- How can I make my light bulbs last longer?
- How can I minimize lighting costs?
- How bad is the current surge when a light bulb is turned on?
- What are some definitions of common lighting types and styles?
- What is a halogen bulb?
- What is a compact fluorescent lamp?
- How can I understand the codes on a fluorescent lamp?
- What are some basic lighting design strategies?
- What is important to consider in kitchen lighting design?
- What is important to consider in bathroom lighting design?
- What is important to consider when designing light for living spaces?
- What are some lighting tips for foyers, halls, and stairways?
- What are some lighting tips for living rooms?
- What are some lighting tips for dining areas?
- What is important to consider in track lighting design?
How can I make my light bulbs last longer?There are a number of things you can do to improve the efficiency of your household lighting. Long-Life Bulbs Many light bulbs are made to operate with a slightly lower filament temperature than usual. This makes the bulbs last much longer with a slight reduction of efficiency. Reduced Power Reducing the voltage applied to a light bulb will reduce the filament temperature, resulting in a dramatic increase in life expectancy. Soft-Start Devices Since bulbs usually burn out during the current surge that occurs when they are turned on, one would expect that eliminating the surge would save light bulbs. When the bulb is first started, the thermistor is cool and has a moderately high resistance that limits current flowing through the bulb. The current flowing through the thermistor's resistance generates heat, and the thermistor's resistance decreases. This allows the current to increase in a fairly gradual manner, and the filament warms up in a uniform manner. However, this extends the life of the bulbs less than one might think. If the filament has thin spots that cannot survive the current surge that occurs when the bulb is turned on, then the filament is already in very bad shape. At this time, the thin spots are significantly hotter than the thicker parts of the filament and are evaporating rather rapidly. As described earlier, this process is accelerating. If the thin spots are protected from surges, the life of the bulb would be extended by only a few percent. Additional life extension occurs only because the thermistor keeps enough resistance to result in enough heat to keep it fairly conductive. This resistance slightly reduces power to the bulb, extending its life somewhat and making it slightly dimmer. DC vs. AC operation As tungsten atoms evaporate from the filament, a very small percentage of them are ionized by the small amounts of short-wave ultraviolet light being radiated by the filament, the electric field around the filament, or by free electrons that escape from the filament by thermionic emission. These tungsten ions are positively charged, and tend to leave the positive end of the filament and are attracted to the negative end of the filament. The result is that light bulbs operated on DC have this specific mechanism that would cause uneven filament evaporation. This mechanism is generally not significant, although it has been reported that light bulbs sometimes have a slight, measurable decrease in lifetime from DC operation as opposed to AC operation. In a few cases, AC operation may shorten the life of the bulb, but this is rare. In rare cases, AC may cause the filament to vibrate enough to significantly shorten its life. In a few other rare cases involving very thin filaments, the filament temperature varies significantly throughout each AC cycle, and the peak filament temperature is significantly higher than the average filament temperature. Ordinarily, one should expect a light bulb's life expectancy to be roughly equal for DC and AC. |
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REDUCED POWER
