Long-distance transmission of electricity to Sacramento depended on voltage step-up transformers, because high-voltage alternating current traveled farther with less loss of power. The first transformers, located on the second floor of the powerhouse, raised the generators' 800-volt output to 11,000 volts for transmission to Sacramento and used draft air for cooling, but Folsom's hot summers caused them to overheat. To manage the heat and meet growing demand for electricity, the powerhouse installed increasingly larger oil-insulated and water-cooled step-up transformers. As transmission voltages rose to 100,000 volts, upgrades also introduced oil circuit breakers that could safely handle high alternating current without dangerous arcing. By the early 1900s, these transformers and oil circuit breakers represented the top of the line in powerhouse electrical equipment.