Abstract:
A rain-tight fitting for connecting electrical metal tubing to an electrical box in a rain-tight fit. The rain-tight fitting includes a fitting body having a leading end adapted to connect to the knockout of an electrical box and a trailing end adapted to create a rain-tight fit with an end of electrical metal tubing (EMT). One or more sleeves are seated within a trailing bore of the fitting body and are held in place by a fastener. A necked-down wall portion on the sleeve contacts the outer periphery of the EMT as it is inserted into the trailing end of the fitting. After the EMT is fully inserted within the trailing end of the fitting, the fastener is tightened to drive the fastener against the outer periphery of the EMT, thereby providing a grounding path between the fitting, the electrical box, and the EMT.

Description:
This application claims priority to provisional U.S. Application No. 62/417,604, filed Nov. 4, 2016, and claims priority to provisional U.S. Application No. 62/287,122, filed Jan. 26, 2016, the contents of which are herein incorporated by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to connection of electrical tubing to an electrical box and more specifically to an electrical fitting for connection of electrical metal tubing (EMT) to an electrical box. 
     BACKGROUND 
     In the wiring of residential or commercial structures, electrical conduit may be used to protect and route electrical wiring in the interior or on the exterior of the structures. Electrical conduit may be rigid or flexible. Rigid metallic conduit (RMC) may be constructed of galvanized steel tubing, with a tubing wall thickness that is thick enough to allow it to be threaded. It is typically used in commercial and industrial construction. An alternative to RMC is electrical metallic tubing (EMT), which is typically constructed of steel, has a thinner wall than RMC, is not threaded, and is commonly used instead of RMC as it is less costly and lighter than RMC. 
     Electrical fittings are typically used to connect an end of EMT to an electrical box. Varying numbers, sizes, and types of conductors can then be pulled through the EMT to provide power to the connected electrical box and any equipment connected to the box. Although EMT provides very good protection to enclosed conductors from moisture, it is critical in some applications, such as outdoor electrical boxes or panels, to provide a rain-tight connection of the EMT to the box in order to prevent moisture and rain from entering the electrical box. 
     Accordingly, what is needed is an electrical fitting and method that enables securing electrical metal tubing to an electrical box in a rain-tight fit. 
     BRIEF SUMMARY OF THE INVENTION 
     The current invention is a rain-tight fitting for connecting electrical metal tubing to an electrical box. The rain-tight fitting includes a fitting body having a leading end adapted to connect to the knockout of an electrical box and a trailing end adapted to create a rain-tight fit with an end of electrical metal tubing (EMT). One or more sleeves are seated within a trailing bore of the fitting body and are held in place by a fastener. A necked-down wall portion on the sleeve contacts the outer periphery of the EMT as it is inserted into the trailing end of the fitting. After the EMT is fully inserted within the trailing end of the fitting, the fastener is tightened to drive the fastener against the outer periphery of the EMT, thereby providing a grounding path between the fitting, the electrical box, and the EMT. The installed fitting at the leading end and trailing end effects a rain-tight fit between the fitting, the electrical box, and the EMT. 
     Objects and Advantages 
     A first object of the current invention is to provide an electrical fitting that provides rain-tight connection of electrical metal tubing (EMT) to an electrical box or panel. 
     A second object of the invention is to provide an electrical fitting that establishes a grounding path between electrical metal tubing (EMT) and an electrical box or panel. 
     A further object of the invention is to provide an electrical fitting that establishes a rain-tight fit between the fitting at the leading end and trailing end, the electrical box, and an inserted end of electrical metal tubing. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
       Reference is made herein to the accompanying drawings, which are not necessarily drawn to scale, and wherein: 
         FIG. 1  is an isometric view, as viewed from the trailing end, of a rain tight fitting for electrical metal tubing (EMT) in accordance with embodiments of the invention. 
         FIG. 2  is a side view of a fitting body that forms a portion of the rain tight fitting of  FIG. 1 . 
         FIG. 3  is a top view of the fitting body. 
