The screw hole for mounting a ground screw on Box II is tapped for which size screws?

The size of the screw hole for mounting a ground screw on Box II is typically tapped for 10-32 screws. This standard size is commonly used in electrical boxes to ensure a secure connection for ground screws. The 10-32 screw is employed because it strikes a balance between strength and compatibility, fitting well with the other components found in electrical installations. This choice supports the requirement for grounding in electrical systems, which is vital for safety, preventing electrical shock and ensuring proper function of circuit protection devices.

The other options, such as 8-32, 6-32, and 4-40, are less frequently utilized in this application and do not meet the common hardware standards for electrical boxes, making them unsuitable for mounting ground screws in Box II.