Abstract:
A junction box assembly for weather-resistant installations is disclosed including a junction box ( 100 ) and an extension ring ( 116, 216 ) adapted to attach with an component such as an alarm signaling unit ( 118, 218 ). The junction box assembly enables a relatively uniform compressive force about the periphery of the alarm signaling unit, such that a good, weather resistant seal is produced between a sealing surface ( 159, 259 ) on the alarm signaling unit and a mounting surface ( 161 ). In an embodiment of the assembly the extension ring ( 216 ) includes a flange ( 244 ) that attaches to the junction box, an large aperture ( 247 ) providing access to the interior of the junction box, and a mounting plate ( 266 ) including a threaded aperture ( 254 ) that is centrally located to align with a mounting aperture ( 242 ) in the alarm signaling unit. A gasket ( 219 ) may be provided between the signaling unit and the sealing surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of U.S. Provisional Application No. 60/389,155, filed Jun. 14, 2002, the benefit of which is hereby claimed under 35 U.S.C. § 119 and incorporated herein by reference. 

   FIELD OF THE INVENTION 
   The present invention relates generally to extension rings and, more particularly, to extension rings for weather-resistant mounting of electrical components, such as alarm signaling units. 
   BACKGROUND OF THE INVENTION 
   Conventional electrical junction boxes are four inches square (i.e., four inches on a side) and two and one-eighth inches deep. In approximately 1978, fire alarm signaling units of the type including a strobe light and either an audio speaker or chimes, sometimes called speaker-strobe or chime-strobe alarm signaling units, were introduced. Conventional junction boxes were inadequate in size to accommodate the alarm signaling units (or similar devices) and the electrical conductors necessary to power the signaling units. Accordingly, the industry began to use an extension ring in combination with a conventional junction box, as shown in FIG.  1 . 
   The extended junction box assembly  70  includes a conventional four inch by four inch by two and one-eighth inch deep junction box  71  having a four inch by four inch by one and one-half inch extension ring  72  connected thereto with screws  73  (one shown). The forward end of the extension ring  72  is provided with a pair of diagonally-opposed flanges or mounting brackets  74  for mounting a device such as an alarm signaling unit thereto (not shown). However, this extended four-inch square combination unit has been found to have a few disadvantages. In particular, the available volume inside the extended junction box assembly  70  is still often inadequate to contain both the alarm signaling unit and various electrical conductors that must be accommodated in the box for powering the particular alarm signaling unit and related components (e.g., other alarm signaling units and/or other electrical devices down the line). 
   The extension ring  72  depth is limited to one and one-half inches because the combined depth of a conventional four square junction box  71  and a one and one-half inch deep extension ring  72  is the maximum that will approximately fit in a three and one-half inch conventional stud space when mounted on a bar hanger. In fact, the combined depth of about three and three-quarters inches may cause a small but undesirable bow on the back side of the wall when mounted on a bar hanger. Furthermore, as shown in  FIG. 1 , the inner flange or ridge  75  that facilitates joining the junction box  71  and the extension ring  72 , can interfere with the conductors and terminal strip of the device as they are installed in the assembly. 
   To mitigate these problems, a second generation electrical junction box and adapter ring assembly was developed, as disclosed in U.S. Pat. No. 6,103,972, the disclosure of which is hereby expressly incorporated by reference. Referring to  FIG. 2 , the second generation junction box  10  defines a cavity  12  that is designed to receive the speaker portion  14  or other protruding structure of an alarm signaling unit  18 , such as a speaker-strobe signaling unit. An adapter or an extension ring  16  provides an interface between the junction box  10  and the alarm signaling unit  18 . 
   The junction box  10  includes a rear wall  20  and four forwardly-extending sidewall panels  22 ,  24 ,  26 , and  28 . In order to accommodate both the speaker portion  14  of the alarm signaling unit  18  and associated electrical wires and connections, and still fit within the space typically provided between a wall (e.g., sheetrock) and an interior bar hanger on which the assembly will typically be mounted, the improved junction box  10  measures approximately five inches square and two and seven-eighths inches deep. The rear wall  20  of the junction box  10  includes a number of conventional knock-outs  30 , as do the sidewalls  22 ,  24 ,  26 , and  28 , for receiving the ends of conductor-carrying conduits (not shown) and connectors (not shown). 
   The extension ring  16  includes a substantially square peripheral flange  44 , each side of which is approximately five inches in length and one-half inch wide, so as to define an approximately four inch square opening  47  for receiving the speaker portion  14  of the signaling unit  18 . Screw slots  46  and  48  are provided in the flange  44  and are positioned so that at least two of the slots will align with screw holes in two of four mounting brackets  50  provided on the front edges of two sidewalls  22  and  26  of the junction box  10 . An approximately four inch square flange or wall  52  extends forwardly from the flange  44 . Mounting brackets  54  are provided in two diagonally opposite corners so as to align with two of the mounting screw holes  42  in the conventional alarm signaling unit  18 . 