         FIG. 4  is a sectional view of the fitting body taken along line  4 - 4  of  FIG. 3 . 
         FIG. 5  is a sectional view of the fitting body taken along line  5 - 5  of  FIG. 2 . 
         FIG. 6  is a sectional view of the fitting body taken along line  6 - 6  of  FIG. 2 . 
         FIG. 7  is a top view of a sleeve that forms a portion of the rain tight fitting of  FIG. 1 . 
         FIG. 8  is an isometric view of the sleeve. 
         FIG. 9  is a sectional view of the sleeve taken along line  9 - 9  of  FIG. 7 . 
         FIG. 10  is an end view of the sleeve as viewed from the right side of  FIG. 7 . 
         FIG. 11  is an exploded side view of the rain tight fitting according to the present invention. 
         FIG. 12  is a top view of the rain tight fitting. 
         FIG. 13  is a side view of the rain tight fitting. 
         FIG. 14  is a sectional view of the rain tight fitting assembly taken along line  14 - 14  of  FIG. 12  and connected to the wall of an electrical box. 
         FIG. 15  is an isometric view, as viewed from the leading end, of the fitting body. 
         FIG. 16  is an isometric view, as viewed from the trailing end, of the fitting body. 
         FIG. 17  is a sectional view of the rain tight fitting assembly taken along line  14 - 14  of  FIG. 12  and connected to the wall of an electrical box and with electrical metal tubing connected to the trailing end. 
         FIG. 18  is a side view of an alternate embodiment of the sleeve. 
         FIG. 19  is a sectional view of the sleeve taken along line  19 - 19  of  FIG. 18 . 
         FIG. 20  is an isometric view of the alternate embodiment of the sleeve. 
         FIG. 21  is an exploded isometric view of a second embodiment of the rain tight fitting according to the present invention. 
         FIG. 21  is an exploded isometric view of a second embodiment of the rain tight fitting assembly including the sleeve of  FIG. 20 . 
         FIG. 22  is an exploded side view of a third and preferred embodiment of a rain tight fitting including an inner and outer sleeve for achieving a rain-tight fit of EMT to an electrical box. 
         FIG. 23  is a side view of an outer sleeve that forms a portion of the rain tight fitting of  FIG. 22 . 
         FIG. 24  is an end view of the outer sleeve. 
         FIG. 25  is a sectional view of the outer sleeve taken along line  25 - 25  of  FIG. 22 . 
         FIG. 26  is an isometric view of the outer sleeve. 
         FIG. 27  is a side view of an inner sleeve that forms a portion of the rain tight fitting of  FIG. 22 . 
         FIG. 28  is a sectional view of the inner sleeve taken along line  28 - 28  of  FIG. 27 . 
         FIG. 29  is an isometric view of the inner sleeve. 
         FIG. 30  is an exploded isometric view of the rain tight fitting of  FIG. 22 . 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIG. 1 , the present invention is a rain tight fitting for electrical metal tubing  20 . The rain tight fitting  20  includes a tubular fitting body  22  with a leading end  24 , a trailing end  26  with a trailing bore  28  therein, and a nose portion  30  at the leading end  24 . A washer  32  and a locknut  34  are included on the nose portion  30 . A sleeve  36  is fitted within the trailing bore  28  of the fitting body  22  and a fastener  38  is engaged within a bore  40  at the trailing end  26  of the fitting body. The bore  40  at trailing end  26  extends through the tubular wall  64  defining the trailing bore  28 , the bore  40  being substantially at a right angle with respect to the central axis  41  of the fitting. 
     Referring to  FIGS. 2 and 3 , the fitting body  22  includes a main body portion  42  including an end flange  44  at the trailing end  26  and a mid-body flange  46  between the main body portion  42  and the nose  30 . 
