Abstract:
The terminal block assembly of this invention provides a finger safe method of distributing power while at the same time enabling the installer to make uniform and correct connections to a multiplicity of taps or ports. Each connection includes an abutment or seat physically to engage the end of the conductor and in addition the construction of the block and its insulating case provides the installer with visual access to the tip of the conductor in its proper seated position before the conductor is secured to the block with clamp screws. In order to provide such visual access the walls partially blocking the seating end of each conductor socket are scalloped or provided with an inverted conical section which enables the tip of each conductor to be seen from the top of the block. To facilitate this visual access the entire top of the insulating case is made from a transparent material. In one embodiment the top is provided with interior projections serving both to gauge and limit retraction of some of the clamp screws to prevent loose screws in the case. In another embodiment the screws, even though fully retracted or disengaged from the blcok, are held in axial alignment with their respective sockets and can&#39;t become loose in the case.

Description:
RELATED APPLICATION 
   This application is a continuation-in-part of application Ser. No. 10/825,019 filed Apr. 15, 2004 now U.S. Pat. No. 7,052,333 entitled Power Distribution Block Assembly. 

   DISCLOSURE 
   This invention relates generally as indicated to a power distribution block assembly and more particularly to a terminal distribution block assembly and method which is finger-safe when energized, whether empty, or at full capacity. 
   BACKGROUND OF THE INVENTION 
   In the distribution of electric power, distribution blocks are often employed. These assemblies have widely been used for distributing incoming electrical power to a number of distinct circuits. Applications may vary widely such as power distribution to houses from a common transformer, or in electrical distribution panel boards where the blocks may be mounted on a common rail for distribution in mono-polar or multi-polar applications. 
   Typically the block includes a connection for a larger conductor cable or bus and a plurality of tap connections for smaller conductors. The bare ends of the conductors are inserted in socket ports or holes and held in place typically by a clamp or binding screw threaded in a hole perpendicular to the socket receiving the conductor. 
   One of the problems with these types of distribution blocks is that many of the tap connections are added at a later time after the system is in operation and the block energized. To make the connection safely the system may require to be shut down, and this in turn may create a raft of problems, particularly if the power is shut down for any length of time. 
   In order to protect the block from incidental contact many are enclosed in insulating enclosures or cases which protect the block from direct contact. To make a connection the case may be provided with large windows or ports or even hinged covers which may be opened for access, or the cases may be removed entirely, all of which permits finger contact with the block by the installer. 
   The use of insulating cases makes the proper installation of primary and tap connections more problematic. In a connection using a typical blind socket port or hole the installer simply inserts the bare or stripped end of the conductor into the socket until resistence is felt and then tightens the binding screw. It may not be determined that an improper connection was made until the power is turned on again or until the connection fails because the bare end of the conductor wasn&#39;t properly positioned with respect to the binding screw. The conductor may have hung-up on an obstruction which was not the blind end of the hole or port. If the conductor is inserted too far, the projecting end may interfere with or obstruct something else, and the binding screw may be tightened on insulation. Moreover non-uniform projecting conductors create a mess, particularly when all the taps are used making service and inspection difficult. 
   It would accordingly be advantageous for the installer to be able to have both the abutment afforded by the blind end of the port and a visual check to see that the conductor is properly inserted or placed before the binding screw is tightened. In this manner, ensured uniform connections can be made for each of the taps, with the ends of the conductors projecting beyond the screws a uniform distance, and not too far or not far enough. 
   Another problem with insulating cases involves loose screws. If there is enough clearance between the top of the block and the cover of the case, the binding screws may be backed out too far and become disengaged with the threaded socket. The result is a loose screw inside the insulating case and the only way it can be repositioned or reinserted in its threaded socket is to open the case, which in turn compromises the goal of providing a finger safe assembly without shutting off the power. 
   It would also of course be desirable that these uniform tap connections could all be made without turning off the power or opening an insulating case. It would therefore be desirable to be able to make such uniform connections having both the visual and physical abutment check without finger contact with the block and without opening the case. A power distribution block with such connections which is finger-safe once the incoming line is installed is highly desirable. 
