A floor opening is an opening measuring ___ inches or more in its least dimension in a floor, platform, or other worksurface, through which persons may fall.

A floor opening is an opening measuring ___ inches or more in its least dimension in a floor, platform, or other worksurface, through which persons may fall.

• A. 8
• B. 12
• C. 10
• D. 14

Answer: (B)

A floor opening is defined by the smallest dimension of the opening being at least twelve inches. This threshold matters because any opening whose narrowest width could allow a person to fall through is considered a floor opening and must be guarded or covered to prevent falls. Think in terms of the least dimension: if an opening is 12 inches by 6 inches, the least dimension is 6 inches, which does not meet the threshold, so it isn’t treated as a floor opening under this rule. Conversely, openings whose smallest width is twelve inches or more are floor openings and require guarding. So the measurement used in the definition is twelve inches.

A floor opening is defined by the smallest dimension of the opening being at least twelve inches. This threshold matters because any opening whose narrowest width could allow a person to fall through is considered a floor opening and must be guarded or covered to prevent falls. Think in terms of the least dimension: if an opening is 12 inches by 6 inches, the least dimension is 6 inches, which does not meet the threshold, so it isn’t treated as a floor opening under this rule. Conversely, openings whose smallest width is twelve inches or more are floor openings and require guarding. So the measurement used in the definition is twelve inches.