What is NEC Article 300.22 concerned with?

NEC Article 300.22 specifically addresses the installation practices for conductors in spaces used for environmental air. This article aims to ensure that electrical installations do not create a hazard when located in areas where air is circulated for heating or cooling systems, which includes plenum spaces.

The key considerations under this article include using appropriate materials and installation methods that minimize the risk of fire and toxic fumes, as these spaces can significantly impact the safety and health of occupants. This is particularly important because if a fire occurs in such areas, it can spread rapidly through the public air system, endangering lives and property.

In the context of the other options, while installation practices for hazardous environments and standards for overhead or underground installations are also critical aspects of the NEC, they are addressed in different articles or sections of the code, rather than in Article 300.22. Therefore, focusing on the specific context and safety measures for conductors in environmental air spaces is why this answer is correct.