   It would also be advantageous to have an assembly where the screws could not be backed out far enough to become disengaged from their respective threaded sockets. But if they did become disengaged, without becoming loose or losing their alignment with their respective threaded socket, and all without losing both the visual and physical check of proper placement of the conductor within the gallery or port of the block. 
   SUMMARY OF THE INVENTION 
   The terminal block assembly of this invention provides a finger safe method of distributing power while at the same time enabling the installer to make uniform and correct connections to a multiplicity of taps or ports. Each connection includes an abutment or seat physically to engage the end of the conductor and in addition the construction of the block and its insulating case provides the installer with visual access to the tip of the conductor in its proper seated position before the conductor is secured to the block. 
   In order to provide such visual access the walls partially blocking the seating end of each conductor socket are scalloped or provided with an inverted conical section which enables the tip of each conductor to be seen from the top of the block. To facilitate this visual access the entire top of the insulating case is made from a transparent material. 
   The cover is provided with respective holes each accommodating an insulated fastener driver so that the clamp screws may be manipulated or tightened from the exterior of the case. 
   The case is also provided with alignment galleries or tap port extensions enabling the insulated bare end conductors to be inserted to the proper seated depth in the tap ports without finger contact with the conductive block. 
   In this manner the terminal or distribution block remains finger-safe while energized from empty to full output capacity while allowing both visual and physical indication of proper conductor placement to make uniform and secure tap connections, avoiding both over or under insertion. 
   In one embodiment the cover is provided with interior projections or steps associated with some of the respective holes which accommodate the fastener driver so that the clamp screw operated through such hole can&#39;t be backed out too far or become loose in the case. In another preferred embodiment the projections may vary in size with the hole and screw and are in the form of split sleeves or tubes which engage and capture screws that are backed out too far, while still providing a clear view of a sight window at the blind end of each of the tap ports. Even if the binding screw is backed completely out of its threaded hole, it will be captured by the projections and held in axial alignment with its respective threaded socket for easy and convenient reinsertion. In either embodiment a loose screw within the case requiring opening for reinsertion is avoided. 
   The projections may also serve as a gauge for the respective bindings screw indicating the lower or clamp end of the screw is clear of the tap port or gallery. 
   To the accomplishment of the foregoing and related ends the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the invention may be employed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of one model of a distribution block in accordance with the present invention showing the case transparent cover open and partially exposing the block; 
       FIG. 2  is a perspective view of the block showing the sight windows in the block at the abutment walls at the inner ends of each tap socket; 
       FIG. 3  is a similar perspective of the block from the opposite end showing the tiered tap sockets; 
       FIG. 4  is an enlarged side elevation of the block; 
       FIG. 5  is an enlarged fragmentary section showing the abutment walls and sight windows; 
       FIG. 6  is an also enlarged fragmentary section showing tap conductors in place and secured to the block; and 
       FIG. 7  is a perspective view of another form of terminal block assembly in accordance with this invention; 
       FIG. 8  is a perspective view of the underside of a cover embodiment which includes projections operative to capture the screws if backed out too far; 
       FIG. 9  is a partial broken-section of the block and cover with the latter in closed position showing the screws of the inner tiers or galleries being restricted or captured; 
       FIG. 10  is a fragmentary elevation of the cover taken transversely of  FIG. 9  and partially in section also showing the gauging and capture of the screws when backed out; 
       FIG. 11  is a view like  FIG. 8  but showing a somewhat modified cover or lid with the projections on the inside of the lid in the form of steps generally corresponding to the steps of the block; and 
       FIG. 12  is a view like  FIG. 9  but showing the lid embodiment of  FIG. 11 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring initially to  FIG. 1  there is illustrated a power distribution block assembly in accordance with the present invention shown generally at  20 . The metal conducting block is shown at  21  while the block is surrounded by insulating case  22  having a hinged top cover  23  shown in the open position. 
   The metal terminal block  21  shown in detail in  FIGS. 2 through 6  is made from conductive metal such as an aluminum alloy and can be extruded and machined. After machining the blocks may then be tin plated to a thickness of approximately 0.05 mm. 
