341:
the 1920s, the three-pin outlet was developed. This format was introduced in order to mitigate the effect of a short circuit event, as the supply would be neutralised with earth. Gradually the desire for trade eliminated some standards that had been used in only a few countries. Former colonies may retain the standards of the colonising country. Sometimes offshore industrial plants or overseas military bases use the wiring practices of their controlling country instead of the surrounding region. Some countries have multiple voltages, frequencies and plug designs in use, which can create inconvenience and safety hazards. Hotels and airports may maintain sockets of foreign standards for the convenience of travellers. By 2018, there were 15 plug and socket types around the world.
396:, the Commission's Regulatory Fitness and Performance (REFIT) programme issued a report in 2017. The report found that "the harmonisation of plug and socket outlet systems in Europe, by introducing changes in national wiring legislations (would have) important transitional periods (above 75 years)", and that the cost to "replace the old socket-outlets (and the corresponding plugs of the appliances being used)" was estimated at 100 billion Euro, "generating a huge environmental impact, producing some 700 000 tons of electrical waste". The report does not recommend harmonising the plugs and socket-outlet systems in Europe.
697:
745:
685:
1081:[Harvey Hubbell Inc. V. General Electric Co. et.al. (262 Fed.Rep. 155) District Court of the United States, Southern District of New York, October 20, 1919. Reported in "The Trade Mark Reporter" Vol 10, 1920, Pages 164 - 175. The court observed that Hubbell's plugs were readily distinguishable from those of other makes by the provision of "nicks" in the pins of Hubbell's plug pins, designed to provide retention when mated with Hubbell's receptacles, so there was no confusion as to their origin. The report of the trial is available from Google Books here:
673:
661:
754:
435:
736:
444:
228:
adaptors were supplied. The 1906 catalogue says of the
Chapman adaptor: "The device avoids fastening the cords together as is necessary with the ordinary Chapman plug when used for more than one purpose." This suggests that Hubbell's original invention was prompted by his observation of the problem that arose with the use of this sort of receptacle and plug. Gradually wall sockets were developed to supplement those that screwed into lampholders.
781:
24:
643:). Prior to the 1930s, when Hubbell's parallel blade plug received its official rating of 125v (and became the United States' general service electrical plug standard), all of his electrical connectors were used interchangeably on either 120 V or 240 V. The two blade tandem configuration plug received its official rating of 250 V in the 1950s but has been "banned" from use since the 1960s because of its lack of a ground or neutral.
186:
202:. On 26 February 1903 he filed two patent applications featuring 2-pin plugs and adaptors for using his plugs with existing designs of lamp sockets and wall receptacles. Hubbell's first plug design had two round pins which differed from those already in use in Europe in that the tips of the pins had annular detents similar to those of present-day jack plugs to positively retain a plug in its socket. In one patent,
596:
549:
283:
409:. A modified version is used in Brazil, but IEC 60906-1 has been adopted only in South Africa (in 1993) becoming the "preferred configuration for new installations" in 2013. A statement released by the South African Bureau of Standards in 2016 said that the roll-out of the new standard would be gradual and that the implementation of a new standard could take " 50 years".
541:
510:
274:, and refused to agree, asserting that it had common law rights in the dimensions of its line. The other conference members pressed on regardless, and agreed to standardize on Hubbell's parallel flat pin configuration and dimensions. Hubbell's court action only served to confirm the legality of their activities, to the great benefit of the U.S. public.
155:
134:
319:
of the socket was not operable with existing two-contact unearthed plugs. Other earthed sockets that are widely used in the U.S. today are operable with unearthed plugs. It is sometimes claimed (e.g., in
Illumin) that the modern American version of the earthed plug, was invented by Philip F. Labre who was issued a
532:
limited lighting circuits to 10 A. In 1923, the code changed to allow lighting circuits to be fused at 15 A, but the previous 10 A rule still applied to circuits over 125 V. The higher voltages were rarely used for lighting and appliances. Most sockets with this rating are of the "T-slot" type.
