Inventors seeking to develop energy-efficient lamps could not simply start with a blank piece of paper. They needed to work within the capabilities of existing lighting and power systems. Sometimes even small features had an influence, like the use of the screw-in base and socket.
What became the standard screw-in lamp base and socket was introduced by Thomas Edison in 1883, and it hasn't changed since. To this day often referred to as an "Edison base," it's formally known as the medium-screw base. While there are other base sizes (and types), the medium-screw base is the most common, especially in residential light fixtures.
Since sockets for this base are so widespread, designers of compact fluorescent lamps (CFLs) like this 1993 Panasonic "Light Capsule" needed to ensure their products would fit that size. This model EFG16LE lamp is an integral unit--it's all in one piece, including the screw-in base. Other modular lamps used specially designed plug-in bases. The plug-in base has several advantages over the medium-screw base. One of the most important is that if the light fixture takes a plug-in base, one can't use a cheap regular lamp in place of the more expensive CFL.
But few homes had fixtures with plug-in bases. And lamp makers realized that few homeowners would replace their fixtures just to use the new lamps. So inventors needed to design their lamps with the screw-base, or develop an adaptor.
Lamp characteristics: Medium-screw base with plastic skirt containing an electronic ballast and starter. Fluorescent tube assembly containing two electrodes, mercury, and an internal phosphor coating. White, G-shaped glass envelope covers the tube assembly. This lamp came in its original package. Rated at 16 watts, it's intended as a replacement for 60 watt incandescent lamps.
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