Branch Circuits & FeedersCâu 15 / 120
A four-wire, three-phase, 208Y/120-volt feeder supplies electric-discharge lighting, and the major portion of the load is nonlinear. How many current-carrying conductors are counted for adjustment purposes?
a.Two
b.Four
c.Three
d.Five
Giải thích
When the major portion of the load is nonlinear, harmonic currents keep the neutral loaded even under balanced conditions, so the neutral counts as a current-carrying conductor along with the three phase conductors, giving four. If the load were linear the neutral would not be counted, giving three, and the equipment grounding conductor is never counted.
Trích dẫn luật: 2023 NEC §310.15(E)Luyện miễn phí toàn bộ 120 câu hỏi — không cần đăng ký.
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