Branch Circuits & FeedersCâu 9 / 120
Which of the following is NOT a standard ampere rating for fuses and inverse-time circuit breakers?
a.110 amperes
b.45 amperes
c.70 amperes
d.55 amperes
Giải thích
The standard ratings listed in 240.6(A) include 45, 50, 60, 70, 80, 90, 100 and 110 amperes, but 55 amperes is not among them. Knowing this list matters because calculated loads are routinely rounded up to the next standard rating, and selecting a size that does not exist is a common exam trap.
Trích dẫn luật: 2023 NEC §240.6(A)Luyện miễn phí toàn bộ 120 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- A 480-volt, three-phase feeder carries 40 amperes 250 feet using 6 AWG copper (26,240 circular mils). Using K = 12.9, what is the approximate voltage drop?
- A 120-volt branch circuit must carry 12 amperes 120 feet with voltage drop held to 3 percent. Using K = 12.9 for copper, what is the smallest conductor that meets the target?
- A feeder supplies 30 amperes of continuous load plus 50 amperes of noncontinuous load. What is the minimum standard overcurrent device rating?
- What is the minimum number of 20-ampere small-appliance branch circuits required for the kitchen, pantry, breakfast room and dining room receptacles of a dwelling unit?
- What is the minimum branch-circuit rating for the receptacle outlets serving a dwelling unit bathroom?
- What is the allowable ampacity of 8 AWG copper Type NM cable?
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