Dịch vụ & Phân phốiCâu 64 / 521
Overload protection for service-entrance conductors must be provided by an overcurrent device in series with:
a.The grounded conductor only
b.Each ungrounded service conductor
c.The grounding electrode conductor
d.The equipment grounding conductor
Giải thích
Per 230.90(A), each ungrounded service-entrance conductor must have overload protection, generally an overcurrent device rated not more than the conductor ampacity. The grounded (neutral) conductor is not fused this way, and grounding/grounding-electrode conductors never carry service overcurrent devices.
Trích dẫn luật: 2023 NEC §230.90Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- A service supplies a continuous load of 80 A and a noncontinuous load of 100 A. What is the minimum required ampacity of the service-entrance conductors?
- What is the minimum rating of the service disconnecting means for a one-family dwelling?
- For a single service, the maximum number of service disconnects permitted for each service permitted by 230.40 is:
- A feeder supplies a continuous load of 40 A and a noncontinuous load of 60 A. The minimum feeder conductor ampacity before applying any adjustment factors is:
- A feeder overcurrent device protecting a feeder that supplies continuous loads must have a rating not less than:
- A service is supplied with 3/0 AWG copper service-entrance conductors. Using Table 250.66, the minimum size copper grounding electrode conductor is:
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