Using snap switches with nonmetallic yokes allows for grounding of what component?

Using snap switches with nonmetallic yokes facilitates the grounding of metal faceplates. This is important because metal components can conduct electricity and need to be grounded to prevent electric shock hazards. When a metal faceplate is installed over a wiring device, the nonmetallic yoke of the switch provides a way to safely connect the grounding system to the faceplate.

In contrast, plastic, wood, and glass faceplates do not conduct electricity, so grounding them is unnecessary and not relevant in this context. The grounding feature is specifically designed for metallic components to ensure safety and compliance with electrical codes. Thus, the option referring to metal faceplates is supported by the requirement for grounding in electrical installations.