Edison screw (ES) is a standardlightbulb socket forelectric light bulbs. It was developed byThomas Edison (1847–1931), patented in 1881,[1] and was licensed in 1909 under General Electric'sMazda trademark. The bulbs haveright-hand threaded metal bases (caps) which screw into matching threaded sockets (lamp holders). For bulbs powered byAC current, the thread is generally connected toneutral and the contact on the bottom tip of the base is connected to the "live" phase.
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. Today Edison screw sockets comply with international standards.
Their types are designated as "Exx", such as "E26", where "xx" indicates the diameter of the socket in millimeters.
In the United States, early manufacturers ofincandescent lamps used several different and incompatible bases in the 1880s and 1890s. 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.[2] Another company, theThomson-Houston Electric Company, used a threaded stud at the bottom of the socket and a flat contact ring.[3]: fig.8 TheSawyer-Man orWestinghouse base used a spring clip acting on grooves in the bulb base and a contact stud at the bottom of the lamp.[3]: fig.7 Most smaller competitors had to produce lamps for all three types,[2] and some used their own designs as well.[4] Other lamp bases include thebayonet mount andwedge base.
All three major designs werepatented. Edison himself filed his applications in 1881[1] and 1890.[3] In response to Edison's patent,Reginald Fessenden invented thebi-pin connector for the1893 World's Fair.
After some design tweaks Edison settled upon a screw 1 inch in diameter with 7 threads per inch of length, which much later becameE26. Screw shells produced as early as 1888 had a lighter taper[5] than the modern ones.[6]
In 1892, Edison General Electric Company merged with Thomson-Houston to foundGeneral Electric, which gradually adopted the Edison screw and made it prevalent.[2] By about 1908, the Edison base was most common in the U.S. with the others falling out of use.[7]
Proposals to introduce one or several international standards for Edison screws began in 1918, when France suggested to theInternational Electrotechnical Commission (IEC) to take up the issue of sockets and holders.[8] All IEC attempts to reach consensus by 1925 failed, but lamp makers continued the work in an independent committee and developed two standards—one for Europe, another for Americas—which were endorsed by the IEC in 1930 and 1931 respectively.[9] It was in this period when E-designations of screws first originated in Germany (where sevenDINVDE standards were enacted in 1924—1925[10]) and then adopted by IEC.[11]
Specifications for all lamp mount types are defined in the followingAmerican National Standards Institute (ANSI)[12] andInternational Electrotechnical Commission (IEC) publications:
Generally, the two standards are harmonized, although several types of screw mount are still defined in only one standard.
In the designation "Exx", "E" stands for "Edison" and "xx" indicates thediameter in millimeters as measured across the peaks of the thread on the base (male), e.g., E12 has a diameter of 12 mm. This is distinct from the glass envelope (bulb) diameter, which in the U.S. is given in eighths of an inch, e.g., A19,MR16, T12.[13]There are four commonly used thread size groups for mains supply lamps:
The E26 and E27 are usually interchangeable, as are the E39 and E40, although less so; although there is only a 1 mm difference in thread outside diameter, there is a small difference in pitch; an E40 cap will often fit in an E39 holder but not the other way around. E11 and E12 are not interchangeable. Other semi-standard screw thread sizes are available for certain specific applications.[14]
The large E39 "Mogul" and E40 "Goliath" base are used onstreet lights, and high-wattage lamps (such as a 100 W / 200 W / 300 W 3-way) and manyhigh-intensity discharge lamps. In areas following the U.S.National Electrical Code, general-use lamps over 300 W cannot use an E26 base and must instead use the E39 base. Medium Edison screw (MES) bulbs for 12 V are also produced forrecreational vehicles. Large outdoor Christmas lights use Intermediate base, as do some desk lamps and manymicrowave 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-efficientLED lamps, which can be purchased inside a conventional Edison base bulb as aretrofit. A medium screw base should not carry more than 25 amperes current; this may limit the practical rating oflow 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 voltACdomestic power, standard-size E27 and small E14 are the most common screw-mount sizes and are prevalent throughout continental Europe[a]andChina.[16]
In 120 voltNorth America, 100 voltJapan and 110 voltTaiwan, the standard size for general-purpose lamps is E26.[17][18]
E12 is typically used for candelabra fixtures. E14 or E17 are also sometimes used, especially in smalltable lamps and novelty lighting, and occasionally the lights on newerceiling fans.Christmas lights may use several base sizes: E17 for C9 bulbs, E12 for C7 bulbs, E10 for decades-oldseries-wired C6 bulb sets[19] in the U.S., and an entirely differentwedge base for T1¾ mini-lights. For a short time early on, these mini lights were manufactured using E5 screw bases.
