CA1120113A - Connector for corrugated-metal-sheathed electric cables - Google Patents
Connector for corrugated-metal-sheathed electric cablesInfo
- Publication number
- CA1120113A CA1120113A CA000334251A CA334251A CA1120113A CA 1120113 A CA1120113 A CA 1120113A CA 000334251 A CA000334251 A CA 000334251A CA 334251 A CA334251 A CA 334251A CA 1120113 A CA1120113 A CA 1120113A
- Authority
- CA
- Canada
- Prior art keywords
- sheath
- connector
- ridge
- tubular body
- helical
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G3/00—Installations of electric cables or lines or protective tubing therefor in or on buildings, equivalent structures or vehicles
- H02G3/02—Details
- H02G3/06—Joints for connecting lengths of protective tubing or channels, to each other or to casings, e.g. to distribution boxes; Ensuring electrical continuity in the joint
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R9/00—Structural associations of a plurality of mutually-insulated electrical connecting elements, e.g. terminal strips or terminal blocks; Terminals or binding posts mounted upon a base or in a case; Bases therefor
- H01R9/03—Connectors arranged to contact a plurality of the conductors of a multiconductor cable, e.g. tapping connections
- H01R9/05—Connectors arranged to contact a plurality of the conductors of a multiconductor cable, e.g. tapping connections for coaxial cables
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R4/00—Electrically-conductive connections between two or more conductive members in direct contact, i.e. touching one another; Means for effecting or maintaining such contact; Electrically-conductive connections having two or more spaced connecting locations for conductors and using contact members penetrating insulation
- H01R4/26—Connections in which at least one of the connecting parts has projections which bite into or engage the other connecting part in order to improve the contact
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R4/00—Electrically-conductive connections between two or more conductive members in direct contact, i.e. touching one another; Means for effecting or maintaining such contact; Electrically-conductive connections having two or more spaced connecting locations for conductors and using contact members penetrating insulation
- H01R4/58—Electrically-conductive connections between two or more conductive members in direct contact, i.e. touching one another; Means for effecting or maintaining such contact; Electrically-conductive connections having two or more spaced connecting locations for conductors and using contact members penetrating insulation characterised by the form or material of the contacting members
- H01R4/64—Connections between or with conductive parts having primarily a non-electric function, e.g. frame, casing, rail
Landscapes
- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Details Of Connecting Devices For Male And Female Coupling (AREA)
Abstract
ABSTRACT
CONNECTOR FOR CORRUGATED-METAL-SHEATHED ELECTRIC CABLES
A connector for corrugated metal sheathed metal electric cables is disclosed The connector is the type comprising a hollow tubular body including a first portion having a helical ridge provided with a sharp edge and exten-ding inwardly from the interior surface of the tubular body of the same pitch as the helical groove on the corrugated me-tal sheath of the cable for threading on such sheath, a second portion consisting of a cylindrical gap through which the ca-ble sheath may freely pass, a third portion adapted to be se-cured to a standing structure, and a radially inwardly exten-ding shoulder within the hollow tubular body between the se-cond and third portions and constituting a sheath stop, whereby the connector may be secured to the sheath with the end of the sheath received within the first and second portions of the tubular body and in abutment with the sheath stop. The im-provement in accordance with the present invention consists in that the helical ridge extending inwardly from the interior surface of the first portion of the tubular body ends short of the sheath stop leaving the above mentioned gap between the end of the ridge and the sheath stop which provides for fitting the connector over varying outer sheath diameters while ensu-ring that the sheath abuts with the sheath stop and causes the connector to align itself with the sheath and the sharp edge of the ridge to penetrate the surface of the sheath throughout its length thereby obtaining an improved electri-cal connection between the connector and the sheath.
