CONNECTOR ASSEMBLY AND METHOD OF USE
United States Patent 3787606
In a combination of electrical connector fitting of the type used to connect conduit to a junction box, the connector fitting having an externally threaded, open mouth throat end and a plug mounted in the throat, the plug has an open-ended throat-engaging tube section, a closed hollow dome projecting outwardly from and substantially beyond the mouth, and an external annular shoulder engaging an annular radial surface of the connector. In the process of construction, the plug is first mounted in the connector, then the connector is mounted in a junction box or the like. After the junction box is emplaced, the part of the plug dome which projects in the box is cut off, providing both a passageway and an insulative throat.
US Patent References:
Connecter fitting and bushing for armored cables
Frederickson - March 1932 - 1850792
Insulated connecter for outlet boxes
Knoderer - May 1932 - 1857197
Combined pipe plug receptacle and insulator
Esher - February 1953 - 2628264
Insulated electrical raceway fitting
Badeau et al. - August 1960 - 2947800
Connecter fitting and bushing for armored cables
Frederickson - March 1932 - 1850792
Insulated connecter for outlet boxes
Knoderer - May 1932 - 1857197
Combined pipe plug receptacle and insulator
Esher - February 1953 - 2628264
Insulated electrical raceway fitting
Badeau et al. - August 1960 - 2947800
Application Number:
05/350331
Publication Date:
01/22/1974
Filing Date:
04/12/1973
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
29/428, 220/3.400, 174/83, 138/89, 29/453, 29/450
International Classes:
H02G3/02; H02G3/08; H02G3/02
Field of Search:
174/64,65R,65SS,65G,83 16/2,108 29/428,450,451,453 138/89,96R 220/3.4 285/161
Primary Examiner:
Askin, Laramie E.
Attorney, Agent or Firm:
Philip, Polster Et Al B.
Claims:
1. In a connector assembly for electrical conduit, having an externally threaded, open-mouth throat end adapted to be mounted in a junction box or the like, the improvement comprising a resilient, electrically insulative, incisable plug mounted in said throat end of said connector, said plug comprising a throat wall-engaging open-ended tube section, and a closed hollow dome section projecting outwardly away from and substantially
2. The assembly of claim 1 wherein the connector has an annular radial surface and the plug has an outwardly projecting annular shoulder with a radial surface contiguous the annular radial surface of said connector.
3. The assembly of claim 2 wherein the said annular radial surface of the
4. The assembly of claim 3 wherein the diameter of the annular shoulder of the plug is no greater than the root diameter of the threads of the throat
5. The assembly of claim 2 wherein the said annular radial surface of the
6. The assembly of claim 2 wherein the connector has two annular radial surfaces, one a mouth-defining rim and the other an internal step, and the plug has two outwardly projecting annular shoulders, each having a radial surface contiguous one of the annular radial surfaces of said connector.
7. The assembly of claim 5 wherein the diameter of the annular shoulder of the plug contiguous the mouth-defining rim of the connector is no greater than the root diameter of the threads of the throat end of the connector.
8. In a connector assembly for electrical conduit and the like comprising a hollow, open-ended connector having an externally threaded, open mouth throat end adapted to be mounted in a junction box or the like, and an internal annular step down to said throat end, the improvement comprising a resilient, electrically insulative, incisable hollow plug mounted in said connector, said plug comprising an open-ended tube section engaging the inner wall of said connector throat end, a closed hollow dome section projecting outwardly away from and substantially beyond said connector mouth, an annular rim at the open end of the tube section with a face contiguous the radial face of the internal step in the connector, and an outwardly projecting annular shoulder outside said connector and contiguous a mouth-defining rim of the connector, said plug shoulder having a diameter no greater than the root diameter of the threads on the
9. The method of installing in a structure such as a junction box with a hole in a wall a connector assembly having an externally threaded open mouth throat end comprising, first, mounting a plug in said connector, said plug having an open ended tube section engaging the inner wall of the throat, and a hollow dome section projecting outwardly from and substantially beyond said plug mouth, said plug having no part external of said plug of a diameter greater than the root diameter of the external threads on the throat end of the connector, said plug being formed of an electrically insulative, incisable material; second, inserting the said throat end and projecting plug through said hole until threads of said throat end clear said wall, and third, screwing a lock nut onto said
10. The method of claim 9 including the additional step of cutting off at least a part of said projecting dome section to provide a passage through said plug and connector and an electrically insulated throat passage in said connector.
