US3757170A

US3757170A - Panelboard with mounting block securing stab contacts

Info

Publication number: US3757170A
Application number: US00294092A
Authority: US
Inventors: H Kobryner
Original assignee: Arrow Hart Inc
Current assignee: Cooper Industries LLC; Arrow Hart Inc
Priority date: 1972-10-02
Filing date: 1972-10-02
Publication date: 1973-09-04
Anticipated expiration: 1990-09-04

Abstract

The invention contemplates an electrical load center construction wherein specially formed cavities and recesses accommodate slidable insertion and captive retention of (a) a neutral-bar assembly, and (b) a multiple-contact conductor assembly. Captive retention is secured upon clamping the mounting face of the block to a base panel. The particular arrangement of through-openings for inserted reception of various areas of the conductor assembly affords selective accommodation of one or more of a variety of possible conductor assemblies, depending upon the desired application and use of the load center.

Description

United States Patent 1 Kobryner [451 Sept. 4, 1973 PANELBOARD WITH MOUNTING BLOCK SECURING STAB-CONTACTS [75] Inventor: Herman H. Kobryner, Forest Hills,

[73] Assignee: Arrow-Hart, lnc., Hartford, Conn.

[22] Filed: Oct. 2, 1972 [21] Appl. No.: 294,092

[52] US. Cl. 317/119, 339/198 N [51] Int. Cl. 1102b 1/04 [58] Field of Search 317/119; 339/198 R, 339/198 N [56] References Cited UNITED STATES PATENTS 3,312,874 4/1967 Stanback 317/119 3,668,591 6/1972 Kobryner.... 339/198 N 3,155,445 11/1964 Johnson .[317/119 Primary ExaminerJ. V. Truhe Assistant ExaminerGerald P. Tolin Attorney- Nichol M. Sandoe, Roy C. Hopgood et a1.

[ 57] ABSTRACT The invention contemplates an electrical load center construction wherein specially formed cavities and recesses accommodate slidable insertion and captive retention of (a) a neutral-bar assembly, and (b) a multiple-contact conductor assembly. Captive retention is secured upon clamping the mounting face of the block to a base panel. The particular arrangement of throughopenings for inserted reception of various areas of the conductor assembly affords selective accommodation of one or more of a variety of possible conductor assemblies, depending upon the desired application and use of the load center.

11 Claims, 12 Drawing Figures PANELBOARD WITH MOUNTING BLOCK SECURING STAB-CONTACTS The invention relates to the construction of an electrical load center, suitable for direct mounting on a plate or panel, or on the base of a suitable box enclosure.

It is an object of the invention to provide an improved construction of the character indicated, particularly adapted for use in mobile homes and recreational housing, where the need does not exist for great numbers of circuits.

Another object is to meet the above object with a construction inherently lending itself to acceptance of conventional self-contained stab-mounted circuitbreaker modules.

A further object is to provide such a load center of basic design, lending itself to varied applications depending upon selection of particular alternative connector parts.

It is also an object to provide such a construction employing unjointed connectors and serving plural circuits.

It is a general object to achieve the above objects with basically simple, inexpensive and foolproof structure, without sacrifice of desirable electrical properties.

Other objects and various further features of novelty and invention will be pointed out or will occur to those skilled in the art from a reading of the following specification in conjunction with the accompanying drawings. In said drawings, which show, for illustrative purposes only, preferred forms of the invention:

FIG. 1 is a plan view of a boxmounted load center of the invention;

FIG. 2 is a perspective view of a removable mounting-block part of the structure of FIG. 1, shown in exploded relation with another part prior to a preassembly operation;

FIG. 3 is another perspective view of the mountingblock part of FIG. 1, shown in exploded relation with a further part prior to a preassembly operation;

FIGS. 4, 5 and 6 are, respectively, plan rear and bottom views of the mounting-block part of FIG. 1;

FIG. 7 is a sectional view at 77 in FIG. 4;

FIGS. 8 and 9 are perspective views of different conductor elements, available as alternates for the preassembly suggested in FIG. 3; and

FIGS. 10, 11 and 12 are simplified plan views showing various selectively available applications of the invention.

