Patent Abstract:
An electrical outlet box for accommodating an electrical fixture comprising a generally rectangular box having a back wall, a perimetrical side wall surrounding said back wall defining an open front face and a box interior, said side wall comprised of a first and second set of generally parallel spaced apart wall portions; and a slidable extension nested within said generally rectangular box, that can be moved from within the generally rectangular box to an extended position beyond the open front face.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/712,777 filed on Aug. 31, 2005, entitled “Electrical Box For Concrete Walls”. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to an electrical outlet box for housing electrical fixtures such as a switch or a receptacle. More particularly, the present invention relates to an improved electrical outlet box for use on concrete wall.  
       BACKGROUND OF THE INVENTION  
       [0003]     It has long been known to house electrical fixtures such as switches and receptacles in an electrical outlet box. The outlet box permits the insertion of electrical wires into the box which are terminated to electrical fixtures. The fixtures then may be mounted to the box which provides protection to the fixtures as well as the wires terminated therein. The outlet box is then mounted to a wall at a convenient location to provide access. Most outlet boxes accommodate one or more electrical fixtures, which terminate standard 110 volt electrical wires.  
         [0004]     Outlet boxes are available in a variety of configurations and sizes. The selection of which type of box to use is dependant upon the specifics of the application. The most commonly employed box is a single-gang outlet box, also referred to as a standard outlet box. The single-gang box is ideal for applications in which only one receptacle is required for the application. Standard outlet boxes have opening dimensions of approximately 3″×2¼″ and are available in a variety of depths. Double-gang and triple-gang boxes are also available, and they typically have the capacity to hold two and three receptacles respectively. A four inch (4″) square box is also commonly employed for multiple receptacle applications.  
         [0005]     Typically, outlet boxes are mounted by affixing mounting ears to a wall stud or other structural member. However, for some applications, such as exterior uses, there is a requirement to install electrical boxes on poured concrete walls, wherein the outlet box, may be mounted within a concrete structure. This is accomplished by attaching the box to a form in the desired location. The form is usually a wooden temporary structure used to contain the poured concrete in the desired shape that is removed after the concrete has hardened. The outlet box remains in the concrete after removal of the form.  
         [0006]     It is necessary when using an electrical box in such an application to insure that it is securely affixed to the form to resist being displaced during the concrete pour. Presently, electrical boxes used by many contractors for installation in concrete walls are not well adapted for use in concrete wall. Specifically, the prior art boxes lack features thereby making them difficult to use in concrete wall applications, or result in additional work for the contractor. For example, many prior art boxes lack ears or other suitable attachment means for firmly and securely attaching the electrical box to the wooden form prior to pouring the concrete. This can result in the contractor having to use less than suitable means to attach the box to the form which can result in a misplaced box, or one that moved during the concrete pour and subsequently became filled with concrete that the contractor must remove in order to utilize the box.  
         [0007]     Therefore, it would be desirable to have an electrical box for use in concrete walls, incorporating features for securely mounting the electrical box to a form, such that it remains stable and firmly attached to the form during the concrete pouring process. Additionally, it is desirable that the electrical box used in a concrete wall prevent infiltration of concrete into the interior of the box during the concrete pouring process, thereby preventing the box from becoming filled with concrete and thus unusable. It is further desirable that the electrical box can be easily modified to extend the open front perimeter of the box after the concrete is poured and hardened such that the perimeter will be flush with the finished wall surface to conform to electrical code requirements.  
       SUMMARY OF THE INVENTION  
       [0008]     Applicant has overcome the shortcomings of prior art outlet box with the present invention by incorporating features for securely attaching the electrical box to a concrete form and further includes a built in extension device that can be pulled out from the front of the box to increase the depth of the box, once it is set in place without the need for attaching a separate extension.  
         [0009]     The present invention therefore provides an electrical outlet box for accommodating an electrical fixture comprising a generally rectangular box having a back wall, a perimetrical side wall surrounding said back wall defining an open front face and a box interior, said side wall comprised of a first and second set of generally parallel spaced apart wall portions; and a slidable extension nested within said generally rectangular box, that can be moved from within the generally rectangular box to an extended position beyond the open front face. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a perspective view of the electrical box according to the present invention, with the slide extension in a retracted position.  
