The Central London Railway was the first underground railway to have the station platforms illuminated electrically. All the platforms were lit by Crompton automatic electric arc lamps, and other station areas by incandescent lamps. Both the City and South London Railway and the Waterloo and City Railway were lit by gas lamps, primarily because the power stations for these lines were designed with no spare capacity to power electric lighting. With the white glazed tiling, all underground Central London Railway platforms were very brightly lit. The use of electric lighting was further made possible because the Central London was also the first tube railway to use AC electrical distribution and the substation transformers were easily able to provide convenient voltages to run the lighting. Earlier tube lines generated DC power at the voltage required to run the trains (500 volts).