In FIG. 1, the invention is shown in application to a rectangular load center box 10 having a base panel or plate 11 and upstanding sides, and being selectively closed by a cover 12 secured by means 13. Box 10 and its cover 12 may be of formed sheet steel, as is conventional, the cover 12 having a cut-out or opening 14 appropriate to the number and size of stab-mounted circuit-breaker modules 15-16 within the load center.

To accommodate the circuit-breaker modules, a plate 17, formed with plural laterally spaced struck-up tabs 18, is secured as by screws 19 to the base panel 11. The heel ends of the module bases engage under these tabs 18, as appropriate and conventional, while the contact ends are pressed into upstanding stabs 20-20 forming part of a mounting assembly 21 of the invention.

The mounting assembly 21 comprises a mounting block 22 of insulating material and is made as a single injection-molded part of suitable plastic, such as the mica-filled polyethylene material commercially available from General Electric Company and known under the mark Noryl"; additional reference is made to FIGS. 2 to 7 in connection with the block 22. To complete the description of box 10 and its contents, the usual grounding connections are provided by a terminal block 23 secured to a side wall of the box, and a bonding jumper 24 may be provided to bond the neutral to the box. The particular electrical arrangement shown in FIG. 1 provides for a three-wire single-phase system, wherein the two hot leads are connected at terminals 25-25', electrically connected to the stabs 20-20, respectively, for the distribution circuit breakers 15-16. The neutral connection for the supply conductor may be made at the large terminal 26 of a neutral-bar connector 27, forming part of the assembly 21.

The mounting block 22 is so devised with retaining cavities that it entraps all conductive members between itself and a flat insulation plate member or sheet 28. The entire assembly is compressionally secured to the back panel 11 of the box by screws 29 which pass through aligned holes in the mounting block and insulation plate and which engage tapped holes in panel 11.

Referring now to FIGS. 2 to 7, and in particular to FIG. 2, the mounting block 22 is seen to comprise an upstanding body portion 30, rising from an integral base-flange portion 31; the underside of flange and body portions will be understood to be in a common mounting plane or surface, to be compressed against insulating sheet 28, upon assembly to panel 11. The aspect of FIG. 2 reveals accommodation for the neutralbar assembly 27, the same being received in a bottomopening cavity 32 upon upward insertion, as suggested by light-phantom projection lines for comer alignments of the prismatic body of the neutral assembly 27. Integral ledges or cleats 33-34-35 provide stops and guides for retention of the inserted assembly 27, when the bottom surface thereof is in substantial registry with the mounting-surface plane of the mounting block 22, and substantial side-access and top-access windows communicate with cavity 32, to provide all necessary neutral clamping and wiring connections to the bar 27, without disturbing the assembled relation to the box 10. Substantial body mass is devoted to the centrally located alignments 29' for the mounting bolts 29 and to a body bridge 36 between these alignments. The mounting-body portion 30 is essentially limited to accommodation of the neutral-bar assembly 27 and bridge 36, leaving a substantial area of the flange portin 31 accomodation of stab and other connector elements, as will more clearly appear from FIG. 3.

In FIG. 3, plural spaced connector openings 37-3- 8-39-40 are seen to be provided along a single alignment within flange portion 31, and a single downwardly open channel alignment interconnects lower regions of these openings; the net result is provision of integral conductor-retaining bridges 41-42-43 between the respective adjacent pairs of openings. Spacing and size of the openings are selected for the particular stab and circuit-breaker geometry for the intended application. As shown in FIG. 3, the single conductor element 44 comprises two arms 25-20, extending upwardly from an integral base or yoke 45. The spacing between and shape of openings 37-38 are such as to receive and accurately locate the respective arms 25-20, and the channel depth beneath bridges 41-42-43 is such as to accommodate the thickness of base 45, upon connector assembly to flange portion 31, at 37-38, all as will be understood from the light-phantom projection lines in FIG. 3 for corners of connector 45; the base 45 is thus insertably received at flange portion 31, substantially flush with the mounting surface plane of block 22. It will be further understood that for the FIG. 1 arrangement wherein breakers 15-16 serve the respective hot sides of a three-wire single-phase system, the conductor element 44 serves one side via openings 37-38, while a second conductor element 44 (not shown in FIG. 3) serves the other side at projecting arm locations 20'-25 via openings 39-40. Buttress or shield elements 46, integrally formed with adjacent parts of the flange and body portions 30-31, between adjacent openings 37-38-39-40, strengthens the retention of conductor elements by adding to the rigidity of the otherwise thin and flexible flange 31.

