What is the difference between the ANSI Main/Feeder - IEC Feeder and IEC Main
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ANSI and IEC Main Breakers are wired differently. ANSI standard wiring practices have CT polarity orientation towards the source of power, where IEC standards has the CT polarity orientation toward the switchgear bus. See Figure 1. Therefore, for IEC main breaker applications, the normal flow of power is into the non-polarity side of the cts. The manufacturing advantage of the IEC switchgear is that the IEC main and feeder are identical. In switchgear constructed per ANSI standards the CT polarity is towards the source for both the Main and the Feeders. IEC and ANSI feeders are the same.