A flow chart methodology for performing low-voltage three-phase motor coordination studies

A flow chart methodology is suggested for performing low-voltage overcurrent device coordination studies for new and existing three-phase motor installations. The flow chart provides references to codes and standards, highlights benchmarks for coordination, provides guides to device selection, and notes the overcurrent values of interest. The text elaborates on the use of the National Electrical Code(R) (NEC) for complying with legal requirements, and notes some significant changes in the 1996 NEC. The text also discusses some device selection criteria and expands on the decision points of the flow charts.