Edison screw

{{Short description|Lightbulb socket standard (E5-E40)}} {{use dmy dates|date=April 2020}} [[File:Gluehlampe 01 KMJ.jpg|thumb|upright|230/240-[[volt]] [[incandescent light bulb]] with E27 screw base]]

'''Edison screw''' ('''ES''') is a standard [[lightbulb socket]] for [[electric light]] bulbs. It was developed by [[Thomas Edison]] (1847–1931), patented in 1881,<ref name="USP0251554_1881"/> and was licensed in 1909 under General Electric's [[Mazda (light bulb)|Mazda]] trademark. The bulbs have [[Screw thread#Handedness|right-hand threaded]] metal bases (caps) which screw into matching threaded sockets (lamp holders). For bulbs powered by [[Single-phase electric power|AC current]], the thread is generally connected to [[Ground and neutral|neutral]] 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.

== History == In the United States, early manufacturers of [[Incandescent light bulb|incandescent lamps]] used several different and incompatible bases in the 1880s and 1890s. In designing his screw,<ref name="USP0251554_1881"/> Edison copied the lid of a kerosene can in his workshop, even sawing it off to make a prototype in 1880.<ref name="Oatman-Stanford" /> Another company, the [[Thomson-Houston Electric Company]], used a threaded stud at the bottom of the socket and a flat contact ring.{{r|"USP0438310_1890"|p=fig.8}} The [[William E. Sawyer|Sawyer-Man]] or [[Westinghouse Electric Corporation|Westinghouse]] base used a spring clip acting on grooves in the bulb base and a contact stud at the bottom of the lamp.{{r|"USP0438310_1890"|p=fig.7}} Most smaller competitors had to produce lamps for all three types,<ref name="Oatman-Stanford">{{cite web |last1=Oatman-Stanford |first1=Hunter |title=Let There Be Light Bulbs: How Incandescents Became the Icons of Innovation |url=https://www.collectorsweekly.com/articles/let-there-be-light-bulbs |website=Collectors Weekly |access-date=7 September 2020 |language=en}}</ref> and some used their own designs as well.<ref name="Jenkins">{{cite web |last1=Jenkins |first1=John |title=Early Incandescent lamps |url=http://www.sparkmuseum.com/LAMP_EARLY.HTM |website=[[SPARK Museum of Electrical Invention]] |access-date=7 September 2020}}</ref> Other lamp bases include the [[bayonet mount]] and [[wedge base]].

All three major designs were [[patent]]ed. Edison himself filed his applications in 1881<ref name="USP0251554_1881">{{US patent|0251554}} (applied 1881, awarded 1881) Two examples of screw system appear, including the kerosene-can lid, but their overall formations are incompatible with today's Edison sockets. No explicit claims for the screw system. Beware patents.google.com's preview mode lacks several pages, must download full PDF.</ref> and 1890.<ref name="USP0438310_1890">{{US patent|0438310}} (applied 1890, awarded 1890) A lamp base that is compatible with 3 competing socket systems (Edison, Westinghouse, Thomson-Houston). This patent is not about Edison system itself. It rather is an enhancement to the already existing Edison system. Beware patents.google.com's preview mode lacks several pages, must download full PDF.</ref> In response to Edison's patent, [[Reginald Fessenden]] invented the [[Bi-pin lamp base|bi-pin connector]] for the [[World's Columbian Exposition|1893 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 became [[#E26|E26]]. Screw shells produced as early as 1888 had a lighter taper<ref>{{cite journal |title=American Standard for Threads for Lamp Sockets and Bases |journal=ASA Bulletin |date=1932 |volume=3 |issue=2 |page=83 |url=https://books.google.com/books?id=dNXNAAAAMAAJ&pg=PA83 |access-date=7 September 2020 |publisher=American Standards Association. |language=en}}</ref> than the modern ones.<ref>Historical American standards: *[[American Society of Mechanical Engineers|ASME]] 1474(1915), [[American Standards Association|ASA]] C44-1931: {{cite encyclopedia|encyclopedia=Screw-thread standards for federal services|edition=1942|year=1942|section=10|title=American national rolled threads for screw shells of electric sockets and lamp bases|pages=140–142|series=National Bureau of Standards Handbook|volume=H28(1942)|publisher=[[National Bureau of Standards]]|url=https://archive.org/details/screwthreadstand2819unit/page/140/mode/1up|access-date=2020-09-08}} *ASA C81.1-1951: {{cite encyclopedia|encyclopedia=Screw-thread standards for federal services|edition=1957|orig-year=1957|year=1960|section=15|title=American standard rolled threads for screw shells of electric lamp holders and screw shells of unassembled lamp bases|pages=34–36|series=National Bureau of Standards Handbook|volume=H28(1957) PART III|publisher=[[National Bureau of Standards]]|url=https://archive.org/details/screwthreadstan2819unit_3/page/n41/mode/1up|access-date=2020-09-08}} </ref>

