When penetrating a concrete fire-resistive wall or floor assembly with RMC, is it acceptable to use mortar to fill the annular space?

When penetrating a concrete fire-resistive wall or floor assembly with rigid metal conduit (RMC), it is not acceptable to use mortar to fill the annular space because this practice does not comply with the requirements set forth in fire protection and electrical safety codes. Instead, the annular space must be sealed with materials specifically designed for fire-resistant applications.

Using the appropriate firestop materials ensures that the integrity of the fire-resistive barrier is maintained, preventing the passage of smoke, fire, or gases through the penetration. Mortar, while a strong construction material, does not provide the necessary fire-resistance properties required to uphold the fire safety standards in such installations. Therefore, compliance with industry standards and safety practices is paramount in these scenarios, leading to the conclusion that the answer indicating that mortar is not an acceptable fill material is correct.