CONNECTOR FOR CORRUGATED-METAL-SHEATHED ELECTRIC CABLES
A connector for corrugated metal sheathed metal electric cables is disclosed The connector is the type comprising a hollow tubular body including a first portion having a helical ridge provided with a sharp edge and exten-ding inwardly from the interior surface of the tubular body of the same pitch as the helical groove on the corrugated me-tal sheath of the cable for threading on such sheath, a second portion consisting of a cylindrical gap through which the ca-ble sheath may freely pass, a third portion adapted to be se-cured to a standing structure, and a radially inwardly exten-ding shoulder within the hollow tubular body between the se-cond and third portions and constituting a sheath stop, whereby the connector may be secured to the sheath with the end of the sheath received within the first and second portions of the tubular body and in abutment with the sheath stop. The im-provement in accordance with the present invention consists in that the helical ridge extending inwardly from the interior surface of the first portion of the tubular body ends short of the sheath stop leaving the above mentioned gap between the end of the ridge and the sheath stop which provides for fitting the connector over varying outer sheath diameters while ensu-ring that the sheath abuts with the sheath stop and causes the connector to align itself with the sheath and the sharp edge of the ridge to penetrate the surface of the sheath throughout its length thereby obtaining an improved electri-cal connection between the connector and the sheath.
Description
0~13 CONNECTOR FOR CORRUGAT~D-METAL-SHEATHED ELECTRI~ CABLES
This invention relates to a connector for corru-gated-metal-sheathed electric cables.
In the electric cable art, it is known to manu-facture cables having metallic sheaths which are provided with helical corrugations. The sheath is usually made of an extruded or a longitudinally welded metal tube which is corrugated by a revolving tool, or set of tools which de-forms the tube so as to produce a continuous helical groove, or trough defined by adjacent convolutions of a continuous helical ridge, or crest. In some embodiments, the groove is provided with a flat bottom from each side of which extends upwardly an arcuate ridge and, in other embodiments, the surface of the cable, when viewed along the line parallel to the longitudinal axis of the cable, is somewhat sinusoidal in configuration.
It is also known in the electric ca~le art to vary sign'ficantly the depth of the corrugation of any given size of sheath in oder to accommodate a wider range of diameters of cable core t~an an acceptable range of clearance between the core and sheath permits. Such variations in corrugation depth result in significant variations in the outer diameter .1 ~
ll~Oil3 of the corrugated tube, that is to say a greater corruga-tion depth will result in a larger reduction in the outer diameter. These variations in outer diameter are larger than the design of known connectors of the types discussed below will accommodate, hence the number of specific sizes of cable sheath required to fit a complete range of cables is increased by constraints arising from the design of con-nectors, whereas it is desirable to reduce the number of cable sheath sizes to the.limit go~erned by the cable sheath manufacturing process and by the cable specifications.
One specific type of connector is disclosed in Canadian Patent No. 651,417 issued on October 30, 1962 to the same assignee as the present application. The connector comprises a hollow tubular body adapted to fit over the end of the sheath and having gripping tongues located on the inside surface of the tubular body which engage the groove of the sheath, and a sheath stop. This arrangement permits the connector to be threaded over the sheath until the sheath end is binding tight against the sheath stop. One limitation of this type of connector is that there is a limited area of contact between the connector and the sheath with the result that the electrical connection may not be adequate under some extreme conditions of use. Another limitation of the above connector is that it is designed to fit cable sheaths having relatively fixed outer helix dia-meters and a more limited range of corrugation depth than is possible.
Another type of connector is disclosed in Cana-0~13 dian Patent ~o~ 664,108 issued on May 28, 1963 to the same assignee as the present application. Such a connector is a more complex type designed to obtain a moisture seal on a cable with no jacket over the corrugated sheath. ~his connector is provided with a sheath gripping ring having a non-circular aperture for binding the sheath against the sheath stop, instead of the gripping tongues of the above mentioned Canadian Patent No~ 651,417. The contact area of such gripping ring is greater than the previously mentioned gripping tongues, but is still not sufficient to provide current conduction adequate for some extreme conditions of use. In addition, this connector is also designed to fit cable sheaths with relatively fixed outer helix diameters and an ever more limited range of corrugation depth than the connector disclosed in Canadian Patent No. 651,417.
