Abstract:
An electrical box assembly for providing a secure electrical enclosure on walls constructed with steel studs of two conventional sizes. The electrical box assembly includes an electrical box including captive fasteners on one sidewall and a bracket that is adjustable in length for attachment to the opposite sidewall. The adjustable length bracket may be used as is for bracing the opposite sidewall of the electrical box for a wide stud. A bend line is provided on the bracket for enabling simple reduction of its length for bracing the electrical box against a narrow stud. The electrical box assembly provides an electrical box that is fastened directly to a stud on one sidewall and braced against the drywall at both ends of the box on the opposite sidewall to securely hold the electrical box with respect to the wall.

Description:
FIELD OF THE INVENTION 
   This invention relates to assemblies for the mounting of electrical devices and specifically to an electrical box and adjustable bracket assembly that will provide a secure mounting box for an electrical device on a wall. 
   BACKGROUND OF THE INVENTION 
   Many commercial buildings have their frameworks constructed of steel. When the buildings are wired for electricity, electrical boxes are typically secured to the vertical steel studs that form a portion of the building&#39;s framework. In wiring a building having a steel framework, typically conventional electrical boxes are secured to the metal studs by driving fasteners through one side of the electrical box. 
   Although fastening one side of a conventional electrical box to a stud is a routine practice, one problem that arises with continued use of the electrical component, such as repeated connection and disconnection of an electrical plug to a duplex receptacle, is the loosening of the electrical box to the stud. This occurs as a result of the repetitive back and forth movement of the electrical box caused by installing and removing the plug. 
   Accordingly, there is a need for providing a more secure mounting for an electrical box that is secured to a metal stud. The device for providing a secure electrical box installation should be of simple construction, easy to apply, and should securely brace the electrical box so that it will not become loose with repetitive use. 
   SUMMARY OF THE INVENTION 
   The invention is an electrical box assembly for providing a secure electrical enclosure on walls constructed with steel studs of two conventional sizes. The electrical box assembly includes an electrical box including captive fasteners on one sidewall and a bracket that is adjustable in length for attachment to the opposite sidewall. The adjustable length bracket may be used as is for bracing the opposite sidewall of the electrical box for a wide stud. A bend line is provided on the bracket for enabling simple reduction of its length for bracing the electrical box against a narrow stud. The electrical box assembly provides an electrical box that is fastened directly to a stud on one sidewall and braced against the drywall at both ends of the box on the opposite sidewall to securely hold the electrical box with respect to the wall. 
   OBJECTS AND ADVANTAGES 
   A first object of the electrical box assembly of the present invention is to provide an electrical box that may be securely mounted to a wall constructed with metal studs. 
   A second object of the electrical box assembly of the present invention is to provide an electrical box assembly that includes captive fasteners held in a first sidewall of an electrical box for easy access by installers in securing the electrical box assembly to a wall stud. 
   A third object is to provide an electrical box that, on a sidewall opposite the captive fasteners, is braced against the inside surfaces of the surrounding drywall to prevent movement of the box with repeated use of an electrical component held therein. 
   A further object is to provide an electrical box assembly that can be secured fast within a wall constructed with either wide or narrow metal studs. 
   Another object of the present invention is to provide an electrical box assembly that includes an adjustable length bracket for bracing an electrical box within a wall. 
   Another object of the present invention is to provide an electrical box assembly containing a single bracket for use with walls constructed of either wide or narrow studs. 
   These and other objects and advantages of the present invention will be better understood by reading the following description along with reference to the drawings. 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a preferred embodiment of an electrical box assembly including an electrical box and an adjustable length bracket. 
       FIG. 2  is a front view of the electrical box portion of the electrical box assembly of  FIG. 1 . 
       FIG. 3  is a sectional view of the electrical box taken along line  3 - 3  of  FIG. 2 . 
       FIG. 4  is an elevation view of a main panel that forms a portion of the electrical box assembly of  FIG. 1 . 
       FIG. 5  is a side view of the main panel depicted in  FIG. 4 . 
       FIG. 6  is a top view of the main panel taken along line  6 - 6  of  FIG. 5 . 
       FIG. 7  is a bottom view of the main panel taken along line  7 - 7  of  FIG. 5 . 
       FIG. 8  is an elevation view of a left-side panel that forms a portion of the electrical box assembly of  FIG. 1 . 
       FIG. 9  is a front view of the left-side panel taken from line  9 - 9  of  FIG. 8 . 
       FIG. 10  is a sectional view of the left-side panel taken from line  10 - 10  of  FIG. 8 . 
       FIG. 11  is an elevation view of a right-side panel that forms a portion of the electrical box assembly of  FIG. 1 . 
       FIG. 12  is a sectional view of the right-side panel taken along line  12 - 12  of  FIG. 11 . 
       FIG. 13  is a plan view of a preferred embodiment of an adjustable length bracket that forms a portion of the electrical box assembly of  FIG. 1 . 
       FIG. 14  is a side view of the adjustable length bracket of  FIG. 13 . 
       FIG. 15  is a side view of the adjustable length bracket of  FIG. 13  after it has been adjusted to a smaller length according to a second embodiment of the present invention. 
       FIG. 16  is a top view of the electrical box assembly of the present invention installed within a wall constructed of wide studs according to the present invention and with a portion of the top wall broken away to depict the captive fasteners. 
       FIG. 17  is a side view of the electrical box assembly taken along line  17 - 17  of  FIG. 16 . 
       FIG. 18  is a top view of the electrical box assembly of the present invention installed within a wall constructed of narrow studs according to the present invention and with a portion of the top wall broken away to depict the captive fasteners. 
       FIG. 19  is a side view of the electrical box assembly taken along line  19 - 19  of  FIG. 18 . 
       FIG. 20  is an exploded perspective view depicting the main panel and two side panels in alignment to be assembled into the electrical box of the present invention. 
   