2. The assembly of claim 1 wherein the connector has an annular radial surface and the plug has an outwardly projecting annular shoulder with a radial surface contiguous the annular radial surface of said connector.
3. The assembly of claim 2 wherein the said annular radial surface of the
4. The assembly of claim 3 wherein the diameter of the annular shoulder of the plug is no greater than the root diameter of the threads of the throat
5. The assembly of claim 2 wherein the said annular radial surface of the
6. The assembly of claim 2 wherein the connector has two annular radial surfaces, one a mouth-defining rim and the other an internal step, and the plug has two outwardly projecting annular shoulders, each having a radial surface contiguous one of the annular radial surfaces of said connector.
7. The assembly of claim 5 wherein the diameter of the annular shoulder of the plug contiguous the mouth-defining rim of the connector is no greater than the root diameter of the threads of the throat end of the connector.
8. In a connector assembly for electrical conduit and the like comprising a hollow, open-ended connector having an externally threaded, open mouth throat end adapted to be mounted in a junction box or the like, and an internal annular step down to said throat end, the improvement comprising a resilient, electrically insulative, incisable hollow plug mounted in said connector, said plug comprising an open-ended tube section engaging the inner wall of said connector throat end, a closed hollow dome section projecting outwardly away from and substantially beyond said connector mouth, an annular rim at the open end of the tube section with a face contiguous the radial face of the internal step in the connector, and an outwardly projecting annular shoulder outside said connector and contiguous a mouth-defining rim of the connector, said plug shoulder having a diameter no greater than the root diameter of the threads on the
9. The method of installing in a structure such as a junction box with a hole in a wall a connector assembly having an externally threaded open mouth throat end comprising, first, mounting a plug in said connector, said plug having an open ended tube section engaging the inner wall of the throat, and a hollow dome section projecting outwardly from and substantially beyond said plug mouth, said plug having no part external of said plug of a diameter greater than the root diameter of the external threads on the throat end of the connector, said plug being formed of an electrically insulative, incisable material; second, inserting the said throat end and projecting plug through said hole until threads of said throat end clear said wall, and third, screwing a lock nut onto said
10. The method of claim 9 including the additional step of cutting off at least a part of said projecting dome section to provide a passage through said plug and connector and an electrically insulated throat passage in said connector.
Description:
BACKGROUND OF THE INVENTION
In the course of construction, and especially in poured concrete construction, as in commercial and industrial buildings, electrical conduit and junction boxes are commonly installed before the wire is pulled through and, in concrete construction, before the concrete is poured. In the latter case, after the concrete is poured and the forms are removed, the junction boxes are opened and the electrical wires run through the conduit. Good practice and many building codes dictate that the ends of the conduit, i.e., the connector fittings by which the conduit is attached to the junction box, be plugged until the time comes to run the wires through the conduit, to keep moisture, dirt, concrete and other foreign matter out of the conduit. The most common expedient has been to put corks in the end, but corks are bulky, easily removed before the time has come to pull the wire, and difficult to remove if concrete, grout or plaster gets into the box. Plastic plugs, in the shape of a low-crowned hat, are used, the crown portion being pushed into the mouth of the connector fitting. These plugs have had three disadvantages: they, like corks, are put in after the connectors have been installed, which means that they must be carried around loose; they have been provided with wide rims to facilitate their being pried out, which precludes their being installed before the connector fitting is mounted in a junction box, and the exteriorly exposed inside of the crown forms a recess into which plaster, concrete and the like can go.
One of the objects of this invention is to provide a connector fitting and plug combination in which the plug is installed in the connector before the connector is mounted in a junction box, which does not interfere with the mounting of the connector, which provides an insulated throat for the connector, and provides a clear passage even when plaster, concrete or the like gets into the junction box.
