Dịch vụ & Phân phốiCâu 106 / 521
A panelboard must have a rating (busbar ampacity) not less than:
a.The minimum feeder capacity required for the load served, as computed per Article 220
b.50% of the service rating
c.The largest single branch circuit only
d.Twice the neutral load
Giải thích
Per 408.30, a panelboard must have a rating not less than the minimum feeder or service capacity required for the load computed under Article 220. Sizing only to a single branch circuit or an arbitrary fraction of the service would leave the busbar under-rated for the actual load.
Trích dẫn luật: 2023 NEC §408.30Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- When circuit conductors are run in parallel in multiple raceways, the equipment grounding conductor in each raceway must be:
- A 208Y/120 V, 3-phase feeder supplies a balanced 50 kVA load. The approximate line current (and therefore the minimum conductor ampacity before continuous factors) is:
- For a 200 A service where the equipment and conductors are all rated for it, the conductor ampacity used for termination sizing is normally based on which temperature column?
- Service-entrance conductors installed in a raceway in a wet location (such as underground or exposed to weather) must be:
- A separately derived system (such as the secondary of a transformer feeding a distribution panel) must have a system bonding jumper connecting:
- A detached garage is supplied by a feeder from the main dwelling. At the garage, the code generally requires:
Cập nhật gần nhất: · quy trình kiểm tra
Đội Ngũ Biên Tập PrepPass · Đối chiếu với California CSLB C-10 Electrical Trade Examination · Quy trình kiểm tra