Buying the right light bulb will cost you less in long run

By , Special to The Christian Science Monitor

Using the right light bulb for the right location depends on bulb performance.

To help make the right choice the Federal Trade Commission (FTC) requires that light-bulb packages show bulb ratings on wattage, lumens, and bulb life. As a consumer you should know what you are buying:

To help make the right choice the Federal Trade Commission (FTC) requires that light-bulb packages show bulb ratings on wattage, lumens, and bulb light. As a consumer you should know what you are buying:

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* Wattage: Many people think the higher the wattage, the brighter the bulb. Wattage doesn't measure the amount of light from a bulb but rather the amount of electricity going into the bulb.

* Lumens: This unit measures bulb performance or brightness. The light-bulb package must tell the average initial lumens, the total amount of light the new bulb gives. The greater the number of lumens, the brighter the bulb.

* Bulb life: This caption tells the time the filament inside the bulb will last. The hours actually listed on the bulb package give the average hours of use you can expect.

Consumers now can buy a light bulb, similar to an incandescent in color, that lasts five times longer and burns no more than 50 watts of electricity while shedding as much light as a 150-watt incandescent bulb. This new bulb, the Electronic Halarc, consists of a glass bulb that contains a miniature arc with two conventional filaments perched atop an electronic control capsule and a base to fit a regular socket.

It looks like a double-dip ice-cream cone. When the switch is on, the filaments light up; once the more efficient arc heats up, the arc takes over.

If these bulbs were to fill only 10 percent of all US sockets, according to the FTC, they could reduce total energy demand by 5 billion kilowatt-hours a year. However, you may not want to pay $10 when you see bulbs for less than $1 a piece.

While long life (5,000 hours) is certainly an important feature of the Electronic Halarc, this same physical characteristic can be misleading as applied to ordinary light bulbs.

Billions of electric-light bulbs are bought every year. You have a choice of the popular 25-, 40-, 60-, 75-, and 100-watt bulbs to fill specific lighting needs. Frequently replacing bulbs is expensive, and this fact certainly leads to the purchase of the ''long life'' incandescent lamps.

While the FTC compels the manufacturers to indicate the life and lumens that each bulb provides, the average person still may have difficulty in interpreting the figures printed on the package.

Suppose you need to replace a 60-watt bulb in a desk lamp.

The burned-out bulb was rated at 1,000 hours (average) life and 860 (average) lumens. This lamp provided adequate lighting for the type of work performed at the desk.

In your weekly shopping, you find on display a bulb that is rated at 3,000 hours (average) life and 765 lumens. At the time you feel the 765 lumens for the gain in 3,000 hours of life is insignificant. So you buy the 3,000-hour bulb at about 99 cents, about double the cost of the shorter-life, 1,000-hour lamp.

But, would you be surprised to know that the initial cost of the bulb is only a fraction of the overall cost of providing the light? And would you also be surprised to know that three 1,000-hour bulbs would give you about 7 percent more light than one 3,000-hour bulb?

The following figures (rounded off) help to explain the answers and comparison: One 3,000-hour, 765 lumen light bulb

Light expected: 3,000 x 765 EQUALS 2,295,000 lumen-hours

Cost for 3,000-hour bulb EQUALS $1 Electricity cost:

3,000 x 60 x 0.05 / 1,000 EQUALS $9

Total cost EQUALS $10

Lumen-hours per $1 EQUALS 229,500 Three 1,000-hour, 860 lumen bulbs

Light expected: 3 x 100 x 860 EQUALS 2,580,000 lumen-hours

Cost for three 1,000-hour bulbs EQUALS $1.50 Electricity cost:

300 x 60 x 0.05 / 1,000 EQUALS $9

Total cost EQUALS $10.50

Lumen-hours per $1 EQUALS 250,000

Another significant factor, related to burning efficiency that you need to consider in the choice of bulbs, is lumens per watt.

The long-life 3,000-hour bulb gives about 13 lumens per watt (765/60); the 1, 000-hour bulb about 14 lumens per watt (860/60). So you can see that the shorter the average rated life of a typical incandescent bulb, the higher the efficiency.

