a 40 watt 36"? 40 watt is usually 48" and 30 watt is usually 36".
Unlikely. A good 3-footer or 4-footer produces more light than a good spiral of the same power consumption. However, if one is og good quality and in good condition and at a favorable temperature and the other is not, the better one may produce more light regardless of which is a 4-footer and which is a spiral.

Light varies with a number of factors:
1. Age, condition and actual temperature of the bulb
2. Quality and general type of the ballast of the ballast (electronic ballasts tend to be better, and the "residential grade" ballasts in cheap fixtures are often what I would call stool specimens.
3. Phosphor formulation of the bulb - which affects color temperature and color rendering properties. There is a usual trend for less light if the color temperature is higher than 4100-5000K and/or if the color rendering index is higher than 86.
- Don Klipstein ( snipped-for-privacy@misty.com)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Don Klipstein wrote:

And to amplify on what Don is saying, there are multiple manufacturers for each lamp type. From manufacturer to manufacturer, from regular to extended life, light output varies.
Just go to a site like 1000bulbs.com and SEE how many variants of bi-pin 48" lamps there are. And Don is correct 30 watt linear is 36" and 40 watt linear is 48" You are mixing apples and oranges in your description.
And at that same web site, i see a CFL 40W 500K with 2600 lumens initial output, and a Sylvania bi-pin 40watt 5000K with 2200 lumens output.
The CFL will seem to be BRIGHTER as the light source is more of a point source compared to the spread out illumination of a linear lamp
And I see now that my kitchen lamps available in 5000K. We'll move before we need more, as I have spares on hand and we move early next year. New owner gets the spares
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.