Edison built on the 1831 work of Michael Faraday to create the electricity generator used to power his lighting system.
Faraday discovered electromagnetic induction, production of an electric current, by spinning a copper disc between the poles of a magnet and detecting the current that resulted in wires connected to the disc.
Edison's innovative application of Faraday's principles was a steam-driven generator that included very large bipolar magnets to improve efficiency and had slight electrical resistance compared to the resistance of the wire distribution network linked to it. It supplied direct current power.
Along with the lamps and the generator, Edison designed and built all of the ancillary equipment: underground supply cables, junction boxes, lampholders, switches, sockets, meters, etc. In effect, this complex combination established the fundamentals of large-scale electricity distribution. The Pearl Street station in Manhattan went live at 3PM on September 4, 1882, supplying 4,400 lamps in one hundred and ninety-three buildings and continued to operate and expand for eight years.
Eventually, Edison's system was replaced due to the work of Nicola Tesla, who had first worked for Edison. He devised alternating current (AC) generators. AC current can be easily and efficiently sent over long distances with little power loss because it is "transformable." The current is generated and its voltage increased (stepped up) for transmission over the wire power grid and then stepped down to lower, safer voltage at its destination. The AC electrical system continues to be the world standard.
Thomas A. Edison Letter (1.4M)
To Walton Clark, Accepting the invitation to dinner and the Franklin Institute Awards ceremony, 5/11/1915