What screw size are the mounting holes in metal boxes tapped for equipment grounding conductors?

The mounting holes in metal boxes are tapped for equipment grounding conductors with a screw size of No. 10-32. This standard size ensures a secure and reliable connection for grounding purposes. The No. 10-32 screw is designed specifically to fit various grounding accessories and terminals, allowing for consistent performance in electrical installations.

Using the correct screw size is critical for maintaining the integrity of the grounding system, as improper sizes could lead to insufficient grounding or connection failures. The use of No. 10-32 screws also aligns with industry standards and codes, which helps ensure safety and compliance in residential electrical systems.