IEEE SpectrumSan Francisco’s Secret DC Grid
One of the best examples is in San Francisco, where 250-volt DC power still flows through underground and overhead cables across the city. These DC lines peacefully coexist with their AC counterparts; you can see this mix of currents straddling utility poles in the city’s South of Market district. DC’s perseverance in that neighborhood seems fitting, for it was just a few blocks away that the tiny California Electric Light Co.—a forebear to California’s dominant Pacific Gas and Electric (PG&E)—became the first power company in the United States, and possibly the world, to supply electricity to multiple customers from a central generating station. It
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