The impending death of incandescent bulbs

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The impending death of incandescent bulbs

Post by philba » Mon Apr 09, 2007 12:53 pm

The writing is on the wall - incandescent bulbs (IBs) will be phased out of the next 5-10 years in favor of the much more energy efficient CFLs. Numerous jurisdictions are moving to outlaw IBs.

I would guess there are at least a few dimmer circuits in every house in the USA. Mine has probably 20. Has anyone played with dimmable CFLs? They are frightfully expensive - about $10 bucks each - but do they work well at all? And do they work off of a standard TRIAC based dimmer?

Any info on this would be greatly appreciated.

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Post by haklesup » Mon Apr 09, 2007 1:22 pm

The writing is not on the wall, its right here

Tell me about it. I just had a building inspection last week on a Kitchen /bath remodel project (final). They guy basically didn't look at anything related to plumbing or electrical code per se (they kind of did in the rough inspections). He focused primarily on the California Title 24 energy Standards.

Dang, after reviewing the spec, you are required to have high efficiency lighting (>40lumens/watt)(for now that primarily means fluorescent but also includes LED) in most living areas. Standard incandescant fixtures with CFC bulbs don't count. They have to be fluorescent only fixtures. In the bath they allow incandescent only if you have a "manual on, automatic off motion sensor switch (@ $24 each). In living areas, incandescent must be on a dimmer and in the kitchen, you have to have 50% watt per watt incandescent to high efficiency.

Simply put, you cannot leagally install an incandescant fixture in new or remodeled construction if you get a permit in CA (and a few other states with similar regs) with some exceptions for automated switches and dimmers. This extends to exterior lighting as well which requires a PIR. In other words, you're not allowed to forget to turn the lights off if they are incandescent.

And thats just the lighting stuff that applied to me. It goes on to dictate insulation and plumbing requirements as well. This goes well beyond the any normal "building codes". You can build to Code Plus standards and still fail title 24 specs.

The old spec was worse on some things, better on others but basically impossible to read no matter what. The new spec is very reader friendly with FAQ type sections in each chapter. (my permit spanned both specs so I was able to confuse him out of rejecting my kitchen overhead for having 300W incandewscent and 128W fluorescent, we reasoned the incandescent part as task lighting and ignored it under the old spec, can't do that now)

I've not used dimmable CFCs but I was also wondering if the more expensive CFCs were worth it (as opposed to the real cheap subsidized ones). Do they warm up faster, last longer, what.

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Post by Bob Scott » Mon Apr 09, 2007 6:05 pm

In Canada a similar ban on use of incandescent bulbs is being proposed by the NDP opposition party. I think the politician in question, having seen the legislation spreading out of California, is just grandstanding for votes because the proposal may not be suitable for all locations outside of California. California houses don't use furnaces or heaters so much in the wintertime as the rest of US and Canada. Outlawing regular light bulbs here in the BC and Washington northwest or makes no economic or environmental sense.

In the wintertime, every watt used by the light bulb is used. It produces light and heat. The so-called inefficient heat produced by the bulb helps heat my house. Even the light waves, when they finish bouncing around and interior room, are absorbed by the walls and converted into heat. This heat takes a load off the furnace which does not have to produce all the heat.

I did a bit of research and you can do it too. Visit Wikipedia for everything you ever wanted to know about light bulbs. They even mention the California legislation and other juristictions where it is spreading. You'll also need to know what you are paying per delivered kilowatt hour for electricity and how much you pay per delivered gigajoule for gas heat. (In California, gas is charged by the million BTU. 1 million BTU = 1.055 gigajoule.) I'm assuming most people with fuel burning furnaces use gas. I have no idea how many people still use oil or how much energy it has per unit volume.

A joule is equal to a watt-second, so 1 gigajoule = 278 Kilowatt-hour.

I compared the cost of electricity here in Vancouver at 6 cents/KWH with gas at $11.30 per gigajoule.

So gas is 11.30/278= 4.06 cents per kilowatt. But since my furnace is just a standard 30 year old model with about 70% efficiency, I only get a value of 5.8 cents per kilowatt-hour for gas. TADAAAA! That is so close to the same cost as electricity at 6 cents.