   The plastic insulation case  22  is preferably made from a plastic such as nylon 6. The cover, however, is made of a transparent plastic material such as polycarbonate such as sold by General Electric Company of Schenectady, N.Y. under its trademark LEXAN® 940A. The cover may be tinted a color such as blue, but is nonetheless fully transparent providing visual access to the interior of the case and block when the cover or lid is closed. 
   As seen in  FIG. 1  the case  22  comprises side walls  26  and  27 , end walls  28  and  29 , and a bottom wall  30  somewhat obscured. The cover  23  may be hinged as indicated at  33  and  34  to the end wall  28  and the cover or lid may be provided with an over-center snap to keep it in the open position shown. The tip of the cover is provided with a snap tang indicated at  36  which seats in snap recess  37  in the top of wall  29 . The underside of the cover or lid is provided with two projecting ribs seen at  38  and  39  which telescope inside the top edge of the case  22  blocking access to the interior of the case when the lid or cover is closed. The insulating case is also provided with certain projections from the bottom wall  30  indicated at  42  and  43  to facilitate the mounting of the power distribution block assembly on an electric panel or din-rail. While each individual assembly is a single-pole or mono-pole block, such assemblies may be ganged together by means of the male and female dovetails shown at the sides for convenient distribution in multi-pole systems. 
   Referring now additionally to  FIGS. 2 through 6  it will be seen that the conductive metal terminal block  21  may be formed from an extrusion and then machined and includes a large section at one end shown generally at  45  which includes a large socket  46  in wall  47 . Extending normal to the socket is a threaded hole  48  in the top wall  49  of the enlarged end  45 . The threaded or tapped hole  48  accommodates large recessed head clamp screw  52  seen in  FIG. 1 . 
   The large socket  46  extends through the interior wall  54  of the enlarged end and partially into the reduced height portion  56  of the block  21 . This extension of the socket beyond the wall  54  is seen at  58  in  FIG. 3 . 
   Situated in the reduced height portion  56  of the block are three tap sockets  60  which open generally to the right hand side of the block as seen in  FIGS. 2 through 6 . Each of the tap sockets is provided with a transverse threaded opening in the top seen at  62 ,  63 , and  64  for accommodating the clamp screws indicated at  66  in  FIG. 1 . 
   Projecting from the reduced height portion  56  of the block is another offset tier of tap ports or sockets shown generally at  70  and projecting from the intermediate tier  70  is a further offset tier  72 . The intermediate tier includes four side-by-side sockets or ports for tap connections indicated at  74  while the top tier includes four side-by-side tap connections indicated by the sockets  75 . Again, each respective socket or port is provided with a transversely extending threaded hole as seen at  76  for the intermediate tier  70  and  77  for the top tier  72 . These tapped holes in the top two tiers accommodate the clamp screws seen at  78  in  FIG. 1 . It is noted that the socket in a single tier may be the same size or they may vary in size as in the bottom tier. 
   Referring now more particularly to  FIGS. 2 and 5  it will be seen that the sockets  75  in the top tier  72  are partially blocked by the adjoining tier  70  while the sockets  74  in the intermediate tier are partially blocked by the portion of the block of reduced height indicated at  56 . 
   The abutment wall at the end of each of the sockets seen at  74  and  75  is slightly beyond the interior wall of the tier and each abutment end of the socket at such wall is provided with an inverted conic relief or scallop as indicated at  80  for the top tier sockets and  81  for the intermediate tier sockets. The two outside sockets in the lower most tier are partially blocked by the wall  83  which also includes the inverted conic projection or scallop  84  opening into sight windows  85  and  86 . These sight windows are formed in the reduced height portion of the block. The center socket in the bottom tier is also provided with an abutment wall partially blocking the interior of the socket and a similar scalloped or inverted conic projection opening into the large socket for the main conductor shown at  46  and  56 . 
   In this manner each of the tap sockets is provided with an internal abutment wall and also a sight window enabling the tip of the conductor inserted into the tap port or socket to be seen from the top of the assembly through the transparent cover  23 . The scallops or projections into the abutment walls of the various tap sockets may be formed by an angled drill point and need not be inverted circular conical sections, but may be other shapes as well. In each of the sockets or tap ports, the abutment wall may extend to approximately half the height of the socket opening or diameter and the angle of the conical section may vary at its center, but is preferably, about  30 ° from vertical. 