   TABLE OF NOMENCLATURE 
   The following is a listing of part numbers used in the drawings along with a brief description: 
   
     
       
             
             
           
             
             
           
         
             
                 
             
             
               Part Number 
               Description 
             
             
                 
             
           
           
             
                 
             
           
        
         
             
               20 
               electrical box assembly 
             
             
               22 
               electrical box 
             
             
               24 
               adjustable bracket 
             
             
               26 
               first sidewall 
             
             
               28 
               second sidewall 
             
             
               30 
               back wall 
             
             
               32 
               top wall 
             
             
               34 
               bottom wall 
             
             
               36 
               enclosure 
             
             
               37 
               front opening 
             
             
               38 
               front edge 
             
             
               39 
               grounding screw 
             
             
               40 
               captive fastener 
             
             
               42 
               main panel 
             
             
               44 
               first side panel 
             
             
               46 
               second side panel 
             
             
               48 
               indentation 
             
             
               50 
               lug 
             
             
               51 
               aperture in lug 
             
             
               52 
               inwardly bent sidewall portion 
             
             
               54 
               aperture in sidewall portion of first sidewall 
             
             
               56 
               end portion of captive fastener 
             
             
               58 
               head portion of captive fastener 
             
             
               60 
               axis 
             
             
               62 
               vertical portion of main panel 
             
             
               64 
               alignment tab 
             
             
               66 
               removable wall portion 
             
             
               68 
               front portion of top wall 
             
             
               70 
               rear portion of top wall 
             
             
               72 
               aperture in second side panel 
             
             
               74 
               groove 
             
             
               76 
               base portion of bracket 
             
             
               78 
               end 
             
             
               80 
               wing 
             
             
               82 
               bend line 
             
             
               84 
               lateral slot 
             
             
               86 
               side of bracket 
             
             
               88 
               stiffening rib 
             
             
               90 
               v-shaped cutout 
             
             
               92 
               edge of cutout 
             
             
               94 
               longitudinal slot 
             
             
               96 
               wall 
             
             
               98 
               2×6-inch stud 
             
             
               100 
               drywall 
             
             
               102 
               bracket fastener 
             
             
               104 
               horizontal axis 
             
             
               106 
               wall 
             
             
               108 
               2×4-inch stud 
             
             
               110 
               bent leg 
             
             
               D1 
               offset distance of lug from front edge of electrical box 
             
             
               D2 
               width of base portion of bracket 
             
             
               D3 
               width of stiffening rib 
             
             
               D4 
               length of bracket in unbent state 
             
             
               D5 
               separation between alignment and aperture in sidewall 
             
             
               D6 
               length of bent bracket 
             
             
               θ 1   
               angle of captive fastener with respect to sidewall 
             
             
               θ 2   
               angle of rear portion of top wall with respect to front 
             
             
               θ 3   
               angle between edges at cutout portion of bracket 
             
             
                 
             
           
        
       
     
   
