Final answer:
The grounding wire should be connected to the case of an appliance. It provides a low-resistance path to the earth, which keeps the connected conductors at zero volts, ensuring safety from electric shocks.
Step-by-step explanation:
The grounding wire must be located on the case of the appliance when using a di-electric connector. Grounding is an essential safety feature in electrical systems, providing a path with low resistance directly to the earth. This ensures that any conductor can be held at zero volts, minimizing the risk of electric shock. The grounding wire is typically connected via a green earth/ground wire, which leads to the case of the appliance, thereby keeping the case at zero volts as well. The standard three-prong plug ensures that the grounding wire is appropriately connected to prevent electrical hazards.