Another similar connector is al50 known having a tubular body with a continuous internal helical groove of the same pitch as the corrugated sheath in place of the sheath gripping tongues or ring used in the above~mentioned patents. This connector provides some contact pressure between the internal surfaces of the connector and the sheath when the connector is threaded up to the point where the internal helical groove runs out. However, it does not provide for a certain penetration of any aluminum oxide on the sheath surface, the presence of which is detrimental to the conduction of induced sheath currents. This connector is also designed to fit cable sheaths with relatively fixed outer helix diameters and a more lim,ited range of corruga-, , _ tion depth than is possible.
A further similar connector is known having aninternal helical ridge which is ~lattened along a plane substantially parallel to the longitudinal axis of the con-nector forming sharp edges at the sidewalls of the ridge, These sharp edges will penetrate any oxide on the surface of the sheath at any point where sufficient force is gene-rated between the edge and the surface of the sheath with which the edge comes into,contact as a result of the action of threading the connector onto the cable sheath. A major disadvantage of this connector is that like the connector described in the preceding paragraph the internal ridge and the corresponding grooves "runs out" in the manner commonly known in the art of producing screw-threads. This "run-out"
may cause the respective axes of the connector and sheath to be at an angle with each other and prevent the sharp edge from contacting the sheath substantially throughout its length. ~he degree of this misali~nment may increase as the outer diameter of the cable sheath decreases when this con-nector is used for cables having significantly varyingdepths of corrugation and outer diameter.
It is therefore the object o~ the present in~en-tion to provide a connector for corrugated-metal-sheathed electric cables which insures an improved electrical connec-tion between the connector and the sheath and which, in ad-dition, will allow greater variations in the depth o~ cor-rugation and the consequent ~ariations in the outer helix diameter of the cable sheath.
0~13 s The connector, in accordance with the in~ention, is of the type comprising a hollow tubular body including a first portion having a helical ridge provided with a sharp edge and extending inwardly from the interior surface of the tubular body of the same pitchas the helical grooveof the corrugated metal sheathed electriccable for threadingon such sheath, a secondportion comprisinga gap, orundercut, which consists of a longitudinalsection cut away toan internal dia-meter at no pointless than the maximumouter diameter of the cable sheath intendedto be accommodated withinthe connector, a third portion adapted to be securedto a standing structure, and a radially inwardly extending shoulder within the hollow tubular body betweenthe second and thirdportions and consti-tuting a sheath stop,whereby the connector maybe secured to the sheath with the end of the sheath received within the ; first and second portions of the tubular body and in abut-; ment with the sheath stop. The helical ridge extending .~ inwardly from the interior surface of the first portion of the tubular body ends short of the sheath stop so as to leave the above mentioned gap between the end of the ridge and the sheath stop to allow the sheath to pass through and completely abut with the sheath stop, and to align the con-nector with respect to the cable sheath, thereby causing the ; sharp edge of the helical ridge to cut into the surface of the sheath substantially throughout its length.
In a second embodiment of the invention, a sealing grommet and a packing nut having an integral retaining ring adapted to be threaded into the end of the tubular bo-... _ il'~O~13 dy are provided for sealing the cable against water and dust.
The connector is preferably made of aluminum or aluminum alloy, but may be of any suitable metal.
The invention will now be disclosed, by way of example, with reference to the accompanying drawings in which:
:,, Fiyure l illustrates a perspective view of a dry type connector in accordance with the invention;
Figure 2 illustrates a section view thro~gh the connector of Figure l with the sheath and cable removed;
Figure 3 illustrates a perspective view of a wet type connector in accordance with the invention;
Figure 4 illustrates a section through the connec-tor of Figure 3 with the sheath and cable removed;
- Figure 5 illustrates a portion of Figures 2 and 4 depicting an alternative typical shape of the groove defi-ned by the helical ridge of the connector; and Figure 6 illustrates a portion of Figures 2 and 4 depicting a further alternative typical shape of the groove : defined by the helical ridge of the connector.