605:
414:
The object of this part of IEC 60906 is to provide a standard for a safe, compact and practical IEC 125 V system of plugs and socket-outlets that could be accepted by many countries as their national standard, now or in the near future. It is therefore recommended that any country in need of a new or
531:
Many older North
American sockets have two different current and voltage ratings, most commonly 10 A 250 V/15 A 125 V. This has to do with a peculiarity of the National Electrical Code from 1923 to the 1950s. Originally, sockets were rated at 10 A 250 V, because the NEC
460:
Some older industrial buildings in Spain used sockets that took a plug rated for higher current and had two flat contacts and a round earth pin, somewhat similar in design to the ones found on
American plugs but larger in size. The two flat contacts are spaced further apart than on an American plug.
375:
The international standard IEC 60884-1 defines the general requirements for plugs and sockets intended for household and similar purposes, IEC 60884-1 does not define specific plug and socket types, which are the subject of national standards in each country. IEC 60884-1 para 9.2 does stipulate that
257:
issued August 16, 1892, for which
Hubbell had taken out a licence), another (unidentified) type following in 1897. Plugs per se with parallel flat pins, such as the "Fort Wayne" design were in common use by 1886, and flush receptacles, such as the "Bryant Electrical Company" design, by 1902. Hubbell
162:
As electricity became a common method of operating labour-saving appliances, a safe means of connection to the electric system other than using a light socket was needed. Thomas Tayler Smith, of London, received
British patent 4162 in 1882 for an "Electric-Circuit Connection" to "enable the electric
378:
in order to promote international uniformity, IEC National
Committees undertake to apply IEC Publications transparently to the maximum extent possible in their national and regional publications. Any divergence between any IEC Publication and the corresponding national or regional publication shall
318:
covers the use of an earthing pin which extends further than the other two contacts to ensure that it is engaged first. Knapp's design was obsoleted in the U.S. before the modern NEMA designations, but is still used in some other countries including China, Argentina and
Australia. The configuration
169:
for the same device in 1885. According to
British Author John Mellanby there were British patents for plug and sockets granted to T.T. Smith in 1883 (No. 3883) and W. B. Sayers & G. Hookham in 1884, (No. 16655). Mellanby also writes that there were two-pin designs by 1885, one of which appears
145:
was first introduced into houses in the 1880s, it was primarily used for lighting. One common approach for other appliances (such as vacuum cleaners, electric fans, smoothing irons and curling tong heaters) was to connect to light bulb sockets using lampholder plugs. However, in
Britain, there were
340:
During the first 50 years of commercial use of electric power, standards developed rapidly based on growing experience. Technical, safety, and economic factors influenced the development of all wiring devices and numerous varieties were invented. After the two-prong electric plug was introduced in
626:
A more recent and fairly common version of this type is the T-slot socket, in which the locations of the tandem and the parallel slots were combined to create T-shaped slots. This version also accepts normal parallel NEMA 1‐15 plugs and also tandem NEMA 2‐15 plugs. Incidentally, a NEMA 5‐20, NEMA
269:
Following the lead set by the lamp manufacturers in standardising lamp bases, a conference of the plug and receptacle manufacturers, including Hubbell, was arranged with a view to agreeing a standard configuration. It was a time of great expansion in the use of electrical appliances such as fans,
227:
Hubbell's catalogue of 1906 includes various three-way adaptors similar to those shown in the US 776,326 patent, but modified for use with the coplanar flat pin plugs. The Chapman receptacle must have been in general use at the time, as it was the only type of non-lampholder receptacle for which
376:"it shall not be possible, within a given system, to engage a plug with a socket-outlet having a higher voltage rating or a lower current rating". IEC 60884-1 para 6.1 defines the preferred voltage ratings for single phase plugs and sockets as 130 V or 250 V. The foreword of IEC 60884-1 states:
234:
A feature common to all of Hubbell's patented designs is the provision of detents to retain a plug in its socket. This would have been a desirable feature in the days before wall receptacles became widespread and, for many consumers, the only source of electricity was an electric light socket.
581:
this socket was and still is commonly used for wiring in places where the voltage is lowered for safety purposes, like in schools, filling stations or in wet areas, and is rated 42 V at 10 A AC. Such an unusual connection is intended specifically to make the connection of standard
243:
Despite Hubbell's objections, other manufacturers adopted the Hubbell pattern (omitting Hubbell's detents as these did not affect interchangeability) and by 1915 the use of Hubbell's configuration was widespread. In 1919 Hubbell unsuccessfully attempted to get an injunction to prevent other
768:
Called "Tripoliki" (τριπολική, meaning "three-pole"), the standard had 3 round pins, similar to the post-1989 Israeli SI 32 and Thai TIS 166-2549 types. The Tripoliki was virtually abandoned by the 1980s, but can still be found in unrenovated houses constructed before 1980. Previous to the
627:
6-15, or NEMA 6‐20 plug with a missing earth pin would fit this socket. This receptacle type has been unavailable at retail since the 1960s but still available from the manufacturer Leviton (model 5000-I) for replacement only, not for new installations and is not "UL listed".
