Tightening terminals to the required torque

What the code requires

When equipment has a tightening torque marked on it or given in its installation instructions, its terminal connections must be tightened to that value. Under the 2023 NEC, an approved means must be used to achieve it.

An informational note gives examples of approved means: torque tools, plus shear bolts and breakaway-style devices that have visual indicators. If the manufacturer gives no torque value, a second note points to Informative Annex I or to the manufacturer. A third note refers to NFPA 70B for torquing threaded connections.

Older checklists may say a calibrated torque tool is required. That was the 2017 wording. Since the 2020 edition, the rule has called for an approved means instead, and the 2023 edition keeps that approach.

On the job

• Inspectors may ask how torque was achieved. A torque screwdriver or torque wrench is the usual approved means.
• NEMA recommends against re-torquing terminations after the initial installation and points to infrared scans and visual checks for finding loose connections. If a torque check is absolutely necessary, NEMA calls for de-energizing the circuit and setting the tool to 90% of the value.
• Because torque values come from the manufacturer, they are also enforceable through 110.3(B), which requires equipment to be installed per its listing instructions.

Related sections

• NEC 110.3(B): Install equipment per its listing instructions
• NEC 110.14(A)
• NEC 110.14(C)

Where this comes from

• Oregon BCD: 2023 Oregon Electrical Specialty Code, Table 1-E (2023 NEC text)
• NFPA: NFPA 70 2026-cycle First Draft, CMP-1 (2023 baseline text)
• NEMA: Bulletin 120, Using Torque Tools for Terminating Building Wire (Mar 17 2021)
• Hubbell: Screw terminations vs. torque requirements (Jan 27 2025)
• Read the official NEC free at NFPA