A listed electrical box for use in fire-resistive assemblies does not require penetration protection as long as the annular space does not exceed what measurement?

The correct answer indicates that when the annular space around a listed electrical box in fire-resistive assemblies does not exceed 1/8 inch, no additional penetration protection is required. This 1/8 inch measurement is significant because it reflects the threshold established by building codes and safety standards designed to maintain the integrity of fire-resistive barriers. Exceeding this measurement could compromise the fire-stopping performance by allowing fire and smoke to spread through the openings more easily, hence the reason for needing additional protection in those cases.

When considering the importance of maintaining fire-resistive features within a structure, adhering to these specified dimensions ensures that essential safety measures are upheld, thereby reducing risk during fire incidents.