Occupational Safety & Health Administration
Guarding floor and wall openings and holes
Subpart Title: Walking-Working Surfaces
"Protect Floor openings"
The construction of floor opening covers may be of any material that meets the strength requirements. Covers projecting not more than one (1) inch above the floor level may be used providing all edges are chamfered to and angle with the horizontal of not over 30 degrees. All hinges, handles, bolts, or other parts shall sit flush with the floor or cover surface.
Every floor hole into which persons can accidentally walk shall be guarded by either
A standard railing with standard toe board on all exposed sides, or,
A floor cover of standard strength and construction (refer to 1926.502(i))
Every floor hole into which persons can not accidentally walk (on account of fixed machinery, equipment, or walls), shall be protected by a cover that leaves openings no more than one (1) inch wide. The cover shall be securely held in place to prevent tools or materials from falling through.
1926.502(i)(2) states: covers shall be capable of supporting without failure, at least twice the weight of employees and materials that may be imposed on the covers at any time.
1926.502(i)(3) states: all covers shall be secured when installed so as to prevent accidental displacement by the wind, equipment, or employees.
1926.502(i)(4) states: all covers shall be color-coded, or they shall be marked with "HOLE" or "COVER" to provide warning of a hazard.