1) For me, saving money on energy by using efficient light bulbs in the winter makes no sense. Also,

the CFL bulbs cost more. CFL bulbs failure rate increases when you turn them of and on often (see Wikipedia info.)

2) Anybody in a state or province with a detached garage knows fluorescent bulbs don't work in the cold of winter. You must use incandescent bulbs for exterior lighting.

3) My using more electricity (eco-friendly hydroelectric power from water dams here) while using less hydroCARBON gas is better for the environment than relying 100% on my furnace for heat.

4) During summer, days are much longer here. Much less electric lighting in the morning and evening while the sun is still out.

Arnold should have explained this stuff to the immitator politicians who are unschooled in issues of technology. Legislation good for sunny southern California may not work elsewhere. One size does not fit all.

Bob :cool:

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Post by dacflyer » Mon Apr 09, 2007 6:11 pm

CFL's altho great. and all...they will never completely replace filiment lamps..

CFL's cannot replace halogens..they cannot reproduce the came color or intensity, also CFL's cannot burn worth a flip in cold weather..

i haven't seen any dimmable CFL's but i have seen the 3-way lamps.
i didn't like mine..because it flickered on low and med levels..but it was fine on Hi..

also theres not a good selection in color tones.
i had to go to a special dealer to get some cool whites..
in the big box hardware stores, you only can find either warm white (yellowish ) or daylight (bluish) , hard to find cool whites.(white light)

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Post by Chris Smith » Mon Apr 09, 2007 6:28 pm

Send them all to me.

In winter they double as small heaters and light, saving me a fortune.

Normally I would have to use a small amount of heat on windy or slightly cold day, or just use incandescent bulbs that produce both heat and light.

Efficiently as well.

100 watts of heat, or three.

I know which ones I use in winter.

In summer its just a quick change of bulbs.

Like every energy saving device we have, we also have government, and thinking past the nose is not required.

They deal with sheep, and sheep aren’t allowed to think either.

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Post by Robert Reed » Mon Apr 09, 2007 8:51 pm

Ahhhh- the soft glow and warmth of incandescant bulbs - something flourescent can never replace.

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Post by haklesup » Tue Apr 10, 2007 12:45 pm

It looks like one great hope for the future will be deep IR LEDs made of Zinc Oxides that can be coated with phosphors to emit any color they want. Then we can have LED lamps with decent color.

Title 24 only regulates permanently installed fixtures such as recessed lighting. Much of the waste heat for those fixtures is retained in the surrounding materials. Go ahead and heat your house with incandescent light bulbs :shock: , just do it with table lamps so the heat can get to you. I have heard of people keeping the freeze out of an outdoor shed with a couple 100W bulbs and that seems like a good use until they burn out on a cold night or continue to light when the temp is above freezing. A space heater is more reliable and efficient in the long run.

The real problem is that there just aren't that many aesthetically pleasing fluorescent fixtures. The electronics design trade mags and emails are packed with new developments with LEDs every month, This is predicted to exceed all other forms of lighting by 2025. While this limitation is a problem for homeowners in the short term, it opens up many opportunuities for new companies to emerge as LED general lighting matures.

"1) For me, saving money on energy by using efficient light bulbs in the winter makes no sense. Also,"

All you need to do is chart your utility bill (electric lighting only if you can seperate it out) vs the day length to see how little sense that makes. And just when does saving money ever not make sense?

"2) Anybody in a state or province with a detached garage knows fluorescent bulbs don't work in the cold of winter. You must use incandescent bulbs for exterior lighting. "

You can, even in CA, they just want you to use a timer or PIR to control them so you don't unintentionally leave them on all day. The most restrictive specs are for the Kitchen and Bath. The 2001 spec allowed no incandescent, the 2005 spec allows some by ratio or with special switches. This is to recognize the limitation in choices for HE lighting. The 2008 spec, who knows.

"3) My using more electricity (eco-friendly hydroelectric power from water dams here) while using less hydroCARBON gas is better for the environment than relying 100% on my furnace for heat. "

Over there in Vancouver, you may be able to convince yourself of that but in Canada as a whole, this is not a very complete picture. See this article from IEEE spectrum\ . THere are also serious envrornmental issues pertaining to the creation of new hydroelectric dams as well, you just can't put one anywhere. If your population grows too much and all of you have the same attitude, you're gonna need more power eventually.

