In hotels and motels, under what conditions does NFPA 13 not require heads in closets?

The correct answer hinges on specific criteria outlined in NFPA 13 regarding sprinkler system requirements in closets within hotels and motels. The code states that heads are not required in closets that are smaller than 24 square feet and where the least dimension is less than 3 feet. This is based on the understanding that smaller closets represent a lower risk for fire spread due to their limited size and the volume of combustibles they typically contain.

Therefore, the rationale is that in such small spaces, the potential for fire growth and the need for sprinkler protection diminishes, allowing for exceptions to the requirement for sprinkler heads. This provision acknowledges that in closely defined measurements, the risks can be effectively managed without the requirement of additional sprinkler protection, thereby both ensuring safety and optimizing resources in building design.

The other options do not align with the specific conditions under which NFPA 13 makes its exceptions for sprinkler protection in closets. For instance, while non-combustible materials, fire doors, or electric outlets might influence fire safety considerations, they do not provide the same standardized spatial criteria that NFPA 13 specifies for exemptions on a broader scale.