Cable Ampacities: Computer Applications for Electric Generating Stations

The cable ampacities in ICEA P-46-426 for underground cables are based upon a paper written by J. H. Neher and M. H. McGrath, in 1957. The Neher/McGrath calculations are complex, requiring a large amount of data and the solution of numerous equations. This paper will discuss the Neher/McGrath theory as applied in ICEA P-46-426. In addition, a new microcomputer program will be discussed which calculates underground cable ampacities for any set of given conditions and which provides an efficient costeffective means of optimizing cable sizes. Although this paper addresses generating stations, the material presented is also applicable to other installations, including substations, industrial, and utility distribution facilities.