US2318860A

US2318860A - Electrical distribution system

Info

Publication number: US2318860A
Application number: US385912A
Authority: US
Inventors: John E Huguelet
Original assignee: National Electric Products Corp
Current assignee: National Electric Products Corp
Priority date: 1941-03-29
Filing date: 1941-03-29
Publication date: 1943-05-11
Anticipated expiration: 1960-05-11

Description

May ll. 1943- J. E. HUGUELETy ELECTRICAL DISTRIBUTION SYSTEM 4 Sheets-Shea? l Filed Marches I l 1 I I 1 1 l l llifliflllllllllllllllllill ..1111 -111.111.1H1H1N1111H. 1,1--- u H 11111.11 111111.@.1 11.1.1. 111u.1.1...1111.1.|11|1 111.111.111 -Wlumn May 1l, 1943. J, E. HusuELET 2,318,860

ELECTRIGAL DISTRIBUTION SYSTEMl Filed March 29,1941 4 sheets-sheet'z ME75- mmawww- May ll 1943- J. E. HuGul-:LE-r

ELECTRICAL DISTRIBUTION SYSTEM Filed March 29, 1941 4 Sheets-Sheet 3 INVENTOR May ll, 1943. J. E.-HUGUELET ELECTRICAL DISTRIBUTION SYSTEM Filed March 29, i941 4 sheets-sheet 4 w NHLN INVENTOR NN RN.

W7, Y M

Patented May 11, 1943 2,318,860 ELECTRICAL DISTRIBUTION sYsTEM 1 John E. Huguelet, Mount Lebanon, Pa., assignor to National Electric Products Corporation, a corporation of Delaware Application March 29, 1941, Serial No. 385,912

14 Claims.

This invention relates to an electrical distribution system of the sort. comprising continuous runs of bus-bars suitably supported from building structures or other mounting structures in factories, public buildings, and the like, and replete assembly in accordance with my invention including bus-bars, bus-bar supports, and housing therefor, showing one end of a length, or unit, of the housed bus-bar assembly. u

Fig. Ia is a fragmentary plan view of the (ci. 17a-334.15

same housed bus-bar assembly, or duct unit, in-

cluding such portion' of the unit as `to show the end thereof opposite that shown in Fig. I.

Fig. II is a fragmentary side elevation of the -housed bus-bar assembly, or duct unit, showing a lates particularly to a housing structure mounted the end thereof which is shown in Fig. I. protectively around the bus-bar runs, and to an Fig. IIa is a fragmentary side elevation of the arrangement of such housing which provides for housed bus-bar assembly. or duct unit, showing the direct attachment of branch circuit conthe end thereof which is shown in Fig. Ia. nectors and circuit breakers to the bus-bars. Fig. III is a cross-sectional view through the Desirably the electrical distribution system housed bus-bar assembly, or duct unit, taken on herein disclosed comprises the bus-bar supportthe section line III-III of Fig. Ia, showing the ing and mounting assemblies disclosed in my assembly on an enlarged scale, and illustrating companion application Serial No. 385,911, filed the manner in which the means for'securlng March 29, 1941, for an Electrical distribution l5 the cover and sides of the duct unit housing to System, because in that system the bus-bar supeach other normally prevent unconside'red access ports wholly perform the function of supporting to the bus-bars of the assembly,v in the absence. the bus-bars, relieving the housing of that load. of a current take-off device. To that, or a similarly organized system of sup- Fig. IV is a cross-sectional view on an enlarged ported busbars,Iapplyahousing. 20 scale, taken in the plane of the section line An object of my invention is to provide in an IV,-IV of Fig. Ia, showing a., current take-off electrical distribution system of that sort a. housdevice in contact-making engagement with the ing which is of light structure and which in assobus-bars of the assembly, and illustrating the ciation with self-contained bus-.bar supports is engagement of the current take-off device with rm and rigid; which is dustproof to protect the the housing structure of the bus-bar assembly, or bus-bars of .the system from dust, filings, and the duct unit. like; which is so arranged for access by current Fig. V is a fragmentary detail sectional view, 'take-off devices that the bus-bars are at all times taken in the plane of the section line V-V of protected against unconsidered access thereto; Fig- I. showing one of lthe doors of fthe housing and which is so associ-ated with the bus-bar supstructure which control access to the contactports of the system lthat adjustment in the sup- `making elements of a current take-oil device, in ports may be made within reasonable limi-ts withclosed position of the said door. y out changing the size of arrangement of the Fig. VI is a similar sectional view of the same housing structural ydetail shown in Fig. V, but showing Another object of my invention is to provide an the door in an intermediate stage of its opening organization of bus-bar supports and housing in movement. which the bus-bar supports relieve the housing Fig. VII is an isometric vertical sectional viewl of the weight of .the .bus-bars, and the thrust of showing fragmentarily a unit of the housingcurrent take-0E devices, in making contact with structure which is associated in assembly with the bus-bars within the housing. the bus-bars and bus-bar supports to form the Another object of my invention is to provide a duct unit. housing structure for mounted bus-bars in which Fig. VIII is a fragmentary vertical sectional the principal structural elements of the housing View. 0n an enlarged scale, through cooperating are few and simple, and in which the elements regions of a duct unit assembly and current takepurposed for opposed mounting in the housing Off device, :showing the relation of these strucassembly are identical, so that. the manufacture tures during application of the current take-off of vthe housing, its fabrication or` assembly in indevice to the duct. stall'ation, and its maintenance are facilitated. Fig. IX is a similar view of 'the same struc- In the accompanying drawings: v tural elements, but showing the current take-off Fig. I is a fragmentary plan view of the com 50 device secured in contact-making position to the duct housing. 1

