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All NEC references by Electrical Helper are interpretations of the NEC by the Electrical Helper staff and are not NEC statements. The official position of the NEC requires that the NEC be referred to in its entirety.
 
Table 430.52 Maximum Rating or Setting of Motor  
Branch-Circuit Short-Circuit and Ground-Fault  
Protective Devices  
  Percentage of Full-Load Current
Type of Motor Nontime Delay Fuse1 Dual Element (Time Delay) Fuse1 Instantaneous Trip Breaker Inverse Time Breaker2
Single Phase motors 300 175 800 250
AC polyphase motors other than wound-rotor
Squirrel cage -other than Design B energy- efficient 300 175 800 250
Design B - energy efficient 300 175 1100 250
Synchronous3  300 175 800 250
Wound rotor 150 150 800 150
Direct current (constant voltage) 150 150 250 150
       
Note: For certain exceptions to the values specifed see 430-54 in the NEC  
1The vaues in the Nontime Delay Fuse column apply to Time-Delay Class CC fuses.  
2The values given in the last column also cover the ratings of nonadjustable inverse time types of circuit breakers athat may be modified as in 430.52(C), Exception No. 1 and No.2  
3Synchronous motors of the low-torque, low-speed type (usually 450rpm or lower), such as are used to drive reciprocating compressors, pumps, and so forth, that start unloaded, do not require a fuse rating or circuit-breaker setting in excess of 200 percent of full-load current