Patent Publication Number: US-2022216678-A1

Title: Pathway isolation fitting for a fiber trough system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is being filed on May 15, 2020 as a PCT International Patent Application and claims the benefit of U.S. Patent Application Ser. No. 62/849,443, filed on May 17, 2019, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to a system for the management of wires and fibers that carry telecommunications signals. More particularly, this disclosure relates to fittings used with troughs and the routing of signal carrying fibers (e.g., optical fibers) and wires (e.g., copper wires) in different regions of the trough defined by the fittings. 
     BACKGROUND 
     Telecommunications networks employ lengths of signal carriers, such as optical fibers and copper wires. The wires and fibers are routed between signal distribution equipment, such as closures, panels, racks, cabinets, and so forth, that serve as distribution nodes between a network provider and network subscribers. Relatively large scale nodes or distribution centers that serve a large number of subscribers can include multiple racks supporting equipment (e.g., cassettes, patch panels, shelves, trays) used to interconnect and distribute fibers and wires. In certain applications, optical fibers and copper wires are routed to the appropriate rack or other telecommunications equipment in the distribution center using troughs. The troughs can be suspended from a structure above the racks or mounted to the tops of the racks. The troughs define a system of channels for routing fibers and wires to desired locations. The channel system can be provided with downspouts, exitways, and other features to guide a given fiber or wire to a desired piece of telecommunications equipment positioned below the trough system. 
     SUMMARY 
     In general terms, the present disclosure is directed to a wire or fiber pathway isolation fitting that is configured to be inserted in and mounted to a sidewall of a trough of a fiber trough system. The wires and fibers are typically carried in telecommunications cables, such as optical fiber cables, copper coaxial cables, copper twisted pair cables, and hybrid optical fiber-copper cables. 
     In an example use application, the fitting can be used to isolate copper wires from optical fibers that are routed in the same trough. However, the disclosure is not limited by the particular use of the fitting and the trough to which the fitting is mounted. 
     For example, an optical fiber can be supported by the fitting while the bottom surface of the trough can support copper cable or vice versa, and/or both the fitting and the bottom surface of the trough can support the same type of signal conduits (copper, optical, etc.). 
     Optical fibers can be sensitive to external loads. The weight of thick or large numbers of copper cables carrying copper wires can damage or cause undesirable bending of optical fibers if the copper cable(s) are positioned on top of the optical fibers in the trough. 
     Features of the present disclosure can minimize potentially damaging loads exerted by cables on relatively fragile fibers by isolating the intra-trough routing paths of the cables (e.g., copper cables) from the intra-trough routing paths of the optical fibers. 
     In some examples, an isolation fitting in accordance with the present disclosure is configured to be mounted at a plurality of selectable positions to a trough or plurality of troughs. 
     In some examples, multiple of the isolation fittings can be inserted and mounted to a sidewall of a trough at intervals along a given length of the trough. 
     The distance of the intervals can be selected to, e.g., prevent the cables held by the fittings from contacting a bottom surface of the trough while also, e.g., minimizing the total number of fittings required for a given length of trough. 
     In some examples, the fittings are substantially rigid and can be made of molded or machined materials, e.g., a sheet metal or a relatively rigid polymeric material. 
     In some examples, the fittings are made from electrically non-conductive material. 
     In some examples, the fitting can include coupling features for securely coupling the fitting to the sidewall of the trough. 
     In some examples, a fastener is used to couple the fitting to the sidewall of the trough. 
     In some examples, a fastener is not needed and the fitting&#39;s coupling feature is configured to self-mount to the sidewall of the trough without a separate fastener. In addition, the fittings can be configured to be easily de-coupled from and recoupled to a trough, allowing for easy customization and modification of a pathway isolation system within a trough system. 
     In some examples, the fitting can be sized such that it does not contact the bottom surface of the trough to which it is mounted, thereby enabling optical cables to pass between the bottom surface of the trough and the fitting, while still extending sufficiently deep into the trough to accommodate a desired number of bulk cables. The maximum interior depth D 1  of the fitting is a measure of a distance between a bottom cable support surface of the fitting and the top of the shortest sidewall of the fitting, while the maximum interior depth D 2  of the trough is a measure of the distance between the top of the trough sidewall and the bottom cable support surface of the trough. A ratio of D 1 :D 2  can be selected to, e.g., maximize the bulk of cables that can be supported by the bottom cable support surface of the fitting while ensuring a desirable spacing or gap between the bottom cable support surface of the trough and the fitting. For example, a ratio of D 1 :D 2  can be in a range from about 19:20 to about 1:2, or outside of this range. The maximum interior width W 1  of the fitting is defined as a maximum interior distance between its sidewalls. The maximum interior width W 2  of the trough is defined as the maximum interior distance between its sidewalls. For example, a ratio of W 1 :W 2  can be, e.g., 1:2 or smaller, such as 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, or anywhere in a range from 1:2 to 1:10, as well as ratios outside of this range. 
