See the light
David Mink gatehouse plus

Today's market has been flooded with light bulbs proclaiming "long life"- in some cases, they advertise a lifeexpectancy of up to 20,000 hours - but in the long run, are they really worth the cost?

Incandescent light bulbs work by running an electric current through a tungsten filament. The current heats the tungsten, causing electrons in the filament to excite, releasing light and heat. However, the resistance of the filament is slightly higher in some areas than in others, causing "hot spots." The hot spots eventually break and the light bulb fails.

For an incandescent lamp, only about 10% of the input electrical energy is converted into light that is in the visible part of the spectrum. If the filament could be operated just a little hotter it would be considerably more efficient. Tungsten lamps are in fact operated as close to the melting point as practical and running them even a few degrees hotter would cause them to fail quickly.

Long-life bulbs work in the same way, but they employ larger filaments. In this way, they can be operated at a slightly lower temperature and can last for considerably longer amounts of time. However, the tradeoff is that they consume more electrical current and produce less light.

For more "bang for your buck," try compact fluorescent bulbs. Typically guaranteed for 8,000 hours, these bulbs produce much more light for their operating power. For instance, a 15-watt CFB produces about 900 lumens, which is the same output as a 60-watt incandescent bulb. The increased cost of a compact fluorescent bulb is then recovered within about 500 hours of usage.