630:
Harvey Hubbell had patented the parallel blade plug in 1913, and patented a polarized version in 1916. He also patented the T-slot single outlet in 1915, and a duplex T-slot outlet in 1916 both meant to take his older 1904 tandem and newer parallel plug design. (Single:
265:
By 1915, Hubbell had sold about 13 million receptacles and plug bases/caps with tandem slots/pins, and about 1.25 million with parallel slots/pins, most of which were then still in active use, meaning that Hubbell's configurations were by far the most widely used.
383:
Consolidation of standards eases international trade and travel. For example, the CEE 7/7 plug has been adopted in several European countries and is compatible with both CEE 7/3 and CEE 7/5 sockets, while the unearthed and unpolarised CEE 7/16
247:
The report of the court proceedings includes a comprehensive review of the development of the art in the US prior to 1919, based on evidence presented to the Court. Separable plugs had been available for more than a decade prior to Hubbell's 1904 design.
214:
the same type of plug was used with various three-way adaptors that could be connected to lampholders or "a receptacle of any ordinary type". Figures 2 and 4 of this patent show an adaptor plugged into what appears to be a "Chapman" receptacle.
1082:
464:
The line and neutral measure 9 by 2 mm (0.354 by 0.079 in), and are 30 mm (1.181 in) apart. All three pins are 19 mm (0.748 in) long, and the earth pin is a cylinder of 4.8 mm (0.189 in) diameter.
495:) or blades (US patent 774251). The 1906 Hubbell catalog shows the blade plug with a flush mounting socket for use in wall or floor. Other manufacturers adopted the Hubbell pattern, and by 1915 they were widespread.
332:-system plug is believed to date from 1925 and is attributed to Albert Büttner. As the need for safer installations became apparent, earthed three-contact systems were made mandatory in most industrial countries.
1083:
https://books.google.co.uk/books?id=XOgsAAAAYAAJ&printsec=frontcover&dq=the+trademark+reporter+volume+10&hl=en&sa=X&ved=0ahUKEwjHgZr29YvXAhUCSRoKHWQaDOAQ6AEIJjAA#v=onepage&q&f=false
1370:
696:
769:
large-scale adoption of Schuko plugs, this was the only way to use an earthed appliance in Greece. It can accept Europlugs, and also (but with no earth connection possible) French and German types.
474:
163:
conductors conveying the current to one or more lamps, or along a flexible cord, to be rapidly and safely brought into connection with the line or main wires". Smith subsequently received
270:
heaters, and cookers, as well as portable devices such as hair curlers and irons, and the public wanted interchangeability. Hubbell's parallel pin configuration was preferred, but Hubbell
177:
Gustav Binswanger, a German immigrant who founded the General Electric Company, obtained a patent (GB189516898) in 1895 for a plug and socket using a concentric (co-axial) contact system.
262:. The existence of both "tandem" and parallel pin configurations had led to the introduction in 1914 of some receptacles having both configurations of slots and others having "T" slots.
360:
in 1934 established technical committee TC 23 for electrical fittings. Only two meetings were held before the outbreak of the Second World War. In mainland Europe, since 1951 the
1159:
368:) describing the plugs and sockets used. In 1953 the CEE published Technical Report 83 (later 60083), which was a listing of plugs and sockets then in use. In North America the
523:. It predated the NEMA sockets and plugs. The plugs and sockets used in countries such as Argentina, Australia and China are based on this type and are physically compatible.
120:
There are approximately 20 types in common use around the world, such as AC power plugs and sockets, and many obsolete socket types which are still found in older buildings.
613:
Left: old "Nurpolian"-brand black parallel and tandem duplex socket rated at 250 V 10 A (although normally supplied with 120 V). Right: T-slot duplex socket.
672:
1316:
1348:
IEC 60906-2:2011, IEC system of plugs and socket-outlets for household and similar purposes - Part 2: Plugs and socket-outlets 15 A 125 V a.c. and 20 A 125 V a.c.
