Incandescent Lighting

The most familiar type of lighting is known as incandescent. The popularity of the incandescent lamp is due to the simplicity with which it can be used and the low price of both the lamp and the fixture. The lamp requires no special equipment, like a ballast, to operate. Incandescent lamps produce light when an electric current passes through their metal filaments heating it to the point it glows.  The down side of incandescent lamps is the are only about 10 percent efficient at producing light.  About 90 percent of the energy they use is given off as heat. During the winter, incandescent lighting is an expensive form of electric heat. While in the summer months, it adds heat to the home, and if you use air conditioning, it increases your cooling bills. So while they are inefficient, they do have advantages and there are ways to use them wisely.

For instance, knowing that the efficiency of incandescent lamps increases as lamp wattage increases can allow you to save energy. This makes it possible to save on both energy and fixture costs whenever you can use one higher wattage lamp instead of two lower wattage lamps.

For example, one 100-watt lamp produces more light, 1740 lumens, than two 60-watt lamps (860 lumens each) for a total of 1,720 lumens. Whenever you can substitute one 100 watt lamp for two 60s, you save 20 watts. Beware though, read the fixture ratings. Some are rated for 60 watt or lower lamps. Be aware that many fixtures may not be rated to accommodate the higher wattage lamp.

The specific type of incandescent lamp used and the kind of fixture involved also make a difference. For example, a 75-watt ellipsoidal reflector lamp delivers more light in a stack-baffled downlight than a 150-watt R lamp of higher wattage. This is because much of the R lamp's light is trapped in the fixture and converted to heat. The 75-watt ER lamp's shape and reflective interior focuses light down, outside of the fixture, thereby producing more light on the surface. And there are energy efficient versions of the 150-watt R lamps available that use only 120 watts and provide only slightly less light.

The rated life of an incandescent lamp is determined by operating a fixed number of lamps at standard voltage until 50% burn out. The voltage at which a lamp is operated affects its life expectancy. A lamp operating with higher voltage will burn brighter, but with dramatically shortened life, and one operated under voltage will not burn as brightly, but will have extended life.

Look for lamps marked "energy efficient."  They use 5 to 13% less energy than standard bulbs. There are energy-efficient replacements for all standard wattages and while they may cost a little more, they more than make up for their extra cost through lower operating costs. Another label that appears on some lamps is "long-life" or "rough service." These bulbs have a thicker filament, which makes them last longer, but it also makes them less efficient and therefore they are not recommended except in locations where changing bulbs is difficult, or where conditions cause standard bulbs to fail prematurely.

The most common types are: the "A" or arbitrary bulb-shaped lamp; the "PS" or pear-shaped lamp; the "R" or reflector lamp; the "PAR" or sealed-beam lamp, and the tungsten-halogen lamp.