The Electric Current War

Thomas Edison Uses Direct Current for his Lighting System

Thomas Edison’s wanted to grow rich while “lighting the world.” He could not, however, achieve his goal until he fought and won the Electric Current War.

On September 4, 1882 Edison flipped a switch and lit 400 electric light bulbs in an office building in New York’s financial district. He had beaten all other inventors that were trying to develop a usable incandescent light bulb.

Thomas Edison used a direct current system to power his light bulb
Thomas Edison

Edison was already known as the “Wizard of Menlo Park” for his work with the phonograph and the kinetoscope. But Edison wanted to be more than just an inventor. He wanted to be one of the industrial titans of the age.

Edison lit his first 400 bulbs with electricity generated at a dynamo located just across the street from the bulbs. Edison had no choice but to place his generator close to his point of use. His system used direct current in which electricity flows in a single direction. Direct current electricity operates at very low voltages and low voltage electricity loses its effectiveness over short distances. If he located his generator too far from the point of use the generated electricity would be too weak to light the bulbs. 

None of this bothered Edison. He just sold lighting systems that relied upon generators located close to the point of use. Each time that Edison wanted to light a factory or an office building he had to install a new generator for that facility. 

George Westinghouse Uses an Alternating Current System to Compete with Edison

George Westinghouse made his fortune off of his invention of the train air brake system. While Edison was expanding his lighting business George Westinghouse was living in his Pittsburgh mansion looking for his next business opportunity. He well understood the inefficiencies of Edison’s direct current system.

George Westinghouse competes with Edison in the Current War with his alternating current system
George Westinghouse

Westinghouse learned that some European inventors had invented something called a transformer. He knew transformer could be used to increase the voltage of alternating current and transmit it for many miles. Westinghouse developed an alternating current system consisting of large central station generating plants, transformers and high voltage transmission lines. The following video explains the differences between direct current and alternating current:

There was, however, a problem with Westinghouse’ system. The motors of the day were designed to operate on direct current rather than alternating current. Westinghouse teamed up with an eccentric Serbian genius named Niclola Tesla to develop motors that could operate on alternating current.

Nicola Tesla designs a motor that helps Westinghouse compete in the Current War.
Nicola Tesla

Beginning in the mid-1880s Edison and Westinghouse engaged in a competition for customers with their respective direct current and alternating current systems. Their competition was well publicized. The press called it the Electric Current War.  

The End of the Electric Current War

Westinghouse’ system was more efficient and less costly than Edison’s. Edison could have acknowledged the benefits of Westinghouse’ system and adopted a form of the alternating current system for himself. In fact, Edison’s investors encouraged him to abandon his direct current system. But Edison stubbornly fought for his direct current system. To try to defeat Westinghouse he engaged in a public relations campaign that accused Westinghouse’ high voltage system of endangering the public. 

The Electric Current War ended in 1892 when, without Edison’s knowledge,  J.P. Morgan engineered a merger of Edison’s company with another firm that was already using a form of the alternating current system. The merged firm was renamed the General Electric Company. Those who like cinema may also like to know that this story has been made into a major motion picture called The Current War in which Benedict Cumberbatch plays Thomas Edison.


I. David Rosenstein worked as a consulting engineer and attorney in the electric industry for 40 years. At various times during his career he worked for utility customers, Rural Electric Cooperatives, traditional investor owned regulated utilities and deregulated power generation companies. Each of his posts in this blog describes a different aspect of the past, present or future of the electric industry. 

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