History of CP

The principles of cathodic protection were first laid out in 1824 as chemist and inventor Sir Humphrey Davy grappled with the best ways to control corrosion on metal-hulled ships in the British navy. During the 19th, 20th and 21st centuries, the science has expanded as industry used the technology in applications ranging from energy-industry pipelines to residential water heaters.

-- Wikipedia

The first recorded stray-current analysis project was conducted during the early 1920s by the People's Gas, Light and Coke Company, a utility based in Chicago. Engineers were concerned about electric-power supplies from streetcar systems in the Windy City and their possible interference with corrosion-prevention systems installed on energy pipelines.

Taking measurements in the Chicago study.