Patent Publication Number: US-2023162888-A1

Title: Cable for distributing network power and data

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of U.S. patent application Ser. No. 17/320,519 filed May 14, 2021, which application claims priority to U.S. Provisional Patent Application Ser. No. 63/026,291, filed May 18, 2020, the entire content of which is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to communication systems and, in particular, to communications systems that deliver power as well as data to remote nodes. 
     BACKGROUND 
     In many information and communication technology systems, network-connected electronic devices are deployed in locations where a local electric power source is not available. With the proliferation of the Internet of Things (“IoT”), autonomous driving, fifth generation (“5G”) cellular service, and the like, it is anticipated that network-connected electronic devices will increasingly be deployed at locations that lack a conventional electric power source. 
     Electric power may be provided to such remote network-connected electronic devices in numerous ways. For example, a local electric utility company can install a connection that connects the remote network-connected electronic devices to the electric power grid. This approach, however, is typically both expensive and time-consuming, and unsuitable for many applications. Composite power-data cables can also be used to power remote network-connected electronic devices and provide data connectivity thereto over a single cabling connection. Power-plus-fiber cables are an example of a type of composite power-data cable that includes both power conductors and optical fibers within a common cable jacket. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram illustrating the increasing power and data connectivity needs for information and communication technology infrastructure in high density access networks. 
         FIG.  2    is a schematic diagram illustrating an embodiment of a node on a network such as shown in  FIG.  1   . 
         FIG.  3    is a cross-section view of a composite power-data cable according to further embodiments of the present inventive concepts. 
         FIG.  4    is a cross-section view of a power cable according to embodiments of the present inventive concepts. 
         FIG.  5    is a partial cutaway side view of another embodiment of a composite power-data cable according to embodiments of the present inventive concepts. 
         FIG.  6    is a section view showing another embodiment of a composite power-data cable according to embodiments of the present inventive concepts. 
         FIG.  7    is a block diagram of a cable including N conductors and M continuity wires, according to embodiments of the present inventive concepts. 
         FIG.  8    is a cross-section view of a power cable illustrating angular spacing between elements, according to embodiments of the present inventive concepts. 
     
    
    
     DETAILED DESCRIPTION 
     Pursuant to embodiments of the present inventive concepts, improved cables, such as composite power and fiber optic data cables and power cables, are provided for data/power grids. For example, it may be desirable to provide in-line distribution of both power and data to radio nodes and other electronic devices in an outside plant environment. This may avoid the need for a local electric power source at each radio node or other electronic device. Electric power can be delivered over insulated metal (e.g., copper) conductors, while the data is often delivered over optical fibers. The insulated metal conductors and the optical fibers can be included in separate cables or a composite or hybrid cable that includes both the insulated metal conductors and the optical fibers may be used to deliver both power and data to one or more remote electronic devices. In some environments it may be desirable to provide only the distribution of power in the cable while in other environments it may be desirable to provide both power distribution and data in a single composite cable. In outside plant environments, such cables are often buried underground, or otherwise located, where the cables are potentially accessible. It is known, for example, that such cables may be inadvertently cut as a result of digging near a buried cable or otherwise damaged even where a cable is suspended above-ground. Power cables or composite power-data cables used, for example, in an outside plant environment for a communications network, may carry electric power signals having voltage and/or current levels (e.g., ±190 Volts) that may result in a safety or fire hazard if the cable is severed while in use. 
     According to embodiments of the present inventive concepts, a power cable and/or a composite power-data cable may comprise continuity wires that carry communication and control signals that are used to sense when the cable is cut so that the electric power that is provided to the power conductors of the cable may be shut off in response to sensing such a cut to the cable. The continuity wires are arranged such that the cut in the cable may be sensed before the power conductors are cut regardless of the orientation of the cable. 
