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Dating from the late 19th century, the first commercially available electric light bulbs produced light by applying electricity to a carbon filament until it heated enough to glow, or incandesce. The glass enclosure created a vacuum to prevent the filament from oxidizing. Since these beginnings, the basic incandescent light bulb technology has been tweaked, but, remarkably, remains closely related to the earliest models. The filaments are now tungsten, a stronger metal with a high melting point allowing higher temperatures to produce brighter light. The space inside the bulb is now filled with inert argon plus a small amount of nitrogen so there is less blackening on the glass from evaporating filament.

The most significant change to incandescent came in the late 1950's with the introduction of halogen gases and small, hard-glass capsules to contain the tungsten filament. This combination allowed for longer filament life and slightly brighter appearing light. Nevertheless, halogen light bulbs use electricity to heat a tungsten filament until it produces light in the same way as incandescent. 

Incandescent Frequently Asked Questions

Has the Incandescent Light Bulb Been Banned?

New U.S. energy standards for incandescent bulbs took effect on January 1, 2012. This did NOT mean the end of the incandescent light bulb. Instead, a new breed of common incandescent light bulbs emerged using more efficient halogen technology. Now you can use 72, 53, 43 and 29 watt bulbs that look identical to and provide the same light as traditional 100, 75, 60 and 40 watt bulbs. Halogen is simply a hybrid incandescent light bulb. Same technology, just more energy efficient.

How does Federal legislation affect incandescent light bulbs?

The Energy Independence and Security Act of 2007 (EISA) requires that certain incandescent bulbs be phased out and replaced by more energy efficient alternatives.

Here is the timeline for common medium screw base bulbs and the minimum requirements for their replacements:

Current Watts (120-130V) New Max Watts Rated Lumens Min. Rated Life Effective Date
100W 72W 1490-2600 1000 hrs 1/1/2012
75W 53W 1050-1489 1000 hrs 1/1/2013
60W (options) 43W 750-1049 1000 hrs 1/1/2014
40W 29W 310-749 1000 hrs 1/1/2014


Notice that "phase out" does not mean the bulbs cannot be purchased, as long as distributors have inventory available. 100W and 75W bulbs have begun to be phased out and we still sell these bulbs on Topbulb. We also sell the alternatives.

There are many exemptions from the law including: appliance bulbs, blacklights, bug, colored, infrared, left-hand thread, marine, marine signal service, marine service, plant light, reflector, rough service, shatter-resistant, sign service, silver bowl, showcase, 3-way incandescent, traffic signal, vibration service, G shape, T shape and AB, BA, CA, F, G16-1/2, G25, G30, S, or M14 of 40 watts or less.

The table below shows three substitution options for the bulbs being phased out. Halogen is a very attractive option because the bulbs are virtually identical and the cost is low. Topbulb carries all of the options. See the "A-Lamp" bulbs in halogen, CFL and LED sections of our site.

(A Lamp)
(A Lamp)
(fits A Lamp socket)
(fits A Lamp socket)
100W 72W 23W 20W
75W 53W 18W 14W
60W 43W 13W 12W
40W 29W 11W 8W

What is the different 120V or 130V Incandescent?

When shopping for incandescent or halogen light bulbs, sometimes you will find an option of buying the exact same bulb in either 120Volt or 130Volt. The 130V bulb will usually claim a much longer rated life. Longer life sounds great, but there is a catch. Operating a 130V rated bulb in a 120V socket will increase bulb life by 200% or more, but it will also reduce the light output by about 25%. So if you can live with less illumination for a particular application, 130V rated incandescent and halogen bulbs can be a very good deal.