Editing Electric power distribution (section)

==== 100–120 volt systems ====
Most of the Americas use 60&nbsp;Hz AC, the 120/240 volt [[Split-phase electric power|split-phase]] system domestically and three phase for larger installations. North American transformers usually power homes at 240 volts, similar to Europe's 230 volts. It is the split-phase that allows use of 120 volts in the home.

[[File:Power Grid of Japan.svg|thumb|Japan's utility frequencies are {{nowrap|50 Hz}} and {{nowrap|60 Hz}}.]]

In the [[electricity sector in Japan]], the standard voltage is 100&nbsp;V, with both 50 and 60&nbsp;Hz AC frequencies being used. Parts of the country use 50&nbsp;Hz, while other parts use 60&nbsp;Hz.<ref name="JapanTimes20110719">{{Cite news|url=http://www.japantimes.co.jp/news/2011/07/19/reference/japans-incompatible-power-grids/|title=Japan's incompatible power grids|last1=Gordenker|first1=Alice|date=2011-07-19|newspaper=The Japan Times Online|language=en-US|issn=0447-5763|access-date=2016-03-12}}</ref> This is a relic from the 1890s. Some local providers in [[Tokyo]] imported 50&nbsp;Hz German equipment, while the local power providers in [[Osaka]] brought in 60&nbsp;Hz generators from the United States. The grids grew until eventually the entire country was wired. Today the frequency is 50&nbsp;Hz in Eastern Japan (including Tokyo, [[Yokohama]], [[Tōhoku region|Tohoku]], and [[Hokkaido]]) and 60&nbsp;Hz in Western Japan (including [[Nagoya]], [[Osaka]], [[Kyoto]], [[Hiroshima]], [[Shikokuchūō|Shikoku]], and [[Kyushu]]).<ref>{{Cite web|url=http://www.japan-guide.com/e/e2225.html|title=Electricity in Japan|website=Japan-Guide.com|access-date=2016-03-12}}</ref>

Most household appliances are made to work on either frequency. The problem of incompatibility came into the public eye when the [[2011 Tōhoku earthquake and tsunami]] knocked out about a third of the east's capacity, and power in the west could not be fully shared with the east since the country does not have a common frequency.<ref name="JapanTimes20110719" />

There are four [[high-voltage direct current]] (HVDC) converter stations that move power across Japan's AC frequency border. [[Shin Shinano]] is a [[Back-to-back connection#Power transmission|back-to-back]] HVDC facility in [[Japan]] which forms one of four [[frequency changer]] stations that link Japan's western and eastern power grids. The other three are at [[Higashi-Shimizu Frequency Converter|Higashi-Shimizu]], [[Minami-Fukumitsu]] and [[Sakuma Dam#HVDC frequency converter|Sakuma Dam]]. Together they can move up to 1.2 GW of power east or west.<ref>{{Cite web|url=https://spectrum.ieee.org/why-japans-fragmented-grid-cant-cope|title=Why Japan's Fragmented Grid Can't Cope|website=Spectrum.IEEE.org|date=6 April 2011 |access-date=2016-03-12}}</ref>