Electric light be made with a screw-thread base, two metal pins, two metal caps or a bayonet cap. The three main categories of electric lights are incandescent lamps, which produce light by a filament heated white-hot by electric current, gas-discharge lamps, which produce light by means of an electric arc through a gas, and LED lamps, which produce light by a flow of electrons across a band gap in a semiconductor. Before electric lighting became common in the early 20th century, people used candles, gas lights, oil lamps, and fires. Cornish chemist Humphry Davy developed the first incandescent light in 1802, followed
Hartford Electric Light Company 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 possible to collect and store water power energy that would have gone unused during low demand periods. This energy could then be returned when the demands were higher. The president of HELCO invented an electric range that had a broiler, cooker, and roaster. The company marketed the electric range.