Patent Grant
10622120
The present disclosure relates generally to a Metal-Clad cable type. More particularly, the present disclosure relates to a Metal-Clad cable assembly including a cabled conductor subassembly surrounded by a jacket layer.
Armored cable (“AC”) and Metal-Clad (“MC”) cable provide electrical wiring in various types of construction applications. The type, use and composition of these cables should satisfy certain standards as set forth, for example, in the National Electric Code® (NEC®). (National Electrical Code and NEC are registered trademarks of National Fire Protection Association, Inc.) These cables house electrical conductors within a metal armor. The metal armor may be flexible to enable the cable to bend while still protecting the conductors against external damage during and after installation. The armor which houses the electrical conductors may be made from steel or aluminum, copper-alloys, bronze-alloys and/or aluminum alloys. Typically, the metal armor sheath is formed from strip steel, for example, which is helically wrapped to form a series of interlocked sections along a longitudinal length of the cable. Alternatively, the sheaths may be made from smooth or corrugated metal.
Generally, AC and MC cable have different internal constructions and performance characteristics and are governed by different standards. For example, AC cable is manufactured to UL Standard 4 and can contain up to four (4) insulated conductors individually wrapped in a fibrous material which are cabled together in a left hand lay. Each electrical conductor is covered with a thermoplastic insulation and a jacket layer. The conductors are disposed within a metal armor or sheath. If a grounding conductor is employed, the grounding conductor is either (i) separately covered or wrapped with the fibrous material before being cabled with the thermoplastic insulated conductors; or (ii) enclosed in the fibrous material together with the insulated conductors for thermoset insulated conductors. In either configuration, the bare grounding conductor is prevented from contacting the metal armor by the fibrous material. Additionally, in type AC cable, a bonding strip or wire is laid lengthwise longitudinally along the cabled conductors, and the assembly is fed into an armoring machine process. The bonding strip is in intimate contact with the metal armor or sheath providing a low-impedance fault return path to safely conduct fault current. The bonding wire is unique to AC cable and allows the outer metal armor in conjunction with the bonding strip to provide a low impedance equipment grounding path.
In contrast, MC cable is manufactured according to UL standard 1569 and includes a conductor assembly with no limit on the number of electrical conductors. The conductor assembly may contain a grounding conductor. The electrical conductors and the ground conductor are cabled together in a left or right hand lay and encased collectively in an overall covering. Similar to AC cable, the assembly is then fed into an armoring machine where metal tape is helically applied around the assembly to form a metal sheath. The metallic sheath of continuous or corrugated type MC cable may be used as an equipment grounding conductor if the ohmic resistance satisfies the requirements of UL 1569. A grounding conductor may be included which, in combination with the metallic sheath, would satisfy the UL ohmic resistance requirement. In this case, the metallic sheath and the grounding/bonding conductor would comprise what is referred to as a metallic sheath assembly.
In many applications it is desirable to provide low-voltage wiring, such as wiring defined by Article 725 of the NEC® as Class 2 and Class 3. Class 2 and Class 3 wiring is used for powering and controlling devices such as dimmers, occupancy sensors, luminaries, lighting controls, security, data, low voltage lighting, thermostats, switches, low-voltage medical devices, and the like. With prior arrangements, such Class 2 or 3 low-voltage wiring is installed separate from higher voltage AC or MC cable (e.g., 120V or 277V). However, this results in a less efficient installation process, as multiple different cabling lines must be measured, cut, installed, connected, etc.
Exemplary approaches provided herein are directed to a Metal-Clad cable assembly. In an exemplary approach, a Metal-Clad (MC) cable assembly includes a core having a plurality of power conductors cabled with a subassembly, each of the plurality of power conductors and the subassembly including an electrical conductor, a layer of insulation, and a jacket layer. The MC cable assembly further includes an assembly jacket layer disposed over the subassembly, and a metal sheath disposed over the core. In one approach, the subassembly is a cabled set of conductors (e.g., twisted pair) operating as class 2 or class 3 circuit conductors, as defined by Article 725 of the NEC®. In another approach, the core includes a polymeric protective layer disposed around the jacket layer along one or more of the plurality of power conductors and the subassembly. In yet another approach, a bonding/grounding conductor is cabled with the plurality of power conductors and the subassembly.
A metal clad cable assembly is disclosed. The metal clad cable assembly may include a core having a plurality of power conductors cabled with a subassembly, each of the plurality of power conductors and the subassembly including an electrical conductor, a layer of insulation, and a jacket layer. The metal clad cable assembly may further include an assembly jacket layer disposed over the subassembly, and a metal sheath disposed over the core.
