Editing AC power plugs and sockets (section)

=== Hybrid and universal sockets ===
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File:Multi plug.jpg|A so-called "universal socket", which meets no official standard<ref>{{cite web |url=https://www.extron.com/download/files/userman/Universal_AC_Outlet_68-1638-01_F.pdf |title=Universal AC Outlet • Setup Guide |publisher=Extron Electronics |location=Anaheim, CA |date=November 2017 |id=68-1638-01 Rev. F |access-date=21 May 2018 |archive-url=https://web.archive.org/web/20180516015051/https://www.extron.com/download/files/userman/Universal_AC_Outlet_68-1638-01_F.pdf |archive-date=16 May 2018 |url-status=dead}}</ref> but is intended to accept a number of different plug types
File:Thai socket.jpg|An earthed Thai socket that complies with figure&nbsp;4 of TIS&nbsp;166-2549. Although it accepts NEMA plugs, the Thai voltage is 220&nbsp;V and thus is electrically incompatible with devices designed only for 120&nbsp;V.
File:Chinasocket.jpg|Chinese dual socket accepting both unearthed two-pin (upper) and earthed three-pin (lower) plugs
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"Hybrid", "multi-standard", or "universal" sockets are intended to accommodate plugs of two or more types. In some jurisdictions, they violate safety standards for sockets.<ref>{{cite web |url=https://www.spring.gov.sg/Building-Trust/Raising-Confidence/Safety-Tips-Alerts/Product-Safety-Alerts/Documents/SafetyAlert_Universal_Portable_Socket_Outlets.pdf |title=Alert noting non-compliant power strips |year=2009 |access-date=25 October 2019 |archive-url= https://web.archive.org/web/20160306184839/https://www.spring.gov.sg/Building-Trust/Raising-Confidence/Safety-Tips-Alerts/Product-Safety-Alerts/Documents/SafetyAlert_Universal_Portable_Socket_Outlets.pdf |archive-date=6 March 2016}}</ref><ref>{{cite web |url=http://www.pucsl.gov.lk/english/news/sri-lanka-sets-national-standard-for-plugs-and-socket-outlets-for-non-industrial-applications-2/ |title=Sri Lanka Sets National Standard for Plugs and Socket Outlets |website=Public Utilities Commission of Sri Lanka |access-date=25 October 2019 |quote=Standardized on Type&nbsp;G; sale of non-compliant sockets is banned as of August, 2018, and buildings must re-wire by August, 2038. |archive-url= https://web.archive.org/web/20190402014847/http://www.pucsl.gov.lk/english/news/sri-lanka-sets-national-standard-for-plugs-and-socket-outlets-for-non-industrial-applications-2/ |archive-date=2 April 2019 |url-status=dead}}</ref> Safety advocates, the United States Army,<ref name="jennings">{{cite web |url=http://www.almc.army.mil/alog/issues/MayJune12/Elelectrical_Safety.html |archive-url=https://web.archive.org/web/20150223190700/http://www.almc.army.mil/alog/issues/MayJune12/Elelectrical_Safety.html |archive-date=23 February 2015 |author=James S. Jennings |title=Army Sustainment: The Three Most Common Electrical Safety Issues in Deployed Environments}}</ref> and a manufacturer of sockets<ref>{{cite web |title=Universal Sockets Are Unsafe |url=http://www.interpower.com/ic/designers/white-papers/universal-sockets-are-unsafe.html |website=Interpower Corporation |publisher=Interpower |access-date=6 July 2018}}</ref> point out a number of safety issues with universal socket and adaptors, including voltage mismatch, exposure of live pins, lack of proper earth ground connection, or lack of protection from overload or short circuit. Universal sockets may not meet technical standards for durability, plug retention force, temperature rise of components, or other performance requirements, as they are outside the scope of national and international technical standards.

A technical standard may include compatibility of a socket with more than one form of plug. The Thai dual socket is specified in figure&nbsp;4 of TIS&nbsp;166-2549 and is designed to accept Thai plugs, and also Type&nbsp;A, B, and C&nbsp;plugs. Chinese dual sockets have both an unearthed socket complying with figure&nbsp;5 of GB&nbsp;1002-2008 (both flat pin and 4.8&nbsp;mm round pin), and an earthed socket complying with figure&nbsp;4 of GB&nbsp;1002-2008. The latter was removed from the 2021 revision of the Chinese standard,<ref name=GBT-1002-2021>{{cite web |last1=State Administration for Market Regulation |last2=Standardization Administration of China |title=GB/T 1002-2021: Single phase plugs and socket-outlets for household and similar purposes – Types, basic parameters and dimensions (English Version) |url=https://www.codeofchina.com/standard/GBT1002-2021.html |website=Code of China |date=11 October 2021 |author1-link=State Administration for Market Regulation |author2-link=Standardization Administration of China}}</ref> but such dual sockets can still be found in many existing installations.

Such Thai or Chinese dual sockets also accept plugs normally fitted to 120&nbsp;V appliances (e.g. 120&nbsp;V rated NEMA&nbsp;1-15 ungrounded plugs). This can cause an electrical incompatibility, since both countries supply residential power at 220&nbsp;V. These dual sockets also accept French and Schuko plugs (Types&nbsp;E and F), but unsafely: no earth contact is established and live pins may be exposed when a plug is partially inserted.<ref name=WorldSTDs/>