Referring to Figures l and 2, there is shown a connector of the so called dry type comprising a hollow tu-. bular body l~ having a first portion 12 adapted to receive a cable sheath 14, a second portion 16 consisting of an un-dercut or gap of predetermined length "a" through which the cable sheath may freely pass and a third portion 18 for at-tachment to a standing structure. The first portion 12 is - ~lZ0113 provided with a helical ridge 20 extending inwardly from the entire surface of the tubular body having a pitch cor-responding to the pitch ~ the groo~e 21 on the cable sheath 14~ The internal ridge 20 of the first portion of the tubular body includes ~ flattened portion forming sharp edges 22 with the sidewalls of the ridge. An integral shoulder 24 is located near the boundary ~etween the second and third portions of the tubular body for butting the ca-ble sheath during threading of the connector onto the cable 1 10 sheath. The second portion 16 is cut away to form the gap "a" between the end of ridge 16 and the sheath stop or - shoulder 24 so as to pre~ent jamming o the connector befo-re a~utment with the sheath stop or shoulder 24, or misa-lignment of the connector with respect to the cable sheath.
The gap, or undercut, "a" will permit easy threading of the connector onto the cable sheath by hand until the end of the sheath abuts the shoulder 24. Further effort to tigh-ten the connector onto the sheath will cause the sharp edge 22 to cut into the side of the crest of the corrugations on the sheath substantially throughout the helical length of the ridge 20 and penetration of any oxide layer formed on such sheath. This is achieved because the un~ercut allows the connector to centre itself on the sheath. The third portion has a shoulder 26 and external threads 28 for ins-tallation `through standard knoc~oùt openings or into stan-dard threaded openings in terminal boxes or other electri-cal fittings.
Another important feature of the invention is :
.:
ll~U113 that the outer helix diameter of the cable sheath may vary significantly for a given size of connector because of the self-alignment mechanism which allows the sharp edge 22 to cut into the side of the ridge of the sheath at various heights throughout the helical length of the ridge 20.
Referring now to Figures 3 and 4, there is shown a connector of the so-called wet type. The connector com-prises a hollow tubular body 30 having a first portion 32 provided with a helical ridge 34 identical to ridge 20 of Figures l and 2, a second portion 35 consisting of a gap, or undercut, of length "a`', and a third portion 36 for at-tachment to a standins structure, such as a terminal ~ox.
A sheath stop 38 is located near the boundary between the second and third portions of the tubular body for the same purpose as in Figure 2 of the drawings. As shown in Figure 4, the internal ridge 34 also includes a flattened portion forming sharp edges 40 for the same purpose as sharp edges 22 of Figure 2. The first portion 32 is provided with ex-ternal threads for screwing an hexagonal nut 42 which com-presses a sealing grommet 44 onto the cable to provide awater and dust-tight seal. The third portion 36 of the tu-bular body is provided with an hexagonal shoulder 46 for permitting tightening of the packing nut and with external - threads 48 for installation through the standard knockout openings or into standard threaded openings of terminal boxes or other electrical fittings~
Referring now to Figures 5 and 6 there are shown alternative shapes of the groove or trough 50 defined by 1120il3 the helical ridge 20 of Figures l and 2 ~or by the helical ridge 34 of Figures 3 and 4~ The shape illustrated in Figures 1 to 4 may be termed arcuate. The shape of the groove 50 s~own in Figure 5 may be termed trapezoidal while the shape ~f the groove 50 shown in Figure 6 may be termed rectangular. It is envisaged that still further shapes which will successfully accommodate the cable sheath may be employed.
;~ Tests of stability of resistance between an assem-bled cable sheath and connector, and a metal plate which served as the simulation of a typical electrical enclosure panel were conducted. The connectors and sheaths were as-sembled into simulated three phase installations, a~d sub-jected to a current cycling test, each cycle consisting of four hours on and four hours off (three cycles per day) with the sheaths short-circuited for a total of lO0 cycles. The results of these tests indicated an initial cold resistance of 0.043 m ~ and a maximum cold resistance of 0.23 m~ during the whole test procedure. Similar tests were made on other known connectors and, in all cases, the connector in accor-dance~with the invention exhibited a lower resistance and a higher degree of stability. The current used was that indu-ced in the sheath by the maximum rated current in the cable.
- The corrugated metal sheaths are usually made of aluminum or an aluminum alloy and the connectors are also preferably made of aluminum or aluminum alloys, but both may be made of any~ suitable metal or combination thereof.