A metal clad cable assembly is disclosed. The metal clad cable assembly may include a core including a plurality of power conductors cabled with a subassembly, each of the plurality of power conductors and the subassembly including an electrical conductor, a layer of insulation, and a jacket layer. The metal clad cable assembly may further include an assembly jacket layer disposed over the subassembly, and a metal sheath disposed over the plurality of power conductors and the subassembly.
A method of making a metal clad cable assembly is disclosed. The method may include providing a core including a plurality of power conductors cabled with a subassembly, each of the plurality of power conductors and the subassembly including an electrical conductor, a layer of insulation, and a jacket layer. The method may further include disposing an assembly jacket layer over the subassembly, and disposing a metal sheath over the core.
The accompanying drawings illustrate exemplary approaches of the disclosed metal clad cable assembly so far devised for the practical application of the principles thereof, and in which:
The present disclosure will now proceed with reference to the accompanying drawings, in which various approaches are shown. It will be appreciated, however, that the disclosed MC cable assembly may be embodied in many different forms and should not be construed as limited to the approaches set forth herein. Rather, these approaches are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. In the drawings, like numbers refer to like elements throughout.
As used herein, an element or operation recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural elements or operations, unless such exclusion is explicitly recited. Furthermore, references to “one approach” of the present disclosure are not intended to be interpreted as excluding the existence of additional approaches that also incorporate the recited features.
As stated above, exemplary approaches provided herein are directed to a Metal-Clad cable assembly. In an exemplary approach, a Metal-Clad (MC) cable assembly includes a core having a plurality of power conductors cabled with a subassembly, each of the plurality of power conductors and the subassembly including an electrical conductor, a layer of insulation, and a jacket layer. The MC cable assembly further includes an assembly jacket layer disposed over the subassembly, and a metal sheath disposed over the core. In one approach, the subassembly is a cabled set of conductors (e.g., twisted pair) operating as class 2 or class 3 circuit conductors, as defined by Article 725 of the NEC®. In another approach, each conductor of the core includes a polymeric protective layer disposed around the jacket layer along the length of each of the electrical conductors. In yet another approach, a bonding/grounding conductor is cabled with the plurality of power conductors and the subassembly. These approaches enable Class 2 or 3 low-voltage wiring to be included with power conductors within the metal sheath of an AC or MC cable to add mechanical protection, simplify installation and reduce overall cost.
Referring now to the side view of
The first and second conductors 6A-B of subassembly 2 may each be, for example, 16 American Wire Gauge (AWG) solid conductors, while plurality of conductors 13A-C may each be, for example, 12 AWG solid and/or stranded electrical conductors. In some approaches, the plurality of power conductors 13A-C includes first, second and third power conductors (e.g., 120V or 277V). In an exemplary approach, each of the conductors 6A-B can have a size between 24 AWG and 6 AWG such that conductors 6A-B are configured to conduct a voltage between zero (0) and approximately 300 Volts. In some approaches, each of the plurality of power conductors 13A-C can have a size between 18 AWG and 2000 KCM.
Metal sheath 10 may be formed as a seamless or welded continuous sheath, and has a generally circular cross section with a thickness of about 0.005 to about 0.060 inches. Alternatively, metal sheath 10 may be formed from flat or shaped metal strip, the edges of which are helically wrapped and interlock to form a series of convolutions along the length of the cable 1. In this manner, metal sheath 10 allows the resulting MC cable assembly 1 to have a desired bend radius sufficient for installation within a building or structure. The sheath 10 may also be formed into shapes other than generally circular such as, for example, rectangles, polygons, ovals and the like. Metal sheath 10 provides a protective metal covering around core 5.
Referring now to the cross-sectional views of
The electrical conductor 12, insulation layer 14 and jacket layer 16 may define an NEC® Type thermoplastic fixture wire nylon (TFN), thermoplastic flexible fixture wire nylon (TFFN), thermoplastic high heat resistant nylon (THHN), thermoplastic heat and water resistant nylon (THWN) or THWN-2 insulated conductor. In other approaches the conductors 6A-B and 13A-C may define an NEC® Type thermoplastic heat and water resistant (THW), thermoplastic high heat and water resistant (THHW), cross-linked polyethylene high heat-resistant water-resistant (XHHW) or XHHW-2 insulated conductor. In one exemplary approach, the insulation layer 14 is polyvinylchloride (PVC) and has a thickness of approximately 15-125 mil. In one approach, jacket layer 16 is nylon and has a thickness of approximately 4-9 mil.