Fig. X is a front elevation of the connecting plate or strap which I incorporate in the frame structure of my bus-bar support, to serve as the base element for making adjustment of the frame in accommodation to the width of bus-bars carried by the support.

Fig. XI is afront elevational view showing the connecting plate or strap of Fig. X, and showing in broken lines two frame elements of the support attached to the connecting strap in such relative position as to give an adjustment appropriate to the minimum width of bus-bar for which adjustment is provided.

Fig. )UI isa front elevational view, similar to Fig. XI but illustrating an attachment of the frame elements to the connecting strap to give an adjustment appropriate to the maximum Width of bus-bar for which adjustment L provided.

Fig. XIII is a front elevational view, similar to Figs. XI and XII but illustrating an attachment of the frame elements to the connecting strap to give an adjustment intermediate those illustrated in Figs. XI and XII.

In the accompanying drawings, reference numeral I designates generally the bus-bar supports of the housed bus-bar assembly, or duct unit. The bus-bars 2 are composed of initially separate rectangular bars of conductive metal, and these conductor lengths are interconnected in suitable manner, as by bolts 3, to form continuous electrically conductive paths. Each o the bus-bar supports I comprises two frame sections t and 5', which are interconnected by connecting members providing for relative adjustment of theframe sections, and which connecting members carry the attaching means for mounting the bus-bar supports. Each of the frame sections Ii and 5 of a bus-bar support consists of a base, at both ends of which side walls extend at right angles. Both the base and side walls of each of the frame sections are provided with anges S which, when the sections are interconnected, extend inwardly into the enclosure of the support to protect insulating members of frangible material mounted in the frame structure of the support. Desirably, the frame sections of the bus-bar supports are made of forged, or formed metal, but may be composed of any material which is sufficiently tough and rigid to be suitable for the purpose.

In these rigid mounting and protective frame sections insulating members for directly contacting and engaging the bus-bars are mounted. As shown, a row of three insulating members l is mounted in the frame section i and a row of three insulating members 8 is mounted in theA frame section 5. The insulating members on one frame section are mounted in opposition to those on the other section, and each of the insulating members has therein a seat 9 to receive one of the bus-bars 2.

Since inmybus-bar support adjustability to accommodate to diierent widths of bus-bar is otherwise provided, the insulating members are rigidly mounted on the frame sections which carry them. This mounting may be by means of bolts threaded into inserts set in the sockets in the insulators, or may be by means of bolts sealed into sockets in the insulators by means of lead, sulphur, or other suitable cementing material. Both of these modes of attaching bolts and screws to insulators are in common use, and may desirably be employed if the insulators are composed of porcelain or similar brittle material. I prefer, however, to mount the insulators in the frame sections of the support in the manner particularly disclosed and claimed in my co-pending application Serial No. 385,913, led March 29,

1941. In this mounting the insulating members are made of some suitable molding composition which has sulcient toughness to sustain the cutting of threads. As shown, screws I0 are directly threaded into the insulating members, and their heads lie against the outer surface of the base portions of the two frame sections.

