Abstract:
The disclosure herein provides for an electrical device housing that includes a protrusion, or bump, for securing a electrical ground wire to the housing. The housing may include a plurality of walls defining an interior space for housing the electrical device, including at least one side wall and a back wall orthogonal to the at least one side wall. The back wall may include an opening configured to allow access to the interior space of the housing. A protrusion may extend forward from the back wall into the interior space of the housing, and may include a mounting surface offset from the back wall in a direction toward the interior space of the housing, and a hole formed in the mounting surface for receiving a fastener to secure a ground wire to the housing.

Description:
RELATED APPLICATION 
     The present application claims priority to and incorporates herein in its entirety U.S. Provisional Patent Application Ser. No. 61/384,043, titled “Open Back Box With Ground Screw Bump,” filed on Sep. 17, 2010. 
    
    
     TECHNICAL FIELD 
     The present application relates generally to an electrical box, housing, can, or receptacle having a bump or protrusion configured to accommodate a ground screw. 
     BACKGROUND 
     An electrical housing, receptacle, housing, or box may have a removable back panel or cover (also known as an “open back” box). When installing a switch, outlet, or other electrical device in an open back box, a ground wire (for example, 10, 12, or 14 AWG copper wire) is often connected from the device (for example, a switch) to the box. Generally, the wire is wrapped around a screw. The ground screw, according to regulations, cannot be used for any purpose other than grounding. 
     Some conventional boxes come pre-assembled, which typically requires the electrician to disassemble the box in order to complete the wiring. To address this problem, electricians used an “extension ring,” which includes an open back and also means to close the opening, to gain access to the box from the back in order to complete the wiring connections. However, such technique did not address the problem of how to complete the grounding requirements of the national electrical Code (NEC), which requires the ground wire to be attached to the box without leaving any extraneous openings, and without attaching the ground wire to the removable back panel. 
     In another conventional method, a grounding clip is secured to a side wall of the box. The grounding clip is generally a U-shaped metal clip that applies pressure from opposing ends to attempt to remain secure along the side wall. A ground wire is fed to the grounding clip and a tool, such as a screwdriver, can be used to force the grounding clip and wire onto an edge of a side wall of the box. The grounding clip and wire are then compressed with the tool to avoid interfering with the device (for example, switch) being installed in the box. Due to the pressure exerted on the clip, installation of a grounding clip can be challenging. Also, grounding clips can only be used for termination of a wire, not connecting two ground wires. Additionally, grounding clips may disengage from the box, may be lost or dropped during installation, and are an additional part that must be added to the box. 
     SUMMARY 
     Some embodiments of the invention provide a ground screw hole in a raised protrusion or bump in the back of the box. The raised bump may allow the screw to be installed without protruding beyond the back of the box. During a preassembly process the ground wire can be attached to the box using the ground screw hole provided in the raised bump. Further, in some embodiments multiport wire connectors are supplied, allowing the electrician to simply plug in the circuit ground wire to the connector, thus completing the circuit wiring, and then attach the back panel to complete the enclosure. 
     In one aspect of the invention, a housing for electrical connections and/or an electrical device includes a plurality of walls defining an interior space for housing an electrical device. The plurality of walls include at least one side wall and a back wall orthogonal to the at least one side wall. The back wall includes an opening configured to allow access to the interior space of the housing through a rear side of the back wall. A protrusion extends forward from the back wall into the interior space of the housing, and includes a mounting surface offset from the back wall in a direction toward the interior space of the housing, and a hole formed in the mounting surface, the hole configured to receive a fastener for securing a wire. 
     In another aspect of the invention, a method for grounding an electrical device in an electrical device housing is provided. A ground wire is secured to an electrical device housing by wrapping a ground wire around a ground screw; inserting the ground screw in a hole formed in a protrusion that extends forward from a back wall of the housing into the interior space of the housing; and tightening the ground screw to secure the ground wire. An electrical device is secured to the housing, and electrically connected to the ground wire. 