Although the invention has been disclosed with ., llZ0~3 re~erence to pre~erred em~odime~ts, it is to be understood that other alternatives of such embodiments are also envi-saged~
This invention relates to a connector for corru-gated-metal-sheathed electric cables.
In the electric cable art, it is known to manu-facture cables having metallic sheaths which are provided with helical corrugations. The sheath is usually made of an extruded or a longitudinally welded metal tube which is corrugated by a revolving tool, or set of tools which de-forms the tube so as to produce a continuous helical groove, or trough defined by adjacent convolutions of a continuous helical ridge, or crest. In some embodiments, the groove is provided with a flat bottom from each side of which extends upwardly an arcuate ridge and, in other embodiments, the surface of the cable, when viewed along the line parallel to the longitudinal axis of the cable, is somewhat sinusoidal in configuration.
It is also known in the electric ca~le art to vary sign'ficantly the depth of the corrugation of any given size of sheath in oder to accommodate a wider range of diameters of cable core t~an an acceptable range of clearance between the core and sheath permits. Such variations in corrugation depth result in significant variations in the outer diameter .1 ~
ll~Oil3 of the corrugated tube, that is to say a greater corruga-tion depth will result in a larger reduction in the outer diameter. These variations in outer diameter are larger than the design of known connectors of the types discussed below will accommodate, hence the number of specific sizes of cable sheath required to fit a complete range of cables is increased by constraints arising from the design of con-nectors, whereas it is desirable to reduce the number of cable sheath sizes to the.limit go~erned by the cable sheath manufacturing process and by the cable specifications.
One specific type of connector is disclosed in Canadian Patent No. 651,417 issued on October 30, 1962 to the same assignee as the present application. The connector comprises a hollow tubular body adapted to fit over the end of the sheath and having gripping tongues located on the inside surface of the tubular body which engage the groove of the sheath, and a sheath stop. This arrangement permits the connector to be threaded over the sheath until the sheath end is binding tight against the sheath stop. One limitation of this type of connector is that there is a limited area of contact between the connector and the sheath with the result that the electrical connection may not be adequate under some extreme conditions of use. Another limitation of the above connector is that it is designed to fit cable sheaths having relatively fixed outer helix dia-meters and a more limited range of corrugation depth than is possible.
Another type of connector is disclosed in Cana-0~13 dian Patent ~o~ 664,108 issued on May 28, 1963 to the same assignee as the present application. Such a connector is a more complex type designed to obtain a moisture seal on a cable with no jacket over the corrugated sheath. ~his connector is provided with a sheath gripping ring having a non-circular aperture for binding the sheath against the sheath stop, instead of the gripping tongues of the above mentioned Canadian Patent No~ 651,417. The contact area of such gripping ring is greater than the previously mentioned gripping tongues, but is still not sufficient to provide current conduction adequate for some extreme conditions of use. In addition, this connector is also designed to fit cable sheaths with relatively fixed outer helix diameters and an ever more limited range of corrugation depth than the connector disclosed in Canadian Patent No. 651,417.
Another similar connector is al50 known having a tubular body with a continuous internal helical groove of the same pitch as the corrugated sheath in place of the sheath gripping tongues or ring used in the above~mentioned patents. This connector provides some contact pressure between the internal surfaces of the connector and the sheath when the connector is threaded up to the point where the internal helical groove runs out. However, it does not provide for a certain penetration of any aluminum oxide on the sheath surface, the presence of which is detrimental to the conduction of induced sheath currents. This connector is also designed to fit cable sheaths with relatively fixed outer helix diameters and a more lim,ited range of corruga-, , _ tion depth than is possible.
A further similar connector is known having aninternal helical ridge which is ~lattened along a plane substantially parallel to the longitudinal axis of the con-nector forming sharp edges at the sidewalls of the ridge, These sharp edges will penetrate any oxide on the surface of the sheath at any point where sufficient force is gene-rated between the edge and the surface of the sheath with which the edge comes into,contact as a result of the action of threading the connector onto the cable sheath. A major disadvantage of this connector is that like the connector described in the preceding paragraph the internal ridge and the corresponding grooves "runs out" in the manner commonly known in the art of producing screw-threads. This "run-out"
may cause the respective axes of the connector and sheath to be at an angle with each other and prevent the sharp edge from contacting the sheath substantially throughout its length. ~he degree of this misali~nment may increase as the outer diameter of the cable sheath decreases when this con-nector is used for cables having significantly varyingdepths of corrugation and outer diameter.
