Which statement about manhole openings is true?

• A. Manhole openings must be not less than 24 inches
• B. Manhole openings must be not less than 23 inches
• C. Manhole openings must be not less than 22 inches
• D. There is no minimum size for manhole openings

Answer: (B)

Safe access to a manhole is the main idea here. The opening must be large enough for a worker to enter, exit, and maneuver tools and equipment without getting stuck, and for supervisors or rescuers to reach the person inside if needed. Because of that, the code sets a minimum size, and that minimum is not less than 23 inches. In other words, any opening must meet or exceed 23 inches to be considered compliant.

If you consider the other possibilities, an opening dimension claimed to be not less than 24 inches would still satisfy the requirement, but it describes a larger minimum than the standard minimum. An opening not less than 22 inches would be too small to meet the rule, and saying there is no minimum would be incorrect because there is a defined minimum for safety.