An insert for a poke-through fitting, including a plurality of sealing elements adapted to absorb heat, expand, and flow into openings under pressure, and a plurality of insulating elements adapted to absorb heat, cure, cross-link, emit water, and dissipate heat, upon activation by heat and flame from a fire. The sealing and insulating elements are adapted to enable the fire rating of the floor in which the poke-through fitting is installed to be substantially the same with or without the hole and fitting therein, to enable the hole in the floor to be smaller to reduce the hazard of transmission of heat and flame from a fire therethrough, and to enable the capacity for passing wires to be greater in the smaller hole for increased wire capacity. The insert further includes a retaining element, assisted by compressible sealing elements, adapted to enable the insert to be retained in the hole in the floor, and, upon the exertion of increased pulling force, to be held fast in the hole in the floor, to prevent the safety hazard of electrical shock and fire from exposed live ends of pulled-apart power wires.