These bulbs are supposed to last much longer than incandescent types. I
have had several of them give up the ghost way too soon (the last was a
Philips brand). Has anyone else had this problem?


---MIKE---
In the White Mountains of New Hampshire
(44° 15' N - Elevation 1580')

Mine don't last very long either. Doesn't matter, they do have a 7
year guarantee, so I keep calling the 800 number and they mail me new
ones. I think the reason they really don't last as long as they say
that they do it because the alleged lifespan is under ideal conditions,
and under ideal conditions a flourescent is on all the time. I try to
only use them in places where the light is on a lot. In places like
hallways and outdoors where flourescents aren't going to work good I
use regular incandescent bulbs.

On Mon, 20 Nov 2006 08:38:11 -0500,
(---MIKE---) wrote:

These bulbs are supposed to last much longer than incandescent types. I
have had several of them give up the ghost way too soon (the last was a
Philips brand). Has anyone else had this problem?

I've installed several of them in my fixtures in the past year, and
none of them have died yet.

Andy comments:

I use them in the summer time when I have to have air conditioning.

In the winter time, I replace them with 100W incandescents.....

Andy in Eureka, Texas

---MIKE--- wrote:
These bulbs are supposed to last much longer than incandescent types. I
have had several of them give up the ghost way too soon (the last was a
Philips brand). Has anyone else had this problem?

Yep. I ran across an article on fluorescent bulb lifespan a while
back. As with incandescent bulbs, turning them on and off is what
shortens the life. If the fluorescent is on 24/7 you'll get the rated
hours. If it's on say a third of that time, you'll get about half of
the rated hours (please note all of my numbers are either right or
wrong or somewhere in between, but the gist of it is correct). The
article calculated that if you were going to be back in the room in a
half hour it made more sense to just leave the light on. This is one
of the stumbling blocks to those automated motion-sensor lights.

The compact fluorescents have healthy warranties - years, so just give
the manufacturer a call.

R

---MIKE--- wrote:
These bulbs are supposed to last much longer than incandescent types. I
have had several of them give up the ghost way too soon (the last was a
Philips brand). Has anyone else had this problem?


---MIKE---
In the White Mountains of New Hampshire
(44° 15' N - Elevation 1580')

Only one of dozens has failed me in 5-7 years, a "Lights of America" or

some-such no-name. Of course, I use them wherever a light would not
be short-cycled- where it would be left on for some time, or off.
Bottom
line: only bathrooms now have incandescents.

True, the one on the porch can take a while to get to full output. Not
a
problem to me.

Meanwhile, each succeeding generation of them seems better than
the previous.

I tried some 40W reflector incandescents in some recessed fixtures;
their longevity was a few months, on average. Maybe resulting from
slight vibration walking on floor above?

J

---MIKE--- wrote:
These bulbs are supposed to last much longer than incandescent types. I
have had several of them give up the ghost way too soon (the last was a
Philips brand). Has anyone else had this problem?


---MIKE---
In the White Mountains of New Hampshire
(44° 15' N - Elevation 1580')

I had an issue with bulbs having very short life in a ceiling fan that
was run more or less constantly; I replaced the bulb with a fluorescent
and it too burned out quickly. However the second fluorescent as far
as I know is still in there and working fine. I'm guessing the
vibration of the fan was causing the incandescents to fail, not sure
why the first fluorescent failed.

I also used one of the fluorescents in a blast cabinet that just ate
light bulbs, that seems to be working out well.

nate

I've had several of these bulbs, and have generally been disappointed
with the life span.
I've had them in lamps and overhead lighting, one of which is a
basement stairs light that I
leave on constantly. That bulb lasted only about 1 1/2 years. The shop
light tubes that I have
last longer than that and they are cycled on and off regularly. Once
the price drops on the
flourecent bulbs to that of incandecents, or once the technology
improves the life span, they will probably be a good choice; but for
now, I'm sticking with incandecents.

Smooth
---MIKE--- wrote:
These bulbs are supposed to last much longer than incandescent types. I
have had several of them give up the ghost way too soon (the last was a
Philips brand). Has anyone else had this problem?


---MIKE---
In the White Mountains of New Hampshire
(44° 15' N - Elevation 1580')

"Andy" wrote:

Andy comments:

I use them in the summer time when I have to have air conditioning.

In the winter time, I replace them with 100W incandescents.....

Andy in Eureka, Texas

I'm going to try the above strategy as well since I
live in north Missouri and winters are cold here.

