Final answer:
A standard electrical plug's design, where one prong is larger than the other, is an example of Poka-yoke, a mechanism to prevent human error by ensuring proper connection and providing a grounded circuit.
Step-by-step explanation:
The standard electrical plug fitting into an outlet in only one way to ensure the creation of a grounded circuit is an example of Poka-yoke. Poka-yoke is a Japanese term that refers to a mechanism that helps an equipment operator avoid (yokeru) mistakes (poka). Its purpose is to eliminate product defects by preventing, correcting, or drawing attention to human errors as they occur.
For instance, the three-prong plug design ensures that it can only be inserted in one way, maintaining the correct connection of live/hot and neutral wires, and providing the safety feature of grounding. A reason why some appliances may still have two-prong plugs is that they have nonconducting, doubly insulated cases; these plugs are designed to fit into the standard asymmetric outlet to also ensure proper connection.