Energy Efficient Light Bulbs

130 volt, also known as severe duty or extended life since they run at a lower temperature.

Good answer.

Ordinary light bulbs contain a small amount of Nitrogen and an even smaller amount of Argon. Halogens contain a higher ratio of Argon to Nitrogen, and also contain some Krypton. This combination of gases acts a heat sink to the filament, allowing the filament to run hotter, thus producing more light without degrading the filament life. It also allows the tungsten re-deposition you mentioned.

Huh, interesting. I've wondered that myself. When I worked for Siemens a few years ago, we shared booth space with Sylvania (a sister company) and I asked something similar to one the lamp guys. He told me that on most of the incandescents that you see in the store, the label saying "60W, uses 48W" is a mostly a marketing gimmick in that it is a 48W lamp, but has a reformulated phosphor coating that luminesces at the same rate as an old 60W frosted lamp used to. So the "60W" is relative only to the lumen output. The thing is, how can we compare now? The old ones are no longer available...

From: http://en.wikipedia.org/wiki/Incandescent_light_bulb

For a supply voltage V near the rated voltage of the lamp:

1. Light output is approximately proportional to V ^3.4
2. Power consumption is approximately proportional to V ^1.6
3. Lifetime is approximately proportional to V ⁻¹⁶

Operating a bulb at a lower voltage has several effects. From (3) the lifetime is vastly extended. From (1) and (2), the power consumption is reduced, but the light output is reduced even more, so it is less efficient.

They basically run a 95 volt lamp at 117 volts and you get more light per watt, but a lot less life. See the formulas above. It's a desperate ploy to stave off the Cree LED lamps.

If the marked power consumption differs significantly from the measured power consumption then someone is being mislead or it's running on the wrong voltage.

Given that most of the power consumed by an incandescent lamp is converted to heat rather than light, then a measure of the lumen output is useful to understand how bright it will look.

With the range of new lamp technologies now on the market, the relationship between power consumed and lumens produced is highly variable.

All of the input energy is converted to heat, it is so hot (2700 K or more) the filament becomes incandescent.

Twenty years ago I got some surplus traffic light bulbs. They are rated at 60 watts but give off the light of a 25 watt bulb. We like the soft warm glow they emit. They're designed to turn on and off continuously and are rated at 8000 hours. It's been ages since one burned out on me. One time the electrician sent them 220 volts. They got eral bright but they didn't burn out.

I visited the State Capitol building recently and high in the middle of the dome is a thousand light chandelier. From my vantage I could see that it was stocked with the all too familiar traffic light bulbs.

I worked at a hotel at one time in the maintenance department. They had hundreds of light bulbs that were rated at 130 volts. For some reason (I don't recall), they wanted to get rid of them and switch to different lamps. I was able to latch on to a few cases of these bulbs. That was over 25 years ago and I don't recall what happened to those lamps. I remember giving some away and using some myself. If I had them today, I would never have to worry about ever being in the dark.

Halogen lamps are available with a infrared reflective coating to recycle some of the heat. Less heat emitted = less electricity needed to keep temperatures up to emit light. When I learned of these from a major manufacturer (had to ask, even though they were trying to sell efficiency!) they said about 30% savings. Direct replacement, dimmable, it is a halogen lamp. I have fixtures in my kitchen with an exposed MR16 lamp. I cannot tell the difference between the 50W and 37W lamps. I don't rememeber specs for longevity, I think it is better.

Maybe similar technology is used for incandescent lamps?

Remember to look at lumens per watts consumed @ voltage when comparing lamps. The selection of LEDs is getting better...

Light is a nutrient.