Wire and Cable Update-1985

Power distribution within a large modern petrochemical complex involves many thousands of feet of instrument and power cables that must be applied and installed with optimum life, reliability, and cost. Current practice and trends in evaluating, sizing, specifying, and installing the more commonly used cables and cable systems in petrochemical plants are reviewed. Current trends in industrial cable design and construction are considered. This includes low-and medium-voltage power cable, control cable, and instrument cable. The relative merits of various materials used in cable constructions are reviewed with particular emphasis on insulations, shields, jackets, and overall sheaths. Protection of cable from harsh environmental conditions is included. Methods are presented for selecting the proper cable construction for differing applications. Installation methods, including conduit, tray, and direct burial systems, are reviewed with emphasis on the additional ampacity tables for the 0-2000-V cables proposed for the 1987 National Electrical Code (NEC). These tables, as well as the existing NEC tables for the 2001-35 000-V cables, were generated using the Neher-McGrath method which permits the calculation of any conductor ampacity for a specific installation. Proper conductor sizing is presented based on short circuit rating, voltage drop, temperature rating, and actual cable installation method.