the intumescent insert 14 is configured to be sandwiched between the bottom plate 12 and the top plate 16 when the assembly 10 is fully assembled electrical wiring such as wiring 58 connected to the electrical receptacle 53 passes through an electrical passage defined by the mounting structure 52 the electrical opening 44 the electrical opening 26 and the channel 27 similarly communication data cables pass through a communication passage defined by the mounting structure 54 the communication opening 46 the communication opening 30 and the channel 32 each upwardly extending leg 50 includes an upright portion 60 having a first end 62 secured to the main body 48 of the top plate 16 and a second end 63 having a mounting tab 64 the mounting tab 64 includes a fastener through hole 66 the mounting tabs 64 are configured to securely support the trim ring 18 the trim ring 18 includes fastener through holes 68 that are configured to align with the fastener through holes 66 of the mounting tabs 64 the trim ring 18 may be secured to the mounting tabs 64 through screws nails rivets and the like alternatively the trim ring 18 may include latching members clasps barbs or the like that are configured to securably engage reciprocal structures formed on the mounting tabs 64 the trim ring 18 includes an annular body 70 defining a central passage 72 the fastener through holes 68 are positioned proximate an internal edge 74 of the annular body 70 but may be formed at different areas of the annular body 70 the trim ring 18 is configured to be securely mounted slightly above or flush with a top surface of a floor.