717:
260:...from 15 to 20 different types of blades and from 15 to 30 different types of receptacles. The line of each was not interchangeable with competing lines. ...
41:
563:
The upper slots connect to silver-coloured wiring screws on the upper side, and the lower slots connect to brass-coloured wiring screws on the lower side.
297:
In Britain, a 1911 book dealing with the electrical products of A. P. Lundberg & Sons of London describes the "Tripin" earthed plug available in 2.5
312:
The earliest American patent application for an earthed plug appears to be 11 January 1915 by George P. Knapp, on behalf of the Harvey Hubbell company.
722:
Before the 1970s, several types of proprietary plugs and sockets were commonly used in Britain, alongside types which conformed to national standards.
817:
489:
in 1904. Hubbell's first design was a socket which screwed into a lampholder (like the early lampholder plugs), but with a separable plug with pins (
88:
1028:
684:
60:
660:
1302:
IEC 60906-1:1986, IEC system of plugs and socket-outlets for household and similar purposes - Part 1: Plugs and socket-outlets 16 A 250 V a.c.
620:
557:
369:
67:
231:
In 1912 Hubbell rotated his tandem pins by 90 degrees to arrive at the parallel flat pin configuration still widely used today (NEMA 1-15).
224:
filed on May 27, 1904 shows lampholder adaptors similar to those of his first patent for use with plugs having coplanar (tandem) flat pins.
560:
5‐20 125 V 20 A or 6‐20 250 V 20 A plug with a missing earth pin would fit this socket, but a NEMA 2‐20 plug is slightly too big to fit.
74:
325:
for an earthed socket and plug in 1928. However, Labre's design is no more similar to the modern version than Knapp's earlier design.
357:
972:
56:
352:
standards became formalised as official national and international standards. The earliest is believed to be British Standard 73
1398:"Leviton Duplex Receptacle, T-SLOT, not UL listed; for Replacement use only - Receptacles - Leviton 5000 - LevitonProducts.com"
654:
These adaptors are obsolete because they are not polarized; polarized versions of these types are still available in the U.S.
936:
878:
Schroeder, Fred E. H. (1986-01-01). "More "Small Things Forgotten": Domestic Electrical Plugs and Receptacles, 1881-1931".
997:
1324:
966:
415:
replacement system for the nominal voltage range 100 V to 130 V a.c. adopt this standard as its only national standard.
1202:
208:
a plug was used with a socket which screwed into a lampholder (like the early lampholder plugs). In the other patent
107:
81:
646:
Note: See the NEMA 1-15 ungrounded (Type A) section of this page for the parallel blade patent reference numbers.
412:
IEC 60906-2 is based on the NEMA 5-15 and NEMA 5-20 plug and socket systems and was originally published in 1992.
1451:
45:
1128:
1258:
IEC 60884-1 ed3.2, Plugs and socket-outlets for household and similar purposes - Part 1: General requirements
827:
309:
Maud Lucas Lancaster mentions an earthed iron-clad plug and socket by the English firm of Reyrolle and Co.
1272:
623:
1‐15 plugs and also tandem NEMA 2‐15 plugs. Both pairs of sockets are fed internally by the same supply.
1365:
1024:
795:
702:
Screws into a light bulb socket to add two receptacles, while still taking the bulb. Made in the US by
1154:
452:
Left: Spanish three-pin plug (Eunea 3023-B/Metropoli) and socket (Eunea 3013-B) with removable fuse.
1093:"SMALL SWITCHES, etc., and their CIRCUITS" (1911), MAYCOCK, W. Perren, London: S. Rentall & Co.
571:
402:
was originally published in 1986 as a common standard for plugs and sockets in countries using 230
388:
is compatible with even more European and other socket types. In response to a suggestion that the
171:
1346:
1232:
556:
Another obsolete socket, made by Bryant, 125 V 15 A and 250 V 10 A rating. A
34:
1256:
1104:
407:
that could be accepted by many countries as their national standard, now or in the near future
301:
and 5 amp models. The pin configuration of the "Tripin" appears virtually identical to modern
291:
1106:
Electric Cooking, Heating and Cleaning: A Manual of Electricity in the Service of the Home
678:
One-to-three plug electrical converter, by General Electric. The plug rotates 180 degrees.