Another object is to provide a method of installing electrical connectors which facilitates installation.
Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
In the drawing, FIG. 1 is a fragmentary view in perspective, partly in phantom lines, showing a connector mounted on a junction box, with one embodiment of plug of this invention mounted within the connector;
FIG. 2 is a plan view of a junction box in which two embodiments of connector assembly of this invention are mounted, the one on the left being the same as the embodiment shown in FIG. 1, and the one on the right being a second embodiment;
FIG. 3 is a sectional view taken along the line 3--3 of FIG. 2;
FIG. 4 is a fragmentary view in side elevation taken along the line 4--4 of FIG. 3; and
FIG. 5 is a sectional view of still another embodiment of connector assembly of this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, particularly to FIGS. 1, 2 and 3, reference numeral 1 indicates a junction box of standard construction with round knock-outs to provide holes to accommodate connector fittings. As indicated in FIG. 2, two of the knock-outs have been removed, and connector fittings 2 are mounted in junction box wall 3, on opposite sides of the junction box.
The connector fittings 2 are also standard commercially available fittings, with an externally threaded conduit receiving end 7, a hexagonal external stop nut 8, and an externally threaded, open mouth throat end 9. The stop nut 8 is integral with the two end sections. Conventionally, the diameter of the throat end 9 is less than that of the conduit receiving end 7, and threads 11 on the conduit end are of less pitch than threads 12 of the throat end 9. A passage 16 extends all the way through the connector 2. Within the passage 16, between the conduit receiving end 7 and the throat end 9, there is an off-set forming a shoulder or step 27 with an annular, generally radial face 17. The passage 16 extends from a conduit receiving opening defined by a radial edge 18 at the conduit receiving end to a mouth defined by a radial mouth-rim 19 at the throat end.
The stop nut 8 is of a size relative to the knockout hole in the junction box to bear against the wall 3 surrounding the knock-out hole, and the fitting is mounted on the junction box by means of a lock nut 15, screwed onto the throat end of the connector and against the inside surface of wall 3.
In the embodiment of assembly shown in FIG. 1 and in the left side of FIGS. 2 and 3, a plug 20 is mounted within the connector 2. The plug 20, and the plugs of all of the other embodiments, are preferably made of polyethylene, rubber, or other elastomeric material, but they may be made of any material which makes the plug resilient enough to permit the mounting of the plug as is described hereafter, which is electrically insulative, and incisable. In this embodiment, the plug 20 has a closed domed projecting section 21, a cylindrical or tube section 22, a radially outwardly extending annular shoulder 23 at the base of the domed section 21, and a radially outwardly extending annular flange or shoulder 25 at an open end of the cylindrical section 22, remote from the domed section 21.
The annular flange 25 is dimensioned to fit within the passage 16 at the conduit receiving end 7 of the connector, and to bear against the face 17 of the shoulder or step 27. The cylindrical section 22 is dimensioned to fit snugly within the part of the passage 16 between the step 27 and the mouth-rim 19 of the throat end 9. The annular shoulder 23 is dimensioned to bear against the mouth-rim 19 of the throat end 9, but its outside diameter is preferably no greater than the root diameter of the threads 12. The distance between the facing radial surfaces of the annular shoulders 23 and 25 is slightly greater than the distance between the radial face 17 of the step 27 and the rim 19.
The resilience of the material of which the plug is made and the shape of the plug are such as to permit the shoulder 23 to be pushed through the throat section of the passage 16 and to cause the shoulder 23 to snap out into the position shown in FIGS. 2 and 3 when the inner radial surface of the shoulder 23 has cleared the rim 19 defining the mouth of the throat end 9.
When the plug has been mounted, the mouth of the connector is sealed by the dome 21, the shoulders 23 and 25 and the cylindrical section 22 of the plug. The shoulders 23 and 25 anchor the plug positively against the displacement in either direction.