In 1892, Edison General Electric Company merged with Thomson-Houston to found [[General Electric]], which gradually adopted the Edison screw and made it prevalent.<ref name="Oatman-Stanford" /> By about 1908, the Edison base was most common in the U.S. with the others falling out of use.<ref name="ICS1908">{{cite encyclopedia|encyclopedia=[[International Correspondence Schools|I.C.S. Reference Library]]|volume=4B|title=Interior wiring|section=20|language=en|page=S43 p41 (web 215/632)|url=https://archive.org/details/icsreferencelibr04inteiala/page/n214/mode/1up|orig-year=1905|year=1908|publisher=Scranton [[International Textbook Company]]|location=New York|access-date=2020-09-08}}</ref>

Proposals to introduce one or several international standards for Edison screws began in 1918, when France suggested to the [[International Electrotechnical Commission]] (IEC) to take up the issue of sockets and holders.<ref>{{cite magazine|magazine=[[The Engineer (UK magazine)]]|issue=127|publisher=Morgan-Grampian|date=1919-03-14|title=(p256)|page=256|url=https://books.google.com/books?id=_uusK-dwO64C&q=screw+lamp|url-access=subscription|access-date=2020-09-08}} (snippet)</ref> 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.<ref>{{cite book |last1=Yates |first1=JoAnne |last2=Murphy |first2=Craig N. |title=Engineering Rules: Global Standard Setting since 1880 |date=30 March 2021 |publisher=JHU Press |isbn=978-1-4214-4003-3 |page=108 |url=https://books.google.com/books?id=10bzDwAAQBAJ&pg=PA108 |url-access=limited|access-date=7 September 2020 |language=en}}</ref> It was in this period when E-designations of screws first originated in Germany (where seven [[Deutsches Institut für Normung|DIN]] [[VDE e.V.|VDE]] standards were enacted in 1924—1925<ref>{{cite book |last1=Dettmar |first1=Georg |title=Wegweiser für die vorschriftsgemäße Ausführung von Starkstromanlagen: Im Einverständnis mit dem Verbande Deutscher Elektrotechniker |date=13 March 2013 |publisher=Springer-Verlag |isbn=978-3-642-47446-0 |page=130 |url=https://books.google.com/books?id=wjSeBgAAQBAJ&pg=PA130 |access-date=7 September 2020 |language=de}}</ref>) and then adopted by IEC.<ref>{{cite magazine|magazine=IEC Report of Plenary Meetings|title=(drawings of screw threads)|year=1935|page=160|quote=Medium screw cap E 27|publisher=International Electrotechnical Commission|url=https://books.google.com/books?id=WwpJAAAAMAAJ&q=e+27|url-access=limited|access-date=2020-09-08}}</ref>

