Thomas Edison championed direct current during the late-nineteenth-century “War of the Currents.”
Edison’s electric-lighting businesses built systems based on direct current, in which electric charge flows in one direction. His early power networks were practical for local areas, but their low distribution voltage required generating stations to be placed relatively close to customers.
Alternating current became the principal rival. AC could be transmitted at high voltages and then reduced for local use, making long-distance distribution more economical. George Westinghouse and other companies supported AC equipment, while Nikola Tesla’s polyphase AC ideas strengthened the competing system.
The rivalry involved engineering, business competition, patents, public demonstrations, and safety arguments. Edison opposed AC because of concerns about its hazards and because his companies were invested in DC infrastructure. AC ultimately became dominant for large electrical grids, although direct current remains important in batteries, electronics, and some modern transmission links. The conflict was not a simple contest between one inventor and one opponent; many engineers contributed to both systems.