It can be seen that the connector and plug can be assembled at the factory or in the shop, so that loose plugs need not be carried at the site. The assembly can be mounted in a junction box as if the plug were not there. Since neither the domed section nor the shoulder 23 projects radially substantially beyond the root of the threads 12, the lock nut 15 can be screwed on, to mount the connector, without interference from the plug.
The connector and the conduit attached to it are sealed by the plug against the entry of any foreign material. When the time comes at which wire is to be pulled, it is only necessary to cut off enough of the domed section 21 with any suitable instrument such as a knife or shears, to produce the desired opening.
It can be seen that the projection of the domed section 21 not only makes cutting off easy, but enables one to provide a passage even though the connector itself and a part of the dome may be buried in concrete, plaster or the like. Furthermore, when the domed section 21 or any part of it is cut off, the mouth and throat of the connector are insulated, and the mouth is provided with a smooth resilient surface which obviates skinning of insulation on the wires or damage to the wires themselves by the mouth-defining surfaces of the connector.
In the embodiment of assembly shown on the right side of FIGS. 2 and 3, a connector fitting 2 identical with the connector fitting just described in connection with the first embodiment, is provided with a plug 220. The plug 220 has a closed domed end 221 which corresponds to the domed end 21 of the first embodiment. The closed end 221 of the plug 220 is shown as being of a somewhat different shape from the domed end 21, but this is merely to illustrate the fact that the closed end of the plug can be of a variety of shapes without affecting its utility. The plug 220 has an annular shoulder or rim 225 around its open end. The shoulder 225 is identical with the shoulder 25 of the first embodiment. The plug 220 has a cylindrical section 222 which is dimensioned to fit snugly the inner wall of the passage 16 of the throat section 9 of the connector 2. In this embodiment, it is more essential that the cylindrical section 22 be in snug frictional engagement with the wall of the connector than it is that the cylindrical section 22 of the first embodiment be in such snug engagement, although it is desirable that section 22 also be in snug engagement with the wall of the connector.
In installing the plug 220, it is only necessary to push the plug through the passage 16, from right to left as viewed in FIGS. 2 and 3, until the flange 225 seats against the face 17 of the step 27. It can be seen that the mounting of the assembly in a junction box and its use will be the same as that of the assembly shown in FIG. 1. The embodiment of plug 220 has the advantages of slightly less cost and slightly greater ease of installation, and the disadvantages of less positive anchorage against displacement in a direction from left to right as shown in FIGS. 2 and 3, and slightly less protection against damage to wires, especially if the closed end section is cut off flush with the mouth-defining surface of the connector, as distinguished from flush with the outer surface of the annular shoulder 23 of the embodiment shown in FIG. 1. The terms "outer" and "inner" as applied to the shoulder 23 are used with respect to the connector, the inner radial surface being contiguous the mouth-rim 19.
Referring now to FIG. 5 for a third embodiment of assembly of this invention, a connector 2 indentical with the connectors shown and described in connection with FIGS. 1 through 4 is provided with a plug 320. The plug 320 has a closed end dome section 321 similar to the section 221 of the embodiment of plug 220, a cylindrical section 322 and an open end 327. The embodiment of plug 320, has an outwardly projecting annular shoulder 323, corresponding in every way to the shoulder 23 of the embodiment of plug 20. As in the embodiment of plug 220, the cylindrical section 322 of plug 320 is dimensioned to engage the throat section of passage 16 of the connector 2 frictionally snugly so as to resist displacement once mounted. The plug 320 is preferably mounted in the opposite direction from the plugs 20 and 220, that is, from left to right as viewed in FIG. 5. Otherwise, the mounting of the plug and the mounting and use of the assembly are the same as those of the embodiments shown in FIGS. 1 through 4. The assembly of the embodiment shown in FIG. 5 has the advantages of economy and ease of installation of the embodiment with the plug 220, and the advantage of protection of the wires against damage by the edge of the mouth-rim afforded by the shoulder 323 as in the assembly shown in FIG. 1. It does share the disadvantage of the plug 220 of not being positively anchored against displacement in both directions.