   Referring now to  FIG. 6  there is illustrated insulated conductors shown at  90 ,  91 , and  92  inserted in the respective sockets  75 ,  74 , and  60 . The tips of the conductors with the insulation removed is seen at  93 ,  94 , and  95  and such tips engage the abutment end of each socket and in such physical contact with the abutment end the tip of the respective bared conductor indicated at  98 ,  99 , and  100  is visible from the top of the assembly through the transparent cover  23 .  FIG. 6  illustrates the cover with access ports seen at  102 ,  103  and  104  which are aligned with the clamp screws of the various ports or sockets. As seen more clearly in  FIG. 1  the cover or lid is provided with a total of eleven (11) ports, one for each of the various tap connections provided by the block  21 . 
   Also as seen in  FIG. 6 , the case  22  includes alignment galleries seen at  107 ,  108 , and  109  which assist the installer in insertion of the bared end of the conductor into the socket and also protect against finger insertion into the case. 
   Accordingly, once the main conductor is inserted and the fastener  52  tightened to activate the block and the cover or lid is closed, the assembly is then finger-safe for installing, one, more, or all of the various tap connections available. 
   Even though the insulated case is closed, as the installer makes the connection, the installer has the benefit of both the physical abutment or engagement of the tip of the conductor against the abutment wall and the visual access to the tip of the conductor through the transparent lid or top. In this manner all of the tap connections will be both uniform and electrically correct, each with the proper uniform extent of the conductor extending beneath and beyond the clamp screw. The operator then simple inserts an insulated tool through the respective access openings  102 ,  103 , or  104  to tighten the clamp screw on the properly positioned conductor bare end. 
   Although not illustrated, it will be appreciated that once the tap conductors are stripped to the specified length they may be installed first in a ferrule placed over the stripped end portion of the conductor. The conductor or ferrule will then proceed to the abutment or bottom of the tap hole that is partially visually exposed and visible through the transparent cover. This visual indication of the conductor placement ensures that the installer has both the physical abutment available as well as a visual check to make sure the conductor is properly in place before the fastener is secured. 
   Referring now to the embodiment of  FIG. 7  there is illustrated a slightly smaller version of the terminal block assembly of the present invention. The embodiment shown generally at  120  includes an insulated case  121  with a transparent cover  122 . The block within the case isn&#39;t shown but the case is provided with alignment galleries shown at  123  and  124  to enable the bared conductor ends with or without ferrules to be inserted into the tap receiving sockets. The clamp screw of each tap receiving socket is provided with an access port in the cover or lid as seen at  126  or  127 . 
   It is noted that the cover of the embodiment of  FIG. 7  is provided with a somewhat larger hole  130  which provides access to the clamp screw for the main conductor. The cover is also provided with a somewhat smaller hole  131  providing access to a clamp screw for another tap. In the smaller version illustrated, the transparent cover  122  for the case may be fixed with the somewhat larger access opening  130  provided for the incoming line. This is in contrast to the larger embodiment of  FIG. 1  where the large fastener  52  for the incoming line has no access opening in the hinged cover. 
   Whether the larger or smaller version of the present invention, both are provided with transparent covers or lids which provide visual access through the sight windows to the tips of the conductors with or without ferrules inserted in the various tap ports or sockets against the abutment walls forming the inner ends of such sockets. 
   Referring now to the embodiment shown in  FIGS. 8 ,  9  and  10 , it will be seen that the case is provided with a transparent cover or lid  140 . The block and the remainder of the case is the same as shown in  FIGS. 1–6 . The inside of the cover adjacent the screw driver access holes  102  and  103  for the lower and intermediate tiers  56  and  70  of the block are provided with paired split sleeve or tube interior projections seen at  142  and  144 , respectively. 