8:
853:
744:
389:
1397:
1177:
903:
895:
858:
786:
146:
recognisable two pin plugs and wall sockets appearing on the market as early as 1885.
907:
822:
753:
1054:
887:
843:
473:
258:
had introduced its own parallel flat pin configuration in 1912. In 1915 there were
244:
manufacturers from making receptacles and plugs to the dimensions used by Hubbell.
498:
517:
A patent for the obsolete "wye" American plug and socket was filed in 1915 under
218:
Hubbell evidently soon found the round pin design unsatisfactory as a subsequent
1001:
434:
198:
Several early American electrical plug and socket arrangements were invented by
703:
482:
393:
199:
639:
633:
519:
362:
International Commission on the Rules for the Approval of Electrical Equipment
321:
314:
1445:
1421:
491:
253:
220:
210:
204:
190:
165:
1300:
1273:"REFIT Platform Opinion on the submission by a citizen on Plugs and Sockets"
735:
366:
Specification for Plugs and Socket-Outlets for Domestic and Similar Purposes
154:
1210:
800:
578:
567:
133:
443:
1102:
504:
399:
142:
354:
Wall plugs and sockets (five ampere two-pin without earthing connection)
899:
848:
604:
566:
In Australia, the same or similar T-configuration sockets are used for
838:
811:
805:
477:
Hubbell plug and receptacle as advertised in the 1906 Hubbell catalog
361:
158:
Early GEC 2 pin plug and socket as depicted in the 1893 GEC Catalogue
891:
830:
lists voltage, frequency, and connector types for over 200 countries
23:
780:
574:(SAPS), on boats and in police vehicles. Polarity is inconsistent.
385:
185:
833:
468:
595:
548:
486:
329:
302:
298:
282:
238:
968:
Electrical specialities : catalogue and price list No. 9
481:
An early American electrical plug and socket was invented by
540:
509:
666:
One-to-three plug electrical converter, by General Electric
403:
690:
Converts a light bulb socket into an electrical receptacle
461:
No domestic appliances were ever sold with these plugs.
294:) consumer plug has several claimants to its invention.
619:
The parallel and tandem socket accepts normal parallel
286:
Illustration of "Tripin" 3-pin earthed plug dated 1911.
1368:, George P. Knapp, "Separable Attachment Plug"
1103:
Lancaster, M.L.; Lancaster, E.W.; Coles, S.L. (1914).
718:
AC power plugs and sockets - British and related types
552:
Perpendicular slot RP-2B socket 10 A 42 V AC
251:
The earliest presented to the court was the "Weston" (
1354:, CH: International Electrotechnical Commission, 2011
1305:, CH: International Electrotechnical Commission, 1986
1261:, CH: International Electrotechnical Commission, 2013
1178:"Why isn't there a universal standard electric plug?"
499:
American 125 V, 15 A / 250 V, 10 A "Australian" style
1025:"The Automobile Storage Battery Its Care and Repair"
776:
137:
Lampholder plug from 1893 GEC Ltd (London) catalogue
964:
762:
Greek old earthed standard adaptor plugs and socket
48:. Unsourced material may be challenged and removed.
1175:
1129:"A Powerful History: The Modern Electrical Outlet"
392:introduce a common system across the whole of the
372:(NEMA) publishes standards for plugs and sockets.
818:Industrial and multiphase power plugs and sockets
585:
1443:
1233:"IEC Webstore preview Retrieved 19 October 2011"
526:
513:Obsolete 125 V, 15 A / 250 V, 10 A duplex outlet
960:
958:
194:. The first US power plug and socket dated 1904
808:high-power industrial and polyphase connectors
454:Right: adaptor for CEE 7/17 and CEE 7/4 plugs.
920:
469:Original American Hubbell plug and receptacle
370:National Electrical Manufacturers Association
1317:"South Africa's new plug standard explained"
1048:
1046:
955:
1364:
1171:
1169:
937:"Photograph of Chapman receptacle and plug"
277:
239:Hubbell versus other American manufacturers
1077:
1075:
535:
1207:International Electrotechnical Commission
1043:
992:
990:
914:
877:
358:International Electrotechnical Commission
307:Electric cooking, heating, cleaning, etc.