Merely by way of illustration and not of limitation, in a connector for half-inch conduit, the tube and domed or closed end sections of the plugs can have a wall of uniform thickness of thirty to forty thousandths of an inch, the shoulders can have an axial width of eighty thousandths of an inch and the dome can project one-half to three-quarters of an inch beyond the mouth of the connector. The other dimensions of the plug will be determined by the dimensions of the connector fitting.
Numerous variations in the details of construction of the plug and connector, and the methods of their use, within the scope of the appended claims, will occur to those skilled in the art in the light of the foregoing disclosure. Merely by way of example, the specific shapes, the length of the domed or closed section of the plug, the wall thickness, the axial width of the shoulders and the types of materials used can all be varied. The assemblies may be used in any place in which connectors are used, not merely in junction boxes. In the embodiment shown in FIG. 5, the closed end section 321 can be made with the same outside diameter as the shoulder 323, since only the cylindrical section 322 need be shoved into the passage 16. The cylindrical or tube section of any of the plugs may be provided with annular ribs, rounded or serrate. The face of the plug flanges 25 and 225 contiguous the face 17 of the connector can be sloped complementarily to a chamfer, commonly provided, on the face 17, and the radially inner edge of the flanges 25 and 225 can be chamfered to facilitate the entry of wire. The term "radially" extending is used to embrace such a surface as well as a surface perpendicular to the axis of the conductor. These are merely illustrative.
In the course of construction, and especially in poured concrete construction, as in commercial and industrial buildings, electrical conduit and junction boxes are commonly installed before the wire is pulled through and, in concrete construction, before the concrete is poured. In the latter case, after the concrete is poured and the forms are removed, the junction boxes are opened and the electrical wires run through the conduit. Good practice and many building codes dictate that the ends of the conduit, i.e., the connector fittings by which the conduit is attached to the junction box, be plugged until the time comes to run the wires through the conduit, to keep moisture, dirt, concrete and other foreign matter out of the conduit. The most common expedient has been to put corks in the end, but corks are bulky, easily removed before the time has come to pull the wire, and difficult to remove if concrete, grout or plaster gets into the box. Plastic plugs, in the shape of a low-crowned hat, are used, the crown portion being pushed into the mouth of the connector fitting. These plugs have had three disadvantages: they, like corks, are put in after the connectors have been installed, which means that they must be carried around loose; they have been provided with wide rims to facilitate their being pried out, which precludes their being installed before the connector fitting is mounted in a junction box, and the exteriorly exposed inside of the crown forms a recess into which plaster, concrete and the like can go.
One of the objects of this invention is to provide a connector fitting and plug combination in which the plug is installed in the connector before the connector is mounted in a junction box, which does not interfere with the mounting of the connector, which provides an insulated throat for the connector, and provides a clear passage even when plaster, concrete or the like gets into the junction box.
Another object is to provide a method of installing electrical connectors which facilitates installation.
Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
In the drawing, FIG. 1 is a fragmentary view in perspective, partly in phantom lines, showing a connector mounted on a junction box, with one embodiment of plug of this invention mounted within the connector;
FIG. 2 is a plan view of a junction box in which two embodiments of connector assembly of this invention are mounted, the one on the left being the same as the embodiment shown in FIG. 1, and the one on the right being a second embodiment;
FIG. 3 is a sectional view taken along the line 3--3 of FIG. 2;
FIG. 4 is a fragmentary view in side elevation taken along the line 4--4 of FIG. 3; and
FIG. 5 is a sectional view of still another embodiment of connector assembly of this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, particularly to FIGS. 1, 2 and 3, reference numeral 1 indicates a junction box of standard construction with round knock-outs to provide holes to accommodate connector fittings. As indicated in FIG. 2, two of the knock-outs have been removed, and connector fittings 2 are mounted in junction box wall 3, on opposite sides of the junction box.
