Abstract:
A circuit breaker lighting panelboard is adapted for both top and bottom feed connections with no field modification requirements. The panelboard interior accepts a variety of branch circuit breaker mounting arrangements and the mounting rails are interconnected by steel straps to reduce shipment damage.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to circuit breakers, and, more particularly, to a modular circuit breaker and modular lighting panelboard for field assembly. 
     Lighting panelboards that are modularly assembled in a factory environment are described in U.S. Pat. No. 4,783,718 entitled Lighting Circuit Breaker Panelboard Modular Assembly, wherein the benefits of computer technology relating to the inventory of parts and simplification of manufacture are fully described. Circuit breakers that are modularly assembled in such a factory environment are disclosed in U.S. Pat. No. 4,713,728 entitled Lighting Circuit Breaker Panelboard Modular Assembly. It has since been determined that the modular concept of panelboard enclosure assembly and circuit breaker assembly can be extended to field installation of new panelboard assemblies as well as field modification of existing panelboard assemblies. 
     A more recent example of a field-installable panelboard assembly is described in U.S. Pat. No. 5,343,356 entitled Panelboard, and a recent example of a modular circuit breaker arrangement for field assembly is found in U.S. Pat. No. 5,351,165 entitled Main Circuit Breaker or Other Circuit Protection Device Connector Installation Kit for Panelboards. 
     SUMMARY OF THE INVENTION 
     In an exemplary embodiment of the invention, a circuit breaker lighting panelboard is adapted for both top and bottom feed connections with no field modification requirements. The panelboard interior accepts a variety of branch circuit breaker mounting arrangements and the mounting rails are interconnected by steel straps to reduce shipment damage. The main circuit breaker support arrangement is not integrated with the branch circuit breaker mounting arrangement to allow field installation of a wide variety of main circuit breakers. 
     The field panelboard installation design includes facilities for converting the panelboard from top to bottom feed, upgrading the panelboard to a two hundred percent neutral rating and changing the main circuit breaker assemblies. The invention provides a panelboard assembly that is amenable to field installation without requiring complete disassembly. The main circuit breaker of the invention provides a configuration that can be employed within a wide variety of existing panelboard assemblies and facilitate connection between the branch circuit breakers contained therein. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front perspective view of a branch circuit breaker support arrangement of the invention with the support components in isometric projection; 
     FIG. 2 is a top perspective view of the branch circuit breaker support arrangement of FIG. 1 prior to attaching the circuit breaker face plate; 
     FIG. 3 is a top perspective view of the split neutral bar with the components arranged in isometric projection; 
     FIG. 4 is a top perspective view of the split neutral assembly of FIG. 3; 
     FIG. 5 is a top perspective view of the main circuit breaker support assembly of the invention with the components arranged in isometric projection; and 
     FIG. 6 is a front perspective view of the panelboard interior with the components arranged in isometric projection. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a branch circuit breaker support assembly is shown at  10  prior to attaching a branch circuit breaker assembly  11  and lug extrusions  19  to support plates  21 . The branch circuit breaker assembly  11  is similar to that described in the aforementioned U.S. Pat. No. 4,783,718 (which is incorporated by reference) and consists of integrally-formed circuit breaker support hooks  12  and upstanding insulators  13  arranged between appositely arranged bus supports  14 . Three bus bars  15  extend beneath the branch circuit breaker assembly  11 , with each one of the bus bars being arranged for connection with one phase of a three phase electric distribution system. As would occur a person of skill in the art, a different number of busbars can be utilized depending on the number of phases being supplied. Lug extrusions  19  are joined by a pair of neutral lug cross-over straps  16  that include a pair of upstanding sidewalls  17 ,  18  at the opposite ends thereof. Both lug extrusions  19  are attached to support plates  21  prior to capturing the opposite sides of the branch circuit breaker assembly  11  within the subjacent upstanding sidewalls  17 ,  18  and attaching upstanding shield supports  20  to the opposite ends of the support plates  21 . 
