The "War of Currents" in the late 1880s was one of the most impactful events in the early electrical industry. Thomas Edison championed direct current (DC), while Nikola Tesla and George Westinghouse advocated for alternating current (AC). This battle between the two titans and their competing electrical systems transformed the landscape of electricity as we know it today.

Edison's Promotion of Direct Current

Thomas Edison is widely regarded as one of America's greatest inventors. In 1879, Edison created the first practical incandescent light bulb. To power his new invention, Edison developed the first electrical distribution system based on direct current or DC.

DC electricity flows in one direction from the power source to the device. Edison outfitted his Pearl Street Station in New York City in 1882 to provide DC power to nearby homes and businesses. This was the first central power plant in the United States.

Edison fiercely promoted DC as the ideal electrical system. He claimed it was safer and more efficient than AC. Edison also had several patents related to DC power, so he had a vested business interest in dominating the "current wars".

The Rise of Alternating Current

Alternating current or AC electricity reverses direction at regular intervals. The frequency of reversals is measured in Hertz (Hz). Tesla and Westinghouse favored AC because it allowed electricity to be transmitted over greater distances.

In 1886, Tesla designed the first AC motor. Westinghouse purchased Tesla's motor patents and hired him to improve the AC system. By using transformers, Westinghouse stepped up AC voltages for efficient transmission over long distances. He then stepped down the voltage for safe distribution within homes and factories.

AC Versus DC: The "War of Currents"

Edison's DC system worked well for cities and nearby suburbs. But for widespread electrification of rural America, AC power transmission was superior. Edison stubbornly refused to acknowledge AC's capabilities.

To protect his business investments, Edison launched a smear campaign against AC power. He spread misinformation to discredit Tesla and Westinghouse, claiming that high voltage AC was dangerous. Edison conducted gruesome public electrocutions of animals to demonstrate the risks of AC.

AC's Victory Despite Safety Concerns

To prove AC's safety, Westinghouse wired electricity to illuminate the 1893 Chicago World's Fair. The dazzling electrical exhibits were a resounding success. Westinghouse also underbid Edison for the contract to power theNiagara Falls hydroelectric project. AC definitively won the "War of Currents".

However, Edison was right that early AC systems did have risks. There were no safety standards, and accidental electrocutions did occur. The development of fuses, circuit breakers, and grounded electrical systems eventually alleviated many of the hazards associated with AC power.

AC Power Transforms Society

The AC system enabled nationwide access to affordable electricity. Homes and businesses could now enjoy electric lighting, appliances, communications and more. AC power drove America's Second Industrial Revolution.

Alternating current could be transmitted over vast distances enabling economies of scale. The interconnection of remote generating stations and transmission lines formed power grids. The reliable AC networks supported mass electrification that powered economic growth.

Edison's DC Legacy

Despite losing the "War of Currents", Edison's DC technology did make important contributions to the electrical industry. DC systems continue to be used in automobiles and aircraft. Low voltage direct current is also essential for modern electronic devices.

Most importantly, Edison's incandescent bulb lit the path toward widespread adoption of electric lighting. His Pearl Street Station pioneered central power distribution. Though AC became the standard for electrical grids, we still owe much to Edison's DC innovations.


The "War of Currents" shaped the future of electricity. Edison's unsafe, but historic DC system ultimately lost to Tesla and Westinghouse's more sophisticated AC approach. AC power enabled our modern electrically driven society. However, DC technology also carved out key niches that continue benefiting society today.