Lighting as a business
The first electric light companies of the early 1880s were not selling bulbs so much as a service. Edison’s company, and rivals such as Swan’s in Britain, wanted to supply lighting from central generating stations along a street or across a district. That approach, with generators in one place and wires running to many customers, was a new idea. It set the pattern for the electricity industry that followed.
Edison is often given credit for the first large, commercial central station of this type, the Pearl Street Station in New York, which began supplying customers in September 1882. Edison’s company also had a station on Holborn Viaduct in London, opened earlier that year. In England, Swan lamps lit the Savoy Theatre in 1881, and the town of Godalming had a small public supply that year as well. Which of these counts as first depends on how a person defines first, such as first theater, first street or first commercial station. It is more accurate to say several systems opened around the same time.
Direct current and its limits
Edison’s early systems used direct current, in which electricity flows in one direction at a steady voltage. It suited lamps and was simple to measure. Its main problem was distance. At the low voltages used in houses, current sent over long cables loses a lot of power as heat, so a station could only serve customers within a short distance, often not much more than a mile. A city needed many small stations, each with its own boilers and engines, which made the system costly.
Alternating current
Alternating current, in which flow reverses many times a second, can be stepped up to a high voltage by a transformer, sent over long distances with less loss, and stepped down again near customers. Inventors including Lucien Gaulard and John Gibbs, and later William Stanley, worked on practical transformer systems in the 1880s. George Westinghouse in the United States backed alternating current, and Nikola Tesla’s polyphase motor designs were important for its later use in power.
The competition between direct and alternating current in the late 1880s and early 1890s is sometimes called the war of the currents. Popular retellings tend to treat it as a duel between two men, but engineers, companies and city governments all played parts. In the end alternating current became the usual choice for long-distance power, though direct current stayed in use for some local systems, and still has roles today.
Hydropower and larger stations
A major step came in the 1890s, when large generators, steam turbines and hydroelectric plants could feed much bigger networks. Power could be generated at a site with plentiful water, much as water mills had long done for grinding grain, and delivered some distance, instead of burning fuel in a small basement plant. Lighting load was concentrated in the evening, so companies looked for other customers who used power during the day. That is one reason the same networks began supplying electric motors for factories, trams and eventually appliances in the home, including electric cooking.
Rural areas and the middle of the twentieth century
City customers got electric light first, because wires were cheaper to run where houses were close together. Farms and villages often had to wait. In many countries, large public or cooperative programs in the early to mid 1900s extended wires into the countryside, and the timing varied widely from one country to another. By the middle of the century, electric light was a normal feature in homes in many industrial countries, though many people elsewhere still lacked reliable supply, and that remains true for some communities now.
Lamps change, the system stays
Over the same period the lamps themselves improved. Tungsten filaments replaced carbon filaments in the first decades of the 1900s. Fluorescent lighting arrived commercially in the late 1930s, and compact versions and LEDs followed in later decades. Each change reduced the electricity needed for the same amount of light. The network built for Edison-era lamps has meanwhile been reused and expanded for appliances, heating, electronics and, increasingly, electric vehicles.
What Edison’s name stands for
Edison’s name is attached to so much of this story that it can hide the contributions of Swan, the engineers who developed alternating current, and the many people who built stations and strung wires. A fair way to read the history is that Edison’s team showed that selling light as a utility could work, and that later engineers changed many of the technical details, including the type of current. His laboratory had also, as a matter of practical business, helped popularize the idea of a research organization focused on commercial results.
Light as a measure of change
Public lighting transformed night life: shop windows, theaters, streets and workplaces could stay open later. Safety improved in some ways, since open flames were removed from crowded buildings, though early wiring also caused fires, which led to safety codes and inspection. The electric light is therefore a good example of a technology whose largest effects came less from the lamp than from the infrastructure that supported it.