It is therefore the object o~ the present in~en-tion to provide a connector for corrugated-metal-sheathed electric cables which insures an improved electrical connec-tion between the connector and the sheath and which, in ad-dition, will allow greater variations in the depth o~ cor-rugation and the consequent ~ariations in the outer helix diameter of the cable sheath.
0~13 s The connector, in accordance with the in~ention, is of the type comprising a hollow tubular body including a first portion having a helical ridge provided with a sharp edge and extending inwardly from the interior surface of the tubular body of the same pitchas the helical grooveof the corrugated metal sheathed electriccable for threadingon such sheath, a secondportion comprisinga gap, orundercut, which consists of a longitudinalsection cut away toan internal dia-meter at no pointless than the maximumouter diameter of the cable sheath intendedto be accommodated withinthe connector, a third portion adapted to be securedto a standing structure, and a radially inwardly extending shoulder within the hollow tubular body betweenthe second and thirdportions and consti-tuting a sheath stop,whereby the connector maybe secured to the sheath with the end of the sheath received within the ; first and second portions of the tubular body and in abut-; ment with the sheath stop. The helical ridge extending .~ inwardly from the interior surface of the first portion of the tubular body ends short of the sheath stop so as to leave the above mentioned gap between the end of the ridge and the sheath stop to allow the sheath to pass through and completely abut with the sheath stop, and to align the con-nector with respect to the cable sheath, thereby causing the ; sharp edge of the helical ridge to cut into the surface of the sheath substantially throughout its length.
In a second embodiment of the invention, a sealing grommet and a packing nut having an integral retaining ring adapted to be threaded into the end of the tubular bo-... _ il'~O~13 dy are provided for sealing the cable against water and dust.
The connector is preferably made of aluminum or aluminum alloy, but may be of any suitable metal.
The invention will now be disclosed, by way of example, with reference to the accompanying drawings in which:
:,, Fiyure l illustrates a perspective view of a dry type connector in accordance with the invention;
Figure 2 illustrates a section view thro~gh the connector of Figure l with the sheath and cable removed;
Figure 3 illustrates a perspective view of a wet type connector in accordance with the invention;
Figure 4 illustrates a section through the connec-tor of Figure 3 with the sheath and cable removed;
- Figure 5 illustrates a portion of Figures 2 and 4 depicting an alternative typical shape of the groove defi-ned by the helical ridge of the connector; and Figure 6 illustrates a portion of Figures 2 and 4 depicting a further alternative typical shape of the groove : defined by the helical ridge of the connector.
Referring to Figures l and 2, there is shown a connector of the so called dry type comprising a hollow tu-. bular body l~ having a first portion 12 adapted to receive a cable sheath 14, a second portion 16 consisting of an un-dercut or gap of predetermined length "a" through which the cable sheath may freely pass and a third portion 18 for at-tachment to a standing structure. The first portion 12 is - ~lZ0113 provided with a helical ridge 20 extending inwardly from the entire surface of the tubular body having a pitch cor-responding to the pitch ~ the groo~e 21 on the cable sheath 14~ The internal ridge 20 of the first portion of the tubular body includes ~ flattened portion forming sharp edges 22 with the sidewalls of the ridge. An integral shoulder 24 is located near the boundary ~etween the second and third portions of the tubular body for butting the ca-ble sheath during threading of the connector onto the cable 1 10 sheath. The second portion 16 is cut away to form the gap "a" between the end of ridge 16 and the sheath stop or - shoulder 24 so as to pre~ent jamming o the connector befo-re a~utment with the sheath stop or shoulder 24, or misa-lignment of the connector with respect to the cable sheath.