     Cellular data traffic has increased by about 4,000 percent over the last decade, and is expected to continue increasing at a rate of over 50% per year for at least the next several years. Cellular operators are beginning to deploy 5G cellular networks in an effort to support the increased cellular data traffic with better coverage and reduced latency. One expected change in the cellular architecture that is anticipated with the roll-out of 5G networks is a rapid increase in the number of so-called small cell base stations that are deployed. Generally speaking, a “small cell” base station refers to an operator-controlled, low-power radio access node that operates in the licensed spectrum and/or that operates in the unlicensed spectrum. The term “small cell” encompasses microcells, picocells, femtocells, and metrocells that support communications with fixed and mobile subscribers that are within, for example, between about 10 meters and 300-500 meters of the small cell base station, depending on the type of small cell used. 
     Small cell base stations are typically deployed within the coverage area of a base station of the macrocell network, and the small cell base stations are used to provide increased throughput in high traffic areas within the macrocell. This approach allows the macrocell base station to be used to provide coverage over a wide area, with the small cell base stations supporting much of the capacity requirements in high traffic areas within the macrocell. In heavily-populated urban and suburban areas, it is anticipated that more than ten small cells will be deployed within a typical 5G macrocell to support the increased throughput requirements. As small cell base stations have limited range, they must be located in close proximity to users, which typically requires that the small cell base stations be located outdoors, often on publicly-owned land, such as along streets. Typical outdoor locations for small cell base stations include lamp posts, utility poles, street signs, and the like, which are locations that either do not include an electric power source, or include a power source that is owned and operated by an entity other than the cellular network operator. A typical small cell base station may require between 200-1,000 Watts of power. 
     As small cell base stations are deployed in large numbers, providing electric power to the small cell base station locations represents a significant challenge. To meet these goals, cellular operators can benefit from a repeatable process for delivering electric power to small cell base station locations that preferably does not require involvement of third parties such as electric utility companies. 
     One solution that has been developed for powering small cell base stations uses composite power-data cables. Composite power-data cables allow a cellular network operator to deploy a single cable between a hub and a node such as a small cell base station that provides both electric power and backhaul connectivity to the small cell base station. The hub may be, for example, a central office, a macrocell base station, or some other network operator owned site that is connected to the electric power grid. 
     According to U.S. Pat. No. 10,770,203, the entire disclosure of which is hereby incorporated by reference herein, power and data connectivity micro grids may be provided for information and communication technology infrastructure, including small cell base stations. These power and data connectivity micro grids may be owned and controlled by cellular network operators, thus allowing the cellular network operators to more quickly and less expensively provide power and data connectivity (backhaul) to new small cell base stations. The power and data connectivity micro grids may be cost-effectively deployed by over-provisioning the power sourcing equipment and cables that are installed, to provide power and data connectivity to new installations, such as new small cell base station installations. 
     The power and data connectivity micro grids may include a network of composite power-data cables that are used to distribute electric power and data connectivity throughout a defined region. The composite power-data cables may be implemented as, for example, power-plus-fiber cables, as such cables have significant power and data transmission capacity. Each micro grid may include a network of composite power-data cables that extend throughout a geographic area. The network of composite power-data cables may be designed to have power and data capacity far exceeding the capacity requirements of existing nodes along the micro grid. Because such excess capacity is provided, when new remote network-connected devices are installed in the vicinity of a micro grid, composite power-data cables can be routed from tap points along the micro grid to the location of the new remote network-connected device (e.g., a new small cell base station). The tap points allow for daisy chain operation and/or splitting of the power and data signal. The newly installed composite power-data cables may themselves be over-provisioned and additional tap points may be provided along the new composite power-data cabling connections so that each new installation may act to further extend the footprint of the micro grid. In this fashion, cellular network operators may incrementally establish their own power and data connectivity micro grids throughout high density areas. In many cases, the only additional cabling that will be required to power such new base stations is a relatively short composite power-data cable that connects the new small cell base station to an existing tap point of the micro grid. Depending on the system architecture, separate power cables and fiber optic cables may be used at the small cell base station to separately deliver power and data to the base station equipment such as the radios. 
     The power delivery component of the power and data connectivity micro grids may comprise a low voltage, direct current (“DC”) power grid in some embodiments. The DC power signals that are distributed over the micro grid may have a voltage that is higher than the (AC) voltages used in most electric utility power distribution systems (e.g., 110 V or 220 V AC), which may help reduce power loss, but the voltage may be lower than 1500 V DC so as to qualify as a low voltage DC voltage under current standards promulgated by the International Electrotechnical Commission (IEC). For example, the micro grid may carry a 380 V DC power signal (or some other DC voltage greater than 48-60 V and less than 1500 V). The 380 V DC power signal may comprise a +/−190 V DC power signal in some embodiments. 
