At what depth in feet does a trench require shoring?

• A. 3 feet
• B. 4 feet
• C. 5 feet
• D. 6 feet

Answer: (B)

Protecting workers from trench cave-ins requires a protective system once the trench reaches a depth where the walls can no longer support themselves. As depth increases, the earth above and beside the trench exerts more pressure, making a collapse more likely. At about four feet, that risk becomes significant enough in this standard to require shoring to brace the sides and keep the trench stable while work is underway. Shoring provides vertical support to the walls, preventing movement and cave-ins. Remember that soil conditions, moisture, and width can change the exact requirements, but four feet is the threshold used in this context.