108:Learn how and when to remove this message
1358:
1166:
1096:
547:
539:
508:
472:
356:which was first published in 1915. The
281:
184:
153:
132:
1176:Conrad H. McGregor (27 November 2018).
1072:
180:
57:"History of AC power plugs and sockets"
1444:
1157:, "Stecker mit Erdungseinrichtung"
1109:. D. Van Nostrand Company. p. 312
987:
424:
364:(CEE) has published a standard (CEE 7
1052:
1022:
941:Smokey Ed's Antiques and Collectables
582:higher-voltage equipment impossible.
925:. London, United Kingdom: Macdonald.
725:
711:
46:adding citations to reliable sources
17:
1135:. University of Southern California
1031:from the original on 24 August 2007
965:Harvey Hubbell, Inc (August 1906).
379:be clearly indicated in the latter.
13:
1203:"IEC - World Plugs: Brief history"
149:
14:
1463:
419:
779:
752:
743:
734:
695:
683:
671:
659:
649:
603:
594:
544:Perpendicular slot duplex socket
442:
433:
344:
335:
272:rebelled against standardization
128:
22:
1414:
1390:
1377:
1339:
1309:
1293:
1265:
1249:
1225:
1195:
1147:
1121:
1000:. Hubbell. 2009. Archived from
33:needs additional citations for
1387:McGraw-Hill, 1924, pp. 198–99.
1087:
1016:
929:
923:The History of Electric Wiring
871:
586:U.S. combination duplex socket
123:
1:
865:
527:Split current/voltage ratings
828:Mains electricity by country
7:
1426:Museum of Plugs and Sockets
1385:Wiring for Light and Power,
772:
10:
1468:
796:AC power plugs and sockets
715:
502:
1133:Illumin Volume X Issue II
572:stand-alone power systems
305:plugs. In her 1914 book
278:Earthed (grounded) plugs
172:General Electric Company
1402:www.levitonproducts.com
536:US perpendicular socket
1452:Mains power connectors
1366:US patent 01179728
921:John Mellanby (1957).
880:Technology and Culture
553:
545:
514:
478:
287:
195:
159:
138:
640:U.S. patent 1,210,176
634:U.S. patent 1,146,938
551:
543:
520:U.S. patent 1,179,728
512:
476:
322:U.S. patent 1,672,067
315:U.S. patent 1,179,728
285:
188:
157:
136:
1155:DE patent 489003
814:appliance connectors
181:Hubbell's inventions
42:improve this article
1327:on 12 December 2017
1280:European Commission
1004:on 14 February 2010
854:Stage pin connector
492:U.S. patent 774,250
425:Old Spanish sockets
390:European Commission
254:U.S. patent 480,900
221:U.S. patent 774,251
211:U.S. patent 776,326
205:U.S. patent 774,250
191:U.S. patent 774,250
174:catalogue of 1889.
166:U.S. patent 311,616
1321:Brand South Africa
859:Anderson Powerpole
787:Electronics portal
554:
546:
515:
479:
288:
196:
160:
139:
1213:on 12 August 2018
1182:WorldStandards.eu
823:Mains electricity
726:Old Greek sockets
712:UK obsolete types
118:
117:
110:
92:
1459:
1437:
1436:
1434:
1432:
1418:
1412:
1411:
1409:
1408:
1394:
1388:
1381:
1375:
1374:
1373:
1369:
1362:
1356:
1355:
1353:
1343:
1337:
1336:
1334:
1332:
1323:. Archived from
1313:
1307:
1306:
1297:
1291:
1290:
1288:
1286:
1277:
1269:
1263:
1262:
1253:
1247:
1246:
1244:
1242:
1237:
1229:
1223:
1222:
1220:
1218:
1209:. Archived from
1199:
1193:
1192:
1190:
1188:
1173:
1164:
1163:
1162:
1158:
1151:
1145:
1144:
1142:
1140:
1125:
1119:
1118:
1116:
1114:
1100:
1094:
1091:
1085:
1079:
1070:
1069:
1067:
1065:
1059:
1050:
1041:
1040:
1038:
1036:
1020:
1014:
1013:
1011:
1009:
994:
985:
984:
982:
980:
962:
953:
952:
950:
948:
933:
927:
926:
918:
912:
911:
875:
844:Polyphase system
789:
784:
783:
756:
747:
738:
699:
687:
675:
663:
642:
636:
607:
598:
568:DC power sockets
522:
494:
446:
437:
324:
317:
256:
223:
213:
207:
193:
168:
113:
106:
102:
99:
93:
91:
50:
26:
18:
1467:
1466:
1462:
1461:
1460:
1458:
1457:
1456:
1442:
1441:
1440:
1430:
1428:
1420:
1419:
1415:
1406:
1404:
1396:
1395:
1391:
1383:Terrell Croft,
1382:
1378:
1371:
1363:
1359:
1351:
1345:
1344:
1340:
1330:
1328:
1315:
1314:
1310:
1299:
1298:
1294:
1284:
1282:
1275:
1271:
1270:
1266:
1255:
1254:
1250:
1240:
1238:
1235:
1231:
1230:
1226:
1216:
1214:
1201:
1200:
1196:
1186:
1184:
1174:
1167:
1160:
1153:
1152:
1148:
1138:
1136:
1127:
1126:
1122:
1112:
1110:
1101:
1097:
1092:
1088:
1080:
1073:
1063:
1061:
1060:. Mosaic shades
1057:
1051:
1044:
1034:
1032:
1027:. Powerstream.