Specifications for all lamp mount types are defined in the following [[American National Standards Institute]] (ANSI)<ref name=ANSIC61>ANSI C81 series: * {{cite web |id=ANSI C81.61 American National Standard |title=Specifications for Bases (Caps) for Electric Lamps |website=[[National Electrical Manufacturers Association|National Electrical Manufacturers Association (NEMA)]] |date=3 July 2019 |format=pdf |url=https://www.nema.org/standards/view/American-National-Standard-for-Electrical-Lamp-Bases-Specifications-for-Bases-for-Electric-Lamps |url-access=subscription |access-date=2020-09-08}} * {{cite web |id=ANSI C81.62 American National Standard |title=Electric Lampholders |website=[[National Electrical Manufacturers Association|National Electrical Manufacturers Association (NEMA)]] |date=3 July 2019 |format=pdf |url=https://www.nema.org/standards/view/american-national-standard-for-electric-lampholders |url-access=subscription |access-date=2020-09-08}} * {{cite web |id=ANSI C81.63 American National Standard |title=Gauges for Electric Lamp Bases and Lampholders |format=pdf |url=https://www.nema.org/standards/view/american-national-standard-for-gauges-for-electric-lamp-bases-and-lampholders |url-access=subscription |website=[[National Electrical Manufacturers Association|National Electrical Manufacturers Association (NEMA)]]|date=6 September 2019 |access-date=2020-09-08}} * {{cite web |id=ANSI C81.64 American National Standard |title=Guidelines and General Information for Electrical Lamp Bases, Lampholders and Gauges |website=[[National Electrical Manufacturers Association |National Electrical Manufacturers Association (NEMA)]] |date=19 June 2020 |url=https://www.nema.org/standards/view/american-national-standard-guidelines-and-general-information-for-electrical-lamp-bases-lampholders-and-gauges |format=pdf |url-access=subscription |access-date=2020-09-08}}</ref> and [[International Electrotechnical Commission]] (IEC) publications: * Lamp Caps – ANSI C81.61 and IEC 60061-1 * Lamp Holders – ANSI C81.62 and IEC 60061-2 * Gauges (to ensure interchangeability) – ANSI C81.63 and IEC 60061-3 * Guidelines for Electrical Lamp Bases, Lampholders and Gauges – ANSI C81.64 and IEC 60061-4

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 the [[diameter]] 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, [[Multifaceted reflector|MR16]], T12.<ref>{{cite web |title=Lamp Size Reference |website=lightopedia.com |url=http://www.lightopedia.com/lamp-size-reference |access-date=2017-04-23}}</ref> {{anchor|Candelabra|E12}}{{anchor|E17}}{{anchor|Standard|E26}}{{anchor|Mogul|E39}}{{anchor|Goliath|E40}} There are four commonly used thread size groups for mains supply lamps:

# Candelabra: E12 North America, E11 in Europe # Intermediate: E17 North America, E14 (Small ES, SES) in Europe # Medium or standard: E26 (MES) in North America, E27 (ES) in Europe # Mogul: E39 North America, E40 (Goliath ES) in Europe.

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.<ref>{{cite web |title=Light Bulb Shape and Size Chart |series=Reference charts |website=Bulbs.com |url=https://www.bulbs.com/learning/shapesandsizes.aspx |access-date=2018-02-05}}</ref>

The large E39 "Mogul" and E40 "Goliath" base are used on [[street light]]s, and high-wattage lamps (such as a 100 W / 200 W / 300 W three-way) and many [[high-intensity discharge lamp]]s. 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 for [[recreational vehicle]]s. Large outdoor Christmas lights use Intermediate base, as do some desk lamps and many [[microwave oven]]s.{{citation needed|date=January 2015}} Previously, [[emergency exit]] signs also tended to use the intermediate base,{{citation needed|date=January 2015}} but U.S. and Canadian rules now require long-life and energy-efficient [[LED lamp]]s, which can be purchased inside a conventional Edison base bulb as a [[Retrofitting|retrofit]]. A medium screw base should not carry more than 25 [[ampere]]s current; this may limit the practical rating of [[low voltage]] lamps.<ref>{{cite report |publisher=General Electric |title=Incandescent Lamps |type=manual |id=publication no. TP 110 |year=1976 |page=12}}</ref>