       FIG.  1    is a schematic diagram illustrating an embodiment of a high density access network in which the cables of the present invention may be used. As shown in  FIG.  1   , in an urban or suburban environment  100 , a telecommunications provider, such as a cellular network operator, may operate a central office  110  and a macrocell base station  120 . In addition, the telecommunications provider may operate a plurality of small cell base stations  130 , WiFi access points  140 , fixed wireless nodes  150 , active cabinets  160 , DSL (e.g., G.fast) distribution points  170 , security cameras  180 , and the like. All of these installations may require DC power to operate active equipment, and most, if not all, of these installations may also require data connectivity either for backhaul connections to the central office  110  and/or for control or monitoring purposes. To reduce costs and increase the speed at which electric power and data connectivity can be deployed to remote network-connected powered devices such as the remote devices  130 ,  140 ,  150 ,  160 ,  170 ,  180  illustrated in  FIG.  1   , the use of power-plus-fiber cables has been proposed. For example, PCT Publication No. WO 2018/017544 A1, which is incorporated herein in its entirety by reference, discloses an approach for providing power and data connectivity to a series of remote powered devices in which power-plus-fiber cables extend from a power source to a plurality of intelligent remote distribution nodes. Each intelligent remote distribution node may include a “pass-through” port so that a plurality of remote distribution nodes may be coupled to the power source in “daisy chain” fashion. Intelligent remote powered devices may be connected to each intelligent remote distribution node and may receive power and data connectivity from the intelligent remote distribution node. 
     According to U.S. Pat. No. 10,770,203, the power source equipment and remote distribution node approach disclosed in PCT Publication No. WO 2018/017544 A1 may be extended so that cellular network operators may create a hard wired power and data connectivity micro grid throughout high density urban and suburban areas. As new installations (e.g., new small cell base stations  130 , security cameras  180 , and the like) are deployed in such areas, the cellular network operator may simply tap into a nearby portion of the micro grid to obtain power and data connectivity without any need to run cabling connections all the way from the power and data source equipment to the new installation. 
     Referring to  FIG.  2   , a schematic view of an embodiment of a portion of a network architecture is shown. A plant  200  provides distributed power from a power source  202  and data from a data source  204  to the network. The power and data may be delivered using the hybrid power-data cables  300 , as will be described herein, to nodes  208  on the network. In the illustrated embodiment, the node  208  is a small cell base station comprising radios  212  mounted on a support structure  214  such as a tower. In some embodiments, at each node  208  a tap point  500  may be provided along the composite power-data cable  300  that allow for daisy chain operation and/or splitting of the power and data signals. As shown in  FIG.  2   , tap point  500  separately delivers the power and data to the equipment at the node. The data may be delivered over a separate data line  218  such as a fiber optic cable. The power may be delivered using a power cable  400  as will be described herein. Separating the power and data at the node may be necessitated by the service provider&#39;s equipment architecture. Separating the power and data at the node also may facilitate maintenance and repair. 
       FIG.  3    shows an embodiment of a composite power-data cable  300 . The composite power-data cable  300  may comprise a central member  304  that may be made of a suitable flexible, dielectric material such as a glass reinforced plastic rod. The glass reinforced rod may be made of pultruded glass/resin. The central member  304  acts a reinforcement member to prevent buckling and stretching of the composite power-data cable  300 . In some embodiments, the glass reinforced rod may be covered in a polyethylene coating  306  to provide the central member  304  of a desired diameter for proper sizing of the composite power-data cable  300 . 
