Abstract:
An electrical box assembly for concrete poured floors. The electrical box assembly includes a concrete can with an open end and a plurality of hubs with integral sockets for connection of electrical conduit thereto. Plugs are provided for closing off unused sockets. The electrical box assembly includes a mounting bracket for installation on the open end of the can, a duplex receptacle, a back plate and a cover plate. The back plate provides a seal between the mounting bracket and the cover plate. Removable threaded blanks are included for sealing the openings in the cover plate in order to gain access to the plug-ins on the duplex receptacle.

Description:
FIELD OF THE INVENTION 
     This invention relates to electrical box assemblies for mounting electrical components and specifically to an electrical box assembly for mounting an electrical component in newly poured concrete. 
     BACKGROUND OF THE INVENTION 
     It is a common desire in residential and commercial construction to install electrical components such as duplex receptacles in concrete floors where they provide a convenient location to plug into the electrical supply. Conventional electrical boxes for installation in concrete are typically constructed of metal. Unfortunately, metal electrical boxes are not ideal for installation in poured concrete. Metal electrical boxes are susceptible to damage from moisture or water seepage, which over time can cause rusting which may compromise the integrity of the electrical box. Secondly, metal electrical boxes have become expensive to manufacture as a result of the high price of metal and the substantial secondary operations to construct the metal box, such as welding or assembly with screws. Also, as a result of the desire to minimize the cost of metal electrical boxes, manufacturers attempt to reduce the thickness of the walls of the box, and this can lead to crushing of the walls when heavy concrete is poured around the box. 
     What is needed therefore is an electrical box assembly for installation in an area that will be poured with concrete. The electrical box assembly should have the strength and integrity to withstand immersion in poured concrete without crushing or damage to the box. The electrical box should be constructed of materials that are not susceptible to corrosion damage caused by moisture or water seepage. The electrical box assembly should be capable of being manufactured at an economical price. Lastly, the electrical box assembly should include a means for adjusting the height of the installed box to adapt to the final floor thickness, such as occurs when carpet, tile, or similar floor coverings are installed on the concrete floor. 
     SUMMARY OF THE INVENTION 
     The invention is an electrical box assembly for concrete poured floors. The electrical box assembly includes a non-metallic concrete can with an open end and a plurality of hubs with integral sockets for connection of electrical conduit thereto. Plugs are provided for closing off unused sockets. The electrical box assembly includes a mounting bracket for installation on the open end of the can, a duplex receptacle, a back plate and a cover plate. The back plate provides a seal between the mounting bracket and the cover plate. Removable threaded blanks are included for sealing the openings in the cover plate in order to gain access to the plug-ins on the duplex receptacle. 
     OBJECTS AND ADVANTAGES 
     The electrical box assembly for concrete poured floors provides several advantages over the prior art, including:
         (1) The electrical box assembly can be manufactured at a more economical price than a conventional metal electrical box assembly.   (2) The electrical box assembly includes rigid walls having the strength and integrity to withstand immersion in poured concrete without crushing or damage.   (3) The electrical box assembly is constructed of materials that are not susceptible to corrosion damage caused by moisture or water seepage.   (4) The electrical box assembly includes a means for adjusting the height of the installed box to adapt to the final floor thickness.       

     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 an exploded perspective view of an electrical box assembly for concrete poured floors according to the present invention. 
         FIG. 2  is a front view of a concrete can that forms a portion of the electrical box assembly of  FIG. 1 . 
         FIG. 3  is a first side view of the concrete can. 
         FIG. 4  is a second side view of the concrete can. 
         FIG. 5  is a sectional view of the concrete can taken along line  5 - 5  of  FIG. 2 . 
         FIG. 6  is a sectional view of the concrete can taken along line  6 - 6  of  FIG. 2 . 
         FIG. 7  is a sectional view of the concrete can taken along line  7 - 7  of  FIG. 2 . 
         FIG. 8  is a top perspective view of a back plate that forms a portion of the electrical box assembly of  FIG. 1 . 
         FIG. 9  is a bottom perspective view of the back plate. 
         FIG. 10  is a perspective view of a pair of spacers that form a portion of the electrical box assembly of  FIG. 1 . 
         FIG. 11  is a perspective view of a second embodiment of a pair of spacers. 
         FIG. 12  is a front elevation view of a spacer according to the present invention. 
         FIG. 13  is a rear view of the spacer of  FIG. 12 . 
         FIG. 14  is a rear perspective view of the concrete can portion of the electrical box assembly of the present invention. 
         FIG. 15  is a perspective view of a mounting bracket that forms a portion of the electrical box assembly of  FIG. 1 . 
         FIG. 16  is a front perspective view of a fully assembled electrical box for concrete poured floors according to the present invention. 
         FIG. 17  is a perspective view of a plug that may form a portion of the electrical box assembly of the present invention. 