         [0011]      FIG. 2  is a perspective view of the electrical box according to the present invention, with the slide extension in an extended position.  
         [0012]      FIG. 3  is a cross sectional view of a typical installation of the electrical box of the current invention with the concrete forms in place along section  3 - 3  of  FIG. 1 .  
         [0013]      FIG. 4  is a cross sectional view of a typical installation of the electrical box of the current invention with the concrete forms removed along section  3 - 3  of  FIG. 1 .  
         [0014]      FIG. 5  is a cross sectional view of a typical installation of the electrical box of the current invention with a finish surface installed over the concrete along section  5 - 5  of  FIG. 2 .  
         [0015]      FIG. 6  is a top cross sectional view of the electrical box according to the present invention, with the slide extension in a retracted position along section  6 - 6  of  FIG. 1 .  
         [0016]      FIG. 7  is a top cross sectional view of the electrical box according to the present invention, with the slide extension in an extended position along section  7 - 7  of  FIG. 2 .  
         [0017]      FIG. 8  is a perspective view of the interior of the electrical box according to the present invention.  
         [0018]      FIGS. 9A and 9B  are close-up side and top views respectively of a component part of the electrical box according to the present invention.  
         [0019]      FIG. 10  is a cross sectional perspective view of an alternate embodiment of the electrical box of the current invention, with the slide extension in a retracted position along section  6 - 6  of  FIG. 1 .  
         [0020]      FIG. 11  is a cross sectional perspective view of an alternate embodiment of the electrical box of the current invention, with the slide extension in an extended position along section  7 - 7  of  FIG. 2 .  
         [0021]      FIG. 12  is a perspective cross sectional view of the electrical box according to the present invention, with the slide extension in a retracted position along section  6 - 6  of  FIG. 1 .  
         [0022]      FIG. 13  is a perspective cross sectional view of the electrical box according to the present invention, with the slide extension in an extended position along section  7 - 7  of  FIG. 2 .  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]     There will be detailed below the preferred embodiments of the present invention with reference to the accompanying drawings. Like members are designated by like reference characters in all figures.  
         [0024]     Turning now to  FIG. 1 , there is shown an embodiment of the outlet box of the present invention. It should be noted that the present invention is shown and described with respect to a single gang outlet box, however the invention can be adapted to multiple gang boxes such as for example a double or triple gang box. The single gang embodiment shown and described, is exemplary and not meant to be limiting to single gang version.  
         [0025]     There is shown an outlet box  100  which is generally a rectangular member having a back wall  102 , a pair of spaced apart side walls  104  extending from back wall  102 , and opposed top and bottom walls  106  and  108 . Back wall  102 , side walls  104  and top and bottom walls  106  and  108  form a box interior  110  having an open front face  112  which accommodates therein an electrical fixture. Open front face  112  has a dimension substantially equivalent to the opening of a single-gang outlet box. The interior length and width of the opening will vary depending on if receptacle mounting flanges disposed on the box are interior or exterior to the box opening. However, the outlet box depicted here is illustrative and not intended to be limiting. It will be appreciated that it would be apparent to have an outlet box according to the present invention having alternate dimensions according to the application of such outlet box. Also visible in the interior of electrical box  100  is slideable extension  113 . The extension  113  is shown in the retracted position within the box. As will be further shown and described with respect to  FIG. 6 , in the retracted position, the extension is held in place by protrusion  115  cooperatively engaging cavity  111 . When the extension is pulled outside the box  100 , the protrusion  115  snaps into a cavity  117  in side wall  104  and cooperatively engages the cavity  117  to lock the extension in place. Box  100  is provided with at least two cavities  111  for the retracted position and cavities  117  for the extended position on opposite side walls  104  which engage a similar number of protrusions  115  on extension  113 .  
