Mạch nhánh & Đi dâyCâu 208 / 521
Six current-carrying 10 AWG THHN copper conductors (40 A at 90°C) run in a raceway at 40°C ambient. Applying the 0.91 ambient correction and the 0.80 conductor-count adjustment, what is the resulting ampacity?
a.40 A
b.35 A
c.32 A
d.29 A
Giải thích
40 A × 0.91 × 0.80 = 29.1 A, or about 29 A. Both factors must be applied from the 90°C base; using only one factor overstates the result.
Trích dẫn luật: 2023 NEC §310.15Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- In a 4-wire, 3-phase wye circuit supplying nonlinear (harmonic-producing) loads, how is the neutral treated for conductor-count adjustment?
- Is an equipment grounding conductor (EGC) ever counted as a current-carrying conductor when applying conductor-count adjustment factors?
- An 8 AWG THHN copper conductor (55 A at the 90°C column) is installed where the ambient temperature is 46–50°C. Using the 90°C correction factor of 0.82, what is the corrected ampacity?
- For a branch circuit rated 100 A or less, which temperature column must be used for conductor ampacity at the terminations unless the equipment or terminals are listed for a higher temperature?
- A 90°C-rated conductor is terminated on equipment whose lugs are listed for 75°C. Which temperature column limits the conductor's final ampacity at that termination?
- Under what circumstance may the 90°C ampacity column of Table 310.16 be used?
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