Thiết bị & Hệ thốngCâu 253 / 521
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?
a.24.15 A
b.21 A
c.26.25 A
d.18.9 A
Giải thích
NEC 430.110(A) requires the disconnecting means to be rated at least 115% of the FLC: 21 x 1.15 = 24.15 A. 21 A ignores the 115% factor, 26.25 A is 125%, and 18.9 A is 90%.
Trích dẫn luật: 2023 NEC §430.110Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- Which motor current rating is used to select the running overload (overcurrent) protection device?
- 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 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?
- In a motor installation, what is the primary function of the motor controller?
- A motor control circuit tapped from the load side of the motor branch-circuit protection is generally protected against overcurrent according to which NEC provision?
- A single hermetic refrigerant motor-compressor has a rated-load current of 24 A. Per NEC 440.32, what minimum branch-circuit conductor ampacity is required?
Cập nhật gần nhất: · quy trình kiểm tra
Đội Ngũ Biên Tập PrepPass · Đối chiếu với California CSLB C-10 Electrical Trade Examination · Quy trình kiểm tra