How to Choose a Light Bulb

Confused about light bulbs? Here are some frequently asked questions with answers from the American Lighting Association.

What types of bulbs are available for home lighting?

There are three basic types:

  1. Halogen incandescent
  2. CFL (Compact Fluorescent)
  3. LED (Light Emitting Diode)

The halogen incandescent is very similar to the traditional household incandescent bulb, except that it is somewhat more eficient. 

The compact fluorescent, or CFL, is more efficient still, but its use is expected to decline due to the growing poularity of LEDs.

Phased-out incandescent              Modern Halogen                       LED Bulb

Today, the LED bulb is the most efficient, long lasting, and often the most suitable for home lighting. The new models look very similar to traditional bulbs. The slightly higher up-front cost of these bulbs is mitigated by their very long life.

I am standing in the store loking at light bulbs; what do I need to look for?

Check the packaging for the following:

  • Lumens: How bright is the bulb?
  • Color: Is the light from the bulb a warm 2700K or a cool 4000K?
  • CRI: Does the bulb render colors beautifully? 80+ is good, 90+ is great!
  • Dimmable: Can I use the bulb with a dimmer switch? What type of dimmer is compatible?

Bulbs are now marked in "lumens" rather than "watts." Why the change?

Watts only measure the amout of power a bulb draws. Bulbs with the same wattage may put out very different amounts of light. Lumens tell you how much light a bulb emits.

Light bulbs seem to come in a choice of colors now; which color is best?

lighting-facts.pngCheck the "Lighting Facts" label on the bulb carton. The label is required for all bulbs sold at retail for residential use and provides operating informaton as well as color information about the light from the bulb. Color information is shown as "Light Appearance." A bulb that provides "warm" light with a rating of 2700 to 3000K (K stands for Kelvins) will closely match the color of a standard incandescent bulb. Bulbs with higher Kelvin ratings, such as 4000 or 5000K, will appear blue-white or "cool." See the bulb lit before buying it, if you can.


I have a dimmable LED bulb in a fixture with a dimmer switch but it isn't working. What's going on?

Dimmers come in several types. You may have a dimmer that is not compatible with your particular LED bulb. If you know the type of dimmer that you have (manufacturer and model), check the dimmer manufacturer's website for a list of compatible LED bulb types.

The bulb in my oven has burned out. Can I use a CFL or LED bulb as a replacement?

No. Both CFL and LED bulbs contain electronic cicuitry, which would fail at oven temperatures. Instead, use a specifically marked incandescent or halogen incandescent bulb. 

How is the efficiency of a light bulb measured and rated?

lumens-per-watt.pngEfficiency (or efficacy) is the light output of the bulb (lumens) divided by its power input (watts), i.e. lumens per watt. The standard household bulb of a few years ago rated for 60 watts generated 800 lumens and had an efficacy of about 13 lumens/watt. Today, an LED bulb rated for 800 lumens would draw about 8 watts, for an efficacy of 100 lumens/watt, making is significantly more efficient!

Are there any harmful materials in LED bulbs?

LED bulbs are electronic products and the materials are similar to what is used for cell phones, TVs and other electronic devices. LED bulbs contain glass, metal and plastics that can - and should - be recycled.

How long should I expect an LED bulb to last?

THe short answer is 10-20 years for home applications where the LED bulb is normally burned for the typical 1-3 hours/day. The rated life of an LED bulb is based upon burning hours, and typically life ratings for LED household bulbs are 10,000 hours or more, with some rating as many as 40- to 50-thousand hours starting in 2017. However, LED bulbs are not likely to fail by simply burning out. It is more likely that they will just gradually get dimmer over time. To claim a rated life of 15,000 hours, for example, Energy Star-qualified bulbs must pass sample tests that require they produce no les than 93.1 percent of their initial light output after they have been burned for 3,000 hours. 

Do LED bulbs generate radio/TV interference?

LED bulbs can generate a small amount of radio frequency interference (RFI), but amounts are strictly limited. Look on the LED bulb or carton to verify that a particular bulb has been tested to meet RFI emission limits. There will be a symbol indicating that the product was tested or a notice with workding, such as that shown below.


Are LED bulbs available in the traditional "Three-way" versions?

Yes. LED bulbs are available with a special base that allows them to be installed in a standard three-way socket that switches output from low, to medium, to high.

Are there LED bulbs for outdoor use?

Yes. LED bulbs are rated and marked for three types of conditions: dry, damp and wet. Bulbs rated for wet conditions can be used in sockets exposed to rain and snow. If the bulb or carton is not marked, assume that the bulb can be used only in dry situations.

How about temperature conditions - do low or high temperatures affect LEDs?

LEDs, in general, operate well at low temperatures, but check the bulb ratings to see the temperature range for which the bulb was designed. High temperatures can drastically shorten LED bulb life, and household bulbs should not be installed in tightly enclosed fixtures where heat build-up might affect the bulb performance. There are LED bulbs available, however, that are rated and marked for enclosed fixtures.

Are LED bulbs avilable for decorative lighting applications, such as chandeliers or wall sconces? I don't want any ugly plastic LED bulb showing in my fixture. 

Decorative LEDs are becomming increasingly popular. There are LEDs today designed to appear in many decorative styles from vintage Edison Bulbs, to Candelabra Bulbs, to the traditional rounded bulb appearance of the incandescents we have all grown to love. You are sure to find an LED to fit any application.


*Information provided by ALA's Director of Engineering and Technology Terry McGowan.