Abstract:
A molded plastic outlet box for electric busway systems comprising: a molded plastic base comprising a plurality of press-fit tabs for attachment of the base to a housing of the electric busway system disposed about a bottom surface of the base.

Description:
BACKGROUND 
   1. Field 
   The present disclosure generally relates to molded plastic outlet boxes which are attached to an electric busway power distribution system at each location along the system, wherein the outlet boxes comprise press fit connectors for connecting each outlet box to an aluminum housing of the electric busway. Preferably, each outlet box include wings on each side thereof to provide a snap-fit retention against the side walls of the aluminum busway housing. 
   2. Discussion of the Background Art 
   Electric busway distribution systems comprise a plurality of rectangular bus bar conductors arranged within a metallic housing for providing electric power to industrial buildings. Every two feet or so, the bus bars are provided with upstanding contact blades to allow for connection with a power take-off assembly. One such power distribution system is described within U.S. Pat. No. 4,758,172 filed Oct. 13, 1987 entitled “Power Distribution Busway System”. This patent application describes contact blades extending from the individual phases of a multi-phase power distribution system that are arranged for electrical connection with a power take-off assembly. In this arrangement, the contact blades are formed from the bus bar conductors themselves. U.S. patent application Ser. No. 203,751 entitled “Insulated Electrical Power Distribution Busway Tabs” describes the use of off-set tabs welded to the individual bus bars to provide the stabs for connecting with power take-off assemblies. U.S. patent application Ser. No. 122,863 filed Nov. 19, 1987 entitled “Thermally Efficient Power Busway Housing” describes a power busway housing design that is used with the molded case outlet box of the instant invention. All of the aforementioned U.S. patent applications are incorporated herein for purposes of reference. 
   U.S. Pat. No. 4,714,431 entitled “Electrical Distribution System Having an Improved Plug-In Assembly for Current Tap-Off” describes the bus bar conductors that are spaced apart at periodic intervals for the insertion of the receiver stabs. The base portion of the plug-in assembly includes insulating means extending between the individual bus bars for electric isolation. 
   U.S. Pat. No. 4,820,178, which is incorporated herein by reference in its entirety discloses a conventional outlet box for use with an electric busway system which affixed to the aluminum housing via four (4) screws.  FIG. 1  describes such a conventions electric busway system, wherein the bus conductors  11  of the type consisting of a rectangular bar  12  of aluminum or copper are each provided with an electrically insulating epoxy coating  13  and are arranged within a continuous housing  14  consisting of first and second side frames  15 ,  16  which support the bus bars as well as provide ground conduction to the busway section. The bus bars are not “bumped” or otherwise separated at each plug-in section as indicated at  7  and  8  herein to facilitate connection with a power take-off assembly (not shown). Instead, welded contact blade tabs such as  20 - 23  are off-set from each other to accommodate connection with the power take-off assemblies. The contact blade tabs that are welded to the individual bus bars and the epoxy coating is removed from a part of the tabs to provide good electrical connection therewith. The contact blade tabs extend above the cross-piece  18  that joins the upstanding rails  17  on the first and second side frames  15 ,  16  that make up the busway section  10  through corresponding cross-piece slots  19 . The busway sections and bus bars are fastened together by means of thru-bolts  9  provided through the busway section where the plug-in sections  7 ,  8  are located. In order to electrically isolate the upstanding contact blade tabs  20 - 23 , a molded plastic plug-in enclosure  6  is arranged over the contact blade tabs by means of threaded openings  26  formed on the cross-piece  18  and by means of bolts or screws  24  and thru-holes  25 . One such molded plastic plug-in enclosure already attached to the plug-in section  8  is depicted at  6 ′ to indicate the electrical isolation of the contact blade tabs  20 - 23  therein. The plug-in enclosure  6  consists of a molded plastic base  27  formed from a phenylene-oxide plastic sold by General Electric Company under the trademark “NORYL” or a polybutylene terepthalate which is sold under the General Electric trademark “Valox”. The base is molded to include a planar bottom, not shown, through which the thru-holes  25  are formed. Also formed within the planar top are opposing channels, not shown, which accommodate a ground lug that is separately attached to the busway section  10  along the cross-piece  18 . A molded plastic cover  40 , which includes a planar top portion  40 A and downwardly depending side portions  40 B and  40 C, is attached to the base  27  by means of a pivot post  41  integrally formed therein and extending between a pair of tabs  42 ,  43 . The cover is attached to the base by positioning the pivot post  41  under a pair of curvilinear projections  32  extending from the planar top  33 . 
   The above busway plug-in outlet insulator utilizes four screws or bolts  24  to mount the outlet to aluminum housing or busway  10 . Such mechanical mounting of the outlet to the housing or busway via screws or bolts is very disadvantageous and requires a substantial increase in manufacturing labor and materials. The present disclosure overcomes these disadvantages by providing a easy mounting devices to allow for rapid and cost effective mounting of the outlet to the housing or busway, without the need for extensive labor required by conventional systems to screw mount the outlet via four (4) bolts. 
   The present disclosure also provides many additional advantages, which shall become apparent as described below. 