     According to certain aspects of the present disclosure, a system comprises: a pathway isolation fitting, the pathway isolation fitting being mountable to a fiber trough having a first bottom cable support surface and first and second opposite sidewalls extending from opposite ends of the first bottom cable support surface, the first and second sidewalls and first bottom cable support surface defining a first channel, the pathway isolation fitting being configured to be mounted to one of the first and second sidewalls and partially positioned in the first channel, the pathway isolation fitting including a second bottom cable support surface and third and fourth opposite sidewalls extending from the second bottom cable support surface, the third and fourth sidewalls and the second bottom cable support surface defining a second channel, the second channel being within the first channel when the fitting is mounted to the trough, the second bottom cable support surface including a planar portion or defining a concavity that faces away from the first bottom cable support surface when the fitting is mounted to the trough. 
     According to further aspects of the present disclosure, a system comprises: a fiber trough having a first bottom cable support surface and first and second opposite sidewalls extending from opposite ends of the first bottom cable support surface, the first and second sidewalls and first bottom cable support surface defining a first channel; and a pathway isolation fitting mounted to one of the first and second sidewalls and partially positioned in the first channel, the pathway isolation fitting including a second bottom cable support surface and third and fourth opposite sidewalls extending from the second bottom cable support surface, the third and fourth sidewalls and the second bottom cable support surface defining a second channel, the second channel being within the first channel, the second bottom cable support surface including a planar portion or defining a concavity that faces away from the first bottom cable support surface. 
     According to further aspects of the present disclosure, a system comprises: a fiber trough having a first bottom cable support surface and first and second opposite sidewalls extending from opposite ends of the first bottom cable support surface, the first and second sidewalls and first bottom cable support surface defining a first channel; and a pathway isolation fitting mountable at any of a plurality of locations to one of the first and second sidewalls such that the fitting is partially positioned in the first channel, the pathway isolation fitting including a second bottom cable support surface and third and fourth opposite sidewalls extending from the second bottom cable support surface, the third and fourth sidewalls and the second bottom cable support surface defining a second channel, the second channel being within the first channel when the fitting is mounted to the trough, the second bottom cable support surface including a planar portion or defining a concavity that faces away from the first bottom cable support surface; wherein the pathway isolation fitting is configured to be moved from one of the location and mounted at another of the locations. 
     According to still further aspects of the present disclosure, a system comprises: a first plurality of cables; a second plurality of cables; a fiber trough having a first bottom cable support surface and first and second opposite sidewalls extending from opposite ends of the first bottom cable support surface, the first and second sidewalls and first bottom cable support surface defining a first channel; and a pathway isolation fitting mounted to one of the first and second sidewalls and partially positioned in the first channel, the pathway isolation fitting including a second bottom cable support surface and third and fourth opposite sidewalls extending from the second bottom cable support surface, the third and fourth sidewalls and the second bottom cable support surface defining a second channel, the second channel being within the first channel, wherein the first plurality of optical cables are routed through the first channel and are supported by the first bottom cable support surface; and wherein the second plurality of optical cables are routed through the second channel and are supported by the second bottom cable support surface. 
     A variety of examples of desirable product features or methods are set forth in the description that follows, and in part, will be apparent from the description, or may be learned by practicing various aspects of this disclosure. The aspects of this disclosure may relate to individual features, as well as combinations of features. It is to be understood that both the foregoing general description and the following detailed description are explanatory only, and are not restrictive of the claimed inventions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following drawings are illustrative of particular embodiments of the present disclosure and therefore do not limit the scope of the present disclosure. The drawings are not to scale and are intended for use in conjunction with the explanations in the following detailed description. Embodiments of the present disclosure will hereinafter be described in conjunction with the appended drawings, wherein like numerals denote like elements. 
         FIG. 1  depicts an example system in accordance with the present disclosure, including an embodiment of a fiber trough supporting optical fibers and an embodiment of a pathway isolation fitting mounted to the fiber trough and supporting cables. 
         FIG. 2  depicts a portion of the system of  FIG. 1 . 
         FIG. 3  depicts a portion of a system including a further embodiment of a fiber trough and a further embodiment of a pathway isolation fitting mounted to the fiber trough. 
         FIG. 4  is an end view of a portion of the system of  FIG. 3 . 
         FIG. 5 . is a perspective view of the pathway isolation fitting of  FIG. 3 . 
         FIG. 6  is an end view the pathway isolation fitting of  FIG. 3 . 
         FIG. 7  is a perspective view of a further embodiment of a pathway isolation fitting in accordance with the present disclosure. 
         FIG. 8  is an end view of the pathway isolation fitting of  FIG. 7 . 
         FIG. 9  is a side view of the pathway isolation fitting of  FIG. 7 . 
         FIG. 10  is a perspective view of a further embodiment of a pathway isolation fitting in accordance with the present disclosure. 
         FIG. 11  is an end view of the pathway isolation fitting of  FIG. 10 . 
