Thiết bị & Hệ thốngCâu 297 / 521
NEC 430.75 requires that motor control circuits be arranged so that:
a.The control circuit is disconnected from all sources of supply when the disconnecting means is open
b.Control circuits are always 24 V
c.Control conductors are the same size as power conductors
d.Control circuits need no overcurrent protection
Giải thích
NEC 430.75 requires the disconnecting means to open the motor control circuit from all sources when placed in the off position (with limited exceptions), so a technician is not exposed to energized controls. Control voltage level, conductor size parity, and 'no protection' are not the rule.
Trích dẫn luật: 2023 NEC §430.75Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- When the Table 430.52 percentage produces a value that does not correspond to a standard fuse or breaker size, NEC 430.52(C)(1) Exception No. 1 permits you to:
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- A small single-phase motor has a nameplate FLA of 14 A, service factor 1.0, no marked temperature rise. What is the maximum overload device rating under NEC 430.32(A)(1)?
- A 15 kVA, single-phase transformer has a 480 V primary. What is the rated primary current?
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- Which of the following is NOT required to be marked on a motor nameplate by NEC 430.7?
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