At what depth does OSHA require a trench box?
OSHA requires a protective system, such as a trench box, at 5 feet deep unless the trench is entirely in stable rock. A shallower trench needs one too when a competent person finds signs of a potential cave-in. At 20 feet or deeper, a registered professional engineer must design the system or approve the tabulated data it follows.
What is a trench per OSHA?
OSHA defines a trench as a narrow excavation, in relation to its length, made below the surface of the ground. In general the depth is greater than the width, and the width measured at the bottom is not greater than 15 feet. Subpart P applies to all open excavations, and trenches are one kind.
Trench box vs other OSHA protective systems
A trench box is a shield: a structure that withstands the forces of a cave-in and protects workers inside it. OSHA also accepts sloping, benching and shoring. The competent person on site inspects the trench before work starts and decides whether protection is needed below 5 feet; a registered engineer decides where the standard requires one.
Sources
Checked 2026-11-02.