Subassembly 2 is disposed within assembly jacket layer 11, which extends along the length of the subassembly 2 and is located within metal sheath 10 in an area adjacent each power conductor 13A-C. In exemplary approaches, assembly jacket layer 11 is PVC and has a thickness in the range of 5-80 mils. In one non-limiting exemplary approach, assembly jacket layer 11 has a thickness of approximately 15-30 mils. However, it will be appreciated that the thickness of assembly jacket layer 11 can vary depending on the diameter of the core it surrounds. For example, larger diameter conductors generally require a thicker jacket layer. As further shown, an assembly tape 15 may be disposed around the cabled core 5.
As stated above, the subassembly 2 may be cabled, in a right or left handed lay, with the plurality of power conductors 13A-C to form core 5. Alternatively, the subassembly and the plurality of power conductors 13A-C may extend longitudinally along the metal sheath 10 such that the longitudinal axis of each conductor runs parallel to a longitudinal axis of metal sheath 10.
Although not shown, it will be appreciated that MC cable assembly 1 may include one or more filler members within metal sheath 10. In one approach, a longitudinally oriented filler member is disposed within metal sheath 10 adjacent to subassembly 2 and/or one or more of the plurality of power conductors 13A-C to press subassembly 2 and power conductors 13A-C radially outward into contact with the inside surface of metal sheath 10. The filler member can be made from any of a variety of fiber or polymer materials. Furthermore, the filler member can be used with MC Cable assemblies having any number of insulated conductor assemblies.
Referring now to the cross-sectional view of
Similar to above, conductors 6A-B and 13A-C shown in
Referring now to
Similar to above, conductors 6A-B and 13A-C shown in
Referring now to the cross-sectional view of
The communication/data cables 21A-D may be cabled within assembly jacket 11, in a right or left hand lay, and the subassembly 2 may then be cabled (again, with a right or left hand lay) with the plurality of power conductors 13A-C to form core 5. Alternatively, communication/data cables 21A-D may extend longitudinally along the metal sheath 10 such that the longitudinal axis of each communication/data cable runs parallel to a longitudinal axis of metal sheath 10. Although the illustrated embodiment shows four individual communication/data cables 21A-D, it will be appreciated that any number of communication/data cables can be provided to form subassembly 2.
Referring now to the cross-sectional views of
The conductors 6A-B can be cabled together and enclosed in an assembly jacket layer 11 to form a subassembly 2 as previously described in relation to
The MC cable assembly 400 of
In some approaches, the polymeric protective layer 18 has a thickness between 2-15 mils and may be disposed over the jacket layer 16 and more particularly, may be extruded over the jacket layer. Although the polymeric protective layer 18 has been disclosed as being polypropylene, in some approaches it can be made from other materials such as, but not limited to, polyethylene, polyester, etc. The polymeric protective layer 18 can provide mechanical strength to resist buckling, crushing and scuffing of the core 5.
In some approaches, the polymeric protective layer 18 may be a foamed polymeric material that includes air pockets filled with gasses, some or all of which may be inert. The polymeric protective layer 18 may provide proper positioning and tensioning of the bonding/grounding conductor 20. It may also be pliable to provide a conforming surface to that of the inside of the metal sheath or the adjacently positioned conductor assemblies.
Metal sheath 10 may be formed as a seamless or welded continuous sheath, and has a generally circular cross section with a thickness of about 0.005 to about 0.060 inches. The sheath 10 may also be formed into shapes other than generally circular such as, for example, rectangles, polygons, ovals and the like. Metal sheath 10 provides a protective metal covering around core 5 and the bonding/grounding conductor 20.
Although not shown, it will be appreciated that MC cable assembly 400 may include one or more filler members (not shown) within metal sheath 10. In one approach, a longitudinally oriented filler member is disposed within metal sheath 10 adjacent to subassembly 2 and/or one or more of the plurality of power conductors 13A-C to press subassembly 2, power conductors 13A-C and/or bonding/grounding conductor 20 radially outward into contact with the inside surface of metal sheath 10. The filler member can be made from any of a variety of fiber or polymer materials. Furthermore, the filler member can be used with MC Cable assemblies having any number of insulated conductor assemblies.
Referring now to the cross-sectional view of
Referring now to
In this embodiment, conductors 6A-B and 13A-C can each include a stranded or solid electrical conductor 12 having a concentric insulation layer(s) 14, and a jacket layer 16 disposed on the insulation layer 14. In this approach, no polymeric protective layer is present over jacket layer 16 along any of conductors 6A-B and 13A-C, as the assembly tape 15 functions in place of the protective polypropylene layer.