Adjustability in the frame structure of the support is obtained by making the two frame sections I and 5 relatively adjustable toward and from each other with respect to connecting members which provide a basis for the adjustment. Thus the side walls II of the frame section B and side walls I2 of frame section E are engageable in various adjusted positions with respect to two connecting straps, or plates I3. For this adjustment both side walls I I and I2 of each of the frame sections are provided with three countersunk screw holes, Ila, IIb and Illc, which are arranged in triangular pattern. As standard bus-bars currently vary in width by one-half inch, the screw holes are (in current manufacture) arranged to give quarter inch adjustments on each frame section, in accordance with the hole which is used to connect each of the frame sections with its associated connecting strap i3. Each connecting strap I3 has therein four tapped holes I5 arranged in transversely aligned pairs to cooperate with screw holes Ila, Mb, and Ic of the frame section side walls at each side oi.' the frame, and with attaching screws I6.

Referring now particularly to Figs. X and XIII inclusive, of the drawings, each connecting strap carries two stud bolts I1, which in assembly of the frame elements with the connecting strap are straddled by the adjacent sidewalls of the frame elements. In Fig. XI attaching screws I6 are inserted through screw holes Ifia of each of the frame elements to engage in one of the tapped holes I5 in each aligned pair in the connecting strap. The screw holes Ilia being the outermost holes in the side wall with respect to the centerline of the connecting strap, this attachment brings the opposed edges IIa and I2a of the walls close together, and gives the closest relative position of the bases of the frame elements and the insulating members which they carry. 'Ihis adjustment is thus for the narrowest bus-bars for which accommodation is provided.

In Fig. XII the attaching screws are inserted through screw holes Mc, which lie closest the opposed edges Iia and IZa of the frame elements, into one of each pair of tapped holes i5 in the connecting strap. This separates the frame elements, and the insulating members they carry, the maximum distance provided, and makes accommodation to the widest bus-bars for which the frame structure of the bus-bar support is organized.

In Fig. XIII the attaching screws I6 are inserted through holes Mb of the frame elements into two of the tapped holes I5 of the connecting strap, to give an adjustment suitable for bus-bars of intermediate width.

The above-described adjustable bus-bar support is also disclosed and is claimed in my corn- `panion application Serial No. 385,911, led March 29, 1941, for an improvement inv Electrical distribution system.

The invention herein deals more particularly with the organization of a housing structure in associationwith bus-bar supports of the above described, or other suitable, structure, and with the mounting of current take-oil devices on said housing to make contact with the bus-bars supported therein.

The housing for the bus-bars and bus-bar supports, which is designed to be carried by the rigid bus-bar supports and to be dustproof, is made up of screening elements consisting primarily of two side plates, or walls, I8, and two cover plates I9. The attachment of the screening elements or side walls I8 to the bus-bar supports is by means of the stud bolts Il carried by the connecting straps I3, and which lie in slots 20 extended from the adjacent edges IIa and I2a of the side Walls II and I2 of the frame sections, to permit adjusting movement of the two frame sections. Since nuts 2I may be run down a variable distance on the Shanks of stud bolts Il, hangers mounting the duct assembly and the side walls I8 of the housing structure may both be connected by the same bolts and nuts without interfering one with vthe other. Also, within the limits prescribed by the width or'lateral extent of the side walls, adjustment of the frame sections may bermade while using the same side wallelements, and without affecting the relation between the side walls and the stud'bolts I1 carried by the connecting straps.

