The earliest electrical power suppliers frequently had complex and varying prices according to different applications for electricity. See this 1903 document fr

The earliest electrical power suppliers frequently had complex and varying prices according to different applications for electricity. See this 1903 document from the National Electric Light Association, "Report of the rates for lighting and power service." https://babel.hathitrust.org/cgi/pt?id=nnc1.cu56609884&seq=11 https://babel.hathitrust.org/cgi/pt?id=nnc1.cu56609884&seq=1... In San Francisco, there were separate rates per kilowatt hour depending on whether the electricity was used for incandescent lighting or "power." San Leandro had 3 separate rate structures -- one for incandescent lighting, one for arc lighting, and a third for power. Eventually, of course, device manufacturers realized that it was possible to tap "power" connections to run "lighting" devices, or vice versa, and the application-specific pricing could not be maintained.