Embeddment for buried system portions must be __________.

The answer indicates that the embeddment for buried system portions must be under floors. This is consistent with best practices within the mechanical code, which emphasize that when systems are installed below ground, they must be adequately protected and embedded to prevent damage from external loads or environmental factors.

Placing buried systems under floors ensures they are shielded from activities or loads directly above them, providing necessary stability and reducing the risk of physical damage. Furthermore, ensuring that these systems are installed in a manner that keeps them secure and accessible for maintenance is often a requirement of the code.

While there are other locations mentioned, such as wall cavities or surface level installations, these options do not provide the necessary protection or support for buried mechanical systems. Locations like above-ground facilities typically refer to systems that are installed at elevations that would be exposed to potential hazards.

Thus, the preference for embedding under floors aligns with creating a safe and compliant environment for buried systems.