Thiết bị & Hệ thốngCâu 252 / 521
A feeder supplies two three-phase, 460 V motors: 20 HP (FLC 27 A) and 10 HP (FLC 14 A). Per NEC 430.24, what minimum feeder conductor ampacity is required?
a.41 A
b.51.25 A
c.54 A
d.47.75 A
Giải thích
NEC 430.24 requires 125% of the largest motor's FLC plus the sum of the others: (27 x 1.25) + 14 = 33.75 + 14 = 47.75 A. 41 A omits the 125% factor, 51.25 A applies 125% to both, and 54 A doubles the largest.
Trích dẫn luật: 2023 NEC §430.24Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- When sizing branch-circuit conductors and short-circuit/ground-fault protection for a standard motor, which current value does the NEC require you to use?
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- A motor nameplate reads 28 A full-load, service factor 1.0, temperature rise not marked. What is the maximum overload rating under NEC 430.32(A)(1)?
- A motor disconnecting means must have an ampere rating at least 115% of the motor FLC. For a 15 HP, 460 V, three-phase motor (FLC 21 A), what is the minimum disconnect ampere rating?
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