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

On Fri, 13 Oct 2006 19:59:40 -0400, Bret Miller
wrote:

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?



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

Tube flourescents go from apx 60-110 Lpw, T8 and electronic ballast
would be the best. CFLs are less efficient overall.

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

Bret Miller writes:

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?


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

Bret Miller wrote:
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?


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




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

In article , Bret Miller wrote:

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?


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.

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?


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

In article , m Ransley wrote:

Tube flourescents go from apx 60-110 Lpw, T8 and electronic ballast
would be the best. CFLs are less efficient overall.


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

Don Klipstein wrote:
In article , Bret Miller wrote:


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?


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.


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?


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 )

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
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