Which component is primarily responsible for ensuring electrical connectivity in back-wire devices?

The terminal screw is primarily responsible for ensuring electrical connectivity in back-wire devices. In back-wiring, wires are typically inserted into the back of the device (such as outlets or switches) and secured in place by the terminal screws. When the screws are tightened, they create a solid connection with the wire, which allows for an efficient and reliable transfer of electrical current. This design helps to minimize connection issues that can arise from loose wires and also sustains the mechanical stability of the electrical connection.

The purpose of other components like the clamping plate is generally related to securing the wires or providing additional support but does not participate directly in making the electrical connection. The mounting bracket is primarily used to secure the device to a junction box or the wall, not to make electrical contacts. The grounding wire serves a safety function, providing a path for fault current but does not facilitate the main electrical connectivity of the device itself. Thus, the terminal screw is key to ensuring that the electrical connection is both secure and functional.