     With reference to  FIGS. 4-6  one or more ribs  48  extending longitudinally along the fitting body  22  and extend substantially from the mid-body flange  46  to the end flange  44 . Adjacent the mid-body flange  46  is a trough portion  50  (see  FIG. 4 ), that is narrower than the main body portion  42  at the trailing end  26 . The ribs  48  include wider rib sections  52  at the trough  50  (see  FIG. 5 ) and narrower rib sections  54  at the trailing end  26  (see  FIG. 6 ). A boss  55  extends outward from a raised area  56  of the fitting body  22  at the trailing end  26  and includes the bore  40  therein. The bore  40  is threaded to accept engagement by fastener  38 . In addition to the trailing bore  28 , the fitting body  22  includes a mid-body bore  60 , and a leading bore  62 . The fitting body  22  further includes a tubular wall  64  as shown in  FIG. 5 . As shown in  FIG. 5 , the ribs  48  are preferably spaced at an angle θ around the outer periphery of the tubular fitting body  22 . Most preferably, the spacing angle θ of the ribs  48  around the fitting body is 60 degrees. 
     Referring to  FIGS. 7-10 , tubular sleeve  36  includes a leading end  66  and a trailing end  68 . The trailing end  68  of sleeve includes a flange  70  at the trailing end  68  and an aperture  72  extending laterally through the sleeve  36  adjacent the flange  70 . As shown in  FIG. 9 , sleeve  36  includes a main body portion  74  having a first inner diameter D 1  and a leading body portion  76  that is turned inward toward the central axis  78 . Sleeve  36  thus includes a necked-down wall  80  that is turned inward to a second inner diameter D 2  at the leading end  66 . Aperture  72  extends through the wall  83  of the sleeve. The flange  70  of the sleeve includes a notch  84  in longitudinal alignment along said sleeve with the aperture  72 . As shown in  FIG. 8 , a bridge  85  extends over the notch  84 . A tab  86  extends outward of the flange  70 . Tab  86  is preferably located 180° opposite aperture  72  on flange  70 . As shown in  FIG. 9 , flange  70  and tab  86  include a leading face  88 . With reference to  FIG. 11 , the rain tight fitting  20  is an assembly of the fitting body  22 , the washer  32 , locknut  34  and the sleeve  36  (see  FIG. 1 ). 
     Referring to  FIG. 14 , when tightened upon nose  30 , washer  32  and locknut  34  function to create a rain tight fit of the leading end  24  against a panel or electrical box  90  and further function to electrically ground the fitting to the box or panel. Fitting body  22  includes an annular seat  93  at the leading end of trailing bore  28 , the annular seat  93  functioning to abut and stop the travel of sleeve  36  as it is inserted within the trailing bore  28  at the trailing end  26  of the fitting body. Fitting body  22  further includes an annular tubing seat  96  for arresting the forward travel of the EMT or tubing as it is inserted within the sleeve  36  at the trailing end of the fitting. 
     As shown in  FIG. 17 , fastener  38 , when tightened within bore  40  of fitting and through aperture  72  of sleeve  36 , the fastener will make firm metal-to-metal contact with electrical metal tubing  92  that is inserted within the trailing bore  28  and will effectively ground the EMT  92  to the fitting  20 . Further, the necked-down wall  80  of sleeve  36  will form a rain tight fit between the EMT and the fitting. At the leading end  24  of the fitting, the locknut  34  is tightened to compress the washer  32  against the electrical box to create a rain-tight fit of the fitting to the electrical box, with washer  32  in a rain-tight fit against the inner wall of the electrical box and mid-body flange  46  in a rain-tight fit against the outer wall of the electrical box  90 . 
     Referring to  FIGS. 15 and 16 , nose portion  30  of fitting body  22  includes truncated threads  94  on opposing sides of the nose. The truncated threads  94  function to prevent flash when the fitting body  22  is die cast of metal. As shown in  FIG. 16 , the trailing end  26  of fitting body  22  includes an annular recessed area  95  within the end flange  44  for nesting of the flange  70  (see  FIG. 8 ) of sleeve  36  when the sleeve is inserted within the trailing bore  28  of the fitting body  22 . 