In order that the housing structure may be both rigid and dustproof, although composed of sheet metal of rela-tively light gauge, the side walls IB and cover plates I9 are joined by means of a lapped engagement; and for reasons hereinafter explained, the engagement ofy the cover plates to the side walls is made in the manner shown in the drawings. Fig. III shows particularly that both longitudinal edges of each of the side Walls are laterally extended beyond the bus-bar supports to provide extended regions 22. Each of the cover plates I9 has along its longitudinal edges outwardly turned ilanges 23, which in assembly lie against the cooperative extensions 22 of the side walls. Desirably the cover plates are of such width that they and their outwardly turned flanges nt tightly between the extended regions 22 of the side walls, and this engagement is made positive by means of bolts 24 the heads of which contact the outer faces of side wall extensions 22, and the shanks of whichproject through the anges 23 of the cover plates and carry nuts 25. Under these circumstances the shanks of bolts 24 overlie the edges of outwardly opening doors 26 which give access by contact prongs to the busbars 2 of the assembly. Y

These doors 26 are simple structures arranged to cover openings 21 in the cover plates I9 of the duct housing. Each of the doors proper is in the form of a plate arranged marginally to overlap the structure of the cover plate surrounding the hole closed by the door. This plate is slotted at 26a. adjacent one of its edges lying across the duct, anda U-shaped boxing 28 has its legs inserted through this slot and through a cooperative slot in the wall of the cover plate. A

lleaf springv 29 lies between the legs of the U- shaped boxing 28, resting upon a cotter pin 30 passing through both those legs, and at its ends contacting the inner surface of the cover plate.

In Fig. VI of the drawings, the door 26 is shown in its central, or neutral, position in opening or closing movement of the door. When moved past this neutral position in either direction of rotation, the door is urged the rest of the way byI spiing 2s into a position flush with the surface -of the cover plate. In its open condition, in a position flush with the surface oi.' the cover plate, the door 26 thus presents n obstruction to the mounting of a take-oi! device in position to make contact with the bus-bars by way ofthe opening controlled by the door. Doors 26, being organized for outward opening, projection of the shanks of bolts 2 4 over the edges oi' the doors thus effectively prevents access tothe interior of the duct unless the bolt'sare removed, as in preparation for the application of a current take-off device to make contact with the bus-bars. When in position, the current take-oil' device itself prevents unconsidered access to the interior of the duct. i

For attaching a current take-0H device to the duct I utilize the same bolts which are used to secure the cover plate of the housing. to the housingside walls, and which overlie the doors in the cover plate in the absence of a take-ofi device. This means of attachment is shown in Fig. IV of the drawings and is shown in detail in Figs. VIII and IX. For positive connection in the assembly tapped holes 3i are provided in the lower region of the side walls 32 of the take-off device, and are so arranged that in contact-making position of the take-off device on the duct they register with bolt holes 33in the side wail extensions of the duct housing and the flanges of the duct cover plate. In contact-making position of the elements, prongs 34 of thecurrent take-olf device embrace the bus-bars 2, and bolt holes 3| and 33 are in register; Bolts 24 which have been removed to permit opening of the doors 26 and contact-making introduction of contact prongs 34, are then replaced and are engaged in the tapped holes 3| in the lower region of the current takeofi' device. This gives simplicity of construction, certainty of. accurate alignment in the organization, and assurance that the bus-bars are at all times protected against undesired contact from outside the housing. The structure of the duct housing which is adapted to unit length construction in association with bus-bars and bus supports, and which gives a dust-proof enclosure for the bus-bars, gives readyy access for contactmakingdevices, and which provides convenient access within the duct for making the assembly of unit lengths of housing and for interconnecting lengths of bus-bars, is shown particularly in Figs.

I, Ia, II, IIa and VII of the drawings.

Referring to these ilgures of the drawings, the side plates, or walls, I8 of the housing are shown connected to the bus-bar supports vI by the stud.

bolts I7 carried by the connecting straps I3 forming elements of those supports; and are shown as connected to the cover plates I9 of the housing structure by the bolts 24 to which reference has been above made. As is clear in these gures of i the drawings, the openings 21 in the two cover plates are in assembly arranged in staggered relation, thus avoiding the possibility of contact bcl tween the contact prongs of take-olf devices which are inserted from opposite sides of the duct to make contact with the bus-bars therein. 'I'his staggering is an incident to thearrangement of the elements which I shall now described.

