Mạch nhánh & Đi dâyCâu 217 / 521
For Type NM cable, the 90°C rating of its conductors may be used for what purpose?
a.Only for adjustment and correction (derating) calculations
b.For establishing the final ampacity
c.It may not be used at all
d.For the load calculation
Giải thích
Per 334.80, the 90°C column may be used as the starting point when applying ambient and conductor-count factors, but the final NM ampacity is still governed by the 60°C column. It cannot set the final ampacity directly.
Trích dẫn luật: 2023 NEC §334.80Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- Per Table 310.16, what is the ampacity of a 10 AWG copper conductor in the 60°C column?
- Per Table 310.16, what is the ampacity of a 6 AWG copper conductor in the 75°C column?
- Per 334.80, the ampacity of Type NM (nonmetallic-sheathed) cable is based on which temperature column of Table 310.16?
- A 12-2 Type NM cable (two 12 AWG conductors plus ground) is used for a general branch circuit. Using the required NM temperature column, what is the ampacity of its 12 AWG conductors?
- Per 334.30, Type NM cable must be secured and supported at intervals not exceeding what distance along the run?
- Per 334.12, which of the following installations is NOT permitted for Type NM cable?
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