   SUMMARY 
   A molded plastic outlet box for electric busway systems comprising: a molded plastic base comprising a plurality of press-fit tabs for attachment of said base to a housing of said electric busway system disposed about a bottom surface of said base. Preferably, the press-fit tabs are integrally molded together with said outlet box. The press-fit tabs are typically disposed about the four corners of said base. 
   The press-fit tabs are disposed perpendicular to said base towards said housing, and wherein said housing includes thru-holes for securably receiving said press-fit tabs. Preferably, the press-fit tab comprising a post and an end tab for securably affixing said outlet box to said housing. 
   Optionally, the base of the outlet box comprises a plurality of press-fit wings disposed on opposite sides of said base so that they are positioned adjacent to oppositely disposed sidewalls of said housing. 
   Furthermore, the base comprises a planar surface at a top surface thereof, said planar surface having a plurality of slots extending therethrough coextensive with associated bus bar contact blades extending from said busway system, said base further including a pair of side members extending downwardly from said planar surface. 
   The base preferably includes a molded plastic cover hingably and removably attached to one end of said top surface thereof by a hinge pin; and a pair of first arcuate projections integrally formed on said top surface at said one end, said hinge pin being trapped under said first arcuate projections in press-fit relation therewith for holding said cover in an open position on said one end of said top surface. 
   It is also an embodiment according to the present invention, wherein a gasket is disposed between said base of said outlet box and an adjacent surface of said housing to provide drip-proofing and/or splash-proofing for required applications. 
   Further objects, features and advantages of the present disclosure will be understood by reference to the following drawings and detailed description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded right side perspective view of a conventional outlet box mounted on an electric busway according to the prior art; 
       FIG. 2  is top right side perspective view of an outlet box according to the present disclosure depicting the side mounted press-fit wings; 
       FIG. 3  is a end view of the busway housing with outlet attached showing engagement between housing and outlet; 
       FIG. 4  is a bottom left side perspective view of the outlet box of  FIG. 2  with insulation disposed thereabout; 
       FIG. 5  is a bottom left side perspective view of the outlet box of  FIG. 2  without insulation depicting both the side mounted press-fit wings and four press-fit tabs disposed about the four corners thereof, together with a portion view of the left side tabs; and 
       FIG. 6  is a front top perspective view of an outlet box according to the present disclosure mounted within a busway aluminum housing with a top door affixed thereto. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The present disclosure can best be describe by reference to the figures, wherein  FIGS. 2-6  include plug-in outlet box  50  as depicted in  FIG. 2  includes a molded plastic base  27  formed from a phenylene-oxide plastic sold by General Electric Company under the trademark “NORYL” or a polybutylene terepthalate which is sold under the General Electric trademark “Valox”. The base is molded to include a planar bottom  28  to which press-fit tabs  52  are preferable molded perpendicular thereto for securing to outlet box  50  to a busway aluminum housing, not shown. A planar top portion  33  defines a plurality of rectangular slots  34 - 37  that are off-set from each other to accommodate the upstanding contact blade tabs, not shown. Also formed within the planar top  33  are opposing channels  38 ,  39  which accommodate a ground lug that is separately attached to the busway section along the cross-piece  18  described earlier with reference to  FIG. 1 . A molded plastic cover  40 , which includes a planar top portion  40 A and downwardly depending side portions  40 B and  40 C, is attached to the base  27  by means of a pivot post  41  integrally formed therein and extending between a pair of tabs  42 ,  43 , as shown in  FIG. 1 . The cover is attached to the base by positioning the pivot post  41  under a pair of curvilinear projections  32  extending from the planar top  33 . A clearance slot  44  is defined between the pivot post  41  and the planar surface  40 A of the cover to allow for the insertion of the curvilinear projections. 
   Preferably plug-in outlet box  50  includes side mounted press-fit wings  54  which allow for box  50  to be press-fit within the busway aluminum housing. Press-fit wings  54  may be formed from any material, but preferably is a plastic material which allows it to single form molded together with outlet box  50  and allows for flexible mounting to the busway aluminum housing. Similarly, press-fit tabs  52  can be the same or different material as outlet box  50  and/or press-fit wings  54 . Tabs  52  are preferably formed perpendicular to planar top  33  of outlet box  50  having a rectangularly shaped post  55  with a securing means or locking tab  56  disposed about the end of post  55  opposite to planar top  33 , as best show in the cut-out of  FIG. 5 . Press-fit wings  54  are disposed along planar bottom  28  of outlet box  50  upwards at an angle adequate to secure to aluminum housing ( 14 ), with bent  58  portion at the outer edge thereof. 
   Optionally, an insulating gasket  60  as show in  FIG. 4 , can be disposed on the bottom portion of outlet box  50  to interface with the busway housing for splash proof and drip-proof applications. For indoor applications no gasket  60  is typically required. 
     FIG. 3  depicts wings  54  engage aluminum housing  14  to provide downward pressure. Outlet tabs  52  provide lateral and longitudinal positioning and locking of outlet  50  to aluminum housing  14 . 
   While we have shown and described several embodiments in accordance with our invention, it is to be clearly understood that the same may be susceptible to numerous changes apparent to one skilled in the art. Therefore, we do not wish to be limited to the details shown and described but intend to show all changes and modifications that come within the scope of the appended claims.