Do you buy just the reg incandescent? Not halogen or
anything?

wrote:

Only one of dozens has failed me in 5-7 years, a "Lights of America" or

Agree. LOA not lasted well for me either

I HAVE had god luck with the ones that Costco sells
tho.

wrote:
I've had several of these bulbs, and have generally been disappointed
with the life span.
I've had them in lamps and overhead lighting, one of which is a
basement stairs light that I
leave on constantly. That bulb lasted only about 1 1/2 years. The shop
light tubes that I have
last longer than that and they are cycled on and off regularly. Once
the price drops on the
flourecent bulbs to that of incandecents, or once the technology
improves the life span, they will probably be a good choice; but for
now, I'm sticking with incandecents.

Smooth
---MIKE--- wrote:
These bulbs are supposed to last much longer than incandescent types. I
have had several of them give up the ghost way too soon (the last was a
Philips brand). Has anyone else had this problem?


---MIKE---
In the White Mountains of New Hampshire
(44° 15' N - Elevation 1580')

I currently have 4 in service, two outside ones that were installed
years ago. I think I replaced one of them. They are on 24/7. Two are
in table lambs that cycle as any table lamp would - on and off. Been
there a long time and haven't replaced either.

Harry K

RicodJour wrote:

... As with incandescent bulbs, turning them on and off is what
shortens the life.

Not much with incandescents. CFs lose about 6 minutes with each start.

... The article calculated that if you were going to be back in the room in a
half hour it made more sense to just leave the light on.

Sounds wrong, at 10 cents/kWh and $2 for a 6-7K hour bulb.

Nick

---MIKE--- wrote:

These bulbs are supposed to last much longer than incandescent types. I
have had several of them give up the ghost way too soon (the last was a
Philips brand). Has anyone else had this problem?

---MIKE---
In the White Mountains of New Hampshire
(44° 15' N - Elevation 1580')

I've got about 20 or so in use and haven't replaced any of them in ages.
They get varying amounts of on time, from 24 hr on a couple to an hour
here and there on others.

Pete C.

wrote:
"Andy" wrote:

Andy comments:

I use them in the summer time when I have to have air conditioning.

In the winter time, I replace them with 100W incandescents.....

Andy in Eureka, Texas

I'm going to try the above strategy as well since I
live in north Missouri and winters are cold here.

Do you buy just the reg incandescent? Not halogen or
anything?

Andy comments:

It doesn't matter. Electric lights are 100% heat, as they require
no
outside air to come intot the house to emit energy. I like a lot of
light. In the winter,
they supplement my heat --- In the summer , they oppose my air
condx...so
I minimize the sources.

Twenty five cents for a 100 watt bulb is a good space heater. Even
cheaper, joule for joule, than space heaters.... If you like halogen,
get
halogen --- it all ends up as heat energy after it bounces off the
walls
a dozen times.... Whatever is the least expensive, tho the differences
in cost are minimal.

Andy in Eureka , registered PE and retired
engineer

---MIKE--- wrote:
These bulbs are supposed to last much longer than incandescent types. I
have had several of them give up the ghost way too soon (the last was a
Philips brand). Has anyone else had this problem?


---MIKE---
In the White Mountains of New Hampshire
(44° 15' N - Elevation 1580')

I typically get at least one year continious on. Thats well above
normal lifespan. I get 61000 hours. An incandesent is only supposed to
last 1500 hrs, thats with a long lasting bulb.
Cycling and other things will certaily matter.

gs

zek wrote:
---MIKE--- wrote:
These bulbs are supposed to last much longer than incandescent types. I
have had several of them give up the ghost way too soon (the last was a
Philips brand). Has anyone else had this problem?


---MIKE---
In the White Mountains of New Hampshire
(44° 15' N - Elevation 1580')

I typically get at least one year continious on. Thats well above
normal lifespan. I get 61000 hours. An incandesent is only supposed to
last 1500 hrs, thats with a long lasting bulb.
Cycling and other things will certaily matter.

I multiplied wrong. I multiplied time 7. It should be 8760 hrs for the
CF.

gs

"Andy" wrote:

Twenty five cents for a 100 watt bulb is a good space heater. Even
cheaper, joule for joule, than space heaters.... If you like halogen,
get
halogen --- it all ends up as heat energy after it bounces off the
walls
a dozen times.... Whatever is the least expensive, tho the differences
in cost are minimal.

Agree

But do you advise on using 100 watt bulbs and not
something smaller like 60 watt?

