War of the Currents (1886-1893): Edison vs Tesla and Westinghouse

The War of the Currents was the struggle in the United States, roughly between 1886 and 1893, over whether electric power should be supplied as direct current (DC) or alternating current (AC). Thomas Edison’s companies had built the first electric networks on DC, while George Westinghouse championed AC, strengthened by Nikola Tesla’s motor patents. The contest involved technical rivalry, lawsuits, a press campaign that linked AC with death and the first electric-chair execution. AC won, and it still powers most of the world’s electricity grids.

Background: Edison’s direct-current empire

After his work on the incandescent light bulb, Edison set out to build a complete system to supply electricity to customers. On 4 September 1882 his Pearl Street Station in Lower Manhattan began supplying direct current at about 110 volts to customers in the surrounding district. Edison also built generating stations in London and elsewhere, and his companies made the dynamos, cables, meters and lamps.

Direct current flows steadily in one direction. Edison’s system worked well and could run electric motors and store energy in batteries, but it had a serious weakness: at low voltage, much of the power is lost as heat in the wires over distance. A DC station could economically serve customers only within a radius of about a mile, so a city needed many power stations and thick, expensive copper cables.

The rise of alternating current

Alternating current reverses its direction many times a second. Its great advantage is that its voltage can be raised and lowered with a transformer, a device built on the principle of electromagnetic induction discovered by Michael Faraday. Power can be sent long distances at high voltage, with small losses, and then stepped down to a safer level for homes.

In the early 1880s Lucien Gaulard and John Dixon Gibbs demonstrated a transformer system in Europe, including at an exhibition in Turin in 1884. In 1885 the Hungarian engineers Károly Zipernowsky, Ottó Bláthy and Miksa Déri at the Ganz company in Budapest developed a more efficient transformer design.

George Westinghouse, a Pittsburgh industrialist who had made his fortune with the railway air brake, saw the potential. He bought the American rights to the Gaulard–Gibbs patents and hired the engineer William Stanley, who in March 1886 lit shops and offices in Great Barrington, Massachusetts, with an AC system using improved transformers. Westinghouse founded the Westinghouse Electric Company that year, and its first commercial AC plant began operating in Buffalo, New York, in November 1886. Within a few years Westinghouse was winning customers rapidly, especially in smaller towns and spread-out areas that DC could not serve economically.

Tesla’s motor

AC had one major gap: there was no practical AC motor, and industry needed motors. Nikola Tesla, a Serbian-born engineer who had come to New York in 1884 and briefly worked for Edison’s company, solved this. His induction motor used several alternating currents out of step with each other (a “polyphase” system) to create a rotating magnetic field that turned the motor without the brushes and commutators that DC motors required.

Tesla filed his patents in 1887, and in May 1888 he presented his “new system of alternate current motors and transformers” to the American Institute of Electrical Engineers. Westinghouse licensed the patents in July 1888, paying cash, shares and a royalty for each horsepower of motor capacity sold. Tesla spent about a year in Pittsburgh helping Westinghouse’s engineers adapt his system to their equipment.

The propaganda war

Edison believed AC’s high voltages were dangerous, and he had invested heavily in DC. In 1886 he predicted privately that Westinghouse’s system would soon kill a customer. In early 1888 the Edison Electric Light Company published a pamphlet, known from its title as “A Warning”, that listed deaths caused by high-voltage AC lines and attacked its rivals.

Fatal accidents gave the warnings force. New York’s streets were tangled with overhead wires for telegraphs, telephones and arc lighting. In October 1889 a lineman named John Feeks was electrocuted among the wires above a busy Manhattan street in full view of crowds, and the city ordered many wires to be cut down and placed underground.

The most notorious figure was Harold P. Brown, an electrical engineer who in June 1888 wrote to the New York Evening Post condemning AC. That summer, with assistance from staff at Edison’s laboratory in West Orange, New Jersey, he staged public demonstrations in which he killed dogs, and later larger animals, with alternating current to show its lethal power.

