War of the currents
The war of the currents was a series of events surrounding the introduction of competing electric power transmission systems in the late 1880s and early 1890s. It grew out of two lighting systems developed in the late 1870s and early 1880s: arc lamp street lighting running on high-voltage alternating current, and large-scale low-voltage direct current indoor incandescent lighting being marketed by Thomas Edison's company. In 1886, the Edison system was faced with new competition: an alternating current system initially introduced by George Westinghouse's company that used transformers to step down from a high voltage so AC could be used for indoor lighting. Using high voltage allowed an AC system to transmit power over longer distances from more efficient large central generating stations. As the use of AC spread rapidly with other companies deploying their own systems, the Edison Electric Light Company claimed in early 1888 that high voltages used in an alternating current system were hazardous, and that the design was inferior to, and infringed on the patents behind, their direct current system.
In the spring of 1888, a media furor arose over electrical fatalities caused by pole-mounted high-voltage AC lines, attributed to the greed and callousness of the arc lighting companies that operated them. In June of that year Harold P. Brown, a New York electrical engineer, claimed the AC-based lighting companies were putting the public at risk using high-voltage systems installed in a slipshod manner. Brown also claimed that alternating current was more dangerous than direct current and tried to prove this by publicly killing animals with both currents, with technical assistance from Edison Electric. The Edison company and Brown colluded further in their parallel goals to limit the use of AC with attempts to push through legislation to severely limit AC installations and voltages. Both also colluded with Westinghouse's chief AC rival, the Thomson-Houston Electric Company, to make sure the first electric chair was powered by a Westinghouse AC generator.
By the early 1890s, the war was winding down. Further deaths caused by AC lines in New York City forced electric companies to fix safety problems. Thomas Edison no longer controlled Edison Electric, and subsidiary companies were beginning to add AC to the systems they were building. Mergers reduced competition between companies, including the merger of Edison Electric with their largest competitor, Thomson-Houston, forming General Electric in 1892. Edison Electric's merger with their chief alternating current rival brought an end to the war of the currents and created a new company that now controlled three quarters of the US electrical business. Westinghouse won the bid to supply electrical power for the World's Columbian Exposition in 1893 and won the major part of the contract to build Niagara Falls hydroelectric project later that year. DC commercial power distribution systems declined rapidly in numbers throughout the 20th century; the last DC utility in New York City was shut down in 2007.
Background
The war of the currents grew out of the development of two lighting systems; arc lighting running on alternating current and incandescent lighting running on direct current. Both were supplanting gas lighting systems, with arc lighting taking over large area/street lighting, and incandescent lighting replacing gas for business and residential indoor lighting.Arc lighting
By the late 1870s, arc lamp systems were beginning to be installed in cities, powered by central generating plants. Arc lighting was capable of lighting streets, factory yards, or the interior of large buildings. Arc lamp systems used high voltages to supply current to multiple series-connected lamps, and some ran better on alternating current.1880 saw the installation of large-scale arc lighting systems in several US cities including a central station set up by the Brush Electric Company in December 1880 to supply a length of Broadway in New York City with a 3,500-volt demonstration arc lighting system. The disadvantages of arc lighting were: it was maintenance intensive, buzzed, flickered, constituted a fire hazard, was really only suitable for outdoor lighting, and, at the high voltages used, was dangerous to work with.