The gap, or undercut, "a" will permit easy threading of the connector onto the cable sheath by hand until the end of the sheath abuts the shoulder 24. Further effort to tigh-ten the connector onto the sheath will cause the sharp edge 22 to cut into the side of the crest of the corrugations on the sheath substantially throughout the helical length of the ridge 20 and penetration of any oxide layer formed on such sheath. This is achieved because the un~ercut allows the connector to centre itself on the sheath. The third portion has a shoulder 26 and external threads 28 for ins-tallation `through standard knoc~oùt openings or into stan-dard threaded openings in terminal boxes or other electri-cal fittings.
Another important feature of the invention is :
.:
ll~U113 that the outer helix diameter of the cable sheath may vary significantly for a given size of connector because of the self-alignment mechanism which allows the sharp edge 22 to cut into the side of the ridge of the sheath at various heights throughout the helical length of the ridge 20.
Referring now to Figures 3 and 4, there is shown a connector of the so-called wet type. The connector com-prises a hollow tubular body 30 having a first portion 32 provided with a helical ridge 34 identical to ridge 20 of Figures l and 2, a second portion 35 consisting of a gap, or undercut, of length "a`', and a third portion 36 for at-tachment to a standins structure, such as a terminal ~ox.
A sheath stop 38 is located near the boundary between the second and third portions of the tubular body for the same purpose as in Figure 2 of the drawings. As shown in Figure 4, the internal ridge 34 also includes a flattened portion forming sharp edges 40 for the same purpose as sharp edges 22 of Figure 2. The first portion 32 is provided with ex-ternal threads for screwing an hexagonal nut 42 which com-presses a sealing grommet 44 onto the cable to provide awater and dust-tight seal. The third portion 36 of the tu-bular body is provided with an hexagonal shoulder 46 for permitting tightening of the packing nut and with external - threads 48 for installation through the standard knockout openings or into standard threaded openings of terminal boxes or other electrical fittings~
Referring now to Figures 5 and 6 there are shown alternative shapes of the groove or trough 50 defined by 1120il3 the helical ridge 20 of Figures l and 2 ~or by the helical ridge 34 of Figures 3 and 4~ The shape illustrated in Figures 1 to 4 may be termed arcuate. The shape of the groove 50 s~own in Figure 5 may be termed trapezoidal while the shape ~f the groove 50 shown in Figure 6 may be termed rectangular. It is envisaged that still further shapes which will successfully accommodate the cable sheath may be employed.
;~ Tests of stability of resistance between an assem-bled cable sheath and connector, and a metal plate which served as the simulation of a typical electrical enclosure panel were conducted. The connectors and sheaths were as-sembled into simulated three phase installations, a~d sub-jected to a current cycling test, each cycle consisting of four hours on and four hours off (three cycles per day) with the sheaths short-circuited for a total of lO0 cycles. The results of these tests indicated an initial cold resistance of 0.043 m ~ and a maximum cold resistance of 0.23 m~ during the whole test procedure. Similar tests were made on other known connectors and, in all cases, the connector in accor-dance~with the invention exhibited a lower resistance and a higher degree of stability. The current used was that indu-ced in the sheath by the maximum rated current in the cable.
- The corrugated metal sheaths are usually made of aluminum or an aluminum alloy and the connectors are also preferably made of aluminum or aluminum alloys, but both may be made of any~ suitable metal or combination thereof.
Although the invention has been disclosed with ., llZ0~3 re~erence to pre~erred em~odime~ts, it is to be understood that other alternatives of such embodiments are also envi-saged~
Claims (6)
1. A connector for electric cables of the type having a tubular metal sheath which is deformed to produce a conti-nuous helical groove of constant pitch defined by adjacent convolutions of a continuous helical ridge, comprising a hol-low tubular body including a first portion having a helical ridge provided with a sharp edge and extending inwardly from the interior surface of the tubular body of the same pitch as the helical groove of said metal sheath for threading on said sheath, a second portion consisting of a cylindrical gap through which the said sheath may freely pass, a third portion adapted to be secured to a standing structure, and a radially inwardly extending shoulder within the hollow tubular body at or near the boundary between said second and third portions and constituting a sheath stop, whereby the connector may be secured to the sheath with the end of the sheath received within the first portion of the tubular body and in abutment with the sheath stop, said helical ridge in the interior wall of the tubular body ending short of the sheath stop so as to leave said gap or undercut between the end of the ridge and the sheath stop to allow the sheath to pass through and completely abut with the sheath stop, and to align the connector with respect to the cable sheath, so as to cause the sharp edge of said ridge to penetrate the surface of the sheath substantially throughout the helical length of the ridge.
