Thiết bị & Hệ thốngCâu 260 / 521
For a hermetic motor-compressor with a rated-load current of 18 A, what is the maximum branch-circuit short-circuit/ground-fault protective device, based on the 175% value of NEC 440.22(A)?
a.22.5 A
b.27 A
c.40.5 A
d.31.5 A
Giải thích
NEC 440.22(A) sizes the protective device at not more than 175% of the rated-load (or branch-circuit selection) current: 18 x 1.75 = 31.5 A. 22.5 A is 125% (conductor factor), 27 A is 150%, and 40.5 A is 225% (the absolute maximum only where needed to start).
Trích dẫn luật: 2023 NEC §440.22Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
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