Edison's direct current company
In 1878 inventor Thomas Edison saw a market for a system that could bring electric lighting directly into a customer's business or home, a niche not served by arc lighting systems. By 1882 the investor-owned utility Edison Illuminating Company was established in New York City. Edison designed his utility to compete with the then established gas lighting utilities, basing it on a relatively low 110-volt direct current supply to power a high resistance incandescent lamp he had invented for the system. Edison direct current systems would be sold to cities throughout the United States, making it a standard with Edison controlling all technical development and holding all the key patents. Direct current worked well with incandescent lamps, which were the principal load of the day. Direct-current systems could be directly used with storage batteries, providing valuable load-leveling and backup power during interruptions of generator operation. Direct-current generators could be easily paralleled, allowing economical operation by using smaller machines during periods of light load and improving reliability. Edison had invented a meter to allow customers to be billed for energy proportional to consumption, but this meter worked only with direct current. Direct current also worked well with electric motors, an advantage DC held throughout the 1880s. The primary drawback with the Edison direct current system was that it ran at 110 volts from generation to its final destination giving it a relatively short useful transmission range: to keep the size of the expensive copper conductors down generating plants had to be situated in the middle of population centers and could only supply customers less than a mile from the plant.Westinghouse and alternating current
In 1884 Pittsburgh, Pennsylvania inventor and entrepreneur George Westinghouse entered the electric lighting business when he started to develop a DC system and hired William Stanley, Jr. to work on it. In 1885 he read an article in UK technical journal Engineering that described alternating current systems under development. By that time alternating current had gained a key advantage over direct current with the development of transformers that allowed the voltage to be "stepped up" to much higher transmission voltages and then dropped down to a lower end user voltage for business and residential use. The high voltages allowed a central generating station to supply a large area, up to long circuits. Westinghouse saw this as a way to build a truly competitive system instead of simply building another barely competitive DC lighting system using patents just different enough to get around the Edison patents. The Edison DC system of centralized DC plants with their short transmission range also meant there was a patchwork of un-supplied customers between Edison's plants that Westinghouse could easily supply with AC power.In 1885 Westinghouse purchased the US patents rights to a transformer developed by French engineer Lucien Gaulard. He imported several of these "Gaulard–Gibbs" transformers as well as Siemens AC generators to begin experimenting with an AC-based lighting system in Pittsburgh. That same year William Stanley used the Gaulard-Gibbs design and designs from the Hungarian Ganz company's Z.B.D. transformer to develop the first practical transformer. The Westinghouse Electric Company was formed at the beginning of 1886.
In March 1886 Stanley, with Westinghouse's backing, installed the first multiple-voltage AC power system, a demonstration incandescent lighting system, in Great Barrington, Massachusetts. Expanded to the point where it could light 23 businesses along main street with very little power loss over 4000 feet, the system used transformers to step 500 AC volts at the street down to 100 volts to power incandescent lamps at each location. By fall of 1886 Westinghouse, Stanley, and Oliver B. Shallenberger had built the first commercial AC power system in the US in Buffalo, New York.
The spread of AC
By the end of 1887 Westinghouse had 68 alternating current power stations to Edison's 121 DC-based stations. To make matters worse for Edison, the Thomson-Houston Electric Company of Lynn, Massachusetts had built 22 power stations. Thomson-Houston was expanding their business while trying to avoid patent conflicts with Westinghouse, arranging deals such as coming to agreements over lighting company territory, paying a royalty to use the Stanley AC transformer patent, and allowing Westinghouse to use their Sawyer-Man incandescent bulb patent. Besides Thomson-Houston and Brush there were other competitors at the time, including the United States Illuminating Company and the Waterhouse Electric Light Company. All of the companies had their own electric power systems, arc lighting systems, and even incandescent lamp designs for domestic lighting, leading to constant lawsuits and patent battles between themselves and with Edison.Safety concerns
of Thomson-Houston was concerned about AC safety and put a great deal of effort into developing a lightning arrestor for high-tension power lines as well as a magnetic blowout switch that could shut the system down in a power surge, a safety feature the Westinghouse system did not have. Thomson also worried about what would happen with the equipment after they sold it, assuming customers would follow a risky practice of installing as many lights and generators as they could get away with. He also thought the idea of using AC lighting in residential homes was too dangerous and had the company hold back on that type of installation until a safer transformer could be developed.Due to the hazards presented by high voltage electrical lines most European cities and the city of Chicago in the US required them to be buried underground. The City of New York did not require burying and had little in the way of regulation so by the end of 1887 the mishmash of overhead wires for telephone, telegraph, fire and burglar alarm systems in Manhattan were now mixed with haphazardly strung AC lighting system wires carrying up to 6,000 volts. Insulation on power lines was rudimentary, with one electrician referring to it as having as much value "as a molasses covered rag", and exposure to the elements was eroding it over time. A third of the wires were simply abandoned by defunct companies and slowly deteriorating, causing damage to, and shorting out the other lines. Besides being an eyesore, New Yorkers were annoyed when a large March 1888 snowstorm tore down a large number of the lines, cutting off utilities in the city. This spurred on the idea of having these lines moved underground but it was stopped by a court injunction obtained by Western Union. Legislation to give all the utilities 90 days to move their lines into underground conduits supplied by the city was slowly making its way through the government but that was also being fought in court by the United States Illuminating Company, who claimed their AC lines were perfectly safe.