US1857197A - Insulated connecter for outlet boxes - Google Patents

Description

y 1932- H. G. KNODERER 1,857,197

I INSULATED CONNECTER FOR OUTLET BOXES Filed Jan. 26, 1929 In Ventor I W H is fltt orney.

Hom e21" G. Kn cleren' Patented May 10, 1932 UNITED STATES PATENT OFFICE HOMER G. KNODERER, OF FAIRFIELD, CONNECTICUT, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK INSULATED GONNEGTER FOR OUTLET BOXES Application filed January 26, 1929. Serial No. 335,35'7.

My invention'relates to an improved combination of elements ;of utility in connection with armored conductors, such as are em ployed in house wiring and the like and more 15" particularly to an improved insulating bushing and connecter combination for securing armored conductors to outlet boxes and the like. An object of my invention is to provide an arrangement of parts which will insure that the insulated wires of armored conductors are protected from the sharp end edges of the armor without the necessity for particular thought or care on the part of the workman in making-the installation.

A further object of my invention is to provide a combination of insulating bushing and connecter which will also protect the conductors from any sharp edges on the part of the connecter, which extends into the outlet box, so that the conductor insulation will not be injured thereby.

A further object of my invention is to provide a construction which will permit conmeters and insulating bushings to be readily assembled and enable the combined connecter and bushing to be shipped and sold as a unit and handled by the workman as a unit when making an installation.

A further object of my invention is to provide an arrangement which when the installation is completed will enable an inspector readily to determine whether or not the installation has been properly made.

A further object of my invention is to prov vide a simple and rugged arrangement of parts which makes it impossible for the bushing to be removed from the connecter after the armor stripped ends of the conductors are inserted into the bushing and whichpermits the workman to force the armored conductor into position for clamping without danger of forcing out the bushing, and which will insure that the conductors are protected from the sharp end edges of the armor when the armor has been pushed into the connecter far enough to permit it to'be secured therein by the clamping means thereof.

While my invention is particularly useful in connection with armored conductors, it is also advantageous for use in connection with flexible metallic conduit which is secured by connecters in a similar way to outlet boxes and the like and into which conduit the conductors are drawn and the electrical connections made after the conduit system has been installed. In such an arrangement my invention protects the conductors from injury by the sharp edges on the conduit and connecter and also provides a smooth uninter rupted runway for the drawn in wires.

My invention will be better understood when considered in connection with the following specification and accompanying drawings and its scope will be pointed out in the appended claims.

Referring to the drawings, Fig. 1 is a side elevation, with part broken away, of an ar mored conductor with the right-hand end stripped of armor; Fig. 2 is an axial section of the connecter with my insulating bushing in place; Fig. 3 are sections of a junction box wall and connecter retaining nut; Fig. 4 is a perspective view of the outerend of the connecter; Fig. 5 is an assembled view of the several parts shown in Figs. 1, 2 and 3; Fig. 6 is a side elevation of another form of armored conductor showing the sharp end edge customarily formed in the cutting of the armor to bare or strip the ends of the insulated wires; Fig. 7 is a part side elevation and part section of a flexible metallic conduit assembled in a connecter provided withmy insulating bushing; Fig. 8 is a perspective view with part broken away of the inner end of a difierent form of connecter and insulating bushing; Fig. 9 is a similar view of another form of connecter and insulating bushing; Fig. 10 is a View of the application of my invention with a different form of clamping means and Fig. ll represents a modified construction of insulating bushing.

As is well known, the armor of armored conductors and the flexible metallic conduits of commerce are composed of continuous metal strips or ribbons profiled in cross section and coiled helically so that the edges thereof become interlocked with a certain amount of freedom-to slip upon each other when the finished article is bent. It is customary in 105 installing armored conductors and flexible metallic conduit to cut the profiled metallic strip by suitable means such as a hack saw. This usually leaves a sharp projecting end edge or corner which is apt to penetrate the insulation of the conductors. Also, unless special care is taken by the wireman, the hack saw may cut. into or through the insulation of the wires of armored conductors di: rectly beneath the sharp end edge thereby increasing the liability of an electrical contact between the armor and the wires. After a portion of the armor has thus been severed and removed, the armored conductor is secured by suitable means such as a connecter to the. outlet box into which the wires project. The manipulation of these wires by the wireman in making connections is likely further to injure the insulation on the wires by reason of sharp edges or projections on the armor or the connecter.

In accordance with my invention I provide an improved insulating bushing which projects between the wires and the armor of the armored conductor to form an insulating and protecting sleeve to protect the wires from injury by sharp edges or projections on the armor and which bushes the end of the connecter which extends into the outlet box to protect the wires against injury from theconnecter. Referring to Figs. 2 and 5 it will be seen that the bushing 4 is mounted in the connecter 8. As will be more particularly set forth hereafter, the bushing is constructed so that when it has been inserted into the connecter it will be securely retained in the connecter and the bushing and connecter may be handled as a unit. After a portion of the armor of the armored conductor has been removed the projecting wires are inserted through the connecter and bushing as above described. In Fig. 1 the projecting wires of the armored conductor are shown at 2 and the armor at 3. In order to enable the bushing to be readily inserted between the wires and the armor, I prefer to use an armored conductor which is provided with a wrapping 1 which may be ofpaper. After the armor has been cut and a portion removed so as to leave the projecting wires a portion of the paper wrapping 1 may be pulled out and the wrapping severed for a distance back into the ar mor sufficient to accommodate the sleeve of the bushing which. projects between the wires and the armor. While I at present prefer to use armored conductors with such a wrapping my invention is also applicable to other forms of armored conductors where there is a small amount of looseness or space between the conductors 2 and the armor 3 which permits the bushing to be forced into place.