FIGS. 8 and 9 illustrate other forms of conductor element, usuable in place of element 44, for diflerent application situations. For example, the element 50 of FIG. 8 provides a simple integral connection 51 between two spaced stab arms 52-53, the connection 51 being centrally grooved at 54 for accurate fit to one of the bridges in the flange portion 31, as at the central bridge 42, for the situation depicted in FIG. 10. FIG. 10 may be considered illustrative of application to a twowire single-phase system having provision for a main breaker, forv example at stab 53, and for a duplex breaker at stab 52; thus providing separate protection for two branch circuits, in addition to main protection; still further, the main breaker could be a duplex breaker having one half at high rating, for the mainbreaker function, and the other half low-rated for branch-line protection.

The conductor element 55 of FIG. 9 resembles that of FIG. 8, except that it provides three spaced upstanding stab arms 56-57-58, integrally joined by a base 59, and suitably contoured for removable insertion through a succession of three of the flange openings. Such an application is depicted in FIG. 11, where more branchcircuit connections may be made in a two-wire singlephase system. For example, the main breaker may be connected to stab 58, and duplex breakers at

stabs

56 and 57 would provide protection for four branch circuits.

The arrangement of FIG. 12 illustrates application of the circuit option of FIG. 1 to a plate-mounted installation, wherein a base plate 60 is secured by means 61 to raised bumps or pedestals offsetting plate 60 from the base panel of a deeper load center box (not shown), as may be necessitated by the larger conduit diameter involved in employing the invention in larger-current rated installations. Again, however, mounting assembly 21 is secured by means 29 to the insulation sheet 28 and plate 60, and the latter is positioned to accommodate breaker modules (e.g., -16) with their exposed faces at the plane of the cover plate (12), as will be understood. I

The described invention will be seen to have achieved all stated objects. Parts are efficiently captivated upon assembly of block 22 to its panel 11 (60) and insulation sheet 28. Manufacturing economies are realized by reducing to a minimum the number and complexity of parts specially needed for different applications. Good electrical properties flow from use of unjointed conductors, and conductor elements as at 50 and 55 lend themselves to economical manufacture, as by sawing from extruded channel stock, to desired element width W.

As an illustration of the varied application and use of theinvention, precisely the same block structure 21 will be seen to selectively serve devices of two different current ratings, for example, 40 amp. and amp., calling for No. 6 (AL) and No. 2 (AL) wire sizes, respectively, in turn calling for conduits of such different size as to employ the shallow-box arrangement of FIG. 1 for a 40-amp. installation, and the offset-plate, deeper-box arrangement of FIG. 12 for a 70-amp. installation. The same flexible adaptation feature characterizes stab accommodation by the same block 21; for example, if the drawings are viewed as showing stab elements 44-5- 0-55 of the relatively narrow width W involved in a 40- amp. installation, then the widened-notch character of the openings 37-38-39-40 will be seen to accommodate stab elements of the greater width and larger wireclamping terminal involved in a 70-amp. installation.

While the invention has been shown and described in detail for the preferred forms shown, it will be understood that modifications may be made without departure from the invention.

What is claimed is:

