The lighthouse was connected to mains electricity in 1922, whereupon South Foreland Lighthouse became the first to use an incandescent lightbulb as its light source. The Holmes generators, which had provided power for fifty years, were then disconnected, and the Holmes arc lamp was given to the Science Museum. The subsequent reduction of required maintenance, and provision of automatic electric equipment (including an electric winder for the clockwork mechanism to turn the lens), led to a reduction in staff numbers from one engineer and four keepers to just a single keeper. In the event of a bulb failure, an automatic lamp changer was activated (and an alarm notified the keeper); if the reserve bulb then failed, the lamp changer caused an acetylene burner to be brought into position and lit.