On November 8, 1904, Harvey Hubbell II patented the first detachable electric plug in the United States. The Separable Attachment-Plug, US patent number 774,250, followed Hubbell’s electric switch design in 1891 and his patent for the pull-chain electrical light socket in 1896. An inventor and industrialist, Hubbell opened his first manufacturing facility, the Harvey Hubbell Manufacturing Company, in Bridgeport in 1888. The company was built on the success of Hubbell’s first patent, a stand with a moveable cutter used to hold and store rolls of wrapping paper for use in retail stores.

The Hubbell flush attachment plug based on the separable attachment plug patent, November 8, 1904

Hubbell’s detachable electric plug revolutionized the way electrical wires were connected or disconnected from a power supply. At the time post terminals would extend out from a wall and any type of electrical device had to be hardwired to the power source. This was extremely inconvenient—and dangerous. If, for example, the device or appliance had to be moved and the wires were not connected to the correct polarity, a potentially damaging short circuit occurred. Hubbell went on to receive another 45 patents, most for electric products, and the company he started, Hubbell Incorporated, is still in business today in Shelton.