         FIG. 18  is a perspective view of the bottom side of a cover plate that forms a portion of the electrical box assembly of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIG. 1  there is shown a preferred embodiment of an electrical box assembly  20  for concrete poured floors according to the present invention. The electrical box assembly  20  includes a concrete can  22 , a mounting bracket  24 , a back plate  26 , and a cover plate  28 . The concrete can  22  includes two end walls  30 , two side walls  32 , and a plurality of hubs  34  with sockets  36  therein extending from the sidewalls. The sockets  36  include openings  38  therein and the concrete can  22  may include one or more plugs  40  to block off any unused openings in the sidewalls. Two stiffening ribs  42  extend longitudinally along each end wall  30  of the concrete can  22  near the corner  44  of the sidewalls. The concrete can  22  includes a top edge  46  and a cavity  48  therein. Each stiffening rib  42  terminates in a flat face  50  that is level with the top edge  46 . Each flat face  50  includes a bore  51  therein. 
     Referring to  FIG. 14 , the concrete can  22  further includes a back wall  52 , a bottom edge  54  at the juncture of the sidewalls  30  and  32  and the back wall, and an anchor leg  56  having an aperture  58  therein extending outwards from the bottom edge  54 . The bottom surface  60  of the each anchor leg  56  is level with the back wall  52 . 
     With reference to  FIG. 1 , the electrical box assembly  20  is used to mount an electrical component in a concrete poured floor such as the duplex connector  62  shown. Cover plate  28  includes a top surface  63 , two threaded openings  64  therein, and a plurality of apertures  66 . Two threaded blanks  68  are provided for closing the threaded openings  64  in the cover plate  28 . The electrical box assembly may further include a pair of spacers  70  as will be described herein with reference to a preferred embodiment. 
     Referring to  FIGS. 2 and 3 , the sockets  36  within hubs  34  are sized to accept various trade sizes of electrical conduit (not shown). The end walls  30  include large hubs  34   a  to accommodate most preferably 1-inch diameter conduit (not shown) and the side walls  32  include small hubs  34   b  to accommodate most preferably ¾-inch conduit, although the hubs could be provided in other trade sizes as well. Most preferably, the concrete can includes hubs to accommodate at least two diameters of electrical conduit. 
     Depending on the particular installation at the job site, any unused hubs  34  can be plugged to block entry of concrete through the hub openings  38 . As shown in  FIG. 17 , each plug  40  includes cylindrical sidewalls  69 , a flange  72 , an end wall  74 , and a knockout  76  in each end wall. The plugs  40 , including a large size for plugging a large hub and a small size for plugging a small hub, can be inserted into one of the sockets  36  to block the hub opening  38 . 
     With reference to various views of the concrete can  22  in  FIGS. 4-7 , the concrete can is most preferably molded in one piece of plastic. The side walls  30  and  32  of the concrete can  22  must be constructed of a thickness to withstand the weight of poured concrete around the can and prevent the weight of the poured concrete from crushing the can  22 . The thickness of end walls  30  and side walls  32  is most preferably at least 0.15 inch. As shown in  FIG. 6 , the stiffening ribs  42  are most preferably at least 0.37 inch. The bores  51  in the stiffening rib  42  enable fastening of the mounting bracket  24  to the concrete can  22  with fasteners  98  as shown in  FIG. 1 . 
     Referring to  FIG. 15 , the mounting bracket  24  includes sidewalls  80  defining an opening  81  therein, and a peripheral flange  82  having outer apertures  84  and inner apertures  86 . Outer apertures  84  include a countersink entry  88  and inner apertures  86  lead into bosses  90 . Inner bosses  92  extending from sidewalls  80  include bores  94  therein that provide connection points for connection of an electrical component (not shown) thereto. The portion of the sidewalls  80  below bosses  90  include truncated corners  96  to facilitate easy entry of mounting bracket  24  into the cavity of the concrete can (not shown) when the two are secured together. Outer apertures  84  are for connection of fasteners  98  (see  FIG. 1 ) for securing the mounting bracket  24  to the concrete can  22 . Fasteners  98 , outer apertures  84  in peripheral flange  82  of mounting bracket  24 , and the bores  51  in the concrete can  22  thereby form a fastening arrangement  97  for securing the mounting bracket to the concrete can. 
     Referring to  FIGS. 8 and 9 , the back plate  26  includes a substantially flat plate  99  having a top side  101 , a bottom side  103  and openings  105  to substantially match the plug receptacles of a duplex receptacle (not shown). An aperture  107  passes through the center of the back plate  26 . The bottom side includes a raised periphery  109  passing around the outer edge of the openings  105 . The raised periphery  109  enables the back plate  26  to seat evenly against a duplex receptacle. As shown in  FIG. 1 , the back plate includes an outer periphery  110  that nests within the sidewalls of the mounting bracket. 