         [0026]     As is well known in the art, outlet box  100  may include one or more access openings, typically known as knockouts  114  which permit entry of electrical wires and cables (not shown) into box interior  110 . In addition, knockouts  114  include secondary smaller knockouts  115 , centrally positioned on knockout  114 . Knockout  127  is oval in shape and adapted to receive the blade of a straight blade screwdriver. Knockout  127  seals electrical box  100  against the infiltration of concrete during the pour. In use the installer of electrical box  100  would first remove knockout  127  with a straight blade screw driver, then insert the blade into the opening resulting from the removal of knockout  127  and pry out knockout  114 .  
         [0027]     The exterior surfaces of side walls  104  include nails  116  and  118  respectively which allow the box to be secured to a concrete form or the like by driving the nails into the form prior to the concrete being poured. The nails  116  and  118  are attached to the box  100  by collars  119 , which permit the nails to slide with respect to the box  100 . Therefore, the nails can be hammered forward into a form as the open front face  112  is pressed against a form. In addition, each nail  116 ,  118  is scored or notched  121  to create a stress raiser. The stress raiser is used to facilitate breaking the nail  116 ,  118  after the form has been removed and the electrical box  100  set in concrete. The score mark  121  is positioned along the nail&#39;s length such that it aligns with the open front face  112  when the nail is fully extended into the form. In that way, when the form is removed, the score mark is even with the cured concrete and can be broken off flush with the concrete wall. The interior surfaces of extension  113  include component retaining flanges  120  and  122  which include threaded apertures  124  for receiving fasteners, usually screws, to securely mount electrical components within the outlet box. In addition, flange  125  is provided, extending from back wall  102  beyond bottom wall  108  and top wall  106  (not visible in this view). Flange  125  provides an additional anchor point for the electrical box  100  to mechanically be affixed to the concrete.  
         [0028]     Turning now to  FIG. 2 , there is shown the electrical box  100  according to the present invention wherein extension  113  is shown in the extended position. In the extended position, the extension  113 , protrudes beyond open front face  112 . By extending the extension  113 , the protrusion  115  comes into cooperative alignment with cavity  117 . The protrusion  115  then snaps into cavity  117  in side wall  104  and locks the extension  113  in place.  
         [0029]     Turning now to  FIG. 3 , there is shown a cross sectional view of the electrical box along section  3 - 3 , according to the present invention showing a typical installation of an outlet box  100  in a concrete wall application.  FIG. 3  shows a side view of the electrical box  100  encased within forms  302  and  304 . The front form  302  and rear form  304  are used to retain poured concrete  306  to construct a vertical wall. As is well known, such forms may be constructed of wood stud, planks or sheets such as plywood. Electrical box  100  is fastened to front form  302 . The outlet box  100  must be securely fastened to the form when the concrete  306  is poured. The electrical box  100  is nailed to the form by driving the nails  116 ,  118  through apertures provided on exterior collars  119  of electrical box into the form. Secure attachment of the box  100  to the form  302  maintains the box  100  in proper position during the concrete pour.  
         [0030]     Also shown in  FIG. 3  is a ground screw  308 , which is positioned at the rear of the electrical box  100  along back wall  102  for attaching a ground connection to an electrical device installed in electrical box  100 . Also visible in the side view are nails  116  which pass through collar  119 . A wire is inserted into the electrical box  100  through knockout holes  114 , which would be fitted with a connector (not shown). The wire would typically be inserted through a conduit (not shown) which would be fastened to the connector. The wires can be installed before or after the concrete is poured. It should be noted that the wire can be routed into the electrical box through knockout holes  114  positioned on any wall of the electrical box, such as for example side wall  104  or back wall  102 . In another embodiment, wires could also be affixed within electrical box  100  by way of a locking clamp (not shown) for firmly affixing the wire such as, for example Romex cable. The locking clamp would typically include a screw which is tightened to clamp the wire in place and prevent it from being pulled out during the construction process. The side view of  FIG. 3  further shows extension  113  in a retracted position. Furthermore, as can be seen the extension  113  has a semicircular cutout  314  which corresponds to the position of the knockout hole  114 . In that way, when the extension is in the retracted position as shown in  FIG. 3 , it does not interfere with the use of the knockout hole  114 . Also seen in the side cross sectional view are protrusion  115  snaps of extension  113  and cavity  117  in side wall  104 . In this view can be seen that when extension  113  is in the retracted position, protrusion  115  and cavity  117  are not cooperatively engaged, but are aligned such that the translational movement of extension  113  will bring protrusion  115  into cooperative engagement with cavity  117  to lock the extension  113  in place. Nails  116  and  118  are shown in an extended position, protruding through form  302 , and thereby holding electrical box  100  flush against the form  302 , such that when the form in removed, the box interior is accessible to the contractor to access wires and install electrical components.  