E29 "Admedium" bases are used for special applications; for example, UV spotlight lamps in magnetic crack detection machines.{{Citation needed|date=January 2015}}

In countries that use 220–240 volt [[alternating current|AC]] [[Mains electricity|domestic power]], standard-size E27 and small E14 are the most common screw-mount sizes and are prevalent throughout continental Europe{{efn| The BC or [[bayonet mount]] fitting is the most common light bulb fitting in the UK and many British Commonwealth countries, and is found in older installations{{citation needed|date=January 2016}} in some other countries, including France and Greece. }} and [[China]].<ref> {{cite web |title=灯泡螺口规格、灯泡的选购技巧 |url=http://home.fang.com/zhishi/17875538.htm |website=搜房网家居装修|access-date=28 February 2017 |language=zh |quote=最长[常]{{sic}}的使用的螺口灯泡规格是：E14和E27}} </ref>

In 120 volt [[North America]], 100 volt [[Japan]] and 110 volt [[Taiwan]], the standard size for general-purpose lamps is E26.<ref>{{cite web |url=https://www.ledwaves.com/pages/frequently-asked-questions |quote=The E26 is the standard 120 Volt American base. |website=LED waves (ledwaves.com) |title=FAQ |access-date=5 February 2018}}</ref><ref>{{cite web |url=http://www.sharp.co.jp/support/advice/led_lighting/select_c1.html |title=E26: – 般電球、ボール電球の多くがこのサイズ。 |archive-url=https://web.archive.org/web/20150210181836/http://www.sharp.co.jp/support/advice/led_lighting/select_c1.html |archive-date=2015-02-10 |publisher=Sharp Japan |series=support pages |access-date=30 January 2015}}</ref>

E12 is typically used for candelabra fixtures. E14 or E17 are also sometimes used, especially in small [[Light fixture|table lamps]] and novelty lighting, and occasionally the lights on newer [[ceiling fan]]s. [[Christmas lights]] may use several base sizes: E17 for C9 bulbs, E12 for C7 bulbs, E10 for decades-old [[Series and parallel circuits#Series circuits|series-wired]] C6 bulb sets<ref>{{cite web |title=C6 bulb sets |series=lamp evolution |url=http://www.oldchristmaslights.com/lamp_evolution.htm |url-status=dead  |archive-url=https://web.archive.org/web/20061020231535/http://www.oldchristmaslights.com/lamp_evolution.htm |archive-date=2006-10-20}}</ref> in the U.S., and an entirely different [[wedge 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 for [[extra-low voltage]]s, such as in interior [[lighting|illumination]] for [[model building]]s, and model [[vehicle]]s such as [[Rail transport modelling|model train]]s. 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 on [[Battery (electricity)|battery]]-powered [[flashlight]]s, as are bayonet mounts (although those are usually held in with a circular [[flange]] located where the base meets the glass envelope of the bulb). The E11 base is sometimes used for 50/75/100 Watt [[halogen lamp]]s in North America, where it is called the "mini-can", and tighter threads are used to keep them out of E12 base [[nightlight]]s and other places where they could start a fire.{{citation needed|date=January 2015}}

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 a [[compact fluorescent lamp]] that is too large to fit in a [[recessed light]]ing fixture.

