thomas edison > a lifetime of invention : interactive modules

identify your lightbulb > bulb identification key

1. A Frequently Asked Question: How Old is That General Electric Light Bulb?

If you are one of those curious fellows who snoops into great-grandpa’s attic in search for some prehistoric relics from his time, perhaps you once came across and pondered over a strange looking GE incandescent light bulb that was long stored away for future use and then forgotten.  How old is that bulb?  Why does it look so odd?   This site can help you answer those questions and many more and also give you an overall history of some of the light bulbs produced by General Electric.

Using this site, you will be able to learn why your typical 60-watt incandescent light bulb that lights up your bedroom is NOT the same light bulb that Thomas Edison “invented.”   You will also learn how it differs from Thomas Edison’s first successful electric lamp and trace the evolution of General Electric light bulbs since they first were commercially sold in 1879.  You will be able to examine the bizarre looking bases and filaments that early light bulbs were once fitted with.  You will also learn why early light bulbs have pointed “tips” at the top and why light bulbs were once commonly referred to as lamps and not light bulbs.*

* In this key the terms “bulb,” “light bulb,” “lamp,” and “electric lamp” are used interchangeably

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2. The Significance of the Light Bulb in Our Lives

Ever since Edison’s first commercial incandescent light bulb came out in late 1879, light bulbs have been used for many lighting purposes - the homes you live in and the schools you attend, the buses and cars you ride on, the aquarium your fish swim in, the tomato seedlings your dad grows in the basement, the ovens and refrigerators that cook and store your food, the ballparks your favorite teams play on, and the streets and parking lots where you and your friends hang out after dark while your parents wonder where you are.  The light bulb has so many uses but we seldom wonder how we had ever gotten along without it.  With Edison’s newly created light bulb, the darkness of the night was transformed into the brightness of day.  No longer did people have to restrict their daily tasks during the time the sun was up. The electric light bulb greatly extended both our working and leisure hours well into the evening and beyond.  Businessmen and scientists could work late into the night and people could read, study or socialize after dinner and before bedtime.  As a result, the light bulb ushered into society a new age of enlightenment as it fostered the growth of science, manufacturing, commerce, education, and leisure, vastly improving the lot of many people’s lives.  In fact, the image of the light bulb is considered an icon of new ideas and thoughts so that when a brilliant idea comes into your mind, the symbolic light bulb clicks on over your head.  It’s conceivable that without the light bulb, the enormous progress of science and technology that has occurred over the past 125 years and that has touched each and every one of us would have never happened and we would still be living in the dark ages, both literally and figuratively.

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3. Say Goodbye to the Incandescent Lamp

Every one knows that all things become obsolete sooner or later, whether it’s the slide rule, the rotary dial telephone, or even the new computer you purchased just a month ago. The incandescent light bulb is no exception to this rule. Today’s incandescent light bulbs, economical and popular though they may be, have not changed since the days of the Great Depression when Franklin Roosevelt was president.  Think about that!  They are very inefficient and use up way too much energy.  In the process, they consume large amounts of coal and oil from the power plants.  Only about 5% of the energy used by an incandescent light bulb is transformed into light.  The rest is wasted as heat.  The ever growing demand of coal and oil for energy along with the associated elevated levels of carbon dioxide emissions into the atmosphere have forced state and federal governments to consider mandating the gradual replacement of these largely inefficient incandescent light bulbs with the more efficient compact fluorescent light bulbs.  So, after over 125 years of faithfully lighting peoples’ homes, the time may soon come when the electric incandescent light bulbs will be as obsolete as the gas and oil lamps they themselves replaced.  (What goes around comes around.)  As you’ll learn in this key, a similar energy conservation method had been implemented in this country before with the abolition of most carbon filament light bulbs in 1918 (during the First World War) in order to reduce the burning of coal.  (Click here A25) if you want to learn more about this story now.)

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4. A Rich Legacy: Collectible Light Bulbs

But whatever the case may be with the future of the incandescent light bulb, we are left with its rich and glorious legacy of the hundred of thousands if not millions of different light bulbs that have come along since Edison successfully marketed the first practical light bulb in late 1879, many of them eagerly sought after by collectors.  Some of these bulbs are simple looking and hardly evoke a second glance.  Others with their delicate tips and gracefully mounted filaments are charming and stir up romantic images of 19th century Victorian homes softly lit by the warm, golden glow of these early electric lamps.  Still others remind us of the years spent by the many talented, brilliant scientists and engineers who labored tirelessly to bring us the best light bulb that Mother Nature would allow them to create at the time.

