OSHA requires a protective system to be installed for trenches that are 5 feet deep or greater unless the excavation is made entirely in stable rock. For trenches less than 5 feet deep, a competent person can determine if a protective system is necessary. Additionally, trenches 20 feet deep or greater require that the protective system be designed or approved by a registered professional engineer. This is to prevent cave-ins and protect workers' safety during trenching operations.