In this embodiment, the conductors 6A-B of MC cable assembly 500 may be cabled together and covered with assembly jacket layer 11 to form subassembly 2. Subassembly 2 may be cabled together, in a right or left hand lay, with the plurality of power conductors 13A-C, and the resulting core 5 may be covered by the assembly tape 15. The bonding/grounding conductor 20 may be cabled with the core 5, or it may be laid parallel to the core 5 within the metal sheath 10.
As shown in the approaches of
As shown in
In one non-limiting exemplary approach, about nineteen (19) crests and troughs may be provided per linear foot of bonding/grounding conductor 20. This number is, of course, not limiting and is provided merely for purposes of example. In addition, the peak amplitude “A” may be selected so that when the cable is fully assembled, the bonding/grounding conductor 20 has an outer dimension (i.e., two times the peak amplitude “A”) that is about equal to or slightly larger (e.g., 0.005 inches) than the outer diameter of the insulated conductors. In other approaches, the peak amplitude “A” may be selected so that when the cable is fully assembled, the bonding/grounding conductor 20 has an outer dimension (i.e., two times the peak amplitude “A”) that is slightly smaller than the outer diameter of subassembly 2 and plurality of power conductors 13A-C.
It will be appreciated that the bonding/grounding conductor 20 can be subject to tension forces during the cabling process, and thus the number of crests and troughs per foot may decrease as the bonding/grounding conductor stretches under such tension. The bonding/grounding conductor 20 may, therefore, be manufactured so that the peak amplitude “A” of the crests 24 and troughs 26 in the non-tensioned state is slightly greater than the peak amplitude “A” of the crests 24 and troughs 26 in the tensioned state (i.e., the cabled state).
It will be appreciated that although sinusoidal and wave geometries have been illustrated, the bonding/grounding conductor 20 can be provided in any of a variety of other geometries to provide the desired undulating arrangement. Examples of such alternative geometries include saw-tooth wave patterns, square wave patterns, spike wave patterns, and the like.
It will be appreciated that the bonding/grounding conductor 20 may have the disclosed undulations (alternating crests and troughs) applied as part of an in-line process of forming an MC cable. Alternatively, the undulations can be imparted to the bonding/grounding conductor 20 in a separate off-line process and then brought “pre-formed” to the cabling/twisting process used to form the MC cable.
The bonding/grounding conductor 20 may be made from any of a variety of materials, including aluminum, copper, copper clad aluminum, tinned copper and the like. In one non-limiting exemplary approach, the bonding/grounding conductor 20 is aluminum.
Referring now to
Referring now to
As will be appreciated, the various approaches described herein for using the cabled subassembly as class 2 or 3 circuit conductors that are covered by a PVC jacket within a metal clad cable containing power conductors provide a variety of advantages/improvements including, but not limited to, reducing cable installation time and cost, reducing materials (e.g., additional fittings for class 2 or 3 cables), and providing mechanical protection for all conductors within the cable.
While the present disclosure has been described with reference to certain approaches, numerous modifications, alterations and changes to the described approaches are possible without departing from the sphere and scope of the present disclosure, as defined in the appended claims. Accordingly, it is intended that the present disclosure not be limited to the described approaches, but that it has the full scope defined by the language of the following claims, and equivalents thereof. While the disclosure has been described with reference to certain approaches, numerous modifications, alterations and changes to the described approaches are possible without departing from the spirit and scope of the disclosure, as defined in the appended claims. Accordingly, it is intended that the present disclosure not be limited to the described approaches, but that it has the full scope defined by the language of the following claims, and equivalents thereof.
This is a continuation application of co-pending non-provisional application Ser. No. 15/983,625, filed on May 18, 2018, which is a continuation application of U.S. Pat. No. 10,002,689, filed on Mar. 31, 2015, which claims the benefit of U.S. provisional application Ser. No. 62/100,452, filed Jan. 7, 2015, the entirety of which applications are incorporated by reference herein.
| Number | Name | Date | Kind |
|---|---|---|---|
| 20090250238 | Picard | Oct 2009 | A1 |
| 20100186987 | Aitken | Jul 2010 | A1 |
| 20130264112 | Xu | Oct 2013 | A1 |
| 20140096996 | Sidlyarevich | Apr 2014 | A1 |
| 20150000954 | Nonen | Jan 2015 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20200005965 A1 | Jan 2020 | US |
| Number | Date | Country | |
|---|---|---|---|
| 62100542 | Jan 2015 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15983625 | May 2018 | US |
| Child | 16567215 | US | |
| Parent | 14674095 | Mar 2015 | US |
| Child | 15983625 | US |
