What is the difference between ANSI® C37 Standard and UL® 489?
Masterpact NW and NT
Both standards require safe and robust designs. The ANSI standard puts additional emphasis on reliability and the UL standard puts extra emphasis on safety.
Masterpact breakers built and tested to these standards are very similar. The main differences are withstand ratings, instantaneous override values, and frame breaks.
See attached for more details on differences in the standards.
See catalog 0613CT0001 for differences in the breakers:
Note: NW breakers with ANSI C37 certification are also listed per UL 1066.