89 Liberty Street: The Birthplace of Commercial Polyphase Power [History]

Today, 89 Liberty Street in New York City is part of the pedestrian plaza of the large office building known as 1 Liberty Plaza. In 1887, it was the site of a small commercial structure in which the first practical induction motor and polyphase system was constructed, patented, and demonstrated. Vital to large-scale commercial electrification, the polyphase system was declared by experts to be the most significant invention of the electrical age. It can be said that the structure at 89 Liberty Street was truly the birthplace of modern ac technology in the United States.