The connector fittings 2 are also standard commercially available fittings, with an externally threaded conduit receiving end 7, a hexagonal external stop nut 8, and an externally threaded, open mouth throat end 9. The stop nut 8 is integral with the two end sections. Conventionally, the diameter of the throat end 9 is less than that of the conduit receiving end 7, and threads 11 on the conduit end are of less pitch than threads 12 of the throat end 9. A passage 16 extends all the way through the connector 2. Within the passage 16, between the conduit receiving end 7 and the throat end 9, there is an off-set forming a shoulder or step 27 with an annular, generally radial face 17. The passage 16 extends from a conduit receiving opening defined by a radial edge 18 at the conduit receiving end to a mouth defined by a radial mouth-rim 19 at the throat end.
The stop nut 8 is of a size relative to the knockout hole in the junction box to bear against the wall 3 surrounding the knock-out hole, and the fitting is mounted on the junction box by means of a lock nut 15, screwed onto the throat end of the connector and against the inside surface of wall 3.
In the embodiment of assembly shown in FIG. 1 and in the left side of FIGS. 2 and 3, a plug 20 is mounted within the connector 2. The plug 20, and the plugs of all of the other embodiments, are preferably made of polyethylene, rubber, or other elastomeric material, but they may be made of any material which makes the plug resilient enough to permit the mounting of the plug as is described hereafter, which is electrically insulative, and incisable. In this embodiment, the plug 20 has a closed domed projecting section 21, a cylindrical or tube section 22, a radially outwardly extending annular shoulder 23 at the base of the domed section 21, and a radially outwardly extending annular flange or shoulder 25 at an open end of the cylindrical section 22, remote from the domed section 21.
The annular flange 25 is dimensioned to fit within the passage 16 at the conduit receiving end 7 of the connector, and to bear against the face 17 of the shoulder or step 27. The cylindrical section 22 is dimensioned to fit snugly within the part of the passage 16 between the step 27 and the mouth-rim 19 of the throat end 9. The annular shoulder 23 is dimensioned to bear against the mouth-rim 19 of the throat end 9, but its outside diameter is preferably no greater than the root diameter of the threads 12. The distance between the facing radial surfaces of the annular shoulders 23 and 25 is slightly greater than the distance between the radial face 17 of the step 27 and the rim 19.
The resilience of the material of which the plug is made and the shape of the plug are such as to permit the shoulder 23 to be pushed through the throat section of the passage 16 and to cause the shoulder 23 to snap out into the position shown in FIGS. 2 and 3 when the inner radial surface of the shoulder 23 has cleared the rim 19 defining the mouth of the throat end 9.
When the plug has been mounted, the mouth of the connector is sealed by the dome 21, the shoulders 23 and 25 and the cylindrical section 22 of the plug. The shoulders 23 and 25 anchor the plug positively against the displacement in either direction.
It can be seen that the connector and plug can be assembled at the factory or in the shop, so that loose plugs need not be carried at the site. The assembly can be mounted in a junction box as if the plug were not there. Since neither the domed section nor the shoulder 23 projects radially substantially beyond the root of the threads 12, the lock nut 15 can be screwed on, to mount the connector, without interference from the plug.
The connector and the conduit attached to it are sealed by the plug against the entry of any foreign material. When the time comes at which wire is to be pulled, it is only necessary to cut off enough of the domed section 21 with any suitable instrument such as a knife or shears, to produce the desired opening.
It can be seen that the projection of the domed section 21 not only makes cutting off easy, but enables one to provide a passage even though the connector itself and a part of the dome may be buried in concrete, plaster or the like. Furthermore, when the domed section 21 or any part of it is cut off, the mouth and throat of the connector are insulated, and the mouth is provided with a smooth resilient surface which obviates skinning of insulation on the wires or damage to the wires themselves by the mouth-defining surfaces of the connector.
