Abstract:
An electrical box assembly is provided for enabling an electrical box to be rapidly installed into a metal framework that supports an interior wall of a building. The assembly includes a supporting member which is attached to the metal framework, and an electrical box of square design having paired outwardly directed flanges. The flanges are positioned to fit into receiving brackets on the supporting member, thereby enabling the electrical box to engage the supporting member by a simple downward sliding motion.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to electrical outlet boxes and box supports particularly adapted for installation into indoor walls comprised of metal support framework. 
     2. Description of the Prior Art 
     The walls of indoor rooms of buildings are generally constructed of front and rear flat rigid panels spaced four to six inches apart about a supporting framework comprised of upper and lower horizontal beams and a series of beams extending vertically between said horizontal beams. The wall space, namely the space between the panels, generally accommodates thermal insulation, plumbing components and electrical wiring. The wiring typically extends from a power source to outlet boxes which house electrical receptacles or switches. 
     The electrical outlet boxes are recessed into the wall space so as to fit flush with the exterior face of the associated front wall panel. In those instances where the supporting framework is of wooden construction, as is typical of residential dwellings, the outlet box is usually installed by nailing to an appropriate vertical beam at a measured height above the lower horizontal beam. The outlet boxes are generally installed either at a low location of about 18″ above the associated floor, to accommodate plug-in receptacles that receive electrical cords, or are installed at a high location of about 53″ above the floor to hold switches that control electrical circuits. 
     Commercial and industrial buildings predominantly employ metal wall-supporting frameworks instead of the wooden framework prevalent in residential buildings, and the panels are usually of gypsum board or equivalent fire-resistant materials. Said panels may be employed in varied thicknesses of between about ½″ and 1½″. The outlet boxes employed with metal wall systems are of substantially the same construction as outlet boxes employed for wooden wall structures, however, the manner of positioning and affixing the outlet box in metal wall systems is considerably different than techniques typically employed with wooden wall systems. 
     Most contractors use prefabricated components to reduce the amount of time required to install outlet/switch boxes in a commercial or industrial building. In a typical on-site installation, a commonplace metal outlet box of 4″ or 4 11/16″ square size is attached with screws to a supporting panel. At low sites intended to receive plug-in receptacles, said supporting panel is of elongated shape, extending in attachment between the lower beam and a horizontal strut joined to contiguous vertical beams. The wires of a power cable are attached to the receptacle or switch within the box, and a “plaster ring” is attached to the supporting panel to cause the installation to fit flush with the exterior face of the wall. Such manner of installation is time-consuming because it requires the alignment of many pairs of holes and rotation of screws. In the course of construction of a new building which may require the installation of hundreds of outlet boxes, the cumulative working time is a significant economic factor. 
     It is accordingly an object of the present invention to provide an electrical outlet box assembly that can be rapidly and accurately installed. 
     It is another object of this invention to provide an electrical box assembly of the foregoing object which is compatible with standard components of metal wall frameworks. 
     These objects and other objects and advantages of the invention will be apparent from the following description. 
     SUMMARY OF THE INVENTION 
     The above and other beneficial objects and advantages are accomplished in accordance with the present invention by an electrical box assembly for installation into a wall-supporting metal framework, said assembly comprising:
     a) an electrical box of metal construction having a base panel of square perimeter with upper and lower walls and paired side walls orthogonally emergent from said perimeter and terminating in straight distal edges in coplanar association defining a square portal forwardly directed from said base panel in parallel relationship thereto and defining therewith a box-like square compartment, the distal edge of each of said side walls having an elongated flange outwardly directed from said compartment within the plane of said square portal and terminating in a straight edge parallel to the associated distal edge, and   b) a supporting member fabricated of sheet metal and having:
       1) a flat panel portion bounded by upper and lower extremities, forward and rearward faces, and opposed side edges,   2) means to facilitate attachment to said metal framework,   3) a pair of spaced-apart elongated brackets on said rearward face in vertical orientation positioned to securely accept in downwardly sliding fashion the flanges of said electrical box,   4) abutment stop means below said brackets to limit the downward sliding motion of said electrical box, and   5) a receiving aperture positioned between said brackets and having a size and shape to align with the square portal of said outlet box in its lowermost position within said brackets.   
       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing forming a part of this specification and in which similar numerals of reference indicate corresponding parts in all the figures of the drawing: 
         FIG. 1  is a fragmentary front view of a structural wall employing a prior art metal framework that would utilize the outlet box assembly of the present invention. 
         FIG. 2  is a perspective front view of an embodiment of the outlet box component of the assembly of this invention. 
         FIG. 3  is a side view of the outlet box component of  FIG. 2 . 
         FIG. 4  is a top view of the outlet box component of  FIG. 2 . 
         FIG. 5  is a fragmentary perspective rear view of an embodiment of the supporting member of the assembly of this invention. 
         FIG. 6  is a top view of the supporting member of  FIG. 5 . 
         FIG. 7  is a top view of the exemplified assembly with accessory prior art components shown in phantom outline. 
         FIG. 8  is an exploded perspective view of the exemplified assembly shown with accessory prior art components. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to  FIGS. 1-8 , an embodiment of the electrical outlet box assembly  10  of the present invention is shown comprised of an electrical outlet box component  11 , and interactive supporting member  12 . The assembly is designed for installation into a wall-supporting metal framework  13 . 