     Four power conductors  308   a - d  are provided adjacent to the central member  304 . Two of the power conductors  308   a  and  308   b  may be used to provide the minus voltage and two of the power conductors  308   c  and  308   d  may be used to provide the plus voltage. In other embodiments, two of the power  308  conductors may carry a ground voltage while the other two power conductors  308  may carry either a plus voltage or a minus voltage. Each power conductor  308   a - d  may comprise, for example, a 12 gauge wire comprised of multiple strands of copper in a jacket of PVC with a nylon coating. In one embodiment, 19 strands of copper are used to make the 12 gauge wire. Such a power conductor is commonly referred to as THWN conductor. The power conductors  308   a - d  may be arranged with the two minus power conductors  308   a  and  308   b  arranged adjacent to one another and the two plus power conductors  308   c  and  308   d  arranged adjacent to one another where the two minus power conductors  308   a  and  308   b  are spaced from the two plus power conductors  308   c  and  308   d . This arrangement lowers the chance that a plus power conductor  308   c  and  308   d  and a minus power conductor  308   a  and  308   b  will be inadvertently cut simultaneously. 
     A plurality of filler members  310  may be provided outside of the central member  304  and adjacent to and between the power conductors  308   a - d  to define a generally cylindrically shaped elongated member. The filler members  310  may comprise polyethylene rods. While three larger diameter filler members and seven smaller diameter filler members are shown, it is to be understood that this arrangement is for illustrative purposes and that a greater or fewer number of filler members  310  may be used and the filler members may be of the same or different diameters. For example, in one embodiment only the three larger diameter filler members  310  may be used to create a generally circular cross-section. 
     The central member  304 , power conductors  308   a - d  and filler members  310  may be covered by a water blocking tape layer  312 . The water blocking tape layer  312  may comprise a non-woven tape having a thickness of approximately 10 mils or less. The water blocking tape  312  may be longitudinally wrapped around the power conductors  308   a - d  and filler members  310  and held in position by binder yarns. 
     Positioned in a layer outside of the water blocking tape layer  312  are the optical fibers  316  and continuity wires  320 . The optical fibers  316  may arranged in groups. In one embodiment, 144 individual optical fibers  316  may be provided arranged in twelve groups or bundles of loose fibers laid helically in respective buffer tubes  318  with each group or bundle comprising twelve optical fibers  316 . A water blocking structure may be provided in buffer tubes  318  such a water absorbing polymer in a polyester yarn. 
     As shown in  FIG.  3   , a plurality of continuity wires  320  are disposed in the same layer with the optical fibers  316 . Each continuity wire  320  may comprise stranded wire such as 18 gauge wire made of 16 individual copper strands. Because the continuity wires  320  only carry communication and control signals the continuity wires  320  may have a higher gauge (thinner wire) as compared to the power conductors  308 . The copper strands may be jacketed in PVC with a nylon coating. The continuity wires  320  carry low voltage communication and control signals for the system in which the composite power-data cable  300  is deployed. The jacket of the continuity wires  320  may include indicia such as symbols, words or the like indicating that the continuity wires  320  are not the high voltage power conductors  308 . The indicia may comprise, for example, colored stripes. 
     The continuity wires  320  are positioned such that a cut in the composite power-data cable  300  will sever one of the continuity wires  320  before a cut into the power conductors  308   a - d  (or at least a cut into two power conductors carrying different voltage power signals) can occur. The severing of a continuity wire  320  interrupts the communication and control signals carried by the continuity wire causing an interruption of the power delivered over the power conductors  308   a - d  to: 1) prevent potential safety and fire hazards that may result from the severing of the power conductors  308   a - d , and 2) notify the network operator that a cut in a cable has occurred. In certain systems, power shut down can occur in less than 10 milliseconds after the severing of a continuity wire  320 . In the illustrated embodiment, four continuity wires  320  are used. In some embodiments, when the composite power-data cables  300  are connected in the network, the continuity wires  320  are connected in loops such that the continuity wires  320  are disposed as pairs where two of the continuity wires  320  are arranged as a first pair forming a first loop and two of the continuity wires  320  are arranged as a second pair forming a second loop. In such a network deployment, the continuity wires  320  may be connected as pairs such that the cable  300  may have, for example, 2, 4, 6, 8 or more even numbers of continuity wires  320 . A generic diagram showing possible configurations of continuity wires is shown in  FIG.  7   . In networks where the continuity wires  320  are not connected in loops an odd number of continuity wires may be used in the composite power-data cable  300 . The arrangement of the continuity wires  320  will be described in greater detail below. 