I prefer to make the insulating bushing 4 in the form of a split tube of fiber or other suitable resilient insulating material provided at the inner or outlet box end with two spaced shoulders, one of which is an end flange 5 and the other a bead 6 between which shoulders the inturned flange or contracted part 7 of the connecter 8 is located when the bushing is in place in the connector. l/Vhen the bushing is forced into the shouldered or contracted part 7 of the connecter 8 the head 6 snaps through the contracted part 7 and the latter is then embraced on opposite sides by the spaced shoulders of parts 5 and 6 and serves thereby to hold the insulating bushing definitely positioned therein with an annular clearance space 9 between the main bore 10 of the connecter 8 and the outside of the main tubular portion of the bushing. This clearance space 9 is open at its outer end and closed at its inner, as shown in Fig. 2.

In order to facilitate the entrance of the split insulating bushing 4 into the space between the insulated conductor-s2 and the inner surface of the armor 3, the outer corners 15 thereof adjacent the split are preferably rounded oil", as shown in Fig. 2, and the outer end of the bushing is preferably made slightly beveled or tapering.

I preferably construct the bushing so that when it is snapped into place in the connecter the longitudinal edges adjacent the split of the bushing come into abutting relation with each other. This serves to resist the collapse of the bushing and provides a complete insulating sleeve. It is within the scope of my invention, however, to make the slit in the bushing sufficiently wide so that when it is contracted to insert it in the connecter the edges come into abutting relation and when the bushing comes into place its resiliency causes it to be held firmly in place. The flange 5 and the bead 6 on the bushing contribute to the resilient action of the bushing.

lVhen the conductors 2 have been inserted through the bushing the collapse of the bushing is prevented so that the workman may grasp the connecter 8 in his hand and apply force to drive the sleeve into place between the armor and the wires and to drive the connecter 8 over the armor 3 without danger of. pushing the bushing out of the connecter.

The particular form of connecter 8 shown in section in Figs. 2 and 5 is shown in perspective in Fig. 4. I provide such alength of bushing 4 with respect to the connecter 8 that when the armor 3 has been forced into the connecter far enough to enable the armored conductor to be fastened into the connecter by tightening the screw 12 the sleeve of the bush- .ing will have been forced between the wires and the armor to the necessary distance to protect the wires from the sharp edges of the armor. In other words when the armored conductor has been inserted into the connecter far enough to enable it to be secured by the clamping means it necessarily follows that the bushing is properly located. After the Em cte h been clamped to the armor the tmgaded and of the connecter 8 is entered through the/hole in the outlet box wall 13, or otheigwall through which the wires are to e led, and the connecter is secured to the wall y d m Fig. 5.

bushing 4 pro ects over and protects the wires from injury f w 7. It will also be observed that the flange 5 of the bushing is in a position where itmay be readily seen by looking into the outlet box. If, therefore, an armor is properly clamped in the connccter and observes the flange 5 of the bushing, he knows at once that the insulating bushing is in place and that the job has been properly done. This is a feature of considerable importance since if the bushing were inside 0 the'contracted portion 7 of the connecter-rit would be practically impossible for the inspector to determine whether or not the bushing was present without disassembling the connection. Even should the inspector disassemble a few connections in a building and find that the bushings were in place he woul even then not be sure that the bushings were in place in the other connections unless he disassembled all of them. ith my arrangement no disassembling at all is necessary an the inspection can be made quickly and with certainty. oreover since the bushing may be shipped in place in the connecter and h dled as a unit by the wireman the wireman does not need to exercise the thought and care which would be necessary if separate bushings d which he would have to remember to insert between the wires and the armor bea the armor in the connecter. will be observed that the sleeve of the bush ing projects within the connecter and is protected by the connecter so' that it will not be damaged by the handling and boxing and shipment of the assembled units comprising the connecters and bushings.

Fig. 6 represents another orm of armored omits the wrapping 1 o the armored conductor shown in ig.

This figure also indicates at 11 the sharp corner which customarily results when the armor is out with a hack saw as heretofore described.

While my invention is of particular utility in connection witharmored conductors, it may also be advantageously used with flexible metallic conduits into which the wires are drawn after the conduit installation has been made. Fig. 7 shows such an application of m invention. 0 lt-will be apparent to those skilled art that my invention is not limited to any one particular type of connecter. Fig. 8 illustrates anothertype of well known conbushing inserted therein.

necter with. .my Fig.9 illustrates still another type of wellin the 1. tween which is known connecter. Fig. 10 illustrates a modified arrangement or clamping armore conductors in an outlet box. In this case the member 16 is mounted inside the outlet box and when the screw passing through the hole 17 is forced down the member 16 is tilted and clamps the armor 3 in the box. With this type of clamp my bushing a may also be used and shipped with the clamping member as a unit. It will thus be seen that my improved arrangement is applicable to many different kinds and types of connecters.