1021:
1017:
1007:
1005:
996:
995:
988:
978:
976:
963:
956:
946:
944:
935:
934:
930:
919:
915:
892:10.2307/3105384
876:
872:
868:
863:
785:
778:
775:
766:
765:
764:
763:
759:
758:
757:
749:
748:
740:
739:
728:
720:
714:
707:
700:
691:
688:
679:
676:
667:
664:
652:
638:
632:
617:
616:
615:
614:
610:
609:
608:
600:
599:
588:
538:
529:
518:
507:
501:
490:
471:
458:
457:
456:
455:
453:
449:
448:
447:
439:
438:
427:
422:
347:
338:
320:
313:
280:
252:
241:
219:
209:
203:
189:
183:
164:
152:
150:British origins
131:
126:
114:
103:
97:
94:
51:
49:
39:
27:
12:
11:
5:
1465:
1455:
1454:
1439:
1438:
1413:
1389:
1376:
1357:
1338:
1308:
1292:
1264:
1248:
1224:
1194:
1165:
1146:
1120:
1095:
1086:
1071:
1053:Crist (2005).
1042:
1023:Witte (1922).
1015:
986:
954:
928:
913:
886:(3): 525–543.
869:
867:
864:
862:
861:
856:
851:
846:
841:
836:
831:
825:
820:
815:
809:
803:
798:
792:
791:
790:
774:
771:
761:
760:
751:
750:
742:
741:
733:
732:
731:
730:
729:
727:
724:
716:Main article:
713:
710:
709:
708:
704:Eagle Electric
701:
694:
692:
689:
682:
680:
677:
670:
668:
665:
658:
651:
648:
612:
611:
602:
601:
593:
592:
591:
590:
589:
587:
584:
577:In the former
537:
534:
528:
525:
500:
497:
483:Harvey Hubbell
470:
467:
451:
450:
441:
440:
432:
431:
430:
429:
428:
426:
423:
421:
420:Obsolete types
418:
394:European Union
346:
343:
337:
334:
279:
276:
240:
237:
200:Harvey Hubbell
182:
179:
151:
148:
130:
127:
125:
122:
116:
115:
30:
28:
21:
9:
6:
4:
3:
2:
1464:
1453:
1450:
1449:
1447:
1427:
1423:
1417:
1403:
1399:
1393:
1386:
1380:
1367:
1361:
1350:
1349:
1342:
1326:
1322:
1318:
1312:
1304:
1303:
1296:
1281:
1274:
1268:
1260:
1259:
1252:
1234:
1228:
1212:
1208:
1204:
1198:
1183:
1179:
1172:
1170:
1156:
1150:
1134:
1130:
1124:
1108:
1107:
1099:
1090:
1084:
1078:
1076:
1056:
1049:
1047:
1030:
1026:
1019:
1003:
999:
993:
991:
974:
970:
969:
961:
959:
942:
938:
932:
924:
917:
909:
905:
901:
897:
893:
889:
885:
881:
874:
870:
860:
857:
855:
852:
850:
847:
845:
842:
840:
837:
835:
832:
829:
826:
824:
821:
819:
816:
813:
810:
807:
804:
802:
799:
797:
794:
793:
788:
782:
777:
770:
755:
746:
737:
723:
719:
705:
698:
693:
686:
681:
674:
669:
662:
657:
656:
655:
650:U.S. adaptors
647:
644:
641:
635:
628:
624:
622:
606:
597:
583:
580:
575:
573:
570:, such as in
569:
564:
561:
559:
550:
542:
533:
524:
521:
511:
506:
496:
493:
488:
484:
475:
466:
462:
445:
436:
417:
416:
410:
408:
405:
401:
397:
395:
391:
387:
381:
380:
373:
371:
367:
363:
359:
355:
351:
345:Consolidation
342:
336:Proliferation
333:
331:
326:
323:
316:
310:
308:
304:
300:
295:
293:
290:The earthed (
284:
275:
273:
267:
263:
261:
255:
249:
245:
236:
232:
229:
225:
222:
216:
212:
206:
201:
192:
187:
178:
175:
173:
167:
156:
147:
144:
135:
129:Early history
121:
112:
109:
101:
98:November 2023
90:
87:
83:
80:
76:
73:
69:
66:
62:
59: –
58:
54:
53:Find sources:
47:
43:
37:
36:
31:This article
29:
25:
20:
19:
16:
1431:19 September
1429:. Retrieved
1425:
1416:
1405:. Retrieved
1401:
1392:
1384:
1379:
1360:
1347:
1341:
1329:. Retrieved
1325:the original
1320:
1311:
1301:
1295:
1283:. Retrieved
1279:
1267:
1257:
1251:
1239:. Retrieved
1227:
1215:. Retrieved
1211:the original
1206:
1197:
1185:. Retrieved
1181:
1149:
1137:. Retrieved
1132:
1123:
1111:. Retrieved
1105:
1098:
1089:
1064:14 September
1062:. Retrieved
1035:14 September
1033:. Retrieved
1018:
1006:. Retrieved
1002:the original
979:19 September
977:. Retrieved
967:
947:19 September
945:. Retrieved
940:
931:
922:
916:
883:
879:
873:
801:DC connector
767:
721:
653:
645:
629:
625:
618:
579:Soviet Union
576:
565:
562:
555:
530:
516:
480:
463:
459:
413:
411:
406:
398:
382:
377:
374:
365:
353:
349:
348:
339:
327:
311:
306:
296:
289:
271:
268:
264:
259:
250:
246:
242:
233:
230:
226:
217:
197:
176:
161:
140:
119:
104:
95:
85:
78:
71:
64:
52:
40:Please help
35:verification
32:
15:
1422:"Tripoliki"
1331:12 December
1285:12 December
1217:1 September
1187:19 December
971:. pp.
505:AS/NZS 3112
400:IEC 60906-1
328:The German
143:electricity
124:Development
1407:2023-11-28
1139:5 February
1113:7 February
1058:(tutorial)
866:References
849:Smart plug
637:; Duplex:
503:See also:
68:newspapers
1055:"Sockets"
998:"History"
908:112928824
839:Plug load
812:IEC 60320
806:IEC 60309
1446:Category
1241:12 March
1029:Archived
1008:20 March
773:See also
487:patented
386:Europlug
350:De facto
292:grounded
900:3105384
834:Perilex
170:in the
82:scholar
1372:
1161:
943:. 2013
906:
898:
330:Schuko
303:BS 546
84:
77:
70:
63:
55:
1352:(PDF)
1276:(PDF)
1236:(PDF)
904:S2CID
896:JSTOR
141:When
89:JSTOR
75:books
1433:2015
1333:2017
1287:2017
1243:2013
1219:2014
1189:2018
1141:2017
1115:2016
1066:2007
1037:2007
1010:2010
981:2015
949:2015
621:NEMA
558:NEMA
485:and
61:news
975:–57
888:doi
299:amp
44:by
1448::
1424:.
1400:.
1319:.
1278:.
1205:.
1180:.
1168:^
1131:.
1074:^
1045:^
989:^
973:56
957:^
939:.
902:.
894:.
884:27
882:.
1435:.
1410:.
1335:.
1289:.
1245:.
1221:.
1191:.
1143:.
1117:.
1068:.
1039:.
1012:.
983:.
951:.
910:.
890::
706:.
404:V
111:)
105:(
100:)
96:(
86:·
79:·
72:·
65:·
38:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