True enough most Californians live in a mild climate but that dosen't mean that high efficiency lighting (or ample insulation or appropriate roof coatings or insulated pipes or or ) won't benifit someone from minnisota just as well (probably more so since at a more northern lattitude would have longer nights in the winter). Legislation dosen't tell you what replacement bulb to buy, it just makes sure contractors don't build inefficient homes from the start out of habit or a desire to skimp on costs. We who do our own remodeling are just caught in the middle cause the law treats everyone the same (supposedly).

Californians use more power in the summer on cooling (I own no AC equipment whatsoever) so the spec goes deeply into insulation and exterior materials (reflective roofing for example ) and HVAC regulation. HE lighting is just part and parcil to the whole picture.

Economically speaking, well built, energy efficient homes sell better and for higher prices. There really is no reason to avoid the spec, its just a pain when you overlok a detail.

If you want to see how well you are doing, try to fill out these compliance forms and do the calculations. (actually it seems too complicated to bother but FWIW) ... _Forms.pdf

We are told there are at least two reasons to conserve energy (or more precisely, regulate what types of energy we use for each purpose)
1. to save money
2. To save the envoirnment even when it cost more money (voilates #1) (for example; hybrid cars).

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Post by k7elp60 » Tue Apr 10, 2007 3:26 pm

My two cents worth. I don't like the fluorescent or LEDs lighting, especially as for reading lights. I think they are a poor substitue for the incandescent bulb. I have some solar panels to charge batteries for my
amateur radio station equipment. I went one step further and installed some RV light fixtures in several places in my home that I use for reading. These fixtures work off 12V dc and are used for mostly reading. I even developed a slow start circuit for them that extends the life of the incandescent bulb for a long time. Two bulbs have been in the fixtures for over 5 years and they are used almost every evening. I approached the RV manufactures to see if they were interested in the bulb saver. The only company that responded to me told me in no certain terms they wouldn't be interested in my circuit. With my current supply of bulbs I won't have to buy bulbs for the fixtures ever.

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Post by dacflyer » Tue Apr 10, 2007 4:11 pm

i wish it was possible to hack some of the CFL's to use them on 12volts.

and i do not mean using a inverter either :P

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Post by Chris Smith » Tue Apr 10, 2007 4:28 pm


Leds are a lot further along than mentioned in the general population. The technology of how to produce more light from the standard LED alone has moven way further than is mentioned in general text.

The different types of material is still moving forward but some of the simplest mechanical ideas ever thought of have improved the LED way past 200% mark from old, and that’s just mechanical.

Also Chemically speaking we have moved light years forward and that’s not slowing down either.

Every month I read about the technical advances of LEDs in the auto industry and the home which would have never existed just ten years ago.

Now the big deal with LEDs is that they produce way too much light quantity and safely for the human eye? Big turn around.

Light bulbs for heat should always not be “buriedâ€

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Post by Dean Huster » Tue Apr 10, 2007 5:12 pm

k7elp60, here's a LONG dissertation on incandescent lamps that is interesting, albiet a bit dated now that the word passe is now being used more and more with them. As I recall (I haven't read this in several months), the lower-voltage lamps tend to have longer lives anyway because of the more-robust filament. Please forgive the fact that the illustrations are non-existant -- they won't come through the translations process I use for converting from WordPerfect 8.0 format to the forum. Here's the piece:


The following material was published as part of a Tektronix, Inc. internal publication, one of their "catalogs" published for company design engineers for the selection of parts already contained within the company's inventory. It is reproduced here as it is a pretty good source of information on incandescent lamps.

The second you turn on a miniature incandescent lamp, it begins to fail. The lamp filament must be placed in a deterioration or failure mode in order to produce illumination.

Application and environmental conditions under which a lamp operates have a different effect on lamp life. Thus, actual lamp life can vary from five seconds to many hours, depending on lamp design, applied voltage, environmental constrictions and applications.

How is lamp life determined and what tradeoffs must be made to maximize incandescent lamp life expectancy?


Published life figures are approximations and intended for use as relative values. Since it is impractical to test all incandescent lamps at rated voltages to determine exact life, accelerated voltages are applied to determine approximate life expectancy.