Again..... my goals is to use same strategy as you....
use incandescent bulbs abs heater/lights in winter....
and the swap to CF lights in summer.

zek wrote:

I typically get at least one year continious on. Thats well above
normal lifespan. I get 61000 hours.

That's a year on your planet? :-)

Nick

On Mon, 20 Nov 2006 08:38:11 -0500,
(---MIKE---) wrote:

These bulbs are supposed to last much longer than incandescent types. I
have had several of them give up the ghost way too soon (the last was a
Philips brand). Has anyone else had this problem?


---MIKE---
In the White Mountains of New Hampshire
(44° 15' N - Elevation 1580')

Yes, things are tested under ideal conditions. They often perform much
worse in real conditions. You get the same thing with wireless
devices, that give much less range than advertised.
--
35 days until the winter solstice celebration

Mark Lloyd
http://notstupid.laughingsquid.com

"I have found Christian dogma unintelligable. Early
in life I absented myself from Christian assemblies."
-- Benjamin Franklin

On 20 Nov 2006 08:35:53 -0800, "Andy" wrote:


wrote:
"Andy" wrote:

Andy comments:

I use them in the summer time when I have to have air conditioning.

In the winter time, I replace them with 100W incandescents.....

Andy in Eureka, Texas

I'm going to try the above strategy as well since I
live in north Missouri and winters are cold here.

Do you buy just the reg incandescent? Not halogen or
anything?

Andy comments:

It doesn't matter. Electric lights are 100% heat, as they require
no
outside air to come intot the house to emit energy. I like a lot of
light. In the winter,
they supplement my heat --- In the summer , they oppose my air
condx...so
I minimize the sources.

Twenty five cents for a 100 watt bulb is a good space heater. Even
cheaper, joule for joule, than space heaters.... If you like halogen,
get
halogen --- it all ends up as heat energy after it bounces off the
walls
a dozen times.... Whatever is the least expensive, tho the differences
in cost are minimal.

Andy in Eureka , registered PE and retired
engineer

Interesting. Having more energy-efficient light bulbs doesn't help you
when you need heat.

Of course, I live far enough south that it's too hot most of the time.
--
35 days until the winter solstice celebration

Mark Lloyd
http://notstupid.laughingsquid.com

"I have found Christian dogma unintelligable. Early
in life I absented myself from Christian assemblies."
-- Benjamin Franklin

On 20 Nov 2006 06:17:40 -0800, "RicodJour"
wrote:

---MIKE--- wrote:
These bulbs are supposed to last much longer than incandescent types. I
have had several of them give up the ghost way too soon (the last was a
Philips brand). Has anyone else had this problem?

Yep. I ran across an article on fluorescent bulb lifespan a while
back. As with incandescent bulbs, turning them on and off is what
shortens the life. If the fluorescent is on 24/7 you'll get the rated
hours. If it's on say a third of that time, you'll get about half of
the rated hours (please note all of my numbers are either right or
wrong or somewhere in between, but the gist of it is correct). The
article calculated that if you were going to be back in the room in a
half hour it made more sense to just leave the light on. This is one
of the stumbling blocks to those automated motion-sensor lights.

The compact fluorescents have healthy warranties - years, so just give
the manufacturer a call.

R

Then you have to keep records of every bulb in use. Figure out a way
to label the bulbs so as to be able to associate them with the correct
records. Complex record-keeping is one way that people get less value
from warranties than they should. It's too easy to throw away the
"trash" that came with that bulb you installed.
--
35 days until the winter solstice celebration

Mark Lloyd
http://notstupid.laughingsquid.com

"I have found Christian dogma unintelligable. Early
in life I absented myself from Christian assemblies."
-- Benjamin Franklin

---MIKE--- wrote:
These bulbs are supposed to last much longer than incandescent types. I
have had several of them give up the ghost way too soon (the last was a
Philips brand). Has anyone else had this problem?


---MIKE---
In the White Mountains of New Hampshire
(44° 15' N - Elevation 1580')

I guess my experience is different from many of the other posters here.
I have had exceptionally good longevity with most of my CF bulbs. We
have dozens of them, almost every light fixture in our house has a CF.
And we have many of them for over a decade.