   DETAILED DESCRIPTION OF THE INVENTION 
   With reference to  FIG. 1 , there is shown a preferred embodiment of the present invention, which is an electrical box assembly  20  including an electrical box  22  and a length-adjustable bracket  24 . 
   Referring to  FIGS. 2 and 3 , the electrical box  22  includes a left or first sidewall  26 , a right or second sidewall  28 , a back wall  30 , a top wall  32 , and a bottom wall  34  that define an enclosure  36  with a front opening  37 . The electrical box  22  includes a front edge  38  defined by the front edges of the top wall  32 , bottom wall  34 , and two sidewalls  26  and  28  and a grounding screw  39  secured in the back wall  30 . As shown in  FIG. 3 , the electrical box  22  includes a captive fastener  40  held within the enclosure  36 . 
   As shown in  FIG. 20 , the preferred embodiment of the electrical box  22  of the present invention includes a main panel  42 , and two side panels including a first side panel  44  and second side panel  46 . The main panel  42  includes the back wall  30 , the top wall  32 , and the bottom wall  34  of the electrical box  22 . The side panels  44  and  46  are secured to the main panel  42  to form the electrical box  22 . Preferably the main panel  42  and the side panels  44  and  46  are constructed of galvanized or plated steel and the side panels  44  and  46  are secured to the main panel  42  by conventional means, such as welding, to construct the electrical box  22 . Most preferably the panels  42 ,  44 , and  46  are formed of zinc plated  1010  steel having a thickness of between 0.050 and 0.080 inch and a minimum zinc plating thickness of 0.0005 inch. The panels may include complementary indentations  48  on separate panels that are mated when the panels are joined that form locations to be spot welded. 
   As shown in  FIGS. 2 and 3 , lugs  50  having apertures  51  therein are provided extending laterally from the top wall  32  and the bottom wall  30  of the electrical box  22  at the front opening  37 . The lugs  50  are offset a slight distance, as denoted by distance D 1  in  FIG. 3 , from the front edge  38  of the electrical box  22 . 
   With reference to  FIG. 3 , the first sidewall  26  includes an inwardly bent sidewall portion or sidewall portion  52  extending into the enclosure  36 . The inwardly bent sidewall portion  52  includes one or more apertures  54  therein and the sidewall portion  52  extends at an angle Θ 1  with respect to the front edge  38  of the electrical box  22 . The captive fasteners  40  include an end portion  56  and a head portion  58 . With end portion  56  of captive fastener  40  secured in aperture  54  of inwardly bent sidewall portion  52 , the head portion  58  of the captive fastener  40 , as a result of sidewall portion  52  being at angle Θ 1  with respect to the front edge  38  of the electrical box  22 , is directed toward the front opening  37  of the electrical box  22 . Preferably, the captive fastener  40  extends from the inwardly bent sidewall portion  52  at an angle Θ 1  of between 50 and 60 degrees with respect to the first sidewall  26 . The captive fastener  40  is aligned with the electrical box  22  such that an axis  60  extending through the axial center of the captive fastener  40  extends through the front opening  37  and is clear of the sidewalls  26  and  28  of the electrical box  22 . Therefore, the captive fasteners  40  are readily accessible by use of a screwdriver (not shown) or similar tool from the front opening  37  of the electrical box  22 . 
   Referring to  FIGS. 4 and 5 , the main panel  42  includes a vertical portion  62  and at least one alignment tab  64  extending from the vertical portion  62 . As shown in  FIGS. 4 ,  6 , and  7 , the main panel  42  includes one or more removable wall portions  66  in the back wall  30 , the top wall  32 , and the bottom wall  34 . The top wall  32  of main panel  42  includes a front portion  68  and a rear portion  70 , with the front portion  68  orthogonal to the back wall  30  of the electrical box  22  and the rear portion  70  of the top wall  32  sloped at an angle Θ 2 , as shown in  FIG. 5 , with respect to the front portion  68 . Preferably, angle Θ 2  is between 30 and 40 degrees. 
   With reference to  FIGS. 8-10 , the first side panel  44  includes the inwardly bent portion or sidewall portion  52  with apertures  54  for accepting and holding the captive fasteners  40  therein. 
   As shown in  FIGS. 11 and 12 , the second side panel  46  includes an aperture  72  and a groove  74  therein which, as shown in  FIG. 20 , will accommodate the alignment tab  64  of the main panel  42  when aligning and assembling the second side panel  46  to the main panel  42 . 
   Referring to  FIGS. 13-14 , the adjustable bracket  24  includes a base portion  76  having two ends  78  and an outward extending wing  80  on each end  78  of the base portion  76 . As shown in  FIG. 14 , the outward extending wings  80  are orthogonal to the base portion  76  of the bracket  24 . The base portion  76  of the bracket  24  further includes a bend line  82  thereon. The bend line  82  includes a lateral slot  84  extending across a substantial portion of the bracket  24 . The bracket  24  further includes two sides  86  and an integral stiffening rib  88  extending longitudinally along one side  86  of the base portion  76 . The stiffening rib  88  includes a V-shaped cutout portion  90  at the bend line  82 . The cutout portion  90  includes edges  92  thereon and the edges  92  of the cutout portion  90  are separated at an angle Θ 3  that is preferably between 90 and 110 degrees. The base portion  76  of the bracket  24  includes a width, denoted by the distance D 2  between the sides  86  in  FIG. 13 . The stiffening rib  88  includes a width, denoted by distance D 3  in  FIG. 14 . Preferably, according to a preferred embodiment of the present invention, the width D 3  of the stiffening rib  88  is at least 25 percent of the width D 2  of the base portion  76  of the bracket  24 . The bracket  24  further includes a substantially long longitudinal slot  94  in the base portion  76 . 
