Services & DistributionCâu 37 / 110
Service phase conductors total 1,500 kcmil Cu per phase (over 1,100 kcmil). Using the 12.5% rule, what is the minimum copper main bonding jumper?
a.4/0 AWG
b.3/0 AWG
c.250 kcmil
d.2/0 AWG
Giải thích
Above 1,100 kcmil, the main bonding jumper is at least 12.5% of the phase area: 0.125 x 1,500 = 187.5 kcmil, so 4/0 Cu (211.6 kcmil) is the smallest that qualifies.
Trích dẫn luật: 2023 NEC 250.28(D)Luyện miễn phí toàn bộ 110 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- A branch circuit is protected by a 100-A overcurrent device. What is the minimum copper equipment grounding conductor?
- A feeder is protected by a 400-A overcurrent device. What is the minimum copper equipment grounding conductor?
- A service has 500-kcmil Cu ungrounded conductors per phase. What is the minimum copper grounded (neutral) service conductor for bonding purposes?
- A panelboard is rated 225 A. What is the maximum rating of the overcurrent device that may protect it?
- Which of the following is the next standard overcurrent device rating above 95 A?
- Absent a specific exception, what is the maximum overcurrent protection for a #12 Cu conductor?
Cập nhật gần nhất: · quy trình kiểm tra
Đội Ngũ Biên Tập PrepPass · Đối chiếu với Master Electrician Licensing Exam (NEC-based) · Quy trình kiểm tra