     Framework  13  is comprised of a metal floor channel  14 , vertical studs  15  interactive with said floor channel at standardized distances of separation, and header channel  16  interactive with the upper extremities of studs  15 . Said framework components are generally fabricated of galvanized steel. At selected intervals, rigid transverse struts  17  span contiguous studs in attachment therewith. The height of said struts above the floor channel is such as to permit installation of an electrical outlet box intended to house receptacles which accommodate plug-in electrical cords. Strut  17  secures the uppermost extremity  32  of a supporting member  12  which extends vertically upward from securement with floor channel  14 . Wall panels  18 , which may be gypsum in thicknesses of ¼″ to 1½″, are secured to the forward surfaces of the aforesaid structural components of the framework. 
     Outlet box  11  is constructed of galvanized steel sheet stock by way of fabricating techniques such as bending, pressing, stamping and/or welding. It has a base panel  20  having a square perimeter  21  of 4 inches or larger. Upper and lower skirting walls  22  and  23 , respectively, and paired side skirting walls  24  are orthogonally emergent from said perimeter and terminate in distal edges  25  in coplanar association, defining a square portal  40  forwardly spaced by about 1½ to 2⅛ inches from base panel  20 . A box-like square compartment  26  is thereby defined. In some embodiments, said distal edges may have one or more opposed paired tabs  27  directed toward the interior of said compartment within the plane of said portal, each tab containing a threaded hole  46 . Said tabs, intended to facilitate other installation methods, may be in paired alignment either parallel to said skirting walls or in diagonal relationship therewith. Various punch-out circles  45  are provided in base panel  20  and said skirting walls to facilitate entry of electrical cables or conduits. For the purpose of clarity of illustration, said punch-out circles are not shown in views subsequent to  FIG. 2 . 
     The distal edge of each side wall  24  has an elongated flange  29  outwardly directed from said compartment within the plane of said portal, and terminating in a straight edge  30  which is parallel to the associated distal edge. The width of flange  29 , measured between wall  24  and edge  30  is between about 5 and 20 millimeters. The flange is either a separate piece which is welded to wall  24 , or is integral with said wall  24 , as having been made by a bending, stamping or pressing operation. The length of said flange may range between one inch and the full 4″ or larger length of the associated side wall  24 . 
     Supporting member  12  is fabricated of rigid sheet metal stock, and has a flat panel portion  60  bounded by upper and lower extremities,  32  and  61 , respectively, forward and rearward faces,  34  and  35 , respectively, and opposed side edges  62 . Attachment means such as gripping ears  48  or screw-receiving holes are associated with upper extremity  32  to facilitate engagement with transverse strut  17 . The exemplified supporting member is designed to extend between floor channel  14  and transverse strut  17  at a proper height for the installation of a low level outlet box. Alternative embodiments of supporting member  12  may be designed for securement to an upright stud  15  at a greater height for installation of a high level outlet box intended to house a conventional switch. 
     Rearward face  35  of supporting member  12  has a pair of spaced apart elongated brackets  36  in vertical orientation positioned to accept in downwardly sliding fashion flanges  29  of outlet box  11 . Abutment stop means  37  located below brackets  36  limit the downward-sliding motion of said outlet box. Brackets  36  are unitary pieces of metal closely spaced from rearward face  35  and comprised of either attached pieces or integral extensions of said supporting member, having been formed by a bending, pressing, or stamping operation. Supplemental locking means, exemplified as punch-formed tab  64 , may be incorporated into rearward face  35  above brackets  36  to prevent inadvertent upward removal of outlet box  11  from supporting member  12 . The interactively contacting surfaces of flanges  29  and brackets  36  may be provided with gripping means such as interlocking indentations for enhanced securement of outlet box  11  to supporting member  12 . 
     A receiving aperture  38 , located between brackets  36 , is configured to have a size and shape to substantially align with portal  40  of outlet box  11  in its lowermost position within said brackets. The size of aperture  38  is designed to be adequate to facilitate access to all regions of compartment  26  of said outlet box. Supporting member  12  may also have holes  49  adapted to align with threaded holes  46  of tabs  27  for the purpose of providing additional securement by way of threaded fasteners in the manner of prior art assembly methods. Supplemental threaded holes  58  are diagonally located about aperture  38 . 
     In the course of installing electrical outlet boxes into walls having an exterior panel layer such as gypsum board, a component called a “plaster ring”  42  is associated with forward face  34  of supporting member  12  for the purpose of causing an electrical receptacle  28  to fit flush with the outer surface of gypsum board  18 . As shown in  FIGS. 7 and 8 , plaster ring  42  has an outwardly projecting barrier wall  50  of vertically elongated rectangular contour surrounded by a flat mounting apron  51  having slotted corners  52 . The height of barrier wall  50  may be effectively adjusted by way of a slidably secured insert sleeve  53 . The forwardmost portion of said sleeve has a rim  54  parallel to apron  51  and is provided with opposed upper and lower threaded tabs  55 . 
     In the installation process, outlet box  11  is slid into engagement with supporting member  12 . Plaster ring  42  is then secured to the forward face  34  of said supporting member by way of screws  57  that engage diagonal slotted corners  52  and supplemental holes  58 . Appropriate electrical wires are attached to electrical receptacle  28 , and said receptacle is attached to rim  54  by way of bolts  59  interactive with tabs  55 . 
     While particular examples of the present invention have been shown and described, it is apparent that changes and modifications may be made therein without departing from the invention in its broadest aspects. The aim of the appended claims, therefore, is to cover all such changes and modifications as fall within the true spirit and scope of the invention.