While I at present prefer to use a bushing which is split throughout its length it is apparent that it is within the scope of my invention to use a bushing which is split or cut through a portion only 0 its length, as indicated in Fig. 11, the split portion being at the end upon which the shoulders 5 an are provide Such a bushing may be either into the connecter from the end opposite the restricted portion or may be inserted from the restricted end of the bushing if the bushing is suitably tapered, as indicated in Fig. 11, so that the uncut portion will pass through the restricted portion of the connecter.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. The combination with an armore electrical conductor and an outlet box, of a connecter provided with means for securing it to the armored conductor and to the outlet box and an insulating bushing comprising a split cylindrical sleeve located the armor and conductors and provided withmeans for attaching it to said connector the parts being d so that when the securing means is operative to connect the armored conductor to the connector the bushing will be located properly to protect and insulate the conductors from the armor and connecter.

2. The combination with an insulator shield comprising a split tubular body, one end portion ofwhich is fashioned to form spaced, outwardly and radially projecting members hean annular recess, of a tubular metallic body, one end portion of which is proinwardly extending flange vided with an adapted to seat in the recess of said shield to retain the tube against displacement from the shield.

3. The combination with a tubular body having an inwardly and radially directe wall, of a shield of insulating material arranged in the bore of said body, and means on said shield adapted to be arrange sides of said wall for retaining said sh against displacement from said body.

4:. In combination with an insulated electric conductor and a sheathing therefor, said conductor having an end portion projecting outwardly from an end of said sheathing, of a coupling adapted to connectsaid conductor ield atopposite ill and its sheathing to an electrical fixture, said means provided on said bod d da t d coupling comprising, a tubular body adapted to grip said sheathing to retain said oupling to e passed over the end of said sheathing thereon. and having a substantially longitudinally ex- 9. A coupling for armored cables coin r 5 tending shield member therewithin adapted ing, a tubular body having a sheathin re- 70 to pro ect into said sheathing in surrounding CGIVIHO I and protecting relation with said insulated 0 an armored cable and a substantially cyo I n a 4 o a o The combination with a connector haviortion extendin lon itudiiiall within said ing a conductor passagewa of a split cylinaperture and concentric therewith for inser- 75 drical insulating bushing having means theretion under the cable sheathing, and an attachon for retaining the same against accidental ing flange formed on said bod portion and displacement from Within the passageway of attached to said tubular body.

tie said connecter so' as to constitute a unit 10. n combination with an armored cable part thereof, the walls of the split portion at comprising an insulated electric conductor 80 tric conductor and a sheath therefor, sa d contially cylindrical split shield member having 8 coupling comprising a tubular body adapted ody portion having a tapered end to facili- 90 mg and protecting relation with said insulata sheathing receiving aperture for receiving 95 tric conductor and a sheathing therefor, said therewith, and an attach n flange formed on 100 coupling comprising, a tubular b dy adapted n witness whereof, I have hereunto set my 105 said tubular body, said shield member being 110 plane at an angle to the longitudinal axis of mg, a tubular body having a sheathing resaid bushing. ceiving aperture for receiving the end por- 6. In combination with aninsulated election 0 said, armored cable and a substanductor having an end portion projecting outa body portion extending longitudinally withvvardly from an end of said sheathing, of a in said aperture and concentric therewith, and coupling adapted to connect said conductor an attaching flange formed on said body porand its sheathing to an electrical fixture, said tion and attached to said tubular body, said to 'e passed over the end of said sheathing tate the insertion of said body portion under and having a substantially longitudinally eX- the cable sheathin q. tending cylindrical split shield member adapt4 11. In combination with an armored cable of ed to project into said sheathing in surrounda coupling comprising, a tubular body having ed conductor, and an attaching flange formed the end portion of said armored cable and on said shield member and attached to said a substantially cylindrical split shield memtubular body. er having a body portion extending longi- In combination with an insulated elec-' tudinally within said aperture and concentric conductor having an end portion projecting said body portion and atta ched to said tubuoutwardly from an end of said sheathing, of a lar body, said body portion having a tapered coupling adapted to connect said conductor end to facilitate the insertion of said body and its sheathing to an electrical fixture, said portion under the cable sheathing.

to be passed over the end of said sheathing hand this 23rd day of J anuary, 1929.

and having a substantially longitudinally ex- HOMER G. KN ODERER. tending cylindrical shield member therewithin in spaced relation from the inner walls of adapted to pro ect under said sheathing and conductor and a sheathing-therefor, said 0011- coupling comprising, a tubular body adapted i to be passed over the end of said sheathing I prising a substantially cylindrical bod portion adapted to surround said insulated conc uctoi and to project under the end portion of said sheathing to protect. said insulated conductor from the abrasive action of'said end portion, said shield member having an outwardly extending annular flange fixedly attached to said tubular body, and clamping

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