         [0031]     Turning now to  FIG. 4 , there is shown the electrical box  100  according to the present invention in a typical installation wherein the concrete has hardened, and the forms are removed. In this view the concrete wall front  402  and rear  404  surface are exposed. Removal of the forms also exposes the front of outlet box, as well as nails  116  and  118  used to affix the electrical box to front form  302 . The removal of the forms exposes the shank and point of the nails  116  and  118 . In accordance with the present invention, as will be explained further with reference to the  FIG. 9 , the shank of fastener nails  116  and  118  which extends beyond concrete front wall  402  can be removed by grasping the extended shank and forcibly bending the shank from side to side, thereby causing the shank to break at the stress raiser score mark or notch  121 .  
         [0032]     Turning now to  FIG. 5 , there is shown a cross sectional view along section  5 - 5  of the electrical box  100  according to the present invention in a typical installation wherein the wall finishing material  502 , such as for example sheetrock has been installed on wall front  402 . In this view extension  113  is shown in the extended position, wherein protrusion  115  of extension  113  and cavity  117  in sidewall  104  are in cooperative engagement, thereby locking the extension  113  in place. To extend the electrical box according to the current invention, the contractor need only pull extension  113  out from the electrical box  100  and snap it in place by aligning the protrusion  115  with cavity  117 . This process is easier and less time consuming than prior art methods, which require an extension piece to be affixed to the front of the electrical box usually by screwing the extension onto the electrical box. In the extended position, it can be seen that electrical box  100  flanges  120  and  122  are aligned with the outside plane  504  of wall finishing material  502 . Furthermore, it can be seen that extension  113  extends electrical box  100  to fully cover the gap from the front open front face  112  to the outside plane  504  of finishing material  502  in conformance with electrical code requirements.  
         [0033]     Turning now to  FIG. 6 , there is shown top cross sectional view of electrical box  100  along section  6 - 6  of  FIG. 1 . In this view, extension  113  is shown in the retracted position, wherein protrusion  115  is visible extending from extension side wall  602 , and into cavity  111  in electrical box sidewall  104 . Protrusion  115  is formed of a resilient tab that angles slightly away from the plane of extension sidewall  602  and is biased to exert a force toward sidewall  104 . In the retracted position, the extension is held in place by protrusion  115  cooperatively engaging cavity  111 .  
         [0034]     Cavity  117  is visible in sidewall  104 , located toward open from face  112  with respect to protrusion  115 . The cavity  117  corresponds in size to protrusion  115  such that when the translational movement of extension  113  moves protrusion  115  into alignment with cavity  117 , the resilient tab moves outward into cavity  117  thereby locking extension  113  in the extended position. In addition, the wall  606  of cavity  111  is angled to provide a ramp for protrusion  115  to disengage from cavity  111  when the installer exerts a force on extension  113  to pull the extension out from electrical box  100 . In this way the force required to pull out the extension is minimized, while still securely locking the extension in the retracted position prior to use.  
