NEC 2011: Table 430.52
Max Rating of Motor Branch-Circuit Short Circuit and Ground-Fault Protective Devices | ||||
Percentage of Full-Load Current | ||||
Type of Motor | Non
Time Delay Fuse |
Dual Element (Time Delay) Fuse |
Instantaneous Trip Breaker |
Inverse
Time Breaker |
Single-phase motors | 300 | 175 | 800 | 250 |
AC Polyphase other than wound-rotor | 300 | 175 | 800 | 250 |
Squirrel Cage - other than Design B | 300 | 175 | 800 | 250 |
Design B energy efficient |
300 | 175 | 1100 | 250 |
Synchronous | 300 | 175 | 800 | 250 |
Wound Rotor | 150 | 150 | 800 | 150 |
Direct Current (constant voltage) | 150 | 150 | 250 | 150 |
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