     The fiber optic buffer tubes  318  and the continuity wires  320  may be covered in a water blocking tape layer  330 . The water blocking tape layer  330  may comprise a non-woven tape having a thickness of approximately 10 mils or less. The water blocking tape may be longitudinally wrapped around the fiber optic buffer tubes  318  and the continuity wires  320  and held in position by binder yarns. 
     A corrugated laminated aluminum layer  332  may surround the water blocking tape layer  330 . The corrugated laminated aluminum layer  332  may comprise 10-12 mils thick layer of corrugated aluminum with an ethylene ethyl acrylate (EAA) coating that is longitudinally wrapped around the water blocking tape layer  330 . An outer jacket  334  may surround the corrugated laminated aluminum tape layer  332  and form the exterior of the composite power-data cable  300 . The outer jacket  334  may be made of a suitable flexible, electrically and environmentally insulating material such as polyvinyl chloride (PVC). 
     As previously explained, the continuity wires  320  are positioned such that a cut in the composite power-data cable  300  will sever at least one of the continuity wires  320  before a cut into the power conductors  308   a - d  can occur. In the illustrated embodiment, the continuity wires  320  are arranged radially outside of and surrounding the power conductors  308   a - d . It is to be appreciated that the power conductors  308   a - d , filler members  310 , fiber optic bundles  318  and the continuity wires  320  are arranged in a generally helical configuration such that the absolute positions of these components vary along the length of the cable while the relative positions of the components is relatively constant over the length of the cable. As a result, in a buried cable, the components may be in any radial spatial position relative to the cable exterior. Because of this, the continuity wires  320  are positioned such that the continuity wires  320  are cut before the power conductors  308   a - d  are cut regardless of where the cut occurs on the composite power-data cable  300 . 
     The continuity wires  320  are positioned radially outside of the power conductors  308   a - d . The term “radially outside” as used herein to describe the relationship between components means that the components are positioned outside of one another in a direction from the center of the cable to the exterior of the cable; however, the components need not be aligned on a radius, although the components may be aligned on a radius. Similarly, the term “radially inside” as used herein to describe the relationship between components means that the components are positioned inside of one another in a direction from the exterior of the cable to the interior of the cable; however, the components need not be aligned on a radius, although the components may be aligned on a radius. In the illustrated embodiment, four continuity wires  320  are used where each continuity wire  320  is spaced approximately 90 degrees from the adjacent continuity wires  320  such that the four continuity wires  320  are spaced equally from one another over the 360 degree angular extent of the cable  300 . It has been found that using four continuity wires  320  provides a composite power-data cable  300  where one of the continuity wires  320  will be cut before the power conductors  308   a - d  are cut. Cutting both a plus power conductor  308   a - b  and a minus power conductor  308   c - d  presents a particularly hazardous condition where arcing may create a fire hazard. Thus, positioning the continuity wires  320  such that one of the continuity wires is cut before both a plus power conductors  308   a - b  and a minus power conductor  308   c - d  is particularly advantageous. 
     While one embodiment using four continuity wires  320  has been shown and described as effectively cutting power to the power conductors  308   a - d  before a hazard is created, a greater or fewer number of continuity wires  320  may be used. For example, using more than four continuity wires  320  spaced around the cable  300  may provide an additional safety factor with a corresponding increase in cost. For example, in some embodiments 6 continuity wires may be used and in other embodiments 8 or even 10 continuity wires may be used. In some embodiments, three continuity wires  320  may be used spaced approximately 120 degrees from one another. The number of continuity wires  320  required for a specific cable may depend, in part, on the diameter of the cable, the location of the power conductors and the network architecture. 