In addition, examine the following calculations to note that over a 1,500 -hour burning period a 100-watt standard frosted bulb will supply almost 25 percent more light per $1 than two 60-watt bulbs. Note also that a Soft White 100-watt bulb providing 1,585 lumens supplies about 15 percent more light per dollar than the two 60s, but that it is about 6 percent less efficient than the 100-watt standard frosted. For example:

10-watt standard frosted - 1,000-hour life, 870 lumens

100-watt standard frosted - 750-hour life, 1,750 lumens

100-watt Soft White - 1,500-hour life, 1,585 lumens Bulbs burning for 1,500 hours Two 60-watt, 1,000-hour life:

Light provided:

1.5 (1,500 / 1,000) x 1,000 x 2 x 870 EQUALS 2,610,000 lumen-hours.

Bulb cost for 1,500 hours: 2 x .35 (per bulb) x 1.5 EQUALS $1.05

Electricity cost: 1,500 x 2 x 60 x 0.05 / 1,000 EQUALS $7.50

Lumen-hours per $1 EQUALS 260,000 One 100-watt standard frosted, 750-hour life:

Light provided: 1,500 x 1,750 EQUALS 2,625,000 lumen-hours

Bulb cost for 1,500 hours: 2 x .35 EQUALS $.70

Electricity cost: 1,500 x 100 x 0.05 / 1,000 EQUALS $7.50

Lumen-hours per $1 EQUALS 320,000 One Soft White 100-watt, 1,500-hour life:

Light provided: 1,500 x 1,585 EQUALS 2,380,000 lumen-hours

Bulb cost for 1,500 hours: $.50

Electricity cost: 1,500 x 100 x 0.05 / 1,000 EQUALS $7.50

Lumen-hours per $1 EQUALS 300,000

Furthermore, if you compare bulbs of other wattage, you'll find similar differences. For example, two 40-watt bulbs provide less light than one 75-watt bulb.

You probably would want to use long-life bulbs for outside, porch, attic, and stairwells where bulb replacement is often difficult or the fixture requires disassembly. In these locations light is for safety and convenience, so you may want the Krypton light bulbs that last about 50 percent longer than standard bulbs, but they also are more expensive.

Three-way bulbs are labeled the same way as standard bulbs in watts, lumens, and hours of life. The rating for bulb life is given for only one of the two filaments (the one shown by tests to burn out first). Reflector bulb

Replace 100-watt isolated lighted locations, such as a kitchen-sink area, with a 50-watt incandescent reflector bulb for the same straight-down beam pattern. The reflector costs more than the 100-watt, but you'll save money because you use less wattage over the 2,000-hour life of the 50-watt reflector.

Further, the reflector bulb is ideal for wall and pole units with bell-shaped fixtures that need to reflect light straight down. These special fixtures only trap the light from regular 100-watt bulbs. Fluorescent lighting

Private and public offices and stores use fluorescents because this light is far more efficient and economical. A four-foot-long, 40-watt fluorescent light gives more light; is twice as efficient as a 100-watt incandescent bulb, even allowing for the added wattage of the ballast in the fixture; and lasts about 20 times longer (20,000 hours).

While efficient, some disadvantages do exist. The life of the fluorescent bulb depends on the number of times it is switched on and off. The longer the light burns, the longer it lasts. Also, switching from incandescent to fluorescent requires special fixtures. The ballasts make a humming noise, some older tubes flicker, and some people object to the light quality.

Yet, by applying fluorescents, you can save as much as 50 percent on your lighting bill.

Add fluorescents under wall cabinets in the kitchen and dispense with the more costly overhead incandescent bulbs. Or you can replace the overhead light with a 20-watt fluorescent fixture to get the same light for half the electricity of one 100-watt or two 60-watt incandescent bulbs.

Use double 40-watt plug-in fluorescents in workshops and utility rooms for 20 times longer life and savings.

A new fluorescent light, the Circlite, which looks much like a 10-inch steering wheel, screws right into the regular lamp or ceiling socket. While the initial cost is high, the 40-watt lamp produces as much light as a 100-watt incandescent bulb and has an average life of about four years.

The entire unit costs from $18 to $20 (with an adaptor that lasts for about 20 years). A replacement tube costs $9 to $10.

When buying a new light bulb, remember that all bulbs are not the same.

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