What is the maximum penetration allowed for screws attaching covers in outlet and device boxes?

The maximum penetration allowed for screws attaching covers in outlet and device boxes is specified in the NEC to prevent damage to internal wiring and components. In this case, the correct answer indicates a maximum screw penetration of 3/8 inch. This limit is established to ensure that screws do not extend too far into the box and potentially puncture or damage the conductors or internal equipment, which could pose safety risks such as electrical shorts or fires.

A penetration of 3/8 inch strikes a balance between securing the cover properly and maintaining safety by preventing any interference with the box's internal components. It is vital for electrical installations to adhere to these specifications to minimize the risk of accidents or malfunctions due to improper installation practices.