   As shown in  FIG. 15 , the adjustable bracket  24  may be bent at the bend line  82  to convert it to a shorter length and thereby enable the electrical box assembly to accommodate walls constructed of narrower studs. When bent at the bend line  82 , the edges  92  of the cutout portion  90  are in contact or substantially close to one another. 
   With reference to  FIG. 16 , there is depicted a top view of a preferred embodiment of the electrical box assembly  20  of the present invention installed within a wall  96  constructed of wide studs  98  such as 2×6-inch metal studs. The electrical box  22  further includes an alignment tab  64  extending outward from the second sidewall  28 . The alignment tab  64  extends outward from the second sidewall  28  of the electrical box  22  and through the longitudinal slot  94  (see  FIG. 17 ) of the bracket  24  thereby aligning the bracket  24  with respect to the electrical box  22 . The adjustable bracket  24 , in its unbent configuration, extends beyond the back wall  30  of the electrical box  22 . The bracket  24  in an unbent state is of a length D 4  to span between the drywall  100  in a wall  96  constructed of conventional 2×6-inch studs  98 . 
   As shown in  FIG. 17 , in the electrical box assembly  20  of the present invention a threaded bracket fastener  102  is provided extending through the longitudinal slot  94  of the bracket  24  and into the aperture  72  of electrical box  22 . The alignment tab  64  and the aperture  72  of the second sidewall  28  of the electrical box  22  are in horizontal alignment along horizontal axis  104  across the second sidewall  28  and separated by a substantial distance D 5  thereby keeping the bracket  24  in horizontal alignment with respect to the electrical box  22  as the bracket  24  is slid with respect to the electrical box  22 . Bracket  24  may therefore be adjusted with respect to electrical box  22  to slide both wings  80  of bracket  24  flush with each drywall  100  surface. 
   With reference to  FIG. 18 , there is depicted a top view of a preferred embodiment of the electrical box assembly  20  of the present invention installed within a wall  106  constructed of narrow studs  108  such as 2×4-inch metal studs. To accommodate a wall  106  constructed with 2×4-inch studs, the adjustable bracket  24 , is bent at a 90 degree angle at bend line  82 . The bent bracket  24  is of a length D 6  to span between the drywall  100 . 
   As shown in  FIG. 19 , the alignment tab  64 , extending outward from the second sidewall  28  of the electrical box  22 , can be loosened to enable adjustment of the bracket  24  with respect to the electrical box  22  so that both ends of the bracket  24  are flush with the drywall  100  as shown in  FIG. 19 . The long length of the longitudinal slot  94  enables a substantial adjustment of the bracket  24  with respect to the electrical box  22 . 
   As shown in  FIG. 1 , the electrical box assembly  20  of the present invention is provided with the bracket  24  attached to the electrical box  22  with bracket fastener  102 . Two captive fasteners  40  are secured therein in inwardly bent sidewall portion  52 . The heads  58  of captive fasteners  40  are within the enclosure  36  but angled towards and near the front opening  37  of the electrical box  22 . Captive fasteners  40  are preferably self-tapping and constructed of hardened steel. The electrical box assembly  20  is typically installed after the wall studs are in place and the rear drywall panel has been installed (see  FIGS. 17 and 19 ). 
   With reference to  FIG. 16  for operation of the present invention on a wall constructed of 2×6-inch studs, the bracket  24  is left in its unbent state, the first sidewall  26  is placed flush against the stud  98  with the front edge  38  of the box  22  extending beyond the stud by the thickness of the front drywall panel  100 , and the electrical box  22  is secured to the stud  98  by driving the captive fasteners  40  into the stud. The bracket  24  can then be adjusted with respect to the electrical box  22  by loosening bracket fastener  102 , sliding rear wing  80  of bracket  24  against the rear drywall panel  100 , and retightening the bracket fastener  102 . 
   With reference to  FIG. 18 , the electrical box assembly  20  is operated in the same manner for a wall constructed of 2×4-inch studs  108 , except the bracket  24  is first bent 90 degrees at bend line  82  to accommodate the narrower wall space. After the captive fasteners  40  are driven into the stud to secure one side of the electrical box  22  to the stud, the bracket  24  is loosened and slid toward the rear of the electrical box  22  until the bent leg  110  is flush against the rear drywall panel. After the adjusting bracket fastener  102  is tightened, the front wing  80  should be flush with the front drywall panel. 
   Having thus described the invention with reference to a preferred embodiment, it is to be understood that the invention is not so limited by the description herein but is defined as follows by the appended claims.