"Rated average life" or "lamp life" ratings in most catalogs and specifications are an approximation of an average lamp under ac operating conditions. Manufacturers do not guarantee a minimum number of operating hours because lamp life is so dependent on application.


High voltage (greater than 6 volts) lamps generally tend to be less stable than lower voltage lamps in terms of brightness and current and they exhibit a more erratic life performance.

One of the most common mistakes in incandescent lamp selection is the assumption that high voltage lamps are less vulnerable to shock and vibration. Just the opposite is true.

For a given lamp size, as the voltage of the filament is increased, there is generally an increase in wire length and a decrease in wire diameter (See Figure 1).

Figure 1: Different Filament Configurations

This means that more grain boundary intersection of the filament are exposed to potential failure. And, higher voltage lamps generally have lower resonant frequencies and a greater number of resonant points which results in a greater tendency for shorting between filament segments.

Being more fragile and more prone to failure, high voltage lamps are best avoided when a low voltage lamp (less than 6 volts) will do. Though more current is required for the same amount of candlepower, low voltage lamps are much more reliable.


Since lamp life is primarily a function of filament evaporation, there is a minimal life loss from ac or intermittent operation. Failures under ac operation are generally due to "crystallization", although some filament evaporation is present.

However, because of filament evaporation, lamp life under dc operating conditions is around 1/5 the rated average life specified. Hot spots are developed as the filament evaporation accelerates from localized increased resistance.

Electromigration on the tungsten filament results in "notching" or a sawtooth surface.

Most Tektronix incandescent lamp applications are under dc operating conditions. The increased filament evaporation causes a substantially lower life expectancy so provisions must be made for easy replacement.

Figure 2 illustrates, among other things, the tradeoffs between applied voltage and average life ratings for lamps operated under ac conditions. This graph is accurate only for lamps at 5000 hours or less rated life. Applying 125% of rated voltage will yield 0.07 x rated average life hours of operation.

For dc applications the suggested formula for life hours is:

life = 1.8 x 104 hours x (d2.5) EXP(f/KT)

where d is wire diameter/N CM
f = 2.72
K = 8.6 x 10-5
T is filament temperature in °K

In general, ac operation is recommended with a maintaining current to avoid high inrush current.

Figure 2: Voltage, Candlepower and Life Tradeoffs


An incandescent lamp is basically a constant current device so, at a lower applied voltage, candlepower can be treaded off for longer life. See Figure 2. A reduction of applied voltage will increase lamp life and decrease candlepower.

As a general rule, candlepower is directly proportional to the 3.5 power of the ratio of applied voltage versus rated voltage. So,

(applied voltage / rated voltage)3.5 x MSCP at design volts

Note: MSCP x 4p = lumens

As illustrated in figure 2, candlepower may be increased at the expense of lamp life. Current consumption is approximately:

(applied voltage / rated voltage)0.55 x current at design volts

The above two formulas are only relative guidelines and apply to ideal conditions. The farther the deviation from rated voltage, the greater the percentage error.


Some lamps might be specified for AS15. This means they are age selected by an industry standard and have a candlepower tolerance of +15%.


As a general rule, to maximize lamp life, you should:

(1) use lower voltage lamps
(2) operate under ac conditions
(3) provide maintaining current
(4) derate to lowest filament temperature
(5) provide impact dampening

Since lamp life is not well predicated, always locate lamps for accessible, easy replacement.

[This last sentence was one guideline that was often ignored when designing the portable scopes. The "new" portables (432, 434, 465, 475, etc.) had incandescent lamps located behind the V/DIV knob skirts. They always required the removal of the vertical preamplifier and/or attenuator assemblies to replace defective lamps and this was not a procedure for the faint-hearted. In addition, the wire-lead lamps were usually soldered to brass eyelets mounted in plastic holders – holders that had melting temperatures comparable to soldering temperatures, so you had to be fast, accurate and experienced! -- ed.]
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).