         [0035]     Turning now to  FIG. 7 , there is shown top cross sectional view of electrical box  100  along section  7 - 7  of  FIG. 2 . In this view, extension  113  is shown in the extended position, wherein protrusion  115  is visible extending from extension sidewall  602 , into cavity  117  thereby locking extension  113  in the extended position. As is depicted in  FIGS. 6 and 7 , the distance  702  that extension  113  extends from open front face  112  corresponds to the positioning of protrusion  115  and cavity  117 . The placement of protrusion  115  can thus be modified to provide for a longer or shorter extension distance  702 . The closer to the inside edge  704  of extension  113  that protrusion is placed, the longer the distance  702  from open front face  112  of electrical box  100  to the extension front edge  706 . In this way, the electrical box  100  according to the present invention can be adapted to use for various thickness finishing material  502 . It is typical that sheetrock of ½″, ⅝″ or ¾″ is used in most applications, however other variations are possible. For example, the electrical box  100  according to the current invention can be adapted for use where sheetrock is overlaid with another material such as ceramic or stone tile. In this type of application, protrusions  115  will be located on extension sidewall  602  at a distance from inside edge  704  such that extension  113  extends to a distance corresponding to the depth of the finish material layers  502 .  
         [0036]     Turning now to  FIG. 8 , there is shown a front perspective view of the electrical box  100  according to the current invention. Shown in this view is the electrical box interior  110 . In this view, knockouts  114  are visible on the top  106  and bottom  108  of electrical box  100 . All knockouts on the box according to the present invention are design to withstand the conditions specific to the use of electrical boxes in a concrete wall. All knockouts  114  are punched to the outside of electrical box  100 , to prevent the knockout opening from the force of the poured concrete pressing against the outside of the electrical box during construction. Furthermore, as previously mentioned, knockouts  114  incorporate a smaller oval or oblong shaped knockout  127  located centrally within knockouts  114 . Knockouts  127  are punched to the inside of the box to facilitate its opening by the contractor, and are adapted to receive a flat head screw driver blade. The contractor installing an electrical box according to the current invention can therefore have a sealed electrical box that will prevent concrete from infiltrating into the box interior  110 . Once the contractor has removed knockout  127  the contractor can use the oblong hole obtained to pry open knockout  114  with a screw driver.  
         [0037]     Also shown in  FIG. 8  is tab  804  for mounting grounding screws  806 , located on back wall  102 . Tab  804  is comprised of a frangible slit  808  on back wall  102 . The tab  804  provides the contractor with additional room to secure the ground wire to the electrical box, once the concrete has been poured and hardened. In typical conditions it is difficult to screw the grounding screws in fully to where the head touches the bottom of the box because the screw cannot penetrate the hardened concrete outside the box. To eliminate that difficulty, tab  804  in the electrical box  100  according to the present invention can be bent forward by the user after the box is installed and the concrete hardened. In that way, there will be enough room behind the screws to fully screw in the grounding screws and affix the ground wires.  
         [0038]     Turning to  FIG. 9  there is a shown a close-up view of side view  9 A and top view  9 B of nails  116  and  118  used to secure electrical box  100  to a concrete form by driving the nails into the form prior to the concrete being poured. Each nail  116 ,  118  is scored  121  to create stress raiser. In side view  9 A, the score  121  is shown as a “v” shaped cut extending partially through the shank of nails  116  and  118  and creates a stress raiser, which can be seen in  FIG. 9B  as a slit in the side of nails  116  and  118 . The stress raiser is used to facilitate breaking the nail after the form has been removed and the electrical box  100  set in concrete. To that end, the score mark  121  is positioned along the nails&#39; length such that it corresponds to the open front face  112  when the nail is fully extended into the form. In that way, when the form is removed, the score mark is even with the cured concrete and can be broken off flush with the concrete wall.  
         [0039]     Turning now to  FIG. 10 , there is shown top cross sectional view of an alternate embodiment of electrical box  100  along section  6 - 6  of  FIG. 1 . In this view, extension  113  is shown in the retracted position, wherein protrusion  115  is visible extending from extension side wall  602 , and bearing against electrical box sidewall  104 . Protrusion  115  is formed of a resilient tab that angles slightly away from the plane of extension sidewall  602  and is biased to exert a force against sidewall  104 . In the retracted position, the extension is held in place by the friction between protrusion  115  and sidewall  104 .  
         [0040]     Cavity  117  is visible in sidewall  104 , located toward open from face  112  with respect to protrusion  115 . The cavity  117  corresponds in size to protrusion  115  such that when the translational movement of extension  113  moves protrusion  115  into alignment with cavity  117 , the resilient tab moves outward into cavity  117  thereby locking extension  113  in the extended position.  
