May 25, 12
The following are excerpts from actual reviews on 1000Bulbs.com. What do they have in common? They’re all from reviews of 130 volt light bulbs.
“…even though the watt ratings are the same…the new ones aren’t as bright as the old ones.”
“The low output also makes the the color of the light very yellow…”
“…for 300 watts I thought it would be brighter.”
These customers, and several others, have a fundamental misunderstanding of 130 volt light bulbs. That’s not their fault, however; it’s ours. So let me try to clear up this issue once and for all.
As discussed briefly in an earlier article, the short, technical version goes like this: 130 volt Halogen and incandescent light bulbs are manufactured with a thick filament designed to withstand a theoretical 130 volts. I say “theoretical” because almost all homes in the US operate on only 110-120 volts. The thicker filament in a 130 volt bulb, when operated on typical 110-120 line voltage, provides less resistance to the electrical current flowing through the filament. As a result, the bulb burns cooler, uses less energy (watts), and lasts longer; however, as a trade-off, the bulb is also slightly dimmer and has a lower (more yellow) color temperature.
Understanding Voltage, Amps & Watts: “Hose Theory”
To understand this phenomenon, an analogy is useful. Think of a garden hose. When you turn on the tap to just a trickle, water flows freely through the hose without resistance. As you turn the tap more, you force a larger volume of water through the hose, which is met by a small amount of resistance from the hose. Now turn the tap to its highest setting. Instead of trickling from the end of the hose, water now sprays across your lawn and into the leather interior of your neighbor’s new convertible.
Because the hose is relatively small, it provides a lot of resistance to the more voluminous water flow, which causes pressure to build inside the hose. The increased pressure in the hose propels the water several feet instead of flowing with the mere trickle you saw when you had the tap at a lower setting. To take this concept further, imagine you continued to increase the volume of water flowing through the hose by attaching it to a fire hydrant (assuming such a thing was possible). At that point, the water pressure would become so intense it would weaken the hose, eventually causing it to rupture.
Maybe that’s a dramatic example, but the thin tungsten filament of a light bulb is not unlike a water hose. In the case of electricity, however, the volume of water is electrical current and the water pressure is voltage. With a 60 watt light bulb, for example, you are forcing 0.5 amp of electrical current (the “water”) through the filament (the “hose”) with 120 volts of pressure. The current meets the resistance of the filament, causing the filament to become hot and glow. Over time, just as with the water hose, this stress will cause the filament to break, making the bulb “burn out.”
130 Volt Bulbs Save Energy & Last Longer
To prolong the life of the bulb, you could lower the volume (amps) or the pressure (voltage). This is the approach taken by old rheostat dimmers.
Voltage Decrease & Bulb Efficiency
However, you could also use a bulb with a thicker filament (a bigger hose), that places less resistance on the current so that it flows more easily. This method, as stated before, is the approach taken by the 130 volt bulb. Because the current moving through the thicker filament meets less resistance, it requires less energy to produce light. The more freely moving current also does not make the filament as hot so that the color temperature of the light is also lower.
As the table to the right shows (from Jack L. Lindsey’s Applied Illumination Engineering), the trade-off is a very good one, too. A very small decrease in voltage and lumens leads to a huge increase in life and a considerable decrease in energy usage (watts). Lowering the voltage only 8%, for example, leads to a 300% increase in life and nearly 15% decrease in energy usage with only a 25% loss in light output!
Now back to the original question: Why buy 130 volt light bulbs? The answer is simple. Buy 130 volt bulbs when you want to save energy, change your bulbs less often, and don’t mind slightly lower light output and warmer color temperature.
May 11, 12
Every light source has a distinct character, from the warm, dim glow of a candle to the blue, bright beam of a street light. Brightness, measured in lumens, is one part of that character; the other part is color temperature. Measured in degrees Kelvin, color temperature is not the ambient hot/cold temperature of our surroundings. In fact, the Kelvin scale goes backwards: The higher the color temperature, the cooler light gets, and the lower the color temperature, the warmer light gets.
Warm Color Temperatures (2000K to 3500K)
Lighted Makeup Mirror
Most homes look best in warm-toned light. This is for several reasons, but the first one is a home’s color scheme. People tend to decorate homes in warm earth tones—reds, oranges, and yellows—which warm light enhances. In addition, people tend to look better in warm light. If your grandmother had a lighting makeup mirror with adjustments based on “office,” “home,” and “evening” lighting, you may remember that you looked a lot better in “home” and “evening” modes than “office” mode. That’s because (you guessed it!) those modes had lower color temperatures than “office” mode.
Cool Color Temperatures (4000K to 4500K)
While warm color temperatures are the residential standard, some people prefer higher or “cooler” color temperatures. Because of their neutral tone, it’s common to see color temperatures of 4000K or higher used as task lighting in offices. Moreover, people often perceive higher color temperatures to be brighter than warm temperatures, while others feel cooler light looks “cleaner.” Finally, higher color temperatures can enhance homes with cooler color schemes, especially those with a lot of blues and whites.
Full Spectrum Color Temperatures (5000K to 6500K)
Less common are very high color temperatures, often referred to as “full spectrum” or “daylight.” Color temperatures of 5000K to 6500K approximate the color of light outdoors on a bright, sunny day. The cast of the light can be a very pronounced blue and can seem harsh to some people. It’s unlikely to see color temperatures of this range in homes, though there is a trend of installing “full spectrum” bulbs in offices as they are sometimes associated with higher productivity.
Making a Decision
There’s nothing that can sour your opinion of CFL or LED lighting like buying a 4000K or 5000K bulb when you meant to buy a 2700K bulb, or vice-versa. When you buy a new, energy efficient bulb, keep your application and color scheme in mind and make sure to buy the bulb with a color temperature to match.
So do you prefer warm or cool color temperatures in your home? Have you ever mistakenly bought a bulb of the wrong color temperature? Share your thoughts and experiences in the comments section below or contact us on Facebook, Twitter, or Google+.