1. (a) Each circuit breaker must—

   1. (1) Meet the general provision of Article 240 of NFPA 70 or IEC 60092-202:2016 (both incorporated by reference; see § 110.10-1 of this subchapter) as appropriate;
   2. (2) Meet subpart 111.55; and
   3. (3) Have an interrupting rating sufficient to interrupt the maximum asymmetrical short-circuit current available at the point of application.
2. (b) No molded-case circuit breaker may be used in any circuit having a nominal voltage of more than 600 volts (1,000 volts for a circuit containing a circuit breaker manufactured to the standards of the IEC). Each molded-case circuit breaker must meet section 9 and marine supplement SA of ANSI/UL 489 or IEC 60947-2:2019 (both incorporated by reference; see § 110.10-1 of this subchapter), except as noted in paragraph (e) of this section.

3. (c) Each circuit breaker, other than a molded-case one, that is for use in any of the following systems must meet the following requirements:

   1. (1) An alternating-current system having a nominal voltage of 600 volts or less (1,000 volts for such a system with circuit breakers manufactured to the standards of the IEC) must meet (all incorporated by reference; see § 110.10-1 of this subchapter):

      1. (i) IEEE C37.13;
      2. (ii) IEEE C37.27; or
      3. (iii) IEC 60947-2:2019.
   2. (2) A direct-current system of 3,000 volts or less (1,500 volts or less for such a system with circuit breakers manufactured to the standards of the IEC) must meet IEEE C37.14 or IEC 60947-2:2019 (both incorporated by reference; see § 110.10-1 of this subchapter).

   3. (3) An alternating-current system having a nominal voltage greater than 600 volts (or greater than 1,000 volts for IEC standard circuit breakers) must meet (all incorporated by reference; see § 110.10-1 of this subchapter):

      1. (i) IEEE C37.04, IEEE C37.010, and IEEE C37.12; or
      2. (ii) IEC 62271-100:2017.

4. (d) A circuit breaker must not:

   1. (1) Be dependent upon mechanical cooling to operate within its rating; or
   2. (2) Have a long-time-delay trip element set above the continuous current rating of the trip element or of the circuit breaker frame.
5. (e) Each circuit breaker located in an engineroom, boilerroom, or machinery space must be calibrated for a 50 degree C ambient temperature. If the circuit breaker is in an environmentally controlled machinery control room where provisions are made for ensuring an ambient temperature of 40 degree C or less, a circuit breaker must have at least the standard 40 degrees C ambient temperature calibration.

[USCG-2020-0075, 88 FR 16363, Mar. 16, 2023]