   To assemble the second generation junction box  10  and extension ring  16  to the signaling unit  18 , the extension ring  16  is first mounted on the junction box  10  via screws  56  which extend through slots  46  or  48  in the flange  44  of the extension ring  16  and through the holes in mounting brackets  50  on the front five inch square peripheral edge of the junction box  10 . The alarm signaling unit  18  is mounted to the extension ring  16  with screws  58  extending through two diagonally-opposed mounting holes  42  in the front grill panel  60  of the alarm signaling unit  18  and into the aligned holes of two diagonally-opposed, aligned mounting brackets  54  of the extension ring  16 , wherein the speaker portion  14  extends into the cavity  12  in the junction box  10 . As the screws  58  are tightened, a sealing surface  59  of the signaling unit  18  is pressed against a mounting surface  61 , such as an interior wall. As so assembled, the enlarged area in the cavity  12  of the junction box  10  will accommodate the speaker portion  14  and a relatively large number of conductors (not shown), some of which will attach to the speaker portion  14 , and others of which will then pass through the junction box  10  and on to the next alarm signaling unit (or other electrical device) down the line, thereby avoiding the need for multiple junction boxes. 
   Although this second generation junction box  10  and extension ring  16  are effective for dry and/or interior applications, there remains a need for a junction box assembly that provides a semi-flush or flush mounted, weather-resistant exterior installation of alarms and the like. It was found that when the signaling unit  18  is mounted to a mounting surface  61  through the use of two diagonally opposed mounting brackets  54 , as shown in  FIG. 2 , it is difficult to achieve a weather-resistant seal between the sealing surface  59  and the mounting surface  61 . The diagonal connections do not provide a uniform force about the perimeter of the signaling unit  18 , and may cause the signaling unit  18  to distort slightly, diminishing the ability of the sealing surface  59  to form a contaminate- and weather-resistant seal upon the mounting surface  61 . Thus, water and other contaminates may infiltrate the signaling unit  18  and electrical components contained within the junction box  10 . Contaminate infiltration may provide a safety hazard, as it may cause electrical shorts resulting in a fire or may cause the signaling unit to become inoperative, in addition to causing costly component damage. 
   In many prior art installations a weather-resistant seal is provided by using a specifically designed box adapted to receive the signaling unit (or similar device). Such boxes are designed to mount directly to an exterior surface of a building. A disadvantage to these prior art boxes is that they protrude relatively far from the wall, and they require the conduit coupled to the junction box to be run along an exterior surface of the wall. Such exterior mounted conduit is unsightly and susceptible to impact damage. 
   Similarly, there is a need for an extension ring compatible for use with alarm signaling units  18  having only a single mounting aperture. For example, the extension ring  16  pictured in  FIG. 2  is incompatible with certain alarm signaling units of the type having a single, centrally located mounting aperture. 
   Accordingly, it is an object of the present invention to provide an electrical junction box extension ring which will permit the convenient and contaminate resistant mounting of an alarm signaling unit upon a mounting surface. 
   Another object of the present invention is to provide an electrical junction box extension ring, which permits the mounting of a signaling unit having a single mounting aperture to an electrical junction box. 
   SUMMARY OF THE INVENTION 
   The foregoing and other objects of the present invention have been realized by providing a junction box having a generally square rear panel and four sidewall panels defining a box that is open at the front end. An extension ring or adaptor is removably attachable to the junction box, generally over the open front end. The extension ring is adapted to engage a component such as an alarm signaling unit having a front panel, such that a relatively uniform sealing force can be applied about the periphery of the front panel, to produce a weather resistant seal. 
   In an embodiment of the invention the extension ring includes a square outer flange portion and a center portion having a large aperture and a transverse plate including a small threaded aperture, the threaded aperture adapted to receive a mounting screw that is inserted through a corresponding aperture in the alarm signaling unit, to attach the alarm signaling unit to the extension ring. 
   In an embodiment of the invention the extension ring is formed from a unitary panel. 