Most Edison screws have right-hand threads (bulb is turned [[clockwise]] 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.<ref>{{cite web |last=Eisenbraun |first=Blair |date=24 March 2011 |title=Left handed incandescent light bulbs? |website=eLightBulbs (lightbulbs.com) |type=blog |url=https://www.lightbulbs.com/blog/left-handed-incandescent-light-bulbs |access-date=27 July 2016}}</ref> Public locations such as railway trains and the [[New York City Subway]] have used light bulbs with left-hand threads to discourage theft of the bulbs for use in regular light fixtures.<ref>{{cite book |last=McManus |first=Chris |year=2004 |title=Right Hand, Left Hand: The origins of asymmetry in brains, bodies, atoms, and cultures |publisher=[[Harvard University Press]] |page=46 |isbn=978-067401613-2 |url=https://books.google.com/books?id=20oza63ZuG4C&q=left+handed+light+bulbs&pg=PA46 |access-date=2015-01-25}}</ref><ref>{{cite book |last=Schneier |first=B. |author-link=Bruce Schneier |year=2003 |title=Beyond Fear: Thinking sensibly about security in an uncertain world |page=221 |publisher=[[Springer Science+Business Media]] |isbn=978-038702620-6 |url=https://books.google.com/books?id=EALEaiVhmjoC&q=light+bulbs&pg=PA221 |access-date=2015-01-25}}</ref>

== Fittings == [[File:E24 E14 E10.jpg|thumb|upright|From left to right: E27, E14, and E10 bulbs]] [[File:Groß und klein 004 2022 07 15.jpg|thumb|upright|E27 (230 V / 200 W) and E10 (2.5 V / 0.5 W)]] {| class="wikitable sortable" ! Designation ! [[Screw thread#Diameters|Base major diameter]] (thread external) ! [[Pitch (screw)|Pitch]] mm<ref>[https://www.gewinde-normen.de/en/e-thread.html Edison thread]</ref> ! Name ! Applications ! [[International Electrotechnical Commission|IEC]] 60061-1 standard sheet |- | {{sort|E05|E5}} (E5.5)<ref>"E5.5" designation does not exist in IEC 60061 database. Examples of usage: *{{Cite web|url=https://www.bailey.nl/en/etimcatalog/lamps-eg000028/indication--and-signalling-lamp-ec000399/08714681118931/articles/eg+ec+nr+eview|title=(advertisement) Pisello E5.5 Fused 3V 1.5W CL|access-date=2021-03-19|website=Bailey - The lamp company|archive-url=https://web.archive.org/web/20210319021415/https://www.bailey.nl/en/etimcatalog/lamps-eg000028/indication--and-signalling-lamp-ec000399/08714681118931/articles/eg+ec+nr+eview|archive-date=2021-03-19|url-status=live}} *{{Cite web|url=https://www.bulbtown.com/Midget_Screw_Base_E5_s/968.htm|title=(advertisement) Midget Screw Base (E5)|access-date=2021-03-19|website=BulbTown|archive-url=https://web.archive.org/web/20170825025832/https://www.bulbtown.com/Midget_Screw_Base_E5_s/968.htm|archive-date=2017-08-25|url-status=live}}</ref> | {{hs|0}}{{cvt|5.5|mm|in|3}} | 1 | Lilliput Edison Screw (LES) | Indicator lights, decorative lights | 7004-25-3<ref name="iec60061"/> |- | E10 | {{cvt|10|mm|in|3}} | 1.81 | Miniature Edison Screw (MES), C6 | Flashlights, bicycle lights | 7004-22 |- | E11 | {{cvt|11|mm|in|3}} | — | Mini-Candelabra Edison Screw (mini-can) | 120 V halogen mini-candelabra | 7004-06-1 |- | E12 | {{cvt|12|mm|in|3}} | 2.6 | Candelabra Edison Screw (CES), C7 | 120 V candelabra/night lamp | 7004-28 |- | E14 | {{cvt|14|mm|in|3}} | 2.82 | Small Edison Screw (SES) | 230 V candelabra/chandelier, night lamps, some pendant lights | 7004-23 |- | E16 | {{cvt|16|mm|in|3}} | 2.5 | | | |- | E17 | {{cvt|17|mm|in|3}} | — | Intermediate Edison Screw (IES), C9 | 120 V appliance, decorative lights | 7004-26 |- | E18 | {{cvt|18|mm|in|3}} | 3.0 | | | |- | E26 | {{cvt|26|mm|in|3}} | — | Medium Edison Screw (ES) | Standard 120 V lamps | 7004-21A-2 |- | E27 | {{cvt|27|mm|in|3}} | 3.62 | Edison Screw (ES) | Standard 230 V lamps | 7004-21 |- | E33 | {{cvt|33|mm|in|3}} | 4.23 | | | |- | E39 | {{cvt|39|mm|in|3}} | — | Mogul Edison Screw | 120 V 250+ W industrial | 7004-24A-1 |- | E40 | {{cvt|40|mm|in|3}} | 6.35 | Goliath Edison Screw (GES) | 230 V 250+ W industrial | 7004-24 |}

