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 cost-effective 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.