   In an embodiment of the invention a rearwardly extending portion of the alarm signaling unit extends through the large aperture in the extension ring and into the junction box. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is a perspective view of a prior art extended junction box; 
       FIG. 2  is an exploded perspective view of a prior art second generation extension ring in combination with a junction box and an alarm signaling unit; 
       FIG. 3  is an exploded perspective view of one embodiment of a junction box assembly formed in accordance with the present invention, shown as a combination including an extension ring, a junction box and an alarm signaling unit; 
       FIG. 4  is a perspective view of the extension ring shown in  FIG. 3 ; 
       FIG. 5  is an exploded perspective view of an alternate embodiment of a junction box assembly, including an extension ring formed in accordance with the present invention, a junction box and an alarm signaling unit; and 
       FIG. 6  is a perspective view of the extension ring shown in FIG.  5 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   One embodiment of a junction box assembly, and in particular, an extension ring  116  formed in accordance with the present invention is illustrated in  FIGS. 3 and 4 . Referring to  FIG. 3 , the improved extension ring  116  provides an interface between a junction box  100  and an alarm signaling unit  118 , such as a speaker-strobe signaling unit. The advantages of the extension ring  116  will become more readily appreciated in comparison to a junction box  100  that will be described first, followed by a discussion of the extension ring  116 . 
   The junction box  100  defines a cavity  112  that is designed to receive the wires and a speaker portion  114  or other protruding structure of the signaling unit  118 . The cavity  112  is defined by a rear wall  120  and four forwardly-extending sidewalls  122 ,  124 ,  126 , and  128 . In order to accommodate both the speaker portion  114  of the signaling unit  118  and various electrical wires and still fit within the space typically provided between the wall and interior bar hanger on which the assembly will typically be mounted, the junction box  100  measures approximately five inches square and two and seven-eighths inches deep. 
   The rear wall  120  of the junction box  100  includes a number of conventional knock-outs  130 , as do the sidewalls  122 ,  124 ,  126 , and  128 , for receiving the ends of conductor-carrying conduits (not shown) and/or connectors (not shown) therefore. The rear wall  120  of the junction box  100  also includes a plurality of mounting holes (not shown) for accommodating screws to mount the junction box  100  on a bar hanger or other structure (not shown). 
   Still referring to  FIG. 3 , and also to  FIG. 4 , which shows a perspective view of the extension ring  116  in isolation, it can be seen that the extension ring  116  serves as an adapter by providing an interface connection between the approximately five inch square junction box  100  and the mounting screw holes  142  provided in the alarm signaling unit  118 , where the mounting holes  142  are spaced to form a square mounting pattern. The extension ring  116  includes a substantially square peripheral flange  144 , each side of which is approximately five inches in length and one-half an inch wide, so as to define an approximately four inch square opening for receiving the speaker portion  114  of the signaling unit  118 . Screw slots  146  and  148  are provided in the flange  144  and are positioned so that at least two of the slots will align with screw holes in two of four mounting brackets  150  provided around the periphery of the front edge of the junction box  100 . An approximately four inch square flange or wall  152  extends forwardly from the flange  144 . In a preferred embodiment the wall  152  extends approximately five-eighths of an inch from the flange; however, the wall  152  may extend a greater or lessor distance from the flange  144  to accommodate different applications, including, for example zero inches or one and a half inches. Four mounting brackets  154  are provided, one located in each corner, so as to align with four diagonally-opposed screw holes  142  (three shown) in the conventional signaling unit  118 . 
   The mounting brackets  154  may be formed as an integral part of the wall  152 —for example, by bending a tab portion inwardly. An aperture  151  is provided, generally near the center of each mounting bracket  154 , and is preferably threaded to receive mounting screws  158 . The mounting brackets  154  may be fixedly attached to two adjacent portions of the wall  152  in a corner, as shown in FIG.  4 . It will be apparent to one of skill in the art that attaching the mounting brackets  154  to two sidewalls will improve the rigidity of both the mounting brackets  154  and the extension ring  116 , as well as ensure precise center-to-center dimensions of the apertures  151  so as to accurately align with the four diagonally-opposed mounting holes  142  in the front grill panel  160  of the signaling unit  118 . 
   To assemble the improved extension ring  116 , junction box  100 , and a conventional signaling unit  118 , the extension ring  116  is first mounted on the junction box  100  with screws  156  that extend through slots  146  or  148  in the flange  144  of the extension ring and through the screw holes in the mounting brackets  150  of the junction box  100 . The signaling unit  118  is then mounted to the extension ring  116  via four mounting screws  158  extending through the four diagonally-opposed mounting holes  142  (three shown) in the front grill panel  160  of the signaling unit  118  and into the aligned holes  151  of four diagonally-opposed, aligned mounting flanges  154  of the extension ring, with a protruding structure of the signaling unit  118 , such as a horn or a speaker  114 , extending into the cavity  112  in the junction box  100 . As the screws  158  are tightened, a sealing surface  159 , that may include a gasket (not shown), is pressed against a mounting surface  161 , such as an exterior surface of an exterior wall. As so assembled, the enlarged area in the cavity  112  of the junction box  100  will accommodate the speaker  114  and a relatively large number of conductors. 