     In another aspect of the invention, an electrical assembly includes a housing and an electrical device. The housing includes a plurality of walls defining an interior space, the plurality of walls including at least one side wall and a back wall orthogonal to the at least one side wall. The back wall includes an opening configured to allow access to the interior space of the housing through a rear side of the back wall. A protrusion extends forward from the back wall into the interior space of the housing, and includes a mounting surface offset from the back wall in a direction toward the interior space of the housing, and a hole formed in the mounting surface. A ground wire is secured to the housing by a ground screw inserted through the hole in the mounting surface of the protrusion in the housing, and an electrical device mounted in the interior space of the housing is electrically connected to the ground wire. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view of an open back electrical box having a ground screw bump, according to an exemplary embodiment. 
         FIG. 1B  is a frontal view of the electrical box of  FIG. 1A , according to an exemplary embodiment. 
         FIG. 1C  is side view of the electrical box of  FIG. 1A , according to an exemplary embodiment. 
         FIG. 1D  is another side view of the electrical box of  FIG. 1A , according to an exemplary embodiment. 
         FIG. 1E  is a side cross-sectional view of the electrical box of  FIG. 1A , taken along section  1 E- 1 E, according to an exemplary embodiment. 
         FIG. 1F  is a perspective view of an open back electrical box having an alternative ground screw bump, according to an exemplary embodiment. 
         FIG. 2A  is a perspective view of an electrical box assembly, showing the electrical box of  FIG. 1A  coupled to a ground screw and wire, according to an exemplary embodiment. 
         FIG. 2B  is a side cross-sectional view of the electrical box assembly of  FIG. 2A , taken along section  2 B- 2 B, according to an exemplary embodiment. 
         FIG. 3A  is a perspective view of another open back electrical box having a ground screw bump, according to an exemplary embodiment. 
         FIG. 3B  is a frontal view of the electrical box of  FIG. 3A , according to an exemplary embodiment. 
         FIG. 3C  is side view of the electrical box of  FIG. 3A , according to an exemplary embodiment. 
         FIG. 3D  is another side view of the electrical box of  FIG. 3A , according to an exemplary embodiment. 
         FIG. 3E  is a side cross-sectional view of the electrical box of  FIG. 3A , taken along section  3 E- 3 E, according to an exemplary embodiment. 
         FIG. 4A  is a perspective view of another electrical box assembly, showing the electrical box of  FIG. 3A  coupled to a ground screw and wire, according to an exemplary embodiment. 
         FIG. 4B  is a side cross-sectional view of the electrical box assembly of  FIG. 4A , taken along section  4 B- 4 B, according to an exemplary embodiment. 
         FIG. 5A  is a perspective view of yet another open back electrical box having a ground screw bump, according to an exemplary embodiment. 
         FIG. 5B  is a frontal view of the electrical box of  FIG. 5A , according to an exemplary embodiment. 
         FIG. 5C  is side view of the electrical box of  FIG. 5A , according to an exemplary embodiment. 
         FIG. 5D  is another side view of the electrical box of  FIG. 5A , according to an exemplary embodiment. 
         FIG. 5E  is a side cross-sectional view of the electrical box of  FIG. 5A , taken along section  5 E- 5 E, according to an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The invention may be better understood by reading the following description of non-limitative, exemplary embodiments with reference to the attached drawings wherein like parts of each of the figures are identified by the same reference characters. 
     The invention relates to an open back electrical box having a ground screw bump in a portion of the back wall. 
     An electrical housing, receptacle, housing, or box can be made of metal (for example, steel), plastic (for example, PVC), or other material and can provide the structure for an electrical switch (for example, a light switch), outlet, or other connection or use. For example, an electrical box can be an outlet box, a switchbox, a junction box, a ceiling box, a ceiling fan box, or other housing known to one of ordinary skill in the art. The exemplary embodiments describe a box, but the box is not intended to be limited only to a box for housing one light switch, outlet, junction or other connection. Instead, the box may house multiple (in other words, a “gang” of) switches. The box can be any type, include any number of outlets or switches, or provide any other use known to one of ordinary skill in the art. 
