What is a requirement for supported or shielded vertical-sided portions in excavation?

The requirement that supported or shielded vertical-sided portions in excavation must not exceed a depth of 20 feet is based on safety guidelines established by OSHA to minimize hazards associated with excavations. This depth limit helps mitigate the risk of cave-ins, which can occur in deeper excavations due to soil instability.

When the excavation is deeper than 20 feet, the potential for serious or fatal accidents increases significantly, necessitating more rigorous safety measures and engineering controls to ensure worker safety. The regulations are designed to protect workers from the dangers associated with deep excavations, such as the weight of the soil and the methods of support required to keep workers safe.

Parameters relating to sloping, extensions, or excavation depths beyond certain limits are also critical but do not directly address the established depth limit for excavation without supports. Hence, keeping the depth at or below 20 feet is a fundamental safety requirement in excavation practices.