When recessed fixtures are installed in floor-ceiling assemblies that require a fire-resistance rating, what must be ensured?

When recessed fixtures are installed in floor-ceiling assemblies that require a fire-resistance rating, it is essential to ensure that they do not reduce the required fire-resistance. This is crucial because the integrity of a fire-resistance-rated assembly is key to preventing the spread of fire and smoke between floors, maintaining structural integrity during a fire event, and ensuring the safety of occupants.

Compliance with fire-resistance ratings involves considering how penetrations, such as those made for recessed fixtures, can impact the overall assembly's performance. If these fixtures compromise the fire-rated assembly, it could allow fire to spread faster than intended, reducing the effectiveness of the building's fire protection system. Therefore, when installing recessed fixtures in such assemblies, it's important to use materials and methods that maintain the required fire-resistance, such as using fire-rated fixtures or ensuring that any penetrations are properly sealed with fire-resistant materials.

Other considerations, such as making fixtures easily accessible for maintenance, ensuring they are installed after inspection, or using non-combustible materials, can be important in certain contexts but do not directly address the critical concern of maintaining the fire-resistance rating of the structure.