     Referring to  FIGS. 1A-1E , various views of an open back electrical box having a ground screw bump according to an exemplary embodiment are shown.  FIG. 1A  shows a perspective view of an exemplary open back electrical box  100 ,  FIG. 1B  shows a frontal view of the electrical box  100 ,  FIG. 1C  shows a side view of the electrical box  100 ,  FIG. 1D  shows another side view of the electrical box  100 , and  FIG. 1E  shows a side cross-sectional view of the electrical box  100 , taken along section  1 E- 1 E shown in  FIG. 1A . 
     The box  100  has four side walls  105 A,  105 B,  105 C,  105 D, collectively referred to as side walls  105 , arranged in a rectangular shape. The box  100  also has a back wall  110  orthogonal to the side walls  105 . The back wall  110  has a flat solid portion  115  in a corner therein, and an opening  120 . The solid portion  115  includes a raised ground screw protrusion or bump  125  formed therein. In other embodiments, ground screw bump  125  may be formed separately from and coupled to solid portion  115 . In still other embodiments, ground screw bump  125  and solid portion  115  may be formed separate from back wall  110 , and then coupled to back wall  110 . 
     Ground screw bump  125  may have any suitable shape and size. For example, in the example embodiment of  FIGS. 1A-1E , bump  125  has a tapered, generally conical shape. In other embodiments, bump  125  may have a generally cylindrical shape projecting forward from the back wall  110 , or a generally rectangular box-shape (e.g., a parallelepiped) projecting forward from the back wall  110 , or any other suitable shape. 
     The ground screw bump  125  includes a threaded hole  125 A sized to receive a ground screw  205  ( FIGS. 2A-2B ) therein. As shown, the hole  125 A of the ground screw bump  125  is formed in a mounting surface  125 C that surrounds the hole  125 A. The mounting surface  125 C including the hole  125 A may be recessed from a top surface  125 B of the ground screw bump  125 , or alternatively the hole  125 A may be flush with the top surface  125 B of the ground screw bump  125 . The mounting surface  125 C may be offset from the back wall  110  in a forward direction (i.e., towards the front of the box  100 ). In the exemplary embodiment shown in  FIGS. 1A-1E , mounting surface  125 C is located in a plane that is parallel to and offset from the back wall  110  in the forward direction, such that when the ground screw  205  is placed therein, the length of the ground screw  205  does not extend beyond the back wall  110 . Thus, the distance by which the mounting surface  125 C is offset from the back wall  110  may be selected based on the anticipated length of the ground screw  205  to be received in hole  125 A (e.g., a ⅜ inch screw). In certain exemplary embodiments, the mounting surface  125 C is located in a plane at least about ⅛ inch forward of the back wall  110 . In some embodiments, the mounting surface  125 C is located in a plane at least about ¼ inch forward of the back wall  110 . In other embodiments, the mounting surface  125 C is located in a plane at least about ⅜ inch forward of the back wall  110 . In other embodiments, as shown in  FIG. 1F  the mounting surface  125 C including the hole  125 A may define a plane that is oblique (i.e., non-parallel) to the back wall  110 . 
     The ground screw bump  125  can be formed or shaped during manufacturing of box  100 , e.g., by molding or pressing, or can be added or coupled to box  100  after box  100  has been formed. In some embodiments, ground screw bump  125  meets appropriate and necessary requirements of Underwriters Laboratories (UL) and the National Electrical Code (NEC). 
     A rear cover  122  can be secured to a back wall  110  of the box  100  using fasteners through holes  110 A. A front side of the assembled box  100  remains open to accommodate a device  121 , such as a switch or an outlet. Side walls  105  can comprise one or more knockouts  135 . It is understood that knockouts  135  can be configured along side walls  105  to provide access to the interior of box  100 , but knockouts  135  are not intended to be limited to any particular configuration. 
     Referring to  FIGS. 2A-2B ,  FIG. 2A  shows a perspective view of an exemplary electrical box assembly  200 , and  FIG. 2B  shows a side cross-sectional view of the electrical box assembly  200 , taken along section  2 B- 2 B shown in  FIG. 2A . The electrical box assembly  200  has a ground screw  205  positioned within the hole  125 A of the ground screw bump  125  of the electrical box  100 . A ground wire  210 , for example a copper wire, can be wrapped around the ground screw  205 . The ground screw  205  can then be tightened with a screwdriver or other tool to secure the ground wire  210 . 