     As previously described, the power conductors  308   a - d , filler members  310 , fiber optic bundles  318  and the continuity wires  320  are arranged in a generally helical configuration. One or both of the continuity wires  320  and the power conductors  3308   a - d  may be arranged in an SZ configuration where the direction of the helix changes after a given number of turns. This creates randomness in the relationship of the position between the continuity wires  320  and the power conductors  3308   a - d . The pitch of a helix is the height of one complete helix turn, measured parallel to the axis of the helix. In one embodiment, the pitch of the continuity wires  320  and the pitch of the power conductors  3308   a - d  may be different. In some embodiments, the pitch of the continuity wires  320  may be made significantly smaller than the pitch of the power conductors  308   a - d  such that for every one complete turn of the power conductors  308   a - d , multiple turns of the continuity wires  320  are made as shown in  FIG.  5   . Certain structures of the cable  300  have been omitted from  FIG.  5    in order to better illustrate the different pitches of the power conductors  308  and the continuity wires  320 . In this manner, a fewer number of continuity wires  320  may cover more area of the cable  300  such that a fewer number of continuity wires  320  may be used. For example, depending upon the pitch of the continuity wires  320  two continuity wires  320  may be used. In such an embodiment, the continuity wires  320  may be disposed in a separate layer radially inside of or radially outside of the layer of fiber optic cables. While fewer continuity wires may be used in such an arrangement, the length of each continuity wire may be greater due to the increased number of turns per unit length. 
     The continuity wires  320  are arranged relative to the power conductors  308   a - d  such that the power conductors  308   a - d  cannot be cut without first cutting at least one of the continuity wires  320 . This arrangement provides both a notification that the cable  300  has been cut even if the cut is not deep enough to penetrate to the power conductors  308   a - d  and provides a safety feature by cutting off power to the power conductors  308   a - d  in the event a cut is made in the cable  300  that would otherwise penetrate to the live power conductors  308   a - d.    
     In some embodiments, the continuity wires  320  are arranged relative to the power conductors  308   a - d  such that a minus power conductor and a plus power conductor  308   a - d  cannot be cut without first cutting at least one of the continuity wires  320 . In some embodiments, the continuity wires  320  are arranged such that they are approximately evenly spaced around the circumference of the cable. For example, four wires may be spaced about 90 degrees from one another, 6 wires may spaced about 60 degrees from one another, 8 wires may be spaced about 45 degrees from one another, 10 wires may be spaced about 36 degrees from one another and so on, as shown, for example, in  FIG.  8   . Terms such as “about” or “approximately” as used herein means plus or minus 10%. As shown in  FIGS.  3  and  4   , all of the continuity wires  320  are shown as being in the same layer of the cable as the optic fibers  316 . However, the continuity wires  320  may be positioned in a layer separate from the other active components as shown in  FIG.  6    where the continuity wires  320  are positioned radially outside of the optic fibers  316  in a separate layer of the cable  300 . In such an embodiment, spacers  310  may be located in the layer with the continuity wires  320  in order to maintain the cylindrical shape of the fiber, if necessary. In  FIGS.  3 ,  4  and  5   , all of the continuity wires  320  are positioned at about the same radial distance from the center of the cable  300 , i.e. in the same layer of the cable. However, all of the continuity wires  320  do not have to be positioned in the same layer of the cable. For example, the continuity wires  320  may be positioned at different radial distances from the center of the cable  300  and may be in different layers of the cable  300 . 
     Referring to  FIG.  4   , an embodiment of a power cable  400  is shown. The power cable  400  is similar to the composite power-data cable  300  of  FIG.  3    except that power cable  400  does not provide data capabilities and is only used as a power cable to deliver electrical power. Like reference numerals are used in  FIG.  4    to identify the same or similar structures previously described with respect to  FIG.  3   . Power cable  400  as illustrated does not include the central member  304  of  FIG.  3   ; however, a central member  304  as previously described may be used in the power cable  400 . Likewise, the central member  304  may not be used in the power-data cable  300 . Two power conductors  308   a ,  308   c  are provided. Power conductor  308   a  may be used to provide the minus voltage and power conductor  308   c  may be used to provide the plus voltage. The power conductors  308   a  and  308   c  may be constructed as described with reference to  FIG.  3   . While two power conductors  308   a  and  308   c  are shown in  FIG.  4   , four power conductors may be provided as shown in the embodiment of  FIG.  3   . A plurality of filler members  310  may be provided adjacent to and between the power conductors  308   a ,  308   c  to define a generally cylindrically shaped elongated member. The filler members  310  may be constructed as described with reference to  FIG.  3   . While two filler members  310  are shown, it is to be understood that this arrangement is for illustrative purposes and that a greater or fewer number of filler members  310  may be used and the filler members may be of the same or different diameters. The power conductors  308   a  and  308   c  and filler members  310  may be covered by a water blocking tape layer  312  as previously described. 