As assembled, the elements, whether they be assembled initially into unit lengths or whether the assembly is progressively made from all the duct elements at the same time, do not at any point of junction along the length of the duct p form ilush edges including both the side walls and cover plates of the housing structure. As shown, the lengths of the side walls at one of their end edges are caused to extend beyond the cover plates and at their opposite end edges to terminate short of cover plates extensions provided by

junction pieces

35 and 35a. One junction piece 35 is mounted at one end of the cover plates of the duct to give a cover extension beyond the side .'alls, and at the opposite end of the opposed cover plate a junction piece 35a is provided to extend beyond the end edges of the side walls. This effect appears in all of Figs. I, Ia, II and IIa, but it is most readily apparent in Figs. II and IIa.

The arrangement with respect to

junction pieces

35 and 35a is shown in Figs. I to IIa of the drawings and is made clearer by the detail showing of Fig. VII. In accordance with this arrangement, the opposed cover plates I9 have at their inner surfaces, and projecting beyond both end edges thereof, splice, or connector,

plates

36 and 36a riveted or otherwise suitably secured to the cover plates. The portions of these plates which extend beyond the edges of the cover plates are provided with tapped screw holes 31 by means of which

junction pieces

35 and 35a are secured to the plates 38 and 38a, with their end edges in abutment with the end edges of the cover plates and with their outer surfaces forming a. smooth continuation with the outer surfaces of the cover plates.

The two side walls I8 at one end thereof, which is the same end of both side walls in the duct unit assembly, have riveted, or otherwise secured to each thereof, splice, or connector. plates 38 which lie against the inner surfaces of the side walls and extend longitudinally beyond the edges of the side walls. The extending portions of these plates 38 vhave therein tapped screw holes 39, so that in assembly the side walls of each unit length of the housing lie outwardly against these plates in edge abutment with the side walls of the adjacent housing unit, to provide a smooth continuous outer surface along the side Walls of the housing assembly.

To secure the housing elements in assembly relation. each of the

junction pieces

35 and 35a has screw holes d adjacent each edge thereof to register with the tapped holes 31 in

connector plates

38 and 36a carried by the cover plates which are interconnected by the junction piece. Similarly, both side plates I8 have adjacent one end of each screw holes QI, to register with screw holes 39 in connector plates 38 carried by the side walls of an adjacent unit.

In the assembly of a reach of the duct including a plurality of duct units, the effect is that each duct unit carries a junction piece overlying the cavity of the duct unit connected at one end thereof, and a junction piece underlying the cavity of the duct unitv connected at the other end thereof. The housing structure has an overlapping dustproof engagement between the housing elements throughout a duct assembly including unit lengths of the housing. It also gives ready access to the interior of in which lengths of bus-bar 2 are interconnected by bolts 3. Thus 'one of the

cover pieces

35 or 35a may be readily removed by withdrawing the screws which at both ends of the junction piece connect it with the connector plates carried by the cover plates which the junction piece interconnects.

The described organization of bus-bars, busbar supports, and housing structure is well adapted to the formation of, and connection with, duct units of specializedI shape to give directional changes in a complete installation of the system. Thus the jointing elements for interconthe housing in the region necting adjacent housing units are well adapted to connect into the system specialized duct pieces organized to present a matching end for connection with the end of one of the standard duct units; and in those specialized units, or fittings, the organization of bus-bar supports and means for mounting the housing elements thereon may be identical with the organization described for the standard duct units.

It will be noticed that at one end of each of the cover plates I9 the opening 21, which gives access to the contact prongs of a take-oi! device, lie closer to the end edge of the cover plate than does the similar hole at the other end of the plate, but that the spacing between the openings is uniform. When, therefore, two of the cover plates I8, identical in structure, are mounted in opposition to each other on the side walls with their ends reversed, the staggered relation of the openings appearing in Figs. I and Ia of the drawings is obtained. Attention is here directed to the fact that every element of the assembly which is mounted in opposition to a similar element is identical with the element in opposition to which it is mounted, and that identical duplicate parts are used throughout the assembly. Side plates I8 are so made that a single form of side plate is adequate at both sides of the housing throughout any assembly length of the duct. This is also true of cover plates I9; of

junction pieces

35 and 35a; of

connector plates

36 and 36a; of connector plates 38; and of the doors 26 which cover the prong-receiving openings 21 in the cover plates the frame sections d and 5 of the bus-bar supports, and of the connecting straps I3 by which those frame sections are adjustably interconnected.

