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The Incessant Incandescent


Incandescent means to emit light as a result of being heated, and that is exactly how an incandescent light bulb works. It gives off light when the filament is heated by the current of electricity that powers the fixture it is installed in. There are several different types of incandescent bulbs, ranging in shape from the standard A-shape, what is typically thought of when light bulbs are mentioned, to decorative flame tipped shapes, and even globe shaped bulbs that light up the marquee at your favorite movie theater. Incandescent light bulbs have benefited mankind for more than a century, and have paved the way for new, and more efficient lighting technologies to emerge. Until the day that incandescent bulbs are no longer in production, however, GoodBulb is the place to find the right incandescent bulb for your needs!

Light Bulb Moments

What is an A-shaped light bulb? What do you think of first when you imagine a light bulb? I can guess that it is most likely the standard A19, teardrop-shaped bulb that has made its presence known around the world since the late 1800s. In addition to the A19 bulb, we are familiar with the A21, A23, and the A15 shapes, as well. But what does the “A” in these types of bulbs mean? Great question and I’m glad you asked! The “A” stands for arbitrary, and in the case of bulbs, we take the definition of that to mean the shape was decided upon based on random choice of its designer. The number that follows the “A” in these bulbs indicates the bulb’s size when measured in 1/8” increments. For instance, a standard A19 bulb diameter measures at 19/8”, or when converted is 2.375”. The A21 bulb measures 21/8”, or 2.625” in diameter, but keep in mind that the A21 bulb is generally also slightly taller than the A19 which may prevent it from properly fitting in some fixtures. Be mindful of this when selecting a replacement bulb for your application. Keep in mind, also, that A-shape bulbs are offered in A15 and A23 sizes, too.

A15 bulbs are more typically associated with uses in appliances, as well as decorative applications and in signs. A15 bulbs also generally feature lower wattage outputs. A23 bulbs are larger in both size and wattage output, giving them a range of uses outside the scope of their smaller counterparts.

Beyond the A-shape bulbs discussed, when higher wattage is required for an application then we will typically see an incandescent bulb move to a P or PS designation, or to make it easier to picture if you are not familiar with this kind of bulb, these bulbs look like a pear. PS-shaped bulbs are further defined by their straight neck. However, just as in the A-shaped bulbs, the number that follows the P or PS designation refers to the bulb’s size in ⅛” increments. Because these larger bulbs offer higher wattage output, they are generally meant for industrial applications rather than residential use. They may also require a Mogul (E39) base (the part that screws into the socket of your fixture) in place of the standard (E26) base.

Did you know?

The typical design of the incandescent A-shaped light bulb has not changed much since the prototype was fabricated by Thomas Edison. Since its inception, there have, of course, been state-of-the-art enhancements to improve its functionality, however. Such developments as the tungsten filament and use of inert gases helped to shape the ways in which the light bulb has impacted the world.



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