I have had two early mortality incidents where two brand new CF bulbs
from the same batch died within a couple weeks of installation. Aside
from that, most failures have been due to breakage. The latest one
broke when my 9-year-old son was throwing a ball in the hallway. (we
made him buy a new on with his own money.) The one before that broke
when we were moving some lumber around in the basement and broke one.
A few others have broken when I was unscrewing them to put them in
another fixture. (We do a bit of shifting around to decide what
wattages are better in different fixtures.) And as others have said,
Lights of America brand is junk. We had a few of those and each one of
those died. Aside from those breakage incidents, and the LOA, I think
only a couple have ever burnt out. I still have the first CF we bought
back when they first came out ~15 years ago. It's not a very good one,
greenish color and not very bright so it has been relegated to the back
of the basement storage area, but it still works as good as the day we
bought it.

We didn't just go out and buy a whole house worth of bulbs all at once,
we tended to buy a few at a time and gradually replaced incandescents,
over a period of about 15 years. So this means that we have a lot of
different generations of CF design. The average age of a CF in our
house is probably about 7 years old, and all of them aside from LOA
seem to be doing just fine.

It appears to significantly reduce our electric usage. We have a 2200
sq. ft. house with 2 adults and 2 kids, and summertime electric usage
is about 200KwH/month. But is goes up in the winter partly due to more
usage of lights, but more significantly due to use of the blower motor
in our gas-fired forced-air furnace. And our stove and clothes dryer
are gas, so that's a couple big electric uses we don't have. Other
than that, we have typical electric loads, so it seems to me that our
electric usage is rather low considering that we don't otherwise go to
any special trouble to lower our usage. So I'm a big proponent of
switching all your lights over to CF.

Ken

"Mark Lloyd" wrote in message

Interesting. Having more energy-efficient light bulbs doesn't help you
when you need heat.

Unless your source of heat is less expensive than electric heat.
If that's the case, it still pays to use efficient bulbs.

Bob

Harry K wrote:

Two are in table lambs that cycle as any table lamp would - on and off.

Ewe sure about that?

R

wrote:
RicodJour wrote:

... As with incandescent bulbs, turning them on and off is what
shortens the life.

Not much with incandescents. CFs lose about 6 minutes with each start.

Incandescent bulbs primarily fail due to the power surge at startup.
Turning them off and on definitely shortens the life.

... The article calculated that if you were going to be back in the room in a
half hour it made more sense to just leave the light on.

Sounds wrong, at 10 cents/kWh and $2 for a 6-7K hour bulb.

You edited out this part of what I wrote: "(please note all of my
numbers are either right or
wrong or somewhere in between, but the gist of it is correct)"

I was certain that would have stopped the bean counters from counting
beans. My error.

R

In , MIKE wrote:
These bulbs are supposed to last much longer than incandescent types. I
have had several of them give up the ghost way too soon (the last was a
Philips brand). Has anyone else had this problem?

There are some reasons this happens - mostly from using them where they
do not do well.

1. Avoid the dollar store ones - I have found them to be stool specimens.

2. Their life will be shortened by being turned on and off a lot. Do not
use them in motion sensor lights. (One exception is the N:Vision 3-watt,
if I am not mistaken about that one being a cold cathode version.)

3. Compact fluorescents easily overheat in small enclosed fixtures,
recessed ceiling fixtures, and other downlights such as ceiling fan
fixtures. This occurs more with higher wattages, especially over 23 watts
(slightly dimmer than a 100W incandescent). Philips SLS ones (not spiral)
of 15, 20 and 23 watts (and not the dimmable one) are specifically rated
to take the heat buildup of recessed ceiling fixtures.

- Don Klipstein )

In article . com,
wrote:
Mine don't last very long either. Doesn't matter, they do have a 7
year guarantee, so I keep calling the 800 number and they mail me new
ones. I think the reason they really don't last as long as they say
that they do it because the alleged lifespan is under ideal conditions,
and under ideal conditions a flourescent is on all the time. I try to
only use them in places where the light is on a lot. In places like
hallways and outdoors where flourescents aren't going to work good I
use regular incandescent bulbs.

Compact fluorescents with outer bulbs over the tubing usually work well
outdoors. They can take several minutes to warm up when it's cold, and
even start off-color when it is cold, but I find them to get to close to
full brightness in several minutes. My favorite here is the 18 watt
Philips EL/O ("Outdoor"). Besides taking cold well, I have found it to
have especially long life.

- Don Klipstein )

In article om, Andy wrote:
Andy comments:

I use them in the summer time when I have to have air conditioning.

In the winter time, I replace them with 100W incandescents.....

If your hiome has gas or oil heat, chances are it will cost less to use
that than electric heating.

- Don Klipstein )

In .com, RicodJour wrote:
---MIKE--- wrote:
These bulbs are supposed to last much longer than incandescent types. I
have had several of them give up the ghost way too soon (the last was a
Philips brand). Has anyone else had this problem?

