Abstract:
A Non-metallic Elbow Conduit Transition Fitting is disclosed. The fitting is specifically suited to interconnect vertical electrical conduit runs and horizontal electrical conduit runs in commercial construction environments. The fitting is suitable for immersion within poured concrete floors used in commercial building construction. The fitting is designed to threadedly engage a vertical run of EMT (metallic) conduit with a horizontal run of nonmetallic (e.g. PVC) conduit. A final aspect of the fitting is that it must have a short sweep angle bend so that it is adequately buried within a concrete floor made from 6 inches of concrete.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     This invention relates generally to electrical wiring and conduit and, more specifically, to a Non-metallic Elbow Conduit Transition Fitting.  
         [0003]     2. Description of Related Art  
         [0004]     Commercial building construction generally involves the use of metal framing and concrete flooring. This approach is used due to the superior long-term durability and fire safety that these types of structures provide. The construction of these buildings is essentially a process of erecting the building floor-by-floor using metal framing members and then pouring a concrete floor as each level is completed.  
         [0005]     As a result of this specialized approach, there are many utilities installation approaches that are radically different in the commercial construction environment as compared to the residential construction environment. A particular distinction exists between residential electrical systems and commercial electrical systems. While in a residential system, electrical wiring passes from floor-to-floor many times through wall studs, floor joists and ceiling rafters, when in the commercial building the concrete flooring prevents this approach.  
         [0006]     When electrical wiring passes from floor-to-floor in a commercial building, it generally rises vertically through a penetration into the concrete floor of the floor above. The wiring then is rerouted to the perimeter of the floor so that it might gain access to exterior walls and/or junction boxes located elsewhere in the building. This approach is used because typically electrical wiring comes from the outer walls towards the center rather than coming up through the floor for use in the center of the floor. This permits the greatest flexibility in moving nonstructural walls within the commercial space.  
         [0007]     In the past when transitioning from a vertical conduit riser into a conduit lateral housed within a concrete floor, there has been no off-the-shelf product available. The problem is that the vertical conduit is typically snap-on or threaded metallic conduit in order to comply with typical electrical building codes, when the conduit passes through concrete it is generally of a non-metallic type.  
         [0008]     In order to interconnect the non-metallic horizontal lateral and the metallic vertical riser, the electrician will typically be required to modify some existing metallic conduit connector because there previously has been none suited for this particular application. The typical off-the-shelf elbow does not provide the non-metallic solvent or slip-fitting at one end while providing the threaded connection for interfacing with metallic conduit at the other end. Furthermore, the bend radius of a typical conduit elbow tends to be greater than is acceptable for encasing in a thin concrete floor.  
         [0009]     What is needed then is a non-metallic low-clearance elbow that provides a transition from metallic conduit to non-metallic conduit without need for further modification.  
       SUMMARY OF THE INVENTION  
       [0010]     In light of the aforementioned problems associated with the prior devices, it is an object of the present invention to provide a Non-metallic Elbow Conduit Transition Fitting. The fitting should be specifically suited to interconnect vertical electrical conduit runs and horizontal electrical conduit runs in commercial construction environments. The fitting should be suitable for immersion within poured concrete floors used in commercial building construction. The fitting should be designed to threadedly engage a vertical run of EMT (metallic) conduit with a horizontal run of nonmetallic (e.g. PVC) conduit. Another important aspect of the fitting is that it must have a short sweep angle bend so that it is adequately buried within a concrete floor made from 6 inches of concrete.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     The objects and features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages, may best be understood by reference to the following description, taken in connection with the accompanying drawings, of which:  
         [0012]      FIG. 1  is a perspective view of a preferred embodiment of the transition fitting of the present invention;  
         [0013]      FIG. 2  is a side view of the fitting of  FIG. 1 ;  
         [0014]      FIGS. 3A and 3B  are bottom and top views, respectively, of the fitting of  FIGS. 1 and 2 ;  
         [0015]      FIG. 4  is an end view of the fitting of  FIGS. 1-3 ;  
         [0016]      FIG. 5  is a cutaway side view of the fitting of  FIGS. 1-4 ; and  
         [0017]      FIGS. 6A and 6B  are cutaway side views depicting the usage pattern for the fitting of  FIGS. 1-5 .  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]     The following description is provided to enable any person skilled in the art to make and use the invention and sets forth the best modes contemplated by the inventor of carrying out his invention. Various modifications, however, will remain readily apparent to those skilled in the art, since the generic principles of the present invention have been defined herein specifically to provide a Non-metallic Elbow Conduit Transition Fitting.  
         [0019]     The present invention can best be understood by initial consideration of  FIG. 1 .  FIG. 1  is a perspective view of the preferred embodiment of the non-metallic elbow conduit transition fitting  10  of the present invention. The fitting  10  is defined by a flat base  12  and an elbow extending upwardly there from. The elbow has a lower first end  14  and an upper second end  16  at a right angle to it. The first end  14  has a threaded socket which is suited for threaded engagement with conventional steel conduit such as EMT. The second end  16  is defined by a slip socket  20  which is designed to provide a convenient solvent conduit connection such as for ENT conduit. The upright portion of the elbow  10  is stabilized by a web  22  interconnecting the base  12  and the second end  16 . The web  22  is essentially a strengthening fin to provide stiffness and stability from the non-metallic material from which the fitting  10  is made. The base  12  is further defined by a plurality of fastener apertures  24  formed in it. The faster apertures  24  are provided so that the fitting  10  can be attached to the metallic sub-floor in the desired locations. Once installed then the conduit can be connected to the fittings first and second ends,  14  and  16  respectively.  
