OSHA 10-Hour Construction ReviewFocus Four HazardsEasy
A worker is preparing to enter a trench that is 6 feet deep and 4 feet wide for utility installation. There are no indications of unstable soil or other immediate hazards. What is the minimum depth at which a protective system (sloping, shoring, or shielding) is generally required for trenches?
- A6 feet
- B3 feet
- C5 feet
- D4 feet
Show answer & explanationAnswer & explanation
Correct answer: C. 5 feet
OSHA requires that trenches 5 feet or deeper must have a protective system in place unless the excavation is made entirely in stable rock. This prevents cave-ins.
Why the other options are wrong
- A. While this trench is 6 feet, the requirement starts at 5 feet, making 6 feet a scenario where protection is definitely needed.
- B. This depth is below the OSHA requirement for protective systems in trenches.
- D. While 4 feet is a threshold for some excavation rules (like ladders), it's not for protective systems.
Excavation Protective System Threshold
OSHA requires protective systems (sloping, shoring, or shielding) for all trenches 5 feet (1.52 meters) or deeper, unless excavated in stable rock.
- Protective systems prevent cave-ins.
- Applies regardless of soil type (unless stable rock).
- Competent person must design or approve system.
Memory trick: Five feet down, safety's crown.