2. A connector as defined in claim 1, wherein the ridge extending inwardly from the interior surface of the first portion of the tubular body is flattened at the top of the ridge to form the sharp edge with the sidewall of the ridge for cutting into the sidewall of the corresponding ridge of the cable sheath when the connector is secured to the sheath so as to provide a good electrical connection between the connector and the sheath.
3. A connector as defined in claim 1, further com-prising a sealing grommet, and a packing nut having an in-tegral retaining ring adapted to be threaded into the end of said tubular body for compressing said sealing grommet onto the cable to provide a water and dust-tight seal.
4. A connector as defined in claims 1, 2 or 3, whe-rein the metal sheath is made of aluminum or an aluminum alloy and the connector is also made of aluminum or an alu-minum alloy.
5. A connector as defined in claims 1, 2 or 3, whe-rein the third portion of said tubular body has external screw threads and a shoulder for installation through stan-dard knockout openings or into standard threaded openings in terminal boxes or other electrical fittings.
6. A connector as defined in claims 1, 2 or 3, whe-rein the shape of the groove defined by adjacent turns of the said helical ridge is arcuate, trapezoidal, rectangular or of any other suitable form.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000334251A CA1120113A (en) | 1979-08-22 | 1979-08-22 | Connector for corrugated-metal-sheathed electric cables |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000334251A CA1120113A (en) | 1979-08-22 | 1979-08-22 | Connector for corrugated-metal-sheathed electric cables |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1120113A true CA1120113A (en) | 1982-03-16 |
Family
ID=4114981
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000334251A Expired CA1120113A (en) | 1979-08-22 | 1979-08-22 | Connector for corrugated-metal-sheathed electric cables |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1120113A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8803008B2 (en) | 2011-03-03 | 2014-08-12 | Sigma Electric Manufacturing Corporation | Conduit connector and methods for making and using the same |
| US8857039B2 (en) | 2010-02-19 | 2014-10-14 | Sigma Electric Manufacturing Corporation | Electrical box conduit connectors and methods for making and using the same |
| US9231388B2 (en) | 2011-09-01 | 2016-01-05 | Sigma Electric Manufactruing Corporation | Conduit connector and method for making and using the same |
| GB2581499A (en) * | 2019-02-19 | 2020-08-26 | Lachlan Ivett Jonathon | Connector assembly for earth-bonding of a piping system |
| US11680666B2 (en) | 2018-07-25 | 2023-06-20 | FlexiGas UKC Ltd | Connector assembly |
-
1979
- 1979-08-22 CA CA000334251A patent/CA1120113A/en not_active Expired
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8857039B2 (en) | 2010-02-19 | 2014-10-14 | Sigma Electric Manufacturing Corporation | Electrical box conduit connectors and methods for making and using the same |
| US8803008B2 (en) | 2011-03-03 | 2014-08-12 | Sigma Electric Manufacturing Corporation | Conduit connector and methods for making and using the same |
| USRE47893E1 (en) | 2011-03-03 | 2020-03-03 | Sigma Electric Manufacturing Corporation | Conduit connector and methods for making and using the same |
| US9231388B2 (en) | 2011-09-01 | 2016-01-05 | Sigma Electric Manufactruing Corporation | Conduit connector and method for making and using the same |
| US11680666B2 (en) | 2018-07-25 | 2023-06-20 | FlexiGas UKC Ltd | Connector assembly |
| GB2581499A (en) * | 2019-02-19 | 2020-08-26 | Lachlan Ivett Jonathon | Connector assembly for earth-bonding of a piping system |
| GB2581499B (en) * | 2019-02-19 | 2022-11-23 | Lachlan Ivett Jonathon | Connector assembly for earth-bonding of a piping system |
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| Date | Code | Title | Description |
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| MKEX | Expiry |