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5. Using the Key

Now that you want learn how old your light bulb is, or learn about its development since the time of Edison, bear in mind that this key is for most mass-produced General Electric household light bulbs only and a few other mostly pear-shaped light bulbs used in the home such as sun lamps and one-time flash bulbs for cameras.  Bulbs for other purposes such as spotlight lamps and bulbs of other companies are not included as the key would have to be extremely large to accommodate every type and brand of light bulb that had been produced over the past 125 years.  Consult our archives for assistance with dating such bulbs.

    5a. Definitions: Kids and adults as well should take a moment to familiarize themselves with the terms used to identify the parts of the light bulb by clicking on the following link: Parts of a Light Bulb (A40) and the Definitions of the Parts of a Light Bulb (SEE NEXT PARAGRAPH). For your convenience, many of the terms cited in the key have been linked to their definitions. Click on any term that is linked to get more info definition as you maneuver through the key.

    To use the key, select the option most closely resembling your light bulb from the drop-down list. If you need more info you may scroll down to the "Options Descriptions" section of the page. This will provide you with a thumbnail and more detailed option descriptions. (You may also select your option from the option description title, which is also linked to the next step of the identify process.) The steps of the program will have you start with the top of the light bulb and subsequently through the remaining features of your bulb, including the base, filament, and other features necessary to narrow down a period when your light bulb was manufactured. If you are not sure if a feature of your bulb matches that shown in the key, either proceed with the key as if the feature matches that of the key or try selecting the next closest feature and work from there until you come to a photograph of the entire bulb.
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6) Dating a Light Bulb is Not an Accurate Science

Bear in mind that dating a light bulb is not an exact science because the usage of a particular feature of a light bulb does not definitely place its age in a specific time period for there is some overlap.  Thus examining multiple features of a bulb (such as the bulb shape, its filament type, and perhaps any labels) will help narrow down the period during which it was manufactured.  But dating to an exact year is seldom possible, except perhaps for the earliest bulbs.  Also, some features of a bulb that were recorded to have been discontinued in a certain year actually have been in use for many years afterwards.  For example, carbon filament light bulbs, long discontinued in favor of the more efficient tungsten light bulbs, are still being manufactured to this day.  Two-threaded screw bases, largely discontinued in 1888, were still used for some applications for years afterwards.  Patent dates listed on the bulb are not reliable either since a bulb could have been manufactured for many years after the last patent date.  So again, there is no guarantee of pin-point accuracy when using this key.

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7) Reproductions of Antique Light Bulbs

Some people may not be aware that there are many reproductions of “antique” light bulbs on the market.  (This key does include some reproductions of Edison’s first successful electric lamp.)  Many of these reproductions are not accurately made and combine both modern and antique features, especially if the “antique bulb” was manufactured for use with modern day 60 volts / 110 amperes electrical outlets.*  A common example are the replicas of Edison’s first successful light bulb (made and used in 1879 but destroyed for scientific analysis) which were produced in 1914 (on the 35th anniversary), 1929 (on the 50th anniversary), and 1979 (on the 100th anniversary of the first successful light bulb).  Replicas have also been made during other years and continue to be manufactured to this day.  Reproductions of later period light bulbs (such as those made during the decades of the 1880s and 1890s) have been manufactured as well.  Such reproductions can be easily identified by noting the combination of modern and old-fashioned features.  For example, a reproduction may have a multi-looped carbon thread filament attached by two beads of carbon paste while an original may have a split Japanese bamboo hairpin filament attached by two metal clamps with screws.

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Inserting a genuine and intact antique light bulb into an electrical socket not designed for the correct current and voltage rating of the bulb may permanently damage the bulb’s filaments.  We at the Schenectady Museum’s International Technology Archives do not advise inserting antique light bulbs in electrical sockets without proper consultation from a certified professional electrician.

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9) About the Photographs of the Light Bulbs in the Key

Most of the photos seen here in this key were used from the 1.5 million photographs in the Schenectady Museum’s International Technology Archives.  A few photographs were those taken of the light bulbs from the museum’s vast collection of technology related items.  Photos of these light bulbs can be ordered for a nominal fee.

Click here to learn more about ordering photographs from our Archives

10) A Trip into History: The Evolution of General Electric’s Incandescent Light Bulbs ...


11) View the Evolution of Filaments ...


12) View the Evolution of Lamp Bases ...


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