Earth Currents in Short Submarine Cables

PRIOR to 1940, faults on submarine telephone cables between Great Britain and the Continent were normally located by direct-current methods employing a good wire in another cable. Confirmatory tests were usually made by the impedance-frequency method¹. When the time came in 1944 to restore telephone communications, no good wires were available. The impedance-frequency method was employed for fault localization with great success, and at the same time confirmatory tests were made by direct-current methods which do not require a good wire, such as the tests due to Mance, Kennelly, Black², etc. As all of these D.C. tests are affected by earth currents, the nature of this current phenomenon was investigated. The work in general was limited to periods when co-operation was being given to Post Office cable ships in restoring communications, and so the results obtained only cover a limited period; but they are sufficiently consistent to be of interest.