Protective devices must always be replaced with one of the _____ type and _____ size.

The correct answer emphasizes that protective devices must always be replaced with one of the same type and the same size to ensure compatibility with the existing system and maintain safety standards. Using a protective device of the same type ensures that the replacement functions in the same manner as the original, providing the same level of protection against faults, overloads, or electrical disturbances. Similarly, the size is critical because a protective device must fit properly in its designated location and be able to handle the same electrical parameters, such as current and voltage ratings. Mismatched devices might lead to inadequate protection or failure to operate under specific conditions, potentially resulting in electrical hazards. Therefore, replacing a protective device with the same type and size is essential to uphold safety and reliability in electrical systems.