     Positioned in a layer outside of the water blocking tape layer  312  are the continuity wires  320  and additional filler members  410 , if needed. Each continuity wire  320  carries low voltage communication and control signals for the system in which the cable is deployed may be constructed as previously described. 
     The continuity wires  320  are positioned such that a cut in the power cable  400  will sever one of the continuity wires  320  before a cut into the power conductors  308   a  and  308   c  can occur as previously described. The severing of a continuity wire  320  interrupts the communication and control signals carried by the continuity wire causing an interruption of the power delivered over the power conductors  308   a  and  308   c  to prevent potential safety and fire hazards that may result from the severing of the power conductors  308   a  and  308   c . As explained above, the continuity wires  320  are arranged relative to the power conductors  308   a  and  308   c  such that the power conductors  308   a  and  308   c  cannot be cut without first cutting at least one of the continuity wires  320 . The description of the arrangement, configuration, spacing and number of continuity wires  320  as described above with respect to the power-data cable  300  also applies to the power cable  400 . In some embodiments, the continuity wires  320  are arranged relative to the power conductors  308   a  and  308   c  such that the minus power conductor and the plus power conductor  308   a  and  308   c  cannot be cut without first cutting at least one of the continuity wires  320 . In some embodiments, the continuity wires  320  are arranged such that they are approximately evenly spaced around the circumference of the cable. As shown in  FIG.  4    all of the continuity wires  320  are shown as being in the same layer of the cable  400 , i.e. all of the continuity wires are positioned at about the same radial distance from the center of the cable  400 . However, all of the continuity wires  320  do not have to be positioned in the same layer of the cable and may be positioned at different radial distances from the center of the cable  400  and may be in different layers of the cable  400 . 
     The continuity wires  320  and fillers  410  may be covered in a water blocking tape layer  330  as previously described. A corrugated laminated aluminum tape layer  332  may surround the water blocking tape layer  330  as previously described. An outer jacket  334  surrounds the corrugated laminated aluminum tape layer  332  and forms the exterior of the hybrid power-data cable  300  as previously described. 
       FIG.  7    is a block diagram of a cable including N conductors and M continuity wires, according to embodiments of the present inventive concepts. N and M are integers. The cable may have, for example, N power conductors and M continuity wires. In some embodiments, M may be 2, 4, 6, 8, 10 or more even numbers of continuity wires. 
       FIG.  8    is a cross-section view of a power cable illustrating spacing between elements, according to embodiments of the present inventive concepts. The cable may include M continuity wires and N power conductors. The M continuity wires may have equal angular spacing based on the number of continuity wires, M. In other words, the angular spacing may be 360°/M. For example, four wires may be spaced about 90 degrees from one another, 6 wires may spaced about 60 degrees from one another, 8 wires may be spaced about 45 degrees from one another, 10 wires may be spaced about 36 degrees from one another and so on. 
     The present inventive concepts have been described above with reference to the accompanying drawings. The present inventive concepts are not limited to the illustrated embodiments. Rather, these embodiments are intended to fully and completely disclose the present inventive concepts to those skilled in this art. In the drawings, like numbers refer to like elements throughout. Thicknesses and dimensions of some components may be exaggerated for clarity. 
     Spatially relative terms, such as “under,” “below,” “lower,” “over,” “upper,” “top,” “bottom,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “under” or “beneath” other elements or features would then be oriented “over” the other elements or features. Thus, the example term “under” can encompass both an orientation of over and under. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     Herein, the terms “attached,” “connected,” “interconnected,” “contacting,” “mounted,” and the like can mean either direct or indirect attachment or contact between elements, unless stated otherwise. 
     Well-known functions or constructions may not be described in detail for brevity and/or clarity. As used herein the expression “and/or” includes any and all combinations of one or more of the associated listed items. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present inventive concepts. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including” when used in this specification, specify the presence of stated features, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, operations, elements, components, and/or groups thereof.