In the embodiment of assembly shown on the right side of FIGS. 2 and 3, a connector fitting 2 identical with the connector fitting just described in connection with the first embodiment, is provided with a plug 220. The plug 220 has a closed domed end 221 which corresponds to the domed end 21 of the first embodiment. The closed end 221 of the plug 220 is shown as being of a somewhat different shape from the domed end 21, but this is merely to illustrate the fact that the closed end of the plug can be of a variety of shapes without affecting its utility. The plug 220 has an annular shoulder or rim 225 around its open end. The shoulder 225 is identical with the shoulder 25 of the first embodiment. The plug 220 has a cylindrical section 222 which is dimensioned to fit snugly the inner wall of the passage 16 of the throat section 9 of the connector 2. In this embodiment, it is more essential that the cylindrical section 22 be in snug frictional engagement with the wall of the connector than it is that the cylindrical section 22 of the first embodiment be in such snug engagement, although it is desirable that section 22 also be in snug engagement with the wall of the connector.
In installing the plug 220, it is only necessary to push the plug through the passage 16, from right to left as viewed in FIGS. 2 and 3, until the flange 225 seats against the face 17 of the step 27. It can be seen that the mounting of the assembly in a junction box and its use will be the same as that of the assembly shown in FIG. 1. The embodiment of plug 220 has the advantages of slightly less cost and slightly greater ease of installation, and the disadvantages of less positive anchorage against displacement in a direction from left to right as shown in FIGS. 2 and 3, and slightly less protection against damage to wires, especially if the closed end section is cut off flush with the mouth-defining surface of the connector, as distinguished from flush with the outer surface of the annular shoulder 23 of the embodiment shown in FIG. 1. The terms "outer" and "inner" as applied to the shoulder 23 are used with respect to the connector, the inner radial surface being contiguous the mouth-rim 19.
Referring now to FIG. 5 for a third embodiment of assembly of this invention, a connector 2 indentical with the connectors shown and described in connection with FIGS. 1 through 4 is provided with a plug 320. The plug 320 has a closed end dome section 321 similar to the section 221 of the embodiment of plug 220, a cylindrical section 322 and an open end 327. The embodiment of plug 320, has an outwardly projecting annular shoulder 323, corresponding in every way to the shoulder 23 of the embodiment of plug 20. As in the embodiment of plug 220, the cylindrical section 322 of plug 320 is dimensioned to engage the throat section of passage 16 of the connector 2 frictionally snugly so as to resist displacement once mounted. The plug 320 is preferably mounted in the opposite direction from the plugs 20 and 220, that is, from left to right as viewed in FIG. 5. Otherwise, the mounting of the plug and the mounting and use of the assembly are the same as those of the embodiments shown in FIGS. 1 through 4. The assembly of the embodiment shown in FIG. 5 has the advantages of economy and ease of installation of the embodiment with the plug 220, and the advantage of protection of the wires against damage by the edge of the mouth-rim afforded by the shoulder 323 as in the assembly shown in FIG. 1. It does share the disadvantage of the plug 220 of not being positively anchored against displacement in both directions.
Merely by way of illustration and not of limitation, in a connector for half-inch conduit, the tube and domed or closed end sections of the plugs can have a wall of uniform thickness of thirty to forty thousandths of an inch, the shoulders can have an axial width of eighty thousandths of an inch and the dome can project one-half to three-quarters of an inch beyond the mouth of the connector. The other dimensions of the plug will be determined by the dimensions of the connector fitting.
Numerous variations in the details of construction of the plug and connector, and the methods of their use, within the scope of the appended claims, will occur to those skilled in the art in the light of the foregoing disclosure. Merely by way of example, the specific shapes, the length of the domed or closed section of the plug, the wall thickness, the axial width of the shoulders and the types of materials used can all be varied. The assemblies may be used in any place in which connectors are used, not merely in junction boxes. In the embodiment shown in FIG. 5, the closed end section 321 can be made with the same outside diameter as the shoulder 323, since only the cylindrical section 322 need be shoved into the passage 16. The cylindrical or tube section of any of the plugs may be provided with annular ribs, rounded or serrate. The face of the plug flanges 25 and 225 contiguous the face 17 of the connector can be sloped complementarily to a chamfer, commonly provided, on the face 17, and the radially inner edge of the flanges 25 and 225 can be chamfered to facilitate the entry of wire. The term "radially" extending is used to embrace such a surface as well as a surface perpendicular to the axis of the conductor. These are merely illustrative.