Kiểm tra & Khắc phục sự cốCâu 515 / 521
Why does over-torquing a lug or terminal screw create a hazard, even though the connection feels 'extra tight'?
a.Over-torque improves conductivity and is always safer
b.Over-torque can crush strands, deform the lug, and damage threads, raising resistance and causing a hot connection or eventual failure
c.Over-torque only matters on aluminum, never copper
d.Torque has no effect on connection reliability
Giải thích
Both under- and over-torque are harmful: over-torquing can crack lugs, crush or shear conductor strands, and strip threads, increasing contact resistance and heat over time. That is why the NEC requires using the manufacturer's specified value with a calibrated tool. It applies to copper and aluminum alike (c), and torque very much affects reliability (d).
Trích dẫn luật: 2023 NEC §110.14(D)Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
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