How are NEC 2023 rules for box fastener lengths impacting wiring safety?

Overview 

Using appropriate screws and fasteners in wiring spaces is essential for electrical safety and system integrity, as improper fasteners can damage wire insulation and cause hazards like short circuits or fires. NEC 2023 introduced Section 314.5 to provide specific guidelines for selecting the correct type and length of screws and fasteners for wiring spaces in boxes and conduit bodies. This section mandates that required screws or fasteners must be provided by the manufacturer and comply with specific length and design criteria. The addition of this section aims to prevent inadvertent damage to wiring insulation during installation and maintenance.

Applying the 2023 Code 

Selecting the right screws and fasteners for wiring spaces within boxes and conduit bodies is essential to uphold electrical safety and system reliability. Properly chosen screws and fasteners guarantee that covers and components are securely fastened without exerting excessive stress or causing deformation, which could compromise the integrity of the entire electrical system. Using the appropriate type of fastener reduces the likelihood of electrical hazards, whereas using inappropriate ones may result in damage to wire insulation, increasing the risk of short circuits, electrical faults, or even fires. 

Previously, the NEC lacked specific guidelines for screws and fasteners used in the wiring spaces of boxes and conduit bodies. The NEC 2023 addressed this gap with the introduction of Section 314.5. This section mandates that screws or fasteners installed in the field must either be provided by the manufacturer or meet specific criteria. These criteria include using machine-type screws with blunt ends, ensuring other fasteners also have blunt ends, and limiting the extension of screws used to attach covers to no more than 10 mm (3/8 in.). Detailed specifications are provided for screws penetrating box walls and covers, with allowances for longer screws if adequately protected. This addition aims to safeguard against damage to conductors caused by sharp projections or exposed threads of screws. Electrical professionals are now required to carefully select and install fasteners according to these guidelines to guarantee compliance and avoid potential damage. 

What’s New for the 2023 NEC? 

The table below presents a comparison between the 2020 NEC and the 2023 NEC regarding Section 314.5.