Final answer:
The primary function of a receptacle face is to provide electrical power to devices, supporting the three-wire system to ensure safety against electrical hazards.
Step-by-step explanation:
The primary function of a receptacle face is to provide electrical power to devices. In the context of a three-hole outlet, it is part of the three-wire system, which includes live/hot, neutral, and earth/ground wires. The receptacle ensures that the standard three-prong plug can only be inserted one way to maintain the correct connection between these wires and safeguard against electrical hazards such as shocks and thermal risks. The receptacle face itself does not protect electrical connections or control the flow of electricity (functions associated with circuit breakers and ground fault interrupters (GFI), nor does it provide a decorative cover. Instead, it serves as the interface for the appliance's plug to connect to the building's electrical wiring system and thus receive power.