A tiny E5 or E5.5 size is only used forextra-low voltages, such as in interiorillumination formodel buildings, and modelvehicles such asmodel trains. These are often called "pea bulbs" if they are globe-shaped, but they commonly look like sub-miniature Christmas bulbs, or large "grain-of-wheat" bulbs. E10 bulbs are common onbattery-poweredflashlights, as are bayonet mounts (although those are usually held in with a circularflange located where the base meets the glass envelope of the bulb). The E11 base is sometimes used for 50/75/100 Watthalogen lamps in North America, where it is called the "mini-can", and tighter threads are used to keep them out of E12 basenightlights and other places where they could start a fire.[citation needed]
There are also adapters between screw sizes, and for adapting to or from bayonet caps. A socket extender makes the bulb stick out further, such as to accommodate acompact fluorescent lamp that is too large to fit in arecessed lighting fixture.
Most Edison screws have right-hand threads (bulb is turnedclockwise to tighten), but left-hand threaded screws are sometimes used, usually for a non-standard voltage or wattage bulb. This prevents the use of an incorrect bulb, which could cause damage.[20] Public locations such as railway trains and theNew York City Subway have used light bulbs with left-hand threads to discourage theft of the bulbs for use in regular light fixtures.[21][22]
| Designation | Base major diameter (thread external) | Pitch mm[23] | Name | Applications | IEC 60061-1 standard sheet |
|---|---|---|---|---|---|
| E5 (E5.5)[24] | 5.5 mm (0.217 in) | 1 | Lilliput Edison Screw (LES) | Indicator lights, decorative lights | 7004-25-3[25] |
| E10 | 10 mm (0.394 in) | 1.81 | Miniature Edison Screw (MES), C6 | Flashlights, bicycle lights | 7004-22 |
| E11 | 11 mm (0.433 in) | — | Mini-Candelabra Edison Screw (mini-can) | 120 V halogen mini-candelabra | 7004-06-1 |
| E12 | 12 mm (0.472 in) | 2.6 | Candelabra Edison Screw (CES), C7 | 120 V candelabra/night lamp | 7004-28 |
| E14 | 14 mm (0.551 in) | 2.82 | Small Edison Screw (SES) | 230 V candelabra/chandelier, night lamps, some pendant lights | 7004-23 |
| E16 | 16 mm (0.630 in) | 2.5 | |||
| E17 | 17 mm (0.669 in) | — | Intermediate Edison Screw (IES), C9 | 120 V appliance, decorative lights | 7004-26 |
| E18 | 18 mm (0.709 in) | 3.0 | |||
| E26 | 26 mm (1.024 in) | — | Medium Edison Screw (ES) | Standard 120 V lamps | 7004-21A-2 |
| E27 | 27 mm (1.063 in) | 3.62 | Edison Screw (ES) | Standard 230 V lamps | 7004-21 |
| E33 | 33 mm (1.299 in) | 4.23 | |||
| E39 | 39 mm (1.535 in) | — | Mogul Edison Screw | 120 V 250+ W industrial | 7004-24A-1 |
| E40 | 40 mm (1.575 in) | 6.35 | Goliath Edison Screw (GES) | 230 V 250+ W industrial | 7004-24 |
Three-way lamps have ad suffix to indicate double contacts, usually E26d or E27d, or rarely E39d. The second contact is used for the lower-wattage filament of the two inside the lamp. This extra contact is a ring located around the main contact. Unlike bayonet sockets, three-way and regular lamps are interchangeable, although the low filament or low setting does not work if mismatched.
The small Edison screw has ninethreads per inch, or apitch of1⁄9 in or 2.8222 mm per thread.
The medium Edison screw has seven threads per inch, or a pitch of1⁄7 in or 3.6286 mm per thread. In the U.S., theEnergy Independence and Security Act of 2007 requirement for greaterenergy efficiency only applies to the medium Edison screw, all other being considered "specialty" lamps.[26]
Diazed fuses DII uses the same E27 thread as standard 230 V lamps, but have a longer body and cannot be screwed into a lamp holder (socket). A lamp base is too short to contact the bottom terminal of a fuse holder. However it is possible (but not useful) to screw a DII fuse holder without a fuse in an E27 lamp holder.
The Edison screw socket was used as an outlet (such as fortoasters) whenmains electricity was still mainly used forlighting, and before wall outlets became common.
In North America,fuses were used in buildings wired before 1960. TheseEdison base fuses would screw into a fuse socket similar to Edison-base incandescent lamps.
Some adapters forwall outlets use an Edison screw, allowing a light socket to become an ungrounded electrical outlet (such as to install Christmas lights temporarily via aporch light), or to make apull-chain switch with two outlets, or to split it for two lamps. Another adapter can make a wall outlet into a lamp holder (lamp socket).
Various other accessories have been made, including asmoke detector thatrecharges 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 oremergency vehicles; others function as adimmer ortimer, or dim gradually in a child'sbedroom in the evening.
Somevacuum tubes, such as certain rectifiers, use an Edison screw base.
Medium screw cap E 27
最长[常] [sic]的使用的螺口灯泡规格是：E14和E27
The E26 is the standard 120 Volt American base.
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