0600DB0102 R11/11, 11/2011 Replaces 0600DB0102 02/2002
HACR Ratings and UL® Listed Molded Case Circuit Breakers
Heating, Air Conditioning, and Refrigeration (HACR)applications are a common example of group motor installations. Most modern heating applications include fans for combustion air, exhaust control, and heated air handling. Air conditioning andrefrigeration equipment use compressors for the refrigerant and fans for cooled air handling. The National Electric Code® (NEC®) provides information on installation of branch circuits and overcurrentprotection equipment for use with group motor installations. Article 430.53(c)(3) of the NEC states that for group motor installations, “Each circuit breaker is listed and is of the inverse time type.” NECArticle 440.21 and 440.51 lists the requirements for applications and selection of the branch circuit overcurrent protection devices for air conditioning and refrigeration equipment.
History ofHACR Ratings
For many years Underwriters Laboratories® (UL)® required special testing of circuit breakers used in group motor applications in air conditioning and refrigeration equipment. UL hadListed these circuit breakers as HACR Type and they were used to meet the requirements of Article 430.53(c)(3). At first, UL restricted the HACR listing to circuit breakers rated 240 Vac or less and 60 Amaximum. In the early 1990s UL redefined the test parameters for UL Listed HACR Type circuit breakers, resulting in HACR ratings for circuit breakers rated 600 Vac and less and 250 A maximum as asecond step. By these test parameters HACR Type circuit breakers were the same as other types of inverse-time circuit breakers except they were additionally investigated by UL and determined to be suitablefor motor branch circuit protection on group installations. Initially, these circuit breakers were tested and Listed to UL 489, the standard for safety for molded-case circuit breakers. Then...