   It will be appreciated that by providing tightening screws at all four corners, a relatively tight, weather-resistant seal may be achieved between the mounting surface  161  and the signaling unit  118 . The signaling unit  118  may therefore be mounted to a mounting surface  161  to impede the entrance of contaminates, such as liquids, air with entrained moisture, and particulates. More specifically, in previous extension rings, only two mounting brackets  154  were used to couple the signaling unit  118  to the extension ring, thereby resulting in an inadequate seal. In the illustrated embodiment of the invention, four mounting brackets  154  are provided, one located in each corner of the extension ring  116 . 
   Moreover, by providing four mounting brackets  154 , with one located in each corner of the extension ring  116 , the distortion of the signaling unit  118  during tightening of the mounting screws  158  is substantially reduced and a tight seal about the entire circumference of the signaling unit  118  can be achieved. Therefore, the weather-resistant seal of the seating surface  159  of the signaling unit  118  upon the mounting surface  161  is substantially maintained. Thus, water and other contaminates are impeded from infiltrating the signaling unit  118  and electrical components contained within the junction box  100 . 
   Referring now to  FIGS. 5 and 6 , an alternate embodiment of an extension ring  216  formed in accordance with the present invention is depicted. The extension ring  216  of this alternate embodiment provides an interface adapter between a five-inch square junction box  100 , as described above, and an alternative signaling unit  218  having a single mounting screw hole  242 , are known in the art. 
   The type of signaling unit typified by signaling unit  218  is typically provided with a rear box member (not shown) that is adapted to be attached to the signaling unit  218  to define an enclosure. Such an enclosure assembly, however, must be mounted to a surface, such as a wall, and therefore projects out significantly from the wall, and anticipates that the conduit to the signaling unit  218  will be positioned, at least in part, externally to the wall, Such prior art assemblies can be aesthetically unpleasing, and exposes the conduit and entire assembly to the elements. The present invention permits an internal junction box  100  to be used for mounting the signaling unit  218  to an exterior wall, while still providing a generally weather-resistant seal for the signaling unit  218 . 
   Previous extension rings are incompatible for use with signaling units  218  having a centrally located mounting screw hole  242 . For example, the extension ring  16  pictured in  FIG. 2  is incompatible with a signaling unit having a centrally located mounting aperture, typically located a small distance vertically above the center of the signaling unit  218 . The extension ring  216  of the illustrated alternate embodiment solves this problem by providing an extension ring  216  that incorporates a centrally located mounting aperture  254 . 
   The extension ring  216 , includes a substantially square peripheral flange  244 , each side of which is approximately five inches in length and one-half an inch wide. Screw slots  246  and  248  are provided in the flange  244  and are positioned so that at least two of the slots  246 ,  248  will align with screw holes in two of four mounting brackets  150  provided around the periphery of a front edge of a junction box  100 . An approximately four inch square flange or tube  251  formed from four sidewalls  252  extends forwardly from the flange  244 . In the illustrated embodiment, the sidewalls  252  extend approximately five-eighths of an inch from the flange; however, it shall be apparent that the sidewalls  252  may extend any distance from the flange  244 , including zero inches, one-half inch three-quarters of an inch, one and a half inches, etc. A rectangular-shaped mounting panel or a transverse plate  266  extends generally between two of the side walls  252  of the extension ring  216  so as to define an approximately three and one half inch by two and one quarter inch rectangular opening  247  for receiving a protruding portion  214  of a signaling unit  218 , such as a horn. A mounting aperture  254  is provided through the mounting panel  266  so as to align with the mounting screw hole  242  of the signaling unit  218 . 
   It should now be appreciated that the central location of the mounting screw hole  242 , and corresponding mounting aperture  254  permits the signaling unit  218  to be mounted against a mounting surface  161  such that a tight seal is provided about the entire circumference of the signaling unit  218 , to enable a weather-resistant interface, similar to that discussed above. As the screw  258  is tightened, a sealing surface that may include a gasket  219  is pressed against a mounting surface  161 , such as an exterior surface of an exterior wall. 
   As should be apparent to one of skill in the art, the use of internally-mounted junction boxes, such as those of the illustrated embodiments, permit the conduit running to these junction boxes to be strung internally, underneath the mounting surface  161 , thus providing an aesthetically pleasing appearance while also impeding impact damage to the conduit. Further, a sealant, such as a well-known silicone based product, may be provided about the periphery of the signaling unit to further improve the weather-resistant characteristics of the seal. 
   While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.