What are the minimum dimensions for a manhole opening?

The minimum dimensions for a manhole opening are established to ensure safe and easy access for personnel and equipment. The option indicating 11 x 15 inches meets the standards required for adequate space, allowing workers to enter and exit safely while also accommodating the necessary tools or equipment that may need to be used within the manhole.

A manhole opening that is properly sized helps to reduce the risk of accidents, such as workers being trapped or having difficulty maneuvering. It also facilitates proper ventilation and accessibility for maintenance and inspections. Each of the other dimensions provided may not sufficiently meet these safety standards, which is why 11 x 15 inches is designated as the minimum requirement.