Yep. I ran across an article on fluorescent bulb lifespan a while
back. As with incandescent bulbs, turning them on and off is what
shortens the life. If the fluorescent is on 24/7 you'll get the rated
hours. If it's on say a third of that time, you'll get about half of
the rated hours (please note all of my numbers are either right or
wrong or somewhere in between, but the gist of it is correct).

Fluorescents are normally rated for 3 hours per start. I wish compact
fluorescents were normally rated for 1 hour per start.

Meanwhile, most incandescents do not suffer much damage from starting.
Even though they usuallie die during a cold start - what mainly happens is
that aging incandescents become unable to survive a cold start a little
while before they become unable to survive continuous operation, due to
temperature overshoot of a thin spot on the filament.
More details in http://www.misty.com/~don/bulb1.html

I once tested one of those "stick on buttons" claimed to double the life
of an incandescent, for voltage drop. It dimmed a 100 watt incandescent
enough to increase its life a good 50%.

- Don Klipstein )

RicodJour wrote:

... As with incandescent bulbs, turning them on and off is what
shortens the life.

Not much with incandescents. CFs lose about 6 minutes with each start.

Incandescent bulbs primarily fail due to the power surge at startup.
Turning them off and on definitely shortens the life.

Not much. Don Klipstein might have something to say about this.

... The article calculated that if you were going to be back in the room in a
half hour it made more sense to just leave the light on.

Sounds wrong, at 10 cents/kWh and $2 for a 6-7K hour bulb.

You edited out this part of what I wrote: "(please note all of my
numbers are either right or wrong or somewhere in between, but
the gist of it is correct)"

I was certain that would have stopped the bean counters from counting
beans. My error.

Your gist is WRONG! Try the numbers, for a 14 W CF.

Nick

I just buy them from Walmart. Lifetime warranty.

--
Steve Barker



"RicodJour" wrote in message
oups.com...
---MIKE--- wrote:
These bulbs are supposed to last much longer than incandescent types. I
have had several of them give up the ghost way too soon (the last was a
Philips brand). Has anyone else had this problem?

Yep. I ran across an article on fluorescent bulb lifespan a while
back. As with incandescent bulbs, turning them on and off is what
shortens the life. If the fluorescent is on 24/7 you'll get the rated
hours. If it's on say a third of that time, you'll get about half of
the rated hours (please note all of my numbers are either right or
wrong or somewhere in between, but the gist of it is correct). The
article calculated that if you were going to be back in the room in a
half hour it made more sense to just leave the light on. This is one
of the stumbling blocks to those automated motion-sensor lights.

The compact fluorescents have healthy warranties - years, so just give
the manufacturer a call.

R

Steve Barker LT wrote:
I just buy them from Walmart. Lifetime warranty.

I have some nearing 20 years old. Most of those have died off though.
You will find a distribution, I did my whole new addtion with them[ say
15 bulbs or more] and lost 2 or 3 pretty quick[months] and none since[2+
years]

On Mon, 20 Nov 2006 10:28:38 -0800, "Bob F"
wrote:


"Mark Lloyd" wrote in message

Interesting. Having more energy-efficient light bulbs doesn't help you
when you need heat.

Unless your source of heat is less expensive than electric heat.
If that's the case, it still pays to use efficient bulbs.

Bob


Yes, I was supposing the people know of the inefficiencies associated
with electric heat.
--
35 days until the winter solstice celebration

Mark Lloyd
http://notstupid.laughingsquid.com

"I have found Christian dogma unintelligable. Early
in life I absented myself from Christian assemblies."
-- Benjamin Franklin

Mark Lloyd wrote:

Yes, I was supposing the people know of the inefficiencies associated
with electric heat.

Agree

But here in north Missouri its cheaper to heat with
electric zone heating right now than it is a forced air
furnace

May not last for long as electric rates go up tho

(Don Klipstein) wrote:

If your hiome has gas or oil heat, chances are it will cost less to use
that than electric heating.

Not sure I agree with that. Maybe

What abt the zone heating that one does with electric
lights as heat source?

usually you will need light in the room you are
in....so by using an incandescent bulb as both light
and heat you zone heat this way

Mark Lloyd wrote:

On Mon, 20 Nov 2006 10:28:38 -0800, "Bob F"
wrote:


"Mark Lloyd" wrote in message

Interesting. Having more energy-efficient light bulbs doesn't help you
when you need heat.