The electric chair

At the same time, New York State was looking for a more humane method of execution than hanging. In 1888 it passed a law making electrocution the method of capital punishment from the start of 1889. Edison, although opposed to the death penalty, advised the state’s commission that AC would be the most effective current. Brown was hired to supply the equipment and obtained Westinghouse generators without Westinghouse’s consent.

Lawyers for the first man sentenced, William Kemmler, appealed, arguing that the punishment was cruel and unusual, and Westinghouse was widely believed to be paying for the appeal, though he denied it. The courts rejected it. On 6 August 1890 Kemmler was executed at Auburn Prison. The first shock did not kill him and a second was needed, and newspapers described the scene as horrifying. Supporters of DC hoped the public would come to associate AC with the electric chair, and Edison even suggested that a person executed by electricity could be said to have been “Westinghoused”.

Business decides the outcome

The propaganda did not stop AC’s growth, because AC was simply cheaper for large-scale supply. Edison’s financial backers were also less committed to DC than he was. In 1889 his companies were combined into Edison General Electric, and in 1892, with the support of the financier J. P. Morgan, it merged with the Thomson-Houston Company, which already sold AC equipment, to form General Electric. Edison’s name was dropped and his influence over the business faded.

Westinghouse also faced difficulties. After a financial crisis in 1890, his company was short of money. According to the commonly told account, Tesla agreed in 1891 to give up his lucrative royalty agreement to help the firm survive; historians agree the contract was ended, though details of the deal are debated.

The Chicago World’s Fair and Niagara Falls

Two great projects settled the contest. Westinghouse underbid General Electric for the contract to light the World’s Columbian Exposition in Chicago, which opened on 1 May 1893. Its AC system lit the fairgrounds with many thousands of incandescent lamps, and a Westinghouse exhibit demonstrated Tesla’s polyphase system to millions of visitors.

In October 1893 the company planning to harness Niagara Falls chose Westinghouse’s polyphase AC system for its generators. The Adams power plant at Niagara Falls began operating in 1895, and in November 1896 it began sending power to Buffalo, more than 30 km away. General Electric, which also adopted AC and licensed Westinghouse’s patents, built the transmission line. Meanwhile in Germany, a three-phase AC line had carried power about 175 km from Lauffen to Frankfurt in 1891, showing that long-distance transmission was possible.

Myths and facts

• Myth: it was a personal duel between Edison and Tesla. The real rivals were Edison’s companies and Westinghouse’s. Tesla’s patents were vital, but he was not the public face of the commercial fight.
• Myth: Edison electrocuted Topsy the elephant. Topsy was killed at Coney Island in 1903, long after the contest, and Edison was not involved. The Edison company’s film of the event caused the confusion.
• Fact: DC never disappeared. It powered city trams and some urban networks for decades, and New York’s utility kept a small DC service until 2007. Today high-voltage DC links carry power over long distances and under the sea.

By the numbers

Timeline

• 1882, 4 September: Edison’s Pearl Street Station opens with direct current.
• 1886, March: William Stanley demonstrates an AC system in Great Barrington.
• 1886, November: Westinghouse’s first commercial AC plant opens in Buffalo.
• 1888, February: Edison’s company publishes “A Warning” against AC.
• 1888, May: Tesla presents his polyphase AC motor; Westinghouse licenses it in July.
• 1888, June–July: Harold P. Brown begins his campaign and public demonstrations.
• 1890, 6 August: William Kemmler is the first person executed in the electric chair.
• 1892, April: Edison General Electric and Thomson-Houston merge into General Electric.
• 1893, 1 May: The AC-lit World’s Columbian Exposition opens in Chicago.
• 1893, October: Westinghouse wins the contract for the Niagara Falls generators.

Why it matters

The War of the Currents decided how the world would be electrified. Alternating current, with transformers and long-distance transmission, made it possible to build large power stations and national grids, while the episode itself became a lasting example of how technical rivalries can be fought through fear, publicity and finance as well as engineering.