- This use of identical parts throughout the assembly not only contributes to increased facility in manufacturing the duct, but also facilitates the operation of assembling the duct parts and units into a continuous reach or run of the duct in installation; because persons making the assembly are not confused by a variety of elements of slightly diiferent structure at different points along the run of the duct, or by elements which must be assembled in right or left hand relation in constructing unit lengths, or a continuous run of the duct.

It will be noted that in the drawings there is shown an auxiliary bus-bar 42 in addition to the three main bus-bars 2, vto provide a neutral Wire for a three-phase system; and that the curren't take-off device is shown with an auxiliary contact prong t3 to engage that auxiliary busbar. Referring to Figs. I and Ia of the drawings, the openings 21 providing access for the contact prongs of current take-off devices are divided each into two portions of unequal length laterally of the cover` plate in which they are made. These two open regions 21a. and 21h are separated by a bridge 44 retained from the structure of the -cover plate in making the openings therein. The larger open region 21a gives access to two of the main contact prongs 34 of the current takeoff device and to the auxiliary contact prong S3 which engages the auxiliary bus-bar 2, providing the neutral wire of the system. The shorter open region 2lb gives access to but one of the main contact prongs 34. It is impossible, therefore, the opening 21 being divided into the open regions 21a and 21h, improperly to make contact with the bus-bars of the system.

In the organimtion above illustrated and de- I9. It is also true of i asiaseo scribed, the thrust of a current take-of! device, or plug, in making contact is first wholly received by the bus-bars, is transmitted by them to the bus-bar supports, and is transmitted by the busbar supports directly to hangers connected with the bus-bar supports and with structure on which the duct assembly is mounted. The housing structure is thus wholly relieved of the thrust of current take-olf devices in making contact with the bus-bars. This is of great advantage, since the bus-bar supports are independent rigid elements, and the housing structure is composed of relatively light-gauge elements.

The entire duct assembly is thus composed of elements which in themselves and in relation to each other perform in superior manner each its intended function. These parts are few in number and are of simple construction. As above noted, they are included as identical duplicates throughout thel duct assembly.

It is to be understood that many changes in the form and arrangement of the parts of which the above described assembly is made, and the material of which they are composed, may be made without going beyond the bounds of my invention, and my invention is therefore to be limited in scope only by the bounds of the claims appended hereto.

I claim as my invention:

1. In an electrical distribution system the combination of a plurality of structurally independent bus-bar supports with a housing including two side members carried by the said busbar supports and having their longitudinal edges extended beyond the structure of the bus-bar supports, a cover member lying between` the two side members of the housing and having along its longitudinal edges flanges lying against the extended portions of the' two said side members, openings protected by doors opening away from the cavity of the housing in said cover, and removable fastening members engaging the flanges of the cover member to the extended portions of the side members and overlying the said doors of the cover member to prevent unconsidered opening thereof.

2. In an electrical distribution system the combination of a plurality of structurally independent bus-bar supports having bus-bar contacting insulators therein, housing side plates carried by the said bus-bar supports, flanged housing cover plates fitting between the said side plates and bolted at uniformly spaced intervals to the longitudinal edges of the housing side plates'. the said cover plates having uniformly spaced openings in line with the points at which the cover plates are bolted to the side plates, and outwardly-opening doors controlling the openings in the cover plates and mounted in position to be overlaid by the bolts securing the cover plates to the side plates.

3. A housing for the bus-bars and bus-bar supports of an electrical distribution system including two identical channel-shape cover plates having openings for the insertion of contactmaking prcngs in the base portion thereof, two identical side plates extended beyond the base porticns of said cover plates and lying outside the flanges thereof, doors controlling said openings hinged to lie flush with the outer surfaces oi tir base portions of the said cover plates both in purition to cover and in position to expose the openligs therein, and removable fastening members securing the said side'plates to the flanges of the said cover plates and extensible over the 5. A housing unifj for inclusion in an electrical distribution system including two side plates,

two cover plates extended between and secured t0 the longitudinal edge regions-of the two side plates, the said cover plates terminating short of both ends of said side plates, junction plates formed and arranged to abut the terminal edges of the said cover plates'and to bridge the intervalsbetween the cover plates of adjacent duct units, and connector plates secured at the inner surface of both side plates at one end of the unit and projecting beyond the end edges of the said plates to lie within and overlap the side plates of an adjacent housing unit.

