Edison screw
Edison screw (ES) is a standard lightbulb socket for electric light bulbs.
In North America and continental Europe, Edison screws displaced other socket types for general lighting.
In the early days of electrification, Edison screws were the only standard connector, and appliances other than light bulbs were connected to AC power via lamp sockets.
In designing his screw,[1] Edison copied the lid of a kerosene can in his workshop, even sawing it off to make a prototype in 1880.
[3] In response to Edison's patent, Reginald Fessenden invented the bi-pin connector for the 1893 World's Fair.
[9] It was in this period when E-designations of screws first originated in Germany (where seven DIN VDE standards were enacted in 1924—1925[10]) and then adopted by IEC.
Large outdoor Christmas lights use Intermediate base, as do some desk lamps and many microwave ovens.
[citation needed] Previously, emergency exit signs also tended to use the intermediate base,[citation needed] but U.S. and Canadian rules now require long-life and energy-efficient LED lamps, which can be purchased inside a conventional Edison base bulb as a retrofit.
A medium screw base should not carry more than 25 amperes current; this may limit the practical rating of low voltage lamps.
[15] E29 "Admedium" bases are used for special applications; for example, UV spotlight lamps in magnetic crack detection machines.
[citation needed] In countries that use 220–240 volt AC domestic power, standard-size E27 and small E14 are the most common screw-mount sizes and are prevalent throughout continental Europe[a] and China.
A socket extender makes the bulb stick out further, such as to accommodate a compact fluorescent lamp that is too large to fit in a recessed lighting fixture.
Various other accessories have been made, including a smoke detector that recharges over a few hours and lasts for a few days or weeks thereafter, and still allows the attached lamp to operate normally.
There have also been electronics that stick onto the end of the screw base and allow the attached lamp to flash, for example, to attract the attention of arriving guests or emergency vehicles; others function as a dimmer or timer, or dim gradually in a child's bedroom in the evening.
