Which factor does NOT contribute to a confined space being designated as "permit-required"?

A confined space is designated as "permit-required" when it poses specific hazards that necessitate greater safety measures for anyone entering it. One critical factor that does not contribute to this designation is the size of the space, particularly when referring to the assertion that the space is less than 1 foot in diameter.

The size itself does not inherently create risks associated with hazardous materials. Instead, a permit-required confined space is primarily defined by its potential for dangerous conditions, which are assessed based on factors like the presence of hazardous atmospheres, limited means of entry and egress, and whether the space is intended for human occupancy.

Limited means of entry and exit can increase the risk during an emergency, while hazardous atmospheres—such as toxic gases, flammable vapors, or insufficient oxygen—are direct threats to safety. Configuration for human occupancy indicates that people could be present, which heightens the need for protections based on the nature of the hazards present.

Thus, the designation of a confined space as “permit-required” is fundamentally concerned with safety threats rather than mere physical dimensions, exemplifying why the factor of diameter is not relevant to this classification.