Abstract:
A pan-style electrical outlet box used to secure an electrical fixture such as a light or a ceiling fan to a ceiling joist. This shallow box has a generally planar back wall bounded by a perimeter sidewall extending therefrom. Also extending from the back wall but in an opposite direction are a plurality of mounting brackets that form a joist receiving channel therebetween. Each mounting bracket is integrally molded with the box and is also configured with at least one joist engaging device so as to engage the joist and hence temporarily hold the box thereto. This permits the installer to use both hands when subsequently permanently affixing the box to the joist, such as via the fasteners supplied with the box.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/778,779, filed on Mar. 3, 2006. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention pertains to a pan type box typically used in association with ceiling joists and more particularly to a pan box having quick attachment features permitting the box to remain temporarily secured to the joist without screws or other separate fasteners prior to the mounting of the electrical fixture to the joist. 
       BACKGROUND OF THE INVENTION 
       [0003]    Pan type boxes, which are used predominately in ceilings, are quite well known in the art. They are often employed when a box of limited depth is required. This occurs mainly when the electrical fixture to be installed (i.e. light, ceiling fan, etc.) is to be mounted directly underneath a ceiling joist. Hence the fixture is generally secured directly to the joist through the box. This is to be contrasted with boxes that can be used alongside a joist or between adjacent joists. 
         [0004]    Generally, pan type boxes consist of nothing more than the box itself. They are often round and made of metal and include one or more mounting screw holes in its back wall so that a fixture fastener can pass vertically therethrough into the joist or other ceiling support. Such a box is exemplified by round ceiling fan support box bearing catalog number 56111-CFB as manufactured by The Thomas &amp; Betts Corporation. 
         [0005]    A variation on such a box is shown in U.S. Pat. No. 5,854,443. In this variation, two separate mounting brackets are attached to the back wall during box assembly. These mounting brackets extend upward away from the back wall and contain fastener openings therein so that a fastener can pass horizontally through the mounting bracket and into a side of the joist. The &#39;443 patent further necessitates a second set of fasteners that secure the box to the mounting bracket and possibly even a third set of fasteners that secures the electrical fixture to the box. Hence, the load passes from one set to the other via the box and/or mounting bracket. Consequently, multiple sets of fasteners are required to properly secure a load. 
         [0006]    Another variation is shown in U.S. Pat. No. 6,207,897. In this patent, again a pair of upright mounting brackets is secured to the back wall via a first set of fasteners during box assembly. These two brackets form a channel for receipt of a joist therein. Upon joist insertion, a second set of horizontally aligned fasteners are driven through openings in the mounting bracket into the side of the joist. Separate fasteners are then employed to secure the electrical fixture to the mounting bracket. In both this patent and the one above, the box assembly is designed so that the fixture load is transmitted via multiple fasteners sets to the mounting brackets and then to the joist itself. 
         [0007]    One feature that is common to all such pan-style boxes described above is the material they are made of. They are all metal boxes which means they are rather expensive to manufacture and hence rather costly for a consumer to purchase. 
         [0008]    It is thus an object of this invention to provide a pan type box that is considerably less expensive to manufacture and hence more affordable for the user. Another object of this invention is to provide a pan type box that features mounting brackets, but such brackets do not necessitate an additional assembly step as is required for the above described boxes. Still another object of this invention is to provide a pan type box that can be temporarily secured to the ceiling support without the need for a separate fastener prior to the installation of the electrical fixture. Yet another object of this invention is to reduce the number of separate fasteners required, and hence reduce costs, by requiring only fixture fasteners and no other separate set of fasteners to secure the load to the joist. These and other objects and advantages of this invention will become obvious upon further review and investigation. 
       SUMMARY OF THE INVENTION 
       [0009]    This invention pertains to an electrical outlet box configured with a back wall and a perimetric side wall extending in a first direction from the back wall. This back wall and this perimetric side wall define an interior volume. Also extending from this back wall, but in an opposite direction, are at least two mounting brackets. These mounting brackets along with a mid-portion of the back wall define a joist receiving channel or cavity. Configured on these mounting brackets are joist engaging structure which extend into the joist receiving cavity and engage the joist, thereby temporarily retaining the outlet box thereon. The back wall, side wall, mounting brackets and joist engaging structure are all integrally formed and of unitary construction. 
         [0010]    The outlet box is preferably non-metallic. The back wall is generally planar and the joist receiving channel and the interior volume extend on opposite sides of the back wall. 
         [0011]    The outlet box further preferably includes a screw retention arrangement configured to temporarily secure at least one screw therein. The screw retention arrangement projects into the interior volume and preferably includes a resilient tab and a fixed post integrally formed on the back wall, wherein the tab and post define a screw receiving space therebetween. 