Unless your source of heat is less expensive than electric heat.
If that's the case, it still pays to use efficient bulbs.

Bob


Yes, I was supposing the people know of the inefficiencies associated
with electric heat.

Don't confuse economy with efficiency, they are two different things.
Electric heat is very efficient, but it's usually not economical based
of the current cost of electricity vs. gas or oil.

Pete C.

"Don Klipstein" wrote in message
I once tested one of those "stick on buttons" claimed to double the life
of an incandescent, for voltage drop. It dimmed a 100 watt incandescent
enough to increase its life a good 50%.

Unfortunately, dimming incandescents results in even more
power consumed per unit of light produced.

Bob

Try a different brand. I had trouble with Sylvanias. But other brands last
forever so far.



"---MIKE---" wrote in message
...
These bulbs are supposed to last much longer than incandescent types. I
have had several of them give up the ghost way too soon (the last was a
Philips brand). Has anyone else had this problem?


---MIKE---
In the White Mountains of New Hampshire
(44° 15' N - Elevation 1580')

In article , Bob F wrote:

"Don Klipstein" wrote in message
I once tested one of those "stick on buttons" claimed to double the life
of an incandescent, for voltage drop. It dimmed a 100 watt incandescent
enough to increase its life a good 50%.

Unfortunately, dimming incandescents results in even more
power consumed per unit of light produced.

Yes, well enough known! Power consumption varies with applied RMS
voltage to the 1.5 to 1.57 power or so, while light output varies with
applied RMS voltage to roughly the 3.4 power (more with more severe
dimming). That means light output goes down slightly worse than square of
power input, or energy efficiency varying slightly more than
proportionately with square root of light output (roughly light output to
the .55 power, more for severe dimming).
As in to dim to 50% of light output, power input is maybe about 73% of
"full".

Since most of the cost of operating incandescents is normally
electricity cost, I would put some work into increasing the energy
efficiency. As in making some bulbs turn off when you want less light.

When dimming is done with a resistor (as opposed to a variable
transformer or the usual waveform-chopping "phase control" circuit that
usually has a triac), the energy efficiency story gets worse. To count
power consumed by the infected lamp and the resistor, power consumption is
typically proportional to the lamp's RMS voltage to the .5-.57 power.
This means power conmsumption goes down about 1/6 as much as light output
does (when the percentages are small).
The "stick-on button" that dimmed a 100 watt incandescent lamp enough to
increase its life 50% also reduced the light output by about 11% while power
consumption by the lamp and the "button" was about 98.2 watts (decreased
about 1.8%). Better to just use a longer life incandescent. Depending on
application, often (probably usually) better still to use a compact
fluorescent!

- Don Klipstein )

"Don Klipstein" wrote in message
...
In article , Bob F wrote:

"Don Klipstein" wrote in message
I once tested one of those "stick on buttons" claimed to double the
life
of an incandescent, for voltage drop. It dimmed a 100 watt incandescent
enough to increase its life a good 50%.

Unfortunately, dimming incandescents results in even more
power consumed per unit of light produced.

Yes, well enough known! Power consumption varies with applied RMS
voltage to the 1.5 to 1.57 power or so, while light output varies with
applied RMS voltage to roughly the 3.4 power (more with more severe
dimming). That means light output goes down slightly worse than square of
power input, or energy efficiency varying slightly more than
proportionately with square root of light output (roughly light output to
the .55 power, more for severe dimming).
As in to dim to 50% of light output, power input is maybe about 73% of
"full".

Since most of the cost of operating incandescents is normally
electricity cost, I would put some work into increasing the energy
efficiency. As in making some bulbs turn off when you want less light.

When dimming is done with a resistor (as opposed to a variable
transformer or the usual waveform-chopping "phase control" circuit that
usually has a triac), the energy efficiency story gets worse. To count
power consumed by the infected lamp and the resistor, power consumption is
typically proportional to the lamp's RMS voltage to the .5-.57 power.
This means power conmsumption goes down about 1/6 as much as light output
does (when the percentages are small).
The "stick-on button" that dimmed a 100 watt incandescent lamp enough to
increase its life 50% also reduced the light output by about 11% while
power
consumption by the lamp and the "button" was about 98.2 watts (decreased
about 1.8%). Better to just use a longer life incandescent. Depending on
application, often (probably usually) better still to use a compact
fluorescent!

- Don Klipstein )

But don't longer life incandescents do the exact same thing as your
"button", giving you less lumens per watt?
--
Peace,
BobJ