Motors & EquipmentQuestion 90 of 120
A feeder supplies a 25-horsepower motor (34 amperes) and a 10-horsepower motor (14 amperes), both 460 volts three phase. What minimum conductor ampacity is required?
a.67.5 amperes
b.60 amperes
c.48 amperes
d.56.5 amperes
Explanation
Feeder conductors for several motors must carry 125 percent of the largest motor full-load current plus the sum of the other full-load currents: (34 x 1.25) + 14 = 42.5 + 14 = 56.5 A. The 48-ampere answer simply adds the two currents, and 67.5 amperes wrongly applies 125 percent to the total of both motors.
Law Reference: 2023 NEC §430.24Practice all 120 questions free — no signup required.
Related questions on this topic
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