     Referring to FIG. 2, the arrangement of the branch circuit breaker assembly  11  subjacent a face plate  22 , and intermediate a neutral lug support plate  27  and a main circuit breaker support plate  28 , is shown. The bus bars  15  extend towards the main circuit breaker support plate and carry main circuit breaker bolt connectors  30  for attachment with a main circuit breaker  74  (FIG. 6) in the manner to be described below. The four upstanding shield supports  20  are arranged with a pair at one end of the neutral lug support plate  27  and another pair at one end of the main circuit breaker support plate  28  for attachment of the face plate  22  by screws  23  (or other suitable means of attachment). The attachment between the upstanding shield supports and the face plate automatically aligns branch circuit breaker handle slots  24  with the branch circuit breaker handles, not shown. This positions a main circuit breaker handle access plate  26  over the main circuit breaker support plate  28  and positions a neutral lug access plate  25  over the neutral lug support plate  27 . 
     Referring to FIG. 3, a split neutral assembly  29  is shown prior to insertion of a U-shaped neutral conductor  35  in an extended recess  131  of an electrically insulative support base  31 . The ends of support base  31 , terminating at the upstanding insulative cover  43 , are raised to receive L-shaped ends  135  of the U-shaped neutral conductor  35  which nests in a slot  133  in an insulating shield  33  and abuts against an outer insulating shield  32 . A pair of bolts  34  are captured within the ends of support plate  31  and pass through thru-holes  36 ,  38  formed in the shaped ends  135  of the U-shaped neutral conductor  35  and a top tab  39  on a top of a neutral connector  37  respectively. A bottom tab  40  on the neutral connector  37  includes a thru-hole  41  for providing connection with an external circuit. With the U-shaped neutral conductor  35  in the electrically insulative support base  31 , an insulating cover  42  is fastened to the support plate by snappingly engaging tabs  44  on the sides of the insulating cover in clips  45  extending from the sides of the support base, as shown in FIG.  4 . An extension  143  on insulative plates  43  extends in the slot  133  in the insulating shield  33  for added insulation to the neutral connector  37  abutting the outer insulating shield  32  and the bolt  34  extending from the top tab  39  of the neutral connector  37 . 
     Referring to FIG. 5, a main circuit breaker assembly  46  includes an integral shaped insulative support (base)  47  defining L-shaped channels (recesses)  48 ,  49 ,  50  having upstanding sidewalls  51 ,  52  for receiving stepped conductors  54 ,  55 ,  56  having thru-holes  57  which align with corresponding pockets  53  formed within the L-shaped channels. Phase conductors  63 ,  64 ,  65  are arranged perpendicular to the stepped shaped conductors and are connected therewith by bolts  59  through holes  66 , aligning with the pockets  53 , and thru-holes  57  within the L-shaped channels  48 ,  49 ,  50  and stepped conductors  54 ,  55 ,  56  respectively. Support covers  60  are then positioned over the assembly such that apertures  61  align with the bolts  59  for access thereto and insulative cylinders  62  upstanding from the top of the support cover provide access to the apertures  67  in the opposing ends of the phase conductors  63 ,  64 ,  65  for connection with the main circuit breaker  74 , as seen in a panelboard interior  68 , shown in FIG.  6 . 
     Assembly of a main circuit breaker to the main circuit breaker assembly  46  will now be described with reference to FIG.  6 . Prior to attaching the face plate  22  (FIG. 2) to the shield supports  20  to complete the panelboard interior assembly, the branch circuit breaker assembly  11  is positioned for attachment of the main circuit breaker assembly  46  in the following manner: Thru-holes  58  within the top tabs  39  of stepped conductors  54 ,  55 ,  56  are positioned over main circuit breaker bolt connectors  30  on the insulating cover  42  and are connected therewith by threaded washers  69  for electrical connection between main circuit breaker  74  and an electrical distribution circuit. Electrical connection between main circuit breaker  74  and the phase conductors  63 ,  64 ,  65  (FIG.  5 ), is provided by bolts  78 , washers  79 , insulative washers  77  and insulative cylinders  62 . Main circuit breaker  74  is mechanically fastened to the main circuit breaker support plate  28  by extended screws  75  through apertures  76  and apertures  73  in the main circuit breaker support plate  46  to complete the assembly of the panelboard interior  68 . 
     Main circuit breaker support plate  46  includes bracket  70  having flange  71 . Screws  72  extend through holes in flange  71  to secure main circuit breaker support plate  46  to main circuit breaker support plate  28 . 
     While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.