         [0012]    In a preferred embodiment, there are two mounting brackets extending from the back wall and joist engaging structure is provided on each mounting bracket. The joist engaging structure is configured with at least one tooth for embedment into a respective side of the joist. More preferably, each mounting bracket is provided with two engagement teeth disposed at opposite longitudinal ends thereof. Each tooth is configured having a joist receiving side, which is sloped to aid in the insertion of the joist into the joist receiving channel. The tooth further includes a joist retention side opposite the joist receiving side, which intersects with the joist receiving side at a sharp point or edge. The joist retention side may extend generally perpendicular to the joist, or it may extend at a downward angle toward the bottom wall of the box. Also, at least a portion of the joist engaging structure may be aligned with indents formed in the perimetric side wall of the box, but such joist engaging structure preferably does not extend beyond the maximum width of the box interior. This is so that the box can be inserted through an existing wall opening in “rework” installations. These indents formed in the side wall of the box also permit access to the joist engaging structure with a tool, as will be discussed in further detail below. 
         [0013]    A preferred form of the electrical outlet box assembly, as well as other embodiments, objects, features and advantages of this invention, will be apparent from the following detailed description of illustrative embodiments thereof, which is to be read in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a top perspective view of the pan type box formed in accordance with the present invention. 
           [0015]      FIG. 2  is a bottom perspective view of the pan type box shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0016]    The invention, in its broadest sense, pertains to a new design for a shallow or pan type box  10  which is used to secure an electrical fixture, such as a ceiling fan or a light, to a ceiling support such as a joist. One unique feature of this box  10  is that all its various components are integrally formed or molded. In other words, it is a one-piece unitary box. Once box  10  is formed, nothing further need be attached to the box to complete its assembly other than possibly attaching removable fasteners as described herein prior to shipping. 
         [0017]    Box  10  is preferably a non-metallic box and hence is made of plastic or some other non-metallic material common in the electrical arts. Being non-metallic, box  10  can be molded rather than stamped, formed and threaded (if required) and hence is easier and cheaper to manufacture. 
         [0018]    Referring initially to  FIG. 1 , the interior volume  12  of the box  10  is defined by a planar back wall  14  and a perimetric side wall  16 . The box  10  shown in  FIGS. 1 and 2  is circular in shape and has a perimetric side wall  16  extending around the circumference of the box. However, the box  10  may take any other shape, such as square, rectangular and octagonal shapes. 
         [0019]    Box  10  may contain one or more knockouts  18  as well as one or more cable entry passageways  20 , all to be determined by the manufacturer. In the embodiment shown, the interior volume  12  of box  10  is also configured with a series of upright tabs  22  that are designed to temporarily hold a fixture fastener  24 . More particularly, and as shown in this embodiment, the upright tabs  22  preferably include at least one resilient tab  22   a  spaced apart from at least one fixed cylindrical post  22   b.  The spacing between the resilient tab  22   a  and the cylindrical post  22   b  is approximately equal to the diameter of the body of the fixture fastener  24 . Further, the resilient tab  22   a  is slightly flexible to provide a biasing force on the fixture fastener  24  against the more rigid cylindrical post  22   b.  In the preferred embodiment, shown in  FIGS. 1 and 2 , there is one resilient tab  22   a  spaced apart from two fixed cylindrical posts  22   b.  However, other combinations of fixed and resilient tabs can be utilized in the present invention. 
         [0020]    Moreover, the resilient tab  22   a  preferably includes a lip  23  for retaining the fixture fastener in the space defined between the resilient tab and the fixed post  22   b.  The lip  23  extends inwardly into the space defined between the resilient tab  22   a  and the post  22   b  and further preferably includes a downwardly chamfered surface  23   a  to facilitate and guide downward insertion of the fixture fastener  24  between the resilient tab  22   a  and the post  22   b.    
         [0021]    In a preferred embodiment, there are two sets of upright tabs  22  for retaining two fixture fasteners  24 . During installation, these fixture fasteners  24  are easily removed from tabs  22  and inserted into mounting holes  26  prior to being driven directly into a ceiling support such as a joist (not shown). The mounting holes  26  are preferably formed in integral boss portions  16   a  of the side wall  16  and extend through the box  10  from the interior side to the bottom side  28  of the box. Hence, when installed, fixture fasteners  24  permanently secure both the electrical fixture as well as the box  10  to the joist, without transferring any weight of the fixture through the box. 
         [0022]    Referring now to  FIG. 2 , the bottom side  28  of box  10  is shown. Extending across the bottom side  28  is a joist receiving channel  30  defined by a mid-portion  14   a  of the bottom side of the back wall  14  and two upstanding mounting brackets  32 . The mounting brackets  32  include opposite parallel channel walls  33  that extend upwardly from the back wall  14  of the box  10  so that the channel  30  does not bisect or extend into the interior volume  12 . The two channel walls  33  are spaced from each other sufficiently enough to permit a joist to fit therebetween and abut against the mid-portion  14   a  of the bottom side  28  of the junction box back wall  14 . 