Three-way lamps have a ''d'' 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 nine [[threads per inch]], or a [[Pitch (screw)|pitch]] of {{cvt|1/9|in|mm|4|disp=or}} per thread.

The medium Edison screw has seven threads per inch, or a pitch of {{cvt|1/7|in|mm|4|disp=or}} per thread. In the U.S., the [[Energy Independence and Security Act of 2007]] requirement for greater [[Efficient energy use|energy efficiency]] only applies to the medium Edison screw, all other being considered "specialty" lamps.<ref name=eb/>

[[IEC 60269#D-system (DIAZED)|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.

== Other uses == [[File:D12cord.jpg|thumb|upright|A 1909 toaster with Edison plug]]

The Edison screw socket was used as an outlet (such as for [[toaster]]s) when [[mains electricity]] was still mainly used for [[lighting]], and before wall outlets became common.

In North America, [[Fuse (electrical)|fuses]] were used in buildings wired before 1960. These [[Fuse (electrical)#North America|Edison base fuses]] would screw into a fuse socket similar to Edison-base incandescent lamps.

Some adapters for [[AC power plugs and sockets|wall outlet]]s use an Edison screw, allowing a light socket to become an ungrounded electrical outlet (such as to install Christmas lights temporarily via a [[porch]] light), or to make a [[Pullstring|pull-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 a [[smoke detector]] that [[Rechargeable battery|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 vehicle]]s; others function as a [[dimmer]] or [[timer]], or dim gradually in a child's [[bedroom]] in the evening.

Some [[vacuum tube]]s, such as certain rectifiers, use an Edison screw base.

==See also== * [[A-series light bulb]] * [[Bayonet mount]] * [[GU24 lamp fitting]] * [[Multifaceted reflector]] * [[Screw thread#Diameters|Screw thread diameters]]

== Notes == {{Notelist}}

== References == {{Reflist|refs= <ref name="iec60061">{{cite web|url=http://webstore.iec.ch/preview/info_iec60061_DB.pdf|title=IEC 60061 International Standard – Lamp caps and holders|date=December 2014|publisher=[[International Electrotechnical Commission|IEC]]|language=fr, en|access-date=22 March 2015|location=[[Geneva]]|archive-url=https://web.archive.org/web/20130416102852/http://webstore.iec.ch/preview/info_iec60061_DB.pdf|archive-date=16 April 2013|edition=3.51}}{{subscription required}}</ref>

<ref name=eb>{{cite web|url=http://homerepair.about.com/od/electricalrepair/ss/2007_energybill_4.htm|title=2007 Energy Bill – Are They Phasing Out or Making Incandescent Bulbs Illegal? Incandescent Exemptions: Where You Can Still Use Existing Bulbs|last=Formisano|first=Bob|work=About.com Home |publisher=About.com|access-date=22 March 2015|archive-url=https://web.archive.org/web/20090427161501/http://homerepair.about.com/od/electricalrepair/ss/2007_energybill_4.htm|archive-date=27 April 2009}}</ref> }}

== External links == * {{Commons category-inline |Edison screw}} * [https://www.gewinde-normen.de/en/e-thread.html Edison screw thread (in English)]

[[Category:Electrical power connectors]] [[Category:Mechanical standards]] [[Category:Standards of the United States]] [[Category:Types of lamp]]

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