Fire retardant modular floor penetration structure

Claim 1

A cable conduit penetration structure comprising: a penetration cell (10) constructed of cementitious material so that it may be cast directly into a concrete floor, and including a cable passageway (11) of substantially rectangular cross section and oriented to provide cable passage from one side of the floor to another side, the cell and its passageway having a length substantially equal to a thickness of the floor into which it is cast, the cable passageway including two support ledges (13) cut into two and opposite sides of the passageway at a distance from one end of the passageway substantially equal to one half the length of the passageway, the support ledge being perpendicular to a direction of the length of the passageway, and the penetration cell further including at least two slots (17) cut into an exterior surface of one outer side wall (16) of the penetration cell to engage connecting clamps (33) whereby a plurality of penetration cells may be joined together, and a top surface of the cell being recessed around the periphery to form a shoulder (22,24) a metallic sheath (51) comprising first and second sheath elements (21) each having a channel-shaped cross section, the two sheath elements each including loops (31) bent in a hook shape along longitudinal edges of the channel-shaped cross section, and a spline clip (30) to engage the bent hook shapes of the two sheath elements when they are positioned together so that the longitudinal edges of the channel are abutted together and operative to secure the two sheath elements positively together and form the metallic sheath, the sheath being positioned on the shoulder to extend the length of the passageway through which the cables pass and having an interior periphery sized so that there is a pressure fit to secure it in place to the shoulder of the penetration cell, and a plurality of intumescent cards (45) inserted between layers of cables passing through the passageway and including cutaway lips (46) on opposite ends of the cards resting upon opposite ones of the two support ledges, respectively whereby the application of heat due to a fire causes material of the intumescent cards to expand into interstices between the cables and seal the passageway.