HELCO constructed in 1899 a dam on the Farmington River at Tariffville, which is on the edge of the town of Simsbury, Connecticut. There a powerhouse was built to generate electricity. This power plant was built with two pairs of 1300 horsepower water wheels. They connected to two seven-hundred kilowatt generators made by Westinghouse. This was the first time aluminum was used for the conductors in a transmission line. The Tariffville dam with the powerhouse was destroyed by flooding that came about because of two sequential hurricanes in August 1955. Connecticut Power Company The Connecticut Power Company was formed in 1899 as the Marine Power Company. A 1909 engineering report describes the station and its equipment as having two water-power stations (See 'HELCO electrical network in 1909') operated in conjunction with it (#1 plant & #2 plant). The two electrical generator plants were located on the Farmington river about twelve miles from Hartford. The three plants were connected together and regulated at the main plant and supplied all the electricity for Hartford. The Connecticut Power Company entered into a power exchange agreement with HELCO in 1915 where they would work together to get electricity to each other's customers as needed. HELCO built a power station in 1921 at South Meadows in Hartford. HELCO had just over three thousand customers in 1900. Fifty years later their customer base was almost ninety thousand. At that time they served Hartford and the surrounding area of about two hundred and fifty square miles. HELCO merged with the Connecticut Power Company in 1958. These merged with the Connecticut Light and Power Company (CL&P) and the Western Massachusetts Electric Company (WMECO) in 1966 to form Northeast Utilities (NU). Innovations HELCO was the first company in America to use a steam turbine for a public utility to generate electricity. They installed the steam turbine generator in 1901 and it became known as "Mary-Ann." HELCO made several innovations in the electrical industry. They became standard practices. HELCO was the first electric company in the United States to transmit three-phase alternating current at high voltage for long distances. The company did this in 1893 from their Rainbow Hydroelectric Station in Windsor, Connecticut, to its main station in Hartford – some eight miles away. Hartford Electric Light Company was the first to use a storage battery in conjunction with the electricity produced at a hydraulic powerhouse. The innovation made it