The Electric Current War

Thomas Edison Uses Direct Current for his Lighting System

Thomas Edison’s goal was 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. Low voltage electricity loses its effectiveness over short distances. If his generator was located too far from the point of use its generated electricity would be too weak to light the bulbs. 

All that did not bother Edison. He started installing lighting systems around the world 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 that would provide the electricity. 

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. At the time that 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. Westinghouse learned that some European inventors had invented something called a transformer. The transformer could be used to increase the voltage of alternating current so that it could be transmitted for many miles.

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

Westinghouse decided to build an alternating current system using transformers and transmission lines to deliver electricity generated at large central station generating plants. 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 genius from Serbia, 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 in favor of an alternating current system. But Edison stubbornly fought for his direct current system by engaging 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. When Edison lost control of his company, which was then renamed the General Electric Company, he gave up the fight for a direct current system. 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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