Testing & TroubleshootingQuestion 515 of 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
Explanation
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).
Law Reference: 2023 NEC §110.14(D)Practice all 521 questions free — no signup required.
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