         [0041]     Turning now to  FIG. 11 , there is shown top cross sectional view of electrical box  100  along section  7 - 7  of  FIG. 2 . In this view, extension  113  is shown in the extended position, wherein protrusion  115  is visible extending from extension sidewall  602 , into cavity  117  thereby locking extension  113  in the extended position. As is depicted in  FIGS. 6 and 7 , the distance  702  that extension  113  extends from open front face  112  corresponds to the positioning of protrusion  115  and cavity  117 . The placement of protrusion  115  can thus be modified to provide for a longer or shorter extension distance  702 . The closer to the inside edge  704  of extension  113  that protrusion is placed, the longer the distance  702  from open front face  112  of electrical box  100  to the extension front edge  706 . In this way, the electrical box  100  according to the present invention can be adapted to use for various thickness finishing material  502 . It is typical that sheetrock of ½″, ⅝″ or ¾″ is used in most applications, however other variations are possible. For example, the electrical box  100  according to the current invention can be adapted for use where sheetrock is overlaid with another material such as ceramic or stone tile. In this type of application, protrusions  115  will be located on extension sidewall  602  at a distance from inside edge  704  such that extension  113  extends to a distance corresponding to the depth of the finish material layers  502 .  
         [0042]     Turning now to  FIG. 12 , there is shown a perspective view of the electrical box  100  along section  6 - 6  of  FIG. 1 . In this view, extension  113  is shown in the retracted position, wherein protrusion  115  is visible extending from extension side wall  602 , and into cavity  111  in electrical box sidewall  104 . Protrusion  115  is formed of a resilient tab that angles slightly away from the plane of extension sidewall  602  and is biased to exert a force toward sidewall  104 . In the retracted position, the extension is held in place by protrusion  115  cooperatively engaging cavity  111 .  
         [0043]     Cavity  117  is visible in sidewall  104 , located toward open from face  112  with respect to protrusion  115 . The cavity  117  corresponds in size to protrusion  115  such that when the translational movement of extension  113  moves protrusion  115  into alignment with cavity  117 , the resilient tab moves outward into cavity  117  thereby locking extension  113  in the extended position. In addition, the wall  606  of cavity  111  is angled to provide a ramp for protrusion  115  to disengage from cavity  111  when the installer exerts a force on extension  113  to pull the extension out from electrical box  100 . In this way the force required to pull out the extension is minimized, while still securely locking the extension in the retracted position prior to use.  
         [0044]     Turning now to  FIG. 13 , there is shown a perspective cross sectional view of electrical box  100  along section  7 - 7  of  FIG. 2 . In this view, extension  113  is shown in the extended position, wherein protrusion  115  is visible extending from extension sidewall  602 , into cavity  117  thereby locking extension  113  in the extended position. As is depicted in  FIGS. 6 and 7 , the distance  702  that extension  113  extends from open front face  112  corresponds to the positioning of protrusion  115  and cavity  117 . The placement of protrusion  115  can thus be modified to provide for a longer or shorter extension distance  702 . The closer to the inside edge  704  of extension  113  that protrusion is placed, the longer the distance  702  from open front face  112  of electrical box  100  to the extension front edge  706 . In this way, the electrical box  100  according to the present invention can be adapted to use for various thickness finishing material  502 . It is typical that sheetrock of ½″, ⅝″ or ¾″ is used in most applications, however other variations are possible. For example, the electrical box  100  according to the current invention can be adapted for use where sheetrock is overlaid with another material such as ceramic or stone tile. In this type of application, protrusions  115  will be located on extension sidewall  602  at a distance from inside edge  704  such that extension  113  extends to a distance corresponding to the depth of the finish material layers  502 .  
         [0045]     It will be appreciated that the present invention has been described herein with reference to certain preferred or exemplary embodiments. The preferred or exemplary embodiments described herein may be modified, changed, added to or deviated from without departing from the intent, spirit and scope of the present invention. It is intended that all such additions, modifications, amendments, and/or deviations be included within the scope of the claims appended hereto.

Technology Classification (CPC): 7