What are the main differences between between IEC rated breakers and UL rated breakers?

Although almost 80-90% of the features are the same, there are differences between the IEC and UL(NEMA)/ANSI/CSA breakers. Depending on the frame, the following components may be different:

• Performer plug

• Instantaneous override values

• Close and latch values

• Rating plug values

• Number of internal contacts

• Reverse current loop for magnetic repulsion

• UL drawout breakers have clusters on the breaker rather than the cradle.

• Rear termination are usually different (larger), since the UL standard require a lower termination temperature.

• Short Circuit Current Breaking performance according to relative standards and tests (IEC/NEMA/UL).

It is also worth mentioning that our IEC rated breakers (Compact NSX/NS) are not tested in accordance to NEMA AB1, anymore. They are tested according to IEC 60947.

We have other breakers (Powerpact breakers) dedicated to the American market. These breakers are in compliance with UL489. The NEMA AB-1 standard and UL489 are exactly the same. as per the NEMA official website (https://www.nema.org/Standards/Pages/Molded-Case-Circuit-Breakers-Molded-Case-Switches-and-Circuit-Breaker-Enclosures.aspx). Both of them test the breaker performance at 480Vac which is not a requirement in the IEC.

You can also refer to the attached document for a comparison between the IEC 60947-2 testing procedures and the testing procedures for UL489. These are the main standards used for circuit breakers (UL 489 vs. IEC comparison.pdf)