How to Use a Torque Wrench for Electrical Panels: Stay Safe and Code-Compliant

Electrical panels require precise torque to prevent overheating and fires—codes like NEC (National Electrical Code) mandate it. A 1/4” drive torque wrench (range: 10–50 in-lbs) works for most panel screws.

First, turn off the main power—never work on a live panel. Use a hex bit that fits the panel screws (most are 1/4” or 5/16”). Set the wrench to the spec: 20–25 in-lbs for copper lugs, 15–20 in-lbs for aluminum (aluminum is softer).

Apply force slowly—stop at the click. Over-tightening strips the screw or crushes the wire, causing resistance (and heat). If you’re unsure of the spec, check the panel manufacturer’s manual—NEC requires specs to be listed.