         [0023]    In the embodiment shown, each mounting bracket  32  is a mirror image of the other and each channel wall  33  extends continuously from one side of the box  10  to the other. In particular, each channel wall  33  preferably begins at one point on the side wall  16  and extends across the back wall  14  to an opposite point on the side wall. Hence joist receiving channel  30  is fully defined therebetween. The channel wall  33  may be arched, as shown, to reduce material cost without diminishing the strength of the bracket  32 . Alternate constructions are also likely such as employing four separate uprights in or adjacent to the four corners of channel  30 . Further or additional such uprights may be employed in a mid-channel region adjacent either knockout  18  or cable entry passageway  20 . The final design of box  10  is dependent upon the manufacturer. 
         [0024]    Each longitudinal end  34  of each channel wall  33  is configured with one or more teeth or other joist engaging device  36 . Such device  36  extends into the joist receiving channel  30  and is designed to engage the joist (such as by biting into it) so as to temporarily hold box  10  in place prior to the application of fixture fasteners  24 . The ability to temporarily secure box  10  on the overhead joist is preferred so that the installer is not required to himself physically hold box  10  in place while also trying to drive fixture fasteners  24  through mounting holes  26 . Joist engaging devices  36  aid the installer by allowing him/her to release their hold on box  10  thereby enabling full attention to be paid to installing fasteners  24 . 
         [0025]    Of course, other designs for joist engaging device  36  are conceivable such as those types that do not bite or embed themselves into the joist. These types can include those that only snugly or frictionally abut the joist or are adhesively secured to the joist. 
         [0026]    In any case, all or a portion of the joist engaging device  36  preferably can be found close or adjacent to the outer perimeter or circumference of the perimetric side wall  16 . Ideally, such joist engaging devices  36  do not extend beyond the maximum width of the interior  12  of the box so as to enable the box  10  to be inserted into existing wall or ceiling openings. However, such devices  36  can project beyond such dimension if so desired. It has been found that maximally spacing the engagement teeth  36  in this manner provides the most stable attachment of the box  10  to the joist. Also, the end  34  of the mounting bracket  32  is preferably provided with an angled web portion  37  which projects upwardly from the back wall  14  and supports the engagement device  36  in its outward location. 
         [0027]    As mentioned above, the joist engaging device  36  is preferably designed as a tooth so as to readily permit the insertion of a joist therein but not necessarily its ready removal. Thus, the insertion and retention of the joist is preferably accomplished by sloping or chamfering an upper side  38  of the tooth  36  to form an alignment guide on the tooth for inserting the joist into channel  30  while the opposite lower side  40  of device  36  is formed generally at a right angle to the joist, or is angled downwardly toward the back wall  14  to form a stop which resists the removal of the joist from channel  30 . The intersection of the sloped upper side  38  and the opposite lower side  40  forms a sharp point or edge  39  adapted to embed or “bite” into a joist. 
         [0028]    Removal of the box  10 , such as to move the box to another location along the joist or to another joist altogether, is accomplished by prying the devices  36  from the joist with a screwdriver or the like. To facilitate such prying, indents  16   b  are preferably formed in the perimetric side wall  16  adjacent the engagement teeth  36  to permit access to the teeth with a screwdriver or other tool. More specifically, the perimetric side wall  16  preferably diverts inwardly toward the center of the box  10  at locations adjacent the teeth  36  to provide a clear path to the engagement teeth for a screwdriver or other tool. 
         [0029]      FIG. 2  shows multiple openings  26  and  42  in the mid-portion  14   a  of bottom wall  14  that forms the bottom of joist receiving channel  30 . Some such openings are the openings for mounting holes  26  while the other openings  42  are simply the result of molding the upright tabs  22  on the opposite side. As described above, fasteners are intended to pass through the fixture securing openings  26  and not the upright tab openings  42 . 
         [0030]    One feature that sets this design apart from that already known is the ability to integrate the joist receiving channel with the box itself into a single integral component. Such a design eliminates any subsequent manufacturing step such as the step of attaching additional components to the box once it is formed (other than, perhaps the step of attaching the fixture fasteners  24 ). Further, the creation of joist engaging devices  36  on channel walls  32  is also formed integral with box  10  and does not require any additional manufacturing step to achieve. 
         [0031]    While select preferred embodiments of this invention have been illustrated, many modifications may occur to those skilled in the art and therefore it is to be understood that these modifications are incorporated within these embodiments as fully as if they were fully illustrated and described herein.