1. An electrical load center, comprising a metal panel plate, a mounting block of insulating material and having a main body and a mounting face, a sheet of insulating material between said plate and face, and means compressionally securing the mounting face of said block to said plate with said sheet therebetween, a generally rectangularly prismatic neutral bar, said block body having a neutral-bar recess open to said mounting face and being adapted to insertably receive said neutral bar via said mounting, face the effective depth of said recess being less than the total height of said block body and adapted to limit neutral-bar insertion at an assembled position when the bottom face of said neutral bar is substantially in register with the plane of said mounting face, said neutral bar having a conductor port on a transverse axis between top and bottom faces of said bar, a clamp screw having threaded access to said port via the top face of said bar, the bar recess of said mounting block being sufficiently open above said top face and along one lateral side of said bar to provide conductor access direct to said port and clampcontrol access to said screw, said mounting block integrally including a flange contiguous to said main body and having a bottom face in common with said mounting face, said flange having a plurality of spaced through openings with a channel of limited depth interconnecting adjacent of said through openings at the plane of said mounting face, and a unitary conductor element comprising two upstanding arms connected by a bridge at the base ends thereof, said arms projecting through adjacent flange openings and upwardly of said flange, and said bridge fitting said channel to a limited depth such that the bottom surface of said bridge is assembled substantially in register with the plane of said mounting face, whereby upon such securing of said mounting block to said plate, said neutral bar and said conductor element are captively retained and located with full neutral-connection access and with said conductive arms projecting for live-connection access.

2. The load center of claim 1, in which said upstanding an'ns are circuit-breaker stabs.

3. The load center of claim 1, in which one of said upstanding arms is a circuit-breaker stab and the other of said arms includes live conductor clamp means.

4. The load center of claim 1, in which the plurality of spaced flange through-openings is at least three, and in which said unitary conductor element comprises three similarly spaced upstanding arms bridgeconnected at their base ends.

5. The load center of claim 4, in which at least two adjacent of said arms are circuit-breaker stabs.

6. The load center of claim 4, in which all three of said arms are circuit-breaker stabs.

7. The load center of claim 1, in which said mounting block includes a brace interposed between said through-openings, said brace being integrally connected to said flange and the adjacent lateral wall of said main body.

8. The load center of claim 7, in which said plurality of flange through-openings is at least three, and in which said brace is one of a plurality providing braced protection between all adjacent through-openings.

9. The load center of claim I, in which said securing means comprises spaced bolts through aligned openings in said mounting block and sheet and plate.

10. The load center of claim 1, in which said plate is the base panel of a load-center box encasing said sheet and mounting block.

11. The load center of claim 1, in which said plate includes a circuit breaker mounting tab offset from said mounting block and at standard circuit-breaker stab spacing from one of said through-openings.

Claims

1. An electrical load center, comprising a metal panel plate, a mounting block of insulating material and having a main body and a mounting face, a sheet of insulating material between said plate and face, and means compressionally securing the mounting face of said block to said plate with said sheet therebetween, a generally rectangularly prismatic neutral bar, said block body having a neutral-bar recess open to said mounting face and being adapted to insertably receive said neutral bar via said mounting, face the effective depth of said recess being less than the total height of said block body and adapted to limit neutral-bar insertion at an assembled position when the bottom face of said neutral bar is substantially in register with the plane of said mounting face, said neutral bar having a conductor port on a transverse axis between top and bottom faces of said bar, a clamp screw having threaded access to said port via the top face of said bar, the bar recess of said mounting block being sufficiently open above said top face and along one lateral side of said bar to provide conductor access direct to said port and clamp-control access to said screw, said mounting block integrally including a flange contiguous to said main body and having a bottom face in common with said mounting face, said flange having a plurality of spaced through openings with a channel of limited depth interconnecting adjacent of said through openings at the plane of said mounting face, and a unitary conductor element comprising two upstanding arms connected by a bridge at the base ends thereof, said arms projecting through adjacent flange openings and upwardly of said flange, and said bridge fitting said channel to a limited depth such that the bottom surface of said bridge is assembled substantially in register with the plane of said mounting face, whereby upon such securing of said mounting block to said plate, said neutral bar and said conductor element are captively retained and located with full neutral-connection access and with said conductive arms projecting for live-connection access.

2. The load center of claim 1, in which said upstanding arms are circuit-breaker stabs.

3. The load center of claim 1, in which one of said upstanding arms is a circuit-breaker stab and the other of said arms includes live-conductor clamp means.

4. The load center of claim 1, in which the plurality of spaced flange through-openings is at least three, and in which said unitary conductor element comprises three similarly spaced upstanding arms bridge-connected at their base ends.

9. The load center of claim 1, in which said securing means comprises spaced bolts thrOugh aligned openings in said mounting block and sheet and plate.