     Referring to Figs.  FIGS. 10-13 , the electrical box assembly includes one or more pairs of spacers  70  such as the preferred embodiment depicted in  FIG. 10 . The paired spacers  70  are used to adjust the height of the electrical box assembly (see  FIG. 1 ) to the final floor thickness. Each spacer  70  is substantially L-shaped with a base portion  111  and two arms  113  extending from the base portion. Each spacer includes a flat top surface  115 , a flat bottom surface  117 , and a mating face  119  at the end of each arm  113 . A boss  121  extends orthogonally from each arm and includes an aperture  123  therein. Each spacer includes a flange  124  extending outward from the base portion  111 . As shown in  FIG. 1 , when assembling the electrical box assembly  20 , the apertures  123  in the pair of spacers  70  are placed in axial alignment with bores  51  in concrete can  22  and also with outer apertures  84  of mounting bracket  24 .  FIG. 11  depicts a second embodiment of the pair of spacers  125 . The distance between top surface  115  and bottom surface  117  in each spacer  125  is less than that of the spacers in  FIG. 10 ; thereby providing a thinner spacer for adjusting the distance of the duplex receptacle a lesser distance above the concrete can (see  FIG. 1 ). When inserting the spacers  70  between the concrete can  22  and the mounting bracket  24  in order to raise the level of the electrical box assembly  20 , base portion  111  and arms  113  will nest within the sidewalls  30  and  32  of the concrete can  22  and the flange  124  of spacers  70  will engage the top edge  46  of the concrete can. 
     With reference to  FIG. 1 , the electrical box assembly  20  is operated by first deciding on the location desired for a floor electrical box within an area that is formed for a concrete pour. The concrete can  22  is set in the desired location and conduit  127  is installed into hubs  34  as required for the installation. Plugs  40  are installed in any sockets not used for conduit. Conductors (not shown) are pulled through the openings  38  into the concrete can  22 . Concrete is then poured around the can  22 . After the concrete sets, the can  22  may be trimmed to the finished floor height by cutting with a saw blade. Mounting bracket  24  is then installed on the concrete can  22  using fasteners  98  through outer apertures  84  on mounting bracket into bores  51  in can  22 . The duplex receptacle  62  is then wired into the can and bracket assembly. The back plate  26  and cover  28  are then installed by driving fasteners  78  through apertures  66  in cover into inner apertures  86  and bosses  90  of mounting bracket  24 . Fasteners  98 , apertures  66  in cover  28 , and inner apertures  86  and bosses  90  of mounting bracket  24  form an attachment arrangement  126  for securing the cover  28  to the mounting bracket  24 . Threaded blanks  68  may be installed in any unused threaded openings  64 . Paired spacers  70  may be installed later as required to raise the electrical receptacle  62 , including the mounting bracket  24 , back plate  26  and cover plate  28  to the level of the final floor thickness. A plurality of spacer pairs  70  of various thicknesses are supplied with the electrical box assembly to enable easy adjustment to various floor thicknesses. The spacers  70  enable the installer to accommodate various floor materials, such as tile, wood, or carpeting by using the spacer that matches the height rise caused by the floor material. As the concrete pour is completed first and a floor material may be added later, providing the spacers in two halves, such as  70   a  and  70   b  in  FIG. 10 , enables the installer to slide each half spacer into place while keeping the fasteners  98  on the opposing side of the box assembly loosely engaged. This enables the installer to maintain axial alignment between the outer apertures  84  in the mounting bracket  24  and the bores  51  in the concrete can  22 . After the first half spacer  70   a  is slid into place and fasteners  98  are loosely tightened, then the fasteners can be removed from the opposing side whereupon second half spacer  70   b  can be slid into place and tightened, all the while maintaining axial alignment between the outer apertures  84  in the mounting bracket  24  and the bores  51  in the concrete can  22 . 
     The fully assembled electrical box assembly  20  for concrete poured floors is shown in  FIG. 16 . The walls of the concrete can are most preferably 6 inches in length from the top edge  46  to the back wall  52  (see  FIG. 14 ) to enable use with substantially all depths of concrete pours. The concrete can  22  includes anchor legs  56  on opposing sides  32  of the box at the back wall  52 . To aid in stabilizing the concrete can  22  and hold it in place during installation of conduit  127 , pulling of electrical cable, wiring, and during the concrete pour, a spike, nail, or similar anchoring rod can be driven through aperture  58  in anchor leg  56  to secure it to the ground. 
     Referring to  FIG. 18 , the cover plate  28  includes a bottom surface  129 , an outer peripheral wall  131 , and an inner peripheral wall  133  extending from the bottom surface. The cover plate  28  includes a flat surface  135  within the inner peripheral wall  133  and the flat surface may include a gasket (not shown) adhered thereto. When cover plate  28  is assembled to the mounting bracket  24  as shown in  FIG. 1 , peripheral flange  82  of bracket  24  nests within the inner peripheral wall  133  of cover plate. After the electrical box assembly  20  is secured to a floor, outer peripheral wall  131  will be substantially flush with the floor surface. 
     With reference to  FIG. 1 , most preferably, the concrete can  22 , mounting bracket  24 , back plate  26 , cover plate  28 , and each spacer half of spacer pair  70 , are each molded of plastic in one piece. The preferred material of construction of the concrete can is polyvinyl chloride (PVC), which has a high specific gravity and is non-corrosive in a wet environment. 
     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.