         [0020]     The portion of the fitting  10  comprising the first end  14  defines a first central axis  19  that is at the center of the first end  14  and is oriented longitudinally thereto. The portion of the fitting  10  comprising the second end  16  defines a second central axis  21  that is at the center of the second end  16  and is oriented longitudinally thereto. As depicted, the first axis  19  is perpendicular relative to the second axis  21 . If we now turn to  FIG. 2 , we can further examine the fitting  10  of the present invention.  
         [0021]      FIG. 2  is a side view of the fitting of  FIG. 1 . As shown here, the threaded socket  18  of the first end  14  is accessed through a hole formed in the bottom of the base  12 . The first end  14  and second end  16  are interconnected by a tubular center section  26 . As should be apparent from the drawing, the height H which is the distance between the top of the base and the center of the slip socket  20  is less than the length L which is the distance from the face of the second end  16  to the center of the first end  14 . What this means is that the fitting  10  has a low profile. This low profile is specifically designed into the fitting  10  so that it will be well below the top surface of the typical poured concrete floor used in commercial high rise buildings. One should also note that the web  22  extends upwardly from the base  12  to the tubular center section  26  adjacent to the second end  16 . If we now turn to  FIGS. 3A and 3B  we can further examine this unique device.  
         [0022]      FIGS. 3A and 3B  are bottom and top views, respectively, of the fitting of  FIGS. 1 and 2 .  FIG. 3A  depicts the bottom view of the fitting  10  of the present invention. The upper end of the fitting is defined by a collar  30 B which is enlarged as compared to the tubular center section. An internal bore  28  is formed in between the first end and the second end. Also shown here are the three fastening apertures  24  that are available for the installation electrician to attach the fitting  10  to the concrete sub-floor prior to running wiring and interconnecting conduit. The base  12  as shown here has a flanged portion surrounding the outer side of the first end. It further has an elongated tapered portion extending towards the second end from the first end. This enlarged flat shape provides supreme stability for the fitting during the installation process.  FIG. 3B  depicts the tubular center section  26  as it interconnects the first end  14  and the second end  16 . If we now turn to  FIG. 4 , we can continue to examine this device.  
         [0023]      FIG. 4  is an end view of the fitting of  FIGS. 1-3 . As shown here, the internal bore  28  executes a right-angle turn within the fitting from the bottom to where it exits at the second end  16 . The first end  14  is defined by an enlarged collar  30 A. The collars  30 A and  30 B have an outer profile that is wider than the tubular center section. This is for two reasons: first is because the internal bore  28  is enlarged in these portions to accept the conduit either threadedly engaged or glued in place inside of the collars  30 A and  30 B; second, the wall thickness at the collars  30 A and  30 B is thicker than at the tubular center section in order to provide additional structural strength and prevent breakage by inadvertently jostling the conduit connected to the fitting at these points. If we now turn to  FIG. 5 , we can see the internal profile of the fitting of the present invention.  
         [0024]      FIG. 5  is a cutaway side view of the fitting of  FIGS. 1-4 . As shown here the tubular center section  23  has a gentle curve to it that is shorter than it is long. Again, this is provided to leave ample space above the fitting for concrete to prevent the concrete floor from being too thin in spots over the conduit fitting  10 . The threaded socket  18  is defined by a plurality of threads formed within it. These threads are configured to accept the standard EMT conduit fitting threaded therein. The slip socket  20  is sized to allow non-metallic, such as PVC, piping to be glued into it. The web  22  is a solid piece of material that again provides a fairly rigid structural brace for the upper portion of the fitting  10 . If we finally turn to  FIGS. 6A and 6B , we can examine how this fitting is used.  
         [0025]      FIGS. 6A and 6B  are cutaway side views depicting the usage pattern for the fitting of  FIGS. 1-5 . In  FIG. 6A , we can see the typical commercial high rise floor section prior to the concrete floor being poured. Here the floor substrate plating  40 , which is generally steel plate, is in place and attached to the structural steel framing of the building (not shown). A hole has been cut through the plating where a metallic conduit riser  46  will be penetrating from the bottom floor to the top floor. The fitting  10  is simply attached to the plating  40  such that the first end  14  is centered on the hole formed in the plating  40 . The metallic conduit riser  46  is threaded into the first end  14  and the fitting  10  is attached using screws or bolts inserted through the attachment apertures formed in the base of the fitting. The non-metallic conduit lateral  50  is glued into the second end  16  and extended until it passes through the concrete form  42 A which in this depiction forms the left side of the concrete floor. The forms  42 A and  42 B have a height that will ultimately define the finished floor line  44 . The wiring  48  is typically threaded through the metallic riser  46  and the non-metallic lateral  50  while the conduit is being attached to the fitting  10 . This is typically the easiest way to thread the wiring through the conduit.  
         [0026]     As can be imagined, this situation will be repeated several times throughout a particular floor of a commercial high rise building until all of the wiring that needs to pass from one floor to the next is complete. Once all of the wiring and other utilities are installed, then concrete is poured into the forms  42 . Once the concrete is cured, the forms  42  are removed and the solid concrete floor of  FIG. 6B  is the result. As can be seen, the wiring  48  now passes upwardly from the bottom floor into the particular concrete floor shown here and then out the side where it can transition to a junction box or more conduit.  
         [0027]     Those skilled in the art will appreciate that various adaptations and modifications of the just-described preferred embodiment can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.