6. A housing unit for inclusion in an electrical distribution system including two side plates, two cover plates extended between and secured to the longitudinal edge regions `oi the said two' side plates, the said cover plates terminating short of both ends 'of said side plates, connector plates secured to one end of eachl side plate at one end of the unit and projecting beyond the end edges of the side plates to lie within and overlap the side plates of an adjacent housing unit, connector plates secured at the inner surfaces of both cover plates at both ends thereof to extend beyond the end edges of the cover plates, andjunction plates lying outside and secured to the said connector plates with their end edges in line with the end edges of the cover plates.

7. In an electrical distributionsystem the combination of bus-bars and supporting structures therefor of a housing unit including two channelshape cover plates having therein longitudinally spaced openings giving access for the contactmaking prongs of a current take-ofi' device, two side plates projecting beyond the base portions of the cover plates to lie outside the flanges of the cover plates, registering holes for connecting members in the said side plates and the flanges of the cover plates in the regions of each of the access openings in the cover plates, and a current ,take-off device having contact-making prongs projectible through the access openings in the cover plates and having in the structure thereof holes registering in contact-making position of the current take-on device with the regis-v tering holes of the cover plates and side plates for attachment therewith by fastening members extending through the said registering holes.

8. In an electrical distribution system the combination of a plurality of rigid structurally independent bus-bar supports, bus-bars mounted therein, an integrated housing surrounding the said bus-bar supports and having therein openings aligned with the bus-bars in regions between bus-bar supports, and connecting members carried by the bus-bar supports and extended through the housing structure for the transmission of contact-making thrust in the connection of current take-off devices with the bus-bars (independently of the housing) from the bus-bar supports to mounting structure attached by the said connecting members to the bus-bar supports.

9. In an electrical distribution system a structural assembly in accordance with the definition of claim 8 in which the housing is an integrated primarily rectangular four-piece structure.

10. In an electrical distribution system the combination of bus-bar-supporting frame structures each comprising a pair of frame sections, two adjusting straps on which the said frame sections are relatively adjustable in accommodation to bus-bars of diierent width, means forinterconnecting the said frame sections and adjusting straps, with screening elements for the bus-bars carried by the said adjusting straps independently of the said frame sections relatively adjustable on the said straps.

11. In an electrical distribution system the combination of bus-bar-supporting frame structures each comprising a pair of frame sections,

two adjusting straps on which the said frame sections are relatively adjustable in accommodation to bus-bars of diierent width, means for interconnecting the said frame sections and adjusting straps, with housing side plates carried by the said adjusting straps independently of the said frame sections relatively adjustable on the said straps.`and cover plates carried by the said side plates out of contact with the said bus-barsupporting frame structures.

12. In an electrical distribution system the combination of a plurality of structurally independent bus-barsupporting frames having bus- -bar contacting insulators therein with a housing Acarried by the said bus-bar-supporting frames and including at least one channel-shape cover .plate fitting between the longitudinal edges of two parallel plate elements of the housing with its anges in contact with the inner surfaces of said parallel plate elements and bolted at spaced intervals thereto, the said cover plate having spaced openings in line with the points at which the cover plate is bolted to`the parallel housing plates contacted by its flanges, and outwardly opening doors controlling the openings in said cover plate and mounted in position to be overlaid by the bolts securing the cover plate to the parallel plates between which it lies.

13. In an electrical distribution system the combination of a plurality of bus-bar-supporting frame structures having bus-bar contacting insulators therein, housing side plates removably carried by the said frame structures, housing cover plates attached to and carried by the said side plates to extend there between, and mounting elements for the assembly attached directly to the said frame structures independently of the housing elements carried thereby.

14. In an electrical distribution system the combination of a plurality of bus-bar-suDporting frame structures, an integrated primarily rectangular housing surrounding and removably carried by the said frame structures, and mounting elements for the assembly attached directly to the said frame structures independently ot the housing by which it is surrounded.

JOHN E. HUGUELET