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Lighting Terms

Remember going to the store in the “good old days” to purchase a pack of light bulbs? Once in the bulb section, may have noticed several brands, but one 60-watt bulb was likely the same as the next. You knew how bright it would be, how its color (warm white) would appear and how long it would likely last (750 to 1,000 hours of use). By multiplying its rated wattage by the hours used and dividing by 1,000, it was easy to determine the kilowatt-hours (kWh) of electricity it used.

These days, the lighting section of hardware and home improvement stores are filled with a myriad of light-emitting diode (LED) bulbs (lamps). To further complicate matters, various lamps have different color appearances, input wattages and rated lifetimes. What’s more, not all LEDs are dimmable and those that are, may not work on a traditional dimmer switch!

How are you supposed to decide what to buy? Fortunately, since 2012, the Federal Trade Commission has required every manufacturer of general-purpose lamps to display a “Lighting Facts” label on their packaging. The label’s five sections explained below can help assure you make the right selection.


While the actual amount of light a lamp produces is measured in lumens, the amount of light provided by a bulb used to be directly related to its wattage. One 60-watt incandescent bulb produced 800 lumens, as much as the next brand’s bulb. One hundred-watt bulbs were twice as bright, producing 1,600 lumens.

As energy efficient compact fluorescent lamps (CFLs) and LED lamps became available, manufacturers started labeling their products with an incandescent equivalent wattage to help customers identify the expected light output. In reality, the actual wattage of LED lamps is 75% to 85% less than its “watts equivalent” rating.

Because lumens produced by LED products can vary significantly, labeling requirements provided the following ranges of output that are considered equivalent to the fixed values of traditional bulbs.

  • 40-watts equivalent = 350 – 749 lumens
  • 60-watts equivalent = 750 – 1,049 lumens
  • 75-watts equivalent = 1,050 – 1,489 lumens
  • 100-watts equivalent = 1,490 – 2,600 lumens

When purchasing, assure the lumen output of new LEDs matches the output of others in the same light fixture to avoid the appearance of brighter and dimmer lamps.

Estimated Yearly Energy Cost

This section identifies the annual energy cost if the LED lamp is operated for three hours everyday for 365 days a year and the consumer pays an average price of 11.0¢ per kWh for electricity. Incidentally, the United States Energy Information Administration identifies Nebraska’s average residential cost of electricity at 11.1¢ per kWh.


The rated life reflected on the Lighting Facts label shows how many years the lamp should last when operated every day of the year for three hours. If operated less than three hours, consumers can expect it to last longer. The converse is also true.

Unlike incandescent bulbs that “burn out,” LEDs tend to lose light output as they are used. Within the lighting industry, LED products are rated by the hours of operation until the lamp drops to 70% of its original output. To determine the number of rated hours from the label, multiply the label’s number of years by 1,095. For example, if the label identifies a life of 13.7 years, the LED is rated at 15,000 hours of operation.

Light Appearance

Throughout history as fluorescent lighting became commonplace, people referred to the appearance of white light as “warm white” and “cool white”. As more options regarding appearance became available, the lamp’s correlated color temperature (CCT), expressed in Kelvin (K) units (without the word “degrees”) was used to describe this attribute.

Today, consumer lighting products are rated from 2200K to 6500K. Sliding up the scale, color appearance starts at a warm, yellow-white light and progresses to a cool, bluish/purplish white. The scale on the Lighting Facts label indicates where on the scale a particular lamp will appear.

Energy Used

Not to be confused with the term “watts equivalent” that may also appear on the package, this value is the actual electrical power required to operate an LED or other lamp. When multiplying this wattage by the number of hours the lamp is operated, dividing by 1,000, then multiplying by the average cost per kWh of electricity, an accurate estimated cost of operation can be determined. Note the efficiency or efficacy of an LED that produces a specific amount of lumens is determined by how many watts are required to achieve that level of brightness. When dividing the rated lumens by the energy (watts) used, energy efficiency is improved as lumens produced per watt increases.

Though not identified on the Lighting Facts label, another consideration you’ll want to remember while shopping is that not all LED lamps can be dimmed. Packaging should indicate whether a particular lamp has this capability. In addition, some existing dimmer switches require a minimum power of 50 watts connected to properly operate. Because LEDs tend to have lower wattages than incandescent bulbs, the electric circuit will not reach the minimum power required. Consequently, LEDs may start to flicker, make buzzing noises or overheat. If so, replacing the switch with a dimmer designed for use with LEDs may be necessary.

Understanding the Lighting Facts label is just the beginning of how you can reduce your lighting costs. In partnership, your local utility can help identify other ways to gain the most value from your energy costs. For more energy-saving ideas for your home, business, or farming operation, contact your local public power utility.

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