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Post by MrAl » Tue Apr 10, 2007 8:07 pm

Hi there,

A friend of mine bought a new tool about a day or two ago and it
had a built in flashlight. After installing batteries and turning it on,
we found the bulb was so darn dim it wasnt worth a hoot.
Taking a short trip to radio shack, we got a replacement bulb
and now it works fine (the bulb was the standard little #222 bulb).
Funny thing is, i noticed on the back of the package something that
surprised me: the life expectancy was only 10 hours! Yes that's
correct, ten friggin hours! That means if you have a job to do
that takes 30 minutes you can only do that job 20 times before
you have to buy a new bulb (well ok they give you two to a pack).
Replace this with a white LED (not always that simple of course)
and you have a life of 10,000 hours! (yes, that's ten thousand hours)
Provided of course you run the LED properly, and you dont get one
of those crappy ones that only last for 500 hours, but those LEDs
are not typical.
There's a big difference between 10 hours and 10,000 hours.
That's a BIGGGGGGGG advantage especially in some applications
where it is hard or expensive to keep swapping bulbs.

If you ask me the future of lighting is definitely in LEDs, but i had
no idea the incand's would be outlawed. That's a surprise too.

I have experimented with dimming fluorescent bulbs in the late
70's, so i know it is possible.

It's true that *some* fluorescent lamps will burn out faster the more
they are turned on and off, but i think it depends on how the bulb
is started. With the newer inverter type fixtures this wont be a's only with the older models.

One big problem i have found with some of the smaller fluor fixtures
is that they try to run the bulb on a waveform that is either part
or fully DC. This causes the bulb to blacken on one end and it fails
much sooner. The good ones use AC.

I gave up on fluor lighting for the most part (except in low useage
applications) and turned to high power white LEDs. I use several
Luxeon high power white LEDs to light my home. They put out a
very true white light but they are also now available in 'warm' white.
They make reading fantastic because their light is so perfectly white
and you can direct the beam onto the page very nicely.

White LEDs are also fairly easy to dim.
LEDs vs Bulbs, LEDs are winning.

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Post by rshayes » Tue Apr 10, 2007 11:09 pm

The main reason for phasing out incandescent lamps is their poor efficiency. They have the advantage of a continuous output spectrum, which makes them good for color rendering. They are simple to control and can torleate some voltage variation without immediate failure. On the negative side, they are about one quarter the efficiency of either common fluorescent lamps or the best LEDs.

I am not sure that LEDs have any significant advantage over fluorescent lamps. They tend to be very small, intense sources that will have to be diffused for general lighting purposes. Both LEDs and fluorescent lamps use phosphors to convert UV light to visible radiation, so both will have the same color characteristics.

Dimming fluorescent lamps is not particularly difficult. The control circuits have to be designed to operate the lamp at variable currents, but this is not particularly difficult with an inverter type of ballast. It adds a few parts and a little bit of cost.

With a reasonable amount of care, fluorescent lamps can be started many times. The old Xerox machines used a bank of fluorescent lamps that were turned on for each copy. The trick was to make sure that the cathodes were at operating temperature before starting the lamp. Under these conditions the lamps could be fired tens of thousands of times without significant problems.

LEDs can also provide long life and frequent starts. The main problem with them is the maunfacturing process. Making LEDs requires ultrapure materials processed through billion dollar maunfacturing facilities. A fluorescent lamp can be made with poorer materials in cheaper plants.
This will be a significant factor when large quantities are required.

From an efficiency point of view, LEDs and fluorescent lamps are similar. I would expect the difference in capital investment to favor fluorescent lamps for general lighting purposes for quite a few years.

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Post by Dean Huster » Wed Apr 11, 2007 5:42 am

Trouble is, the fluorescent lamps are more hazardous to the environment (if anyone cares) assuming that even the CFLs also have a bit of mercury in them, while the LEDs in and of themselves are not. The manufacturing process may be a different story. Properly discarding an efficient little CFL is a lot more complicated that disposing of a bulb of aluminum and glass with a bit of tunsten and copper thrown in.

MrAl, I don't ever remember seeing an open #222 lamp! I have a whole drawer full of the things with a layer of dust on top. However, #47 lamp seems to have the life expectancy of a housefly!

Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).


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Post by Craig » Wed Apr 11, 2007 6:03 am

What exactly is it that burns out in a fluorescent bulb?

Also, what is the largest LED bulb available? How does the brightness/efficiency work out as LED's get larger or smaller? Does it make sense (or would it be possible) to make something like a 1 inch LED?

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