   Each of the paired projections are arcuate as seen at  146  and  148  and extend downwardly toward the block  21  a sufficient distance to engage and grip or capture the fastener in the associated threaded hole. These tube sections on the inside of the cover are designed to let the user or installer know when the clamp or binding screws clear the conductor tap hole or port as shown. When the binding screw comes in contact with the end of the tube sections, or the underside of the cover or lid for the top tier the respective tap hole is completely open. In addition to this gauging function, the function of the tube sections is to retain the binding screws in the lower and intermediate tiers should the user continue to unscrew them. Thus the binding screws for the lower and intermediate tiers can be backed out and disengaged from the block, but will be retained in the respective tube sections. The tube sections in this event still keep the binding screws aligned with the threads of the respective socket for reinstallation without opening the lid. Accordingly, even if disengaged, the screws are not loose in the case. 
   The projections may cover from about 60 to about 90° of a full circle and the gap or split between the retainer sleeve pairs or projections shown at  150  in  FIGS. 8 and 10  enables a clear and unobstructed view of the windows for the lower tier ports shown at  84 , as well as the intermediate tier ports, shown at  81 , when the cover or lid is closed as shown in  FIG. 9 . The gap or split between the paired projections extends the entire distance from the lower or distal end of the projections seen at  154  to the underside of the cover or lid at the respective access hole. 
   The inside diameter of the split retainer tube or sleeve sections is designed to engage and grip or capture the top of the respective clamp or binding screw as it is backed out. The projections yield slightly and grip the top of the clamp screw as shown at  156  in  FIG. 10  for the screw  158 . The further the screw is backed out the tighter the grip or interference. However, initial contact with the retainer tube sections as seen at  160  for the screw  162  indicates that the gallery or port for the conductor is clear of the lower tip of the screw. The projections thus not only keep the screws from becoming loose in the case, but also may be used to gauge the fully retracted position. 
   It will be appreciated that the length or extent or size of the projections may vary depending on the size and length of the clamp screws and their respective threaded sockets. For example, the center projection pair for the lower tier shown at  164  may be slightly longer and smaller than those pairs at either side shown in the row of projection  142  simply because of the size and length of the screw  158 . The same variation may exist with the intermediate tier  70  projections  144 . 
   As illustrated there are four sets of split sleeve or retainer tubes for the intermediate tier, since there are four screws and sockets provided by the intermediate tier. For the lower tier there are three split sleeve projections, again one for each screw and respective port or socket. For the top tier projections aren&#39;t required since the cover itself adjacent the undersize access holes  104  would interfere with a screw backed out too far. 
   As seen in  FIGS. 11 and 12 , there is shown another embodiment of the transparent cover or lid  170  which is provided with interior projections in the form of recessed steps  172  and  174  generally corresponding to the distal ends of the interior projections seen in the embodiment of  FIGS. 8 ,  9  and  10 . Again the block and the remainder of the case is the same as shown in  FIGS. 1–6 . 
   The innermost step  172  is provided with three access holes shown at  176  for the binding screws of the lowermost tier, while the intermediate step  174  is provided with four access holes  178  for the binding screws of the intermediate tier. The top tier access holes are shown at  180  and all are slightly smaller than the head or outer ends of the binding screws accessed thereby. The holes permit access of a wrench or small screwdriver but are too small for the screw itself. It will be appreciated that the steps may be at different depths transversely of the block depending upon the length or size of the binding screws employed. 
   Even though the cover or lid is transparent, the corners of the steps may be provided with sight holes seen at  182 ,  184  and  186  to ensure clear visual access to the tip of the conductor fully seated in the respective tap ports. 
   In this embodiment the lid also acts to prevent loose screws in the case and as a gauge ensuring proper conductor connection without the necessity of opening the case. 
   It can be seen that the cover or lid of the embodiments of  FIGS. 8–12  may be used to gauge the position of the clamping screws and prevent loose screws within the case all while providing both the visual and physical checks for proper uniform tap connections. The invention also provides a large capacity for power distribution but at a low cost and in a finger-safe manner enabling the installer to make uniform proper connections avoiding both over or under insertion of the tap connections. 
   Although the invention has been shown and described with respect to certain preferred embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification. The present invention includes all such equivalent alterations and modifications, and is limited only by the scope of the claims.