The construction of floors, ceilings, and walls using concrete is very well known within the construction industry. It is frequently necessary to supply utility service (electrical power, telephone, thermostat control) through the concrete structures, passing from room to room or from floor to floor. There are several well-known methods of supplying utility service through the concrete structures. Perhaps the most obvious method involves simply drilling completely through the formed concrete slab to provide access to the other side of the slab. Another approach which achieves the same result involves placing a sleeve insert at the desired hole location before the concrete is poured. These two methods provide passageways between each side of the slab.
It is also common to bury service-carrying conduit within the concrete slabs to provide utility service to a wall or to a floor receptacle. An extensive network of rigid conduit is frequently constructed within the concrete form used to retain the wet concrete during pouring and define the boundaries of the slab. Steel reinforcement mesh is also often used to strengthen the concrete slab and conveniently provides a support location for securing the rigid conduit network. Access to the conduit network is normally needed above the finished slab in walls, floor receptacles, and utility rooms.
Because there are several types of rigid conduit currently being used in the industry, several different methods of providing above-the-slab access to the conduit network are used. For galvanized rigid steel (GRS) and intermediate metallic conduit (IMC), small sections of conduit are oriented in a relatively vertical direction and simply connected, through the use of conduit connection members, to the conduit network at desired access locations. During the pouring of the concrete, the vertical sections of conduit resist the force of the flowing concrete and remain securely placed in their original, intended positions. After the concrete is poured, the top ends of the vertical sections of conduit remain exposed, providing access to the network.
Construction of the conduit network, including providing above-the-slab access, typically requires extensive time and effort in cutting and re-connecting the rigid conduit sections with special connectors to change the direction of the conduit. Rigid non-metallic conduit (commonly referred to as PVC) is also used in the industry. Although PVC can be cut and re-connected in a manner similar to GRS and IMC, it can also be heated and bent to change the direction of the conduit. This process also requires extensive time and effort. Similarly, electrical metallic tubing (EMT), although slightly more flexible than GRS, IMC, or PVC, requires the use of special bending tools to change the direction of the conduit. This requirement also introduces excessive time and effort into the construction process.
More recently, flexible conduit, known as electrical non-metallic tubing (ENT), has been used in place of the less workable rigid conduit. Because the newer flexible conduit readily bends around corners without the need for heat or special bending tools, fewer sections of conduit and less time are required to construct the network. Ideally, only one section of conduit is required to travel between one access point and another access point. Each access point is provided by simply bending one end of the flexible conduit upward above the intended upper level of the slab. In this manner, no additional conduit connection members are necessary to provide access to the network.
Although flexible conduit offers the advantage of minimizing time and effort in being easily bent around corners in the horizontal network, it also offers several disadvantages. After the flexible conduit is bent upward, it tends to fall back down into the intended concrete slab area without proper support. Flexible conduit requires an adequate supporting force to hold it in a bent position. The steel reinforcement mesh typically can not provide an adequate support for correctly positioning the flexible conduit. Also, the flexible conduit does not effectively resist the force of flowing concrete during the pouring and moves from the original intended position.
Furthermore, after the concrete is poured, the exposed flexible conduit is susceptible to many hazards. For example, one of the many workman on the construction site may inadvertently kick and damage the exposed flexible conduit before a wall or floor receptacle is installed. There is, therefore, a need in the art to provide solutions to these and other serious problems.