     Referring to  FIGS. 3A-3E , various views of an open back electrical box having a ground screw bump according to another exemplary embodiment are shown.  FIG. 3A  shows a perspective view of an exemplary open back electrical box  300 ,  FIG. 3B  shows a frontal view of the electrical box  300 ,  FIG. 3C  shows a side view of the electrical box  300 ,  FIG. 3D  shows another side view of the electrical box  300 , and  FIG. 3E  shows a side cross-sectional view of the electrical box  300 , taken along section  3 E- 3 E shown in  FIG. 3A . The box  300  is similar to the box  100  ( FIGS. 1A-1E ), but with different dimensions of the side walls of the box. All other components of the box  300  may be similar to the box  100  discussed above with respect to  FIGS. 1A-1B , including the ground screw bump  125 . The box  300  has four side walls  305 A,  305 B,  305 C,  305 D, collectively referred to as side walls  305 , arranged in a rectangular shape. The side walls  305  are wider than the side walls  105  ( FIGS. 1A-1E ), which provides a deeper cavity  315  than the box  100 , thereby providing an increased volume to allow for a greater number of conductors and/or other devices herein. 
     Referring to  FIGS. 4A-4B ,  FIG. 4A  shows a perspective view of an exemplary electrical box assembly  400 , and  FIG. 4B  shows a side cross-sectional view of the electrical box assembly  400 , taken along section  4 B- 4 B shown in  FIG. 4A . The electrical box assembly  400  has a ground screw  405  positioned within the hole  125 A of the ground screw bump  125  of the electrical box  300 . A ground wire  410 , for example a copper wire, can be wrapped around the ground screw  405 . The ground screw  405  can then be tightened with a screwdriver or other tool to secure the ground wire  410 . 
     Referring to  FIGS. 5A-5E , various views of an open back electrical box having a ground screw bump according to yet another exemplary embodiment are shown.  FIG. 5A  shows a perspective view of an exemplary open back electrical box  500 ,  FIG. 5B  shows a frontal view of the electrical box  500 ,  FIG. 5C  shows a side view of the electrical box  500 ,  FIG. 5D  shows another side view of the electrical box  500 , and  FIG. 5E  shows a side cross-sectional view of the electrical box  500 , taken along section  5 E- 5 E shown in  FIG. 5A . The box  500  is similar to the box  100  shown in  FIGS. 1A-1E , but with different dimensions of the side walls and the back wall of the box. All other components of the box  500  may be similar to the box  100  shown in  FIGS. 1A-1E , including the ground screw bump  125 . The box  500  has four side walls  505 A,  505 B,  505 C,  505 D, collectively referred to as side walls  305 , arranged in a rectangular shape. The box  500  also has a back wall  510  orthogonal to the side walls  505 . The side walls  505 A,  505 C are longer than the side walls  105 A,  105 C shown in  FIGS. 1A-1E , thereby providing an elongated rectangular-shaped gang box, which can accept the same types of devices as the boxes  100 ,  300 , as well as low voltage devices such as network ports, data ports, and coaxial connectors, for example. In certain embodiments, a low voltage partition can be used to separate standard voltage from low voltage. 
     Therefore, the present invention is well adapted to attain the ends and advantages mentioned, as well as those that are inherent therein. The particular embodiments disclosed herein are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those having ordinary skill in the art and having the benefit of the teachings herein. While numerous changes may be made by those having ordinary skill in the art, such changes are encompassed within the spirit and scope of this invention as defined by the appended claims. For example, while the ground screw bump has been shown to have a circular configuration, it is understood that the ground screw bump can be any shape, including oval and square. In addition, the electrical box can have a shape other than square or rectangular. Further, the opening in the back wall of the electrical box can have sharp edges, as opposed to curved edges as shown in the drawings. Furthermore, no limitations are intended to the details of construction or design herein shown. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present invention.