At what depth must a trench be cut back or shored?

The correct answer is associated with the regulations and safety guidelines regarding trenching operations. Specifically, for trenches that are 1.5 meters (5 feet) deep or more, proper shoring or cutting back the edges is mandated to ensure worker safety and prevent cave-ins.

Trenching can be a dangerous activity due to the potential for soil collapse. The 1.5 meters depth threshold is significant because it aligns with established safety protocols, which dictate that as the depth increases, so too does the risk of collapse requiring additional protective measures. Shoring, which involves installing structures to prevent soil from collapsing, or cutting back the trench walls can significantly improve safety for workers entering the trench.

Other options do not align with the regulatory standards, as they indicate depths that either pass the safety threshold or do not require shoring. Understanding these requirements is crucial for maintaining safety on job sites during pipe installation and other underground work.