Editing Overhead power line (section)

==History==
The first transmission of electrical impulses over an extended distance was demonstrated on July 14, 1729 by the physicist [[Stephen Gray (scientist)|Stephen Gray]].{{Citation needed|date=May 2014}} The demonstration used damp hemp cords suspended by silk threads (the low resistance of metallic conductors not being appreciated at the time).

However the first practical use of overhead lines was in the context of [[electrical telegraph|telegraphy]]. By 1837 experimental commercial telegraph systems ran as far as  20&nbsp;km (13 miles).   Electric power transmission was accomplished in 1882 with the first high-voltage transmission between [[Miesbach–Munich Power Transmission|Munich and Miesbach]] (60&nbsp;km). 1891 saw the construction of the first three-phase [[alternating current]] overhead line on the occasion of the International Electricity Exhibition in [[Frankfurt]], between [[Lauffen]] and Frankfurt.

In 1912 the first 110 kV-overhead power line entered service followed by the first 220 kV-overhead power line in 1923. In the 1920s [[RWE]] AG built the first overhead line for this voltage and in 1926 built a [[Rhine]] crossing with the pylons of [[Voerde]], two masts 138 meters high.

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In 1953, the first 345 kV line was put into service by [[American Electric Power]] in the [[United States]]. In Germany in 1957 the first 380 kV overhead power line was commissioned (between the transformer station and Rommerskirchen). In the same year the overhead line traversing of the Strait of Messina went into service in Italy, whose [[Pylons of Messina|pylons]] served the Elbe crossing 1. This was used as the model for the building of the Elbe crossing 2 in the second half of the 1970s which saw the construction of the highest overhead line pylons of the world. Earlier, in 1952, the first 380 kV line was put into service in [[Sweden]], in 1000&nbsp;km (625 miles) between the more populated areas in the south and the largest hydroelectric power stations in the north.
Starting from 1967 in Russia, and also in the USA and Canada, overhead lines for voltage of 765 kV were built. In 1985 [[Powerline Ekibastuz-Kokshetau|overhead power line]] was built in Soviet Union between [[Kokshetau]] and the power station at [[Ekibastuz]], this was a three-phase alternating current line at 1150 kV. In 1999, in Japan the first powerline designed for 1000 kV with 2 circuits were built, the [[Kita-Iwaki Powerline]]. In 2002 the building of the highest overhead line commenced in China, the [[Yangtze River Crossing]], its two {{convert|346.5|m|ft|0|abbr=on}} high [[suspension tower]]s beginning service in 2004.<ref>{{Cite web|url=https://structurae.net/en/structures/jiangyin-yangtze-high-voltage-crossing-pylons|title = Jiangyin Yangtze High-Voltage Crossing Pylons (Jiangyin, 2004)}}</ref>

In the 21st century, replacing steel with carbon fiber cores ([[advanced reconductoring]]) became a way for utilities to increase transmission capacity without increasing the amount of land used.