The Victor Company developed from his patents. (Alexander Graham Bell impressed sound tracks on cylindrical shellac records; Berliner invented disk records. Edison's later dictating machine, the Ediphone, used disks.)

To research incandescence, Edison and others—including J. P. Morgan—organized the Edison Electric Light Company in 1878. (Later it became the General Electric Company.) Edison made the first practical incandescent lamp in 1879, and it was patented the following year. After months of testing metal filaments, Edison and his staff examined 6,000 organic fibers from around the world and decided that Japanese bamboo was best. Mass production soon made the lamps, although low-priced, profitable.

Prior to Edison's central power station, each user of electricity needed a dynamo (generator), which was inconvenient and expensive. Edison opened the first commercial electric station in London in 1882; in September the Pearl Street Station in New York City marked the beginning of America's electrical age. Within 4 months the station was lighting more than 5,000 lamps for 230 customers, and the demand for lamps exceeded supply. By 1890 it supplied current to 20,000 lamps, mainly in office buildings, and to motors, fans, printing presses, and heating appliances. Many towns and cities installed central stations. Increased use of electricity led to Edison-base sockets, junction boxes, safety fuses, underground conduits, meters, and the three-wire system. Jumbo dynamos, with drum-wound armatures, could maintain 110 volts with 90 percent efficiency. The three-wire system, first installed in Sunbury, Pennsylvania, in 1883, superseded the parallel circuit, used 110 volts, and necessitated high-resistance lamp filaments (metal alloys were later used).

In 1883 Edison made a significant discovery in pure science, the Edison effect—electrons flowed from incandescent filaments. With a metal-plate insert, the lamp could serve as a valve, admitting only negative electricity. Although "etheric force" had been recognized in 1875 and the Edison effect was patented in 1883, the phenomenon was little known outside the Edison laboratory. (At this time existence of electrons was not generally accepted.) This "force" underlies radio broadcasting, long-distance telephony, sound pictures, television, electric eyes, x-rays, high-frequency surgery, and electronic musical instruments.