Branch Circuits & FeedersCâu 14 / 120
Nine current-carrying 10 AWG THHN copper conductors share one raceway at a 30 degrees C ambient. What is the adjusted ampacity of each?
a.35 amperes
b.24.5 amperes
c.26.3 amperes
d.28 amperes
Giải thích
The 90 degrees C ampacity of 10 AWG copper is 40 A, and the adjustment factor for 7 through 9 current-carrying conductors is 70 percent: 40 x 0.70 = 28 A. The 26.3 A answer applies 70 percent to the 75 degrees C value, 24.5 A uses the 50 percent bracket that begins at 10 conductors, and 35 A ignores adjustment entirely.
Trích dẫn luật: 2023 NEC §310.15(C)(1)Luyện miễn phí toàn bộ 120 câu hỏi — không cần đăng ký.
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