Under what conditions are excavations considered safe from cave-ins?

Excavations made entirely in stable rock are considered safe from cave-ins primarily due to the inherent structural integrity of the material itself. Stable rock provides a solid foundation, meaning that it has a much lower likelihood of collapsing compared to other materials such as loose soil or sand. This stability is crucial for preventing cave-ins, which pose significant risks to the safety of workers in excavation sites.

In contrast, other listed scenarios may still carry risks. High-water areas can lead to erosion and instability, night work does not inherently provide safety from cave-ins without proper conditions, and the depth of an excavation exceeding 10 feet necessitates specific safety measures but does not guarantee safety from cave-ins without proper support systems in place. Therefore, excavations in stable rock are universally recognized as much safer, reducing the need for additional protective measures compared to other environments.