In single-phase motor installations, the branch-circuit protection is based on NEC Table 430.52 as a percentage of full-load current. (Note: Full-load current referred to here is the Code book value.) The full-load current is listed in Table 430.248 for single-phase motors. If using a typical inverse time breaker, the percentage for single-phase motors is 250% of the Code book value for the size of the motor at the connected voltage.
Briefly explain why this high percentage is allowed.

Question

Quizplus · Accepted Answer

The Answer of In single-phase motor installations, the branch-circuit protection is based on NEC Table 430.52 as a percentage of full-load current. (Note: Full-load current referred to here is the Code book value.) The full-load current is listed in Table 430.248 for single-phase motors. If using a typical inverse time breaker, the percentage for single-phase motors is 250% of the Code book value for the size of the motor at the connected voltage.
Briefly explain why this high percentage is allowed.

In Single-Phase Motor Installations, the Branch-Circuit Protection Is Based on NEC