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Comments on present underground cable practice

Wallace S. Clark
1906 Proceedings of the American Institute of Electrical Engineers  
There are certain practices now so general in underground cable work for light and power in America as to be almost standard. Some of these practices may be examined with ad vantage. Cable making was an established art at least a quarter of a century before cables were made for service beyond signal transmission. Its development, therefore, has been somewhat more gradual than the development of the apparatus for gener ating the energy transmitted. Perhaps this greater age has tended to undue
more » ... tended to undue conservatism. Practically all cables of the class under consideration have continuous metallic sheaths. Is this the best engineering? LOW-TENSION CABLES. These are run in conduits with some portion of the circuit grounded. In railway practice one leg of a two-wire circuit, and in lighting the neutral wire, is permanently earthed. The continuous sheath on these cables is an invitation to stray currents and consequent electrolysis. While dry, well-vitrified tile is a fair insulator, but in time the joints between the sections provide leakage spots. Further, many ducts are damp at cer tain seasons if not during the entire year, making the dirt which accumulates a sufficiently good conductor to offer an addi tional path for stray currents. Grounding the sheath at each manhole was announced as a cure for electrolysis, but instead of a cure it has been found in some cases to be a cause of trouble. The amount of current
doi:10.1109/paiee.1906.6742240 fatcat:e2kady5e7rckzoh36sawgm7tje