Which of the following statements about plug and receptacle compatibility is not true?

The statement that a 20 amp plug will fit into a 15 amp receptacle is not true. In electrical systems, plugs are designed to match their corresponding receptacles for safety and compatibility. A 20 amp plug has a different configuration than a 15 amp receptacle, which prevents the 20 amp plug from being inserted into a 15 amp receptacle. This design ensures that devices requiring higher current cannot be connected to lower-rated circuits, reducing the risk of overheating and potential electrical fires.

In contrast, a 15 amp plug fitting into a 20 amp receptacle is correct because the 20 amp receptacle is designed to accept both 15 amp and 20 amp plugs. Furthermore, a 30 amp plug will not fit into a 20 amp receptacle due to the differences in design, ensuring that the higher current capacity of the 30 amp plug does not connect to a receptacle that cannot handle that load. Lastly, a 15 amp plug being compatible with a 15 amp receptacle is inherently true because they are designed to work together safely. This ensures that devices and circuits are appropriately matched, maintaining the safety and efficacy of the electrical system.