     With reference to  FIGS. 18-20 , there is shown an alternate embodiment of the sleeve  101  according to the present invention. Similar to the first embodiment, sleeve  101  includes a leading end  66 , a trailing end  68  with a flange  70 , a central axis  78 , a main body portion  74 , and a leading body portion  76  that is turned inward toward the central axis  78 . Sleeve  101  includes apertures  103  opposed at 180° across the trailing end  68  of the sleeve main body  74 . The apertures  103  are slots that extend from the trailing end  68 . Thus flange  70  includes a notch  105  in two places and flange is a discontinuous flange that includes, as shown in  FIG. 20 , a first flange portion  70 A and a second flange portion  70 B opposed at 180° across the trailing end  68  of the sleeve  101 . 
     With reference to  FIG. 21 , the second embodiment of the rain tight fitting assembly  110  incorporates the sleeve of  FIGS. 18-20  into the trailing bore of the connector body  22 . Sleeve  101  can be rotated 180°, in either of two orientations with respect to the connector body  22 , to align with screw  38  and thus provides for simpler assembly of the rain tight fitting. 
     Referring to  FIG. 22 , a third and preferred embodiment of the rain tight fitting  200  for connection of EMT to an electrical box includes the fitting body  22  with threaded nose portion  30  and a washer  32  and locknut  34  on the leading end  24  for connecting the leading end of the fitting to an electrical box (not shown). To provide an improved rain-tight fit and improved locking of an inserted EMT into the trailing end of the fitting  200 , the third embodiment of the rain tight fitting  200  includes a tubular inner sleeve  202  to provide the rain-tight functionality and a tubular outer sleeve  204  to provide a more secure means of locking the EMT to the fitting. The inner sleeve  202  is preferably constructed of flexible material and is compressible. The compressible inner sleeve  202  is preferably constructed of plastic. Compressible inner sleeve  202  includes a leading end  66 , a trailing end  68  and a flange  70  at the trailing end  68 . 
     With reference to  FIGS. 23-26 , tubular outer sleeve  204  includes a sleeve body  206  having a leading end  208  and a trailing end  210 . Both ends of the body  206  include a chamfer  212  on the inner and outer edges. An aperture  214  extends through the body  206  from the outer circumference  215  of the ring and is perpendicular to the axial center  216  of the sleeve body. The outer sleeve  204  is a rigid sleeve, preferably constructed of steel, zinc, or zinc alloy. 
     Referring to  FIGS. 27-29 , tubular inner sleeve  202  includes a sleeve body  218  having a leading end  220 , a trailing end  222 , and an end flange  224  on the trailing end. An outer nose  226  having a reduced diameter is included on the leading end  220 . End flange  224  includes a front abutment surface  228 . The inner wall  230  of the sleeve body  218  includes a leading body portion  232  that is of smaller diameter than the trailing inner portion  234 . Leading body portion  232  gradually slopes inward from a mid-point  236  of the sleeve body  206  to the leading end  220 . 
     To operate the invention, as shown in  FIG. 30 , the leading end  24  of the rain tight fitting  200  may be connected to an electrical box using the washer  32  and locknut  34 . At the trailing end  26  of the fitting, compressible inner sleeve  202  and rigid outer sleeve  204  may be loosely assembled with fitting body using screw  38 . EMT may then be inserted within the trailing bore  28  of the fitting. The inserted end of the EMT is contacted by the gradually sloping leading body portion  232  of compressible sleeve  202  and forms a snug, rain-tight fit around the inserted end of the EMT. Screw  38  is then be tightened within threaded bore  40  of fitting  200  and through aperture  214  of rigid outer sleeve  204  until making firm contact with the EMT, securely locking the EMT to the trailing end of the fitting and effectively grounding the EMT to the fitting  200 . The rigid outer sleeve  204  will bear against the compressible inner sleeve  202  and force the leading wall  80  of sleeve  202  against the abutment surface  65  of the fitting, thereby further forming a rain tight fit between the EMT and the fitting. 
     The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.