         FIG. 12  is a side view of the pathway isolation fitting of  FIG. 10 . 
         FIG. 13  is a top view of the pathway isolation fitting of  FIG. 10 . 
         FIG. 14  is an exploded view of an example fastener assembly that can be used to fasten a pathway isolation fitting of the present disclosure to a fiber trough. 
         FIG. 15  is a perspective view of a further embodiment of a pathway isolation fitting in accordance with the present disclosure. 
         FIG. 16  is an enlarged view of a portion of the pathway isolation fitting of  FIG. 15 . 
         FIG. 17  is a perspective view of an example rack and trough system to which one or more pathway isolation fittings in accordance with the present disclosure can be mounted. 
         FIG. 18  is a perspective view of a further embodiment of a pathway isolation fitting in accordance with the present disclosure. 
         FIG. 19  is an end view of the pathway isolation fitting of  FIG. 18 . 
         FIG. 20  is a side view of the pathway isolation fitting of  FIG. 18 . 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments of the present invention will be described in detail with reference to the drawings, wherein like reference numerals represent like parts and assemblies throughout the several views. Reference to various embodiments does not limit the scope of the invention, which is limited only by the scope of the claims attached hereto. Additionally, any examples set forth in this specification are not intended to be limiting and merely set forth some of the many possible embodiments for the claimed invention. 
     Referring to  FIGS. 1-2 , a fiber trough  10  includes a bottom cable support surface  12  and a pair of opposite sidewalls  14 ,  16  extending upwards from the bottom cable support surface  12 . The bottom cable support surface  12 , and sidewalls  14  and  16  define a channel  18  for supporting and guiding optical fibers  20  and cables  22 . The trough  10  can be arranged together with other troughs or trough components to create a channel system. Such a channel system can be supported, e.g., above telecommunications equipment. The troughs can include exitways or, e.g., downspouts such as the downspout  24  to guide desired cables from the channel  18  to a particular component of telecommunications equipment, such as patch panel, splice cassette, shelf, etc. For example, referring to  FIG. 17 , an example arrangement  26  of fiber troughs  28  supported above telecommunications racks  30  is depicted. In this example, the troughs  28  are mounted to the racks  30 . In other examples, the troughs can be, e.g., suspended from a ceiling or other support structure positioned above the racks. Cables routed in the troughs  28  can be routed down to the racks  30  as needed. The racks  30  can support any of a number of different types of cable management and/or connectivity equipment. 
     Referring again to  FIGS. 1-2 , a pathway isolation fitting  32  is mounted to the sidewall  14  and partially inserted into the channel  18 . The fitting  32  includes opposite sidewalls  34 ,  36  extending upward from a bottom cable support surface which, together with the sidewalls  34  and  36  defines a substantially U-shaped or squared U-shaped sub-channel  38  within the channel  18 . A flange  39  extends from the sidewall  36  and over the top of the sidewall  14 . The fitting  32  is coupled to the trough  10  exteriorly to the channel  18 . The sub-channel  38  is at least partially isolated from the remainder of the channel  18  within which it is positioned. Cables  22  are supported by the bottom cable support surface of the fitting  32  and within the sub-channel  38 , thereby isolating the pathway of the cables  22  within the trough  10  from the pathway of the fibers  20  supported by the bottom cable support surface  12 . Thus, for example, external loads exerted by the cables  22  against the fibers  20  can be minimized. In some examples, the cables  22  carry copper conductors, such as copper wires. In some examples the cables  22  carry optical fibers. In some examples the cables  22  carry both copper conductors and optical fibers. The cables or fibers can be bundled in bundles, such as the bundles  27 ,  29  of cables  22 , which are bundled by wraps  31 ,  33  at intervals. Different bundles of cables can be routed to different locations. 
     A plurality of the fittings  32  can be positioned at intervals along the longitudinal dimension of the sidewall  14  such that the cables  22  can be supported within the sub-channels formed by the fittings  32  along an entire longitudinal length of the trough  10 . 
     The fitting  32  is sized such that there is a gap between the bottom of the fitting  32  and the bottom cable support surface  12  of the trough  10 . Thus, fibers  20  supported by the bottom cable support surface  12  can pass underneath the fitting  32 . 
     Referring now to  FIGS. 3-6 , a system  40  includes a fiber trough  42  and a pathway isolation fitting  44 . The trough  42  includes a bottom cable support surface  46  for supporting fibers and a pair of opposing sidewalls  48  and  50  which, together with the bottom cable support surface  46  define a channel  70  for a fiber routing pathway. The fitting  44  includes first and second opposing sidewalls  52  and  54  and a bottom cable support surface  56  that has a concavity facing away from the support surface  46 . The bottom cable support surface  56  and sidewalls  52  and  54  together define a channel  68  which is a sub-channel within the channel  70  and isolated from the rest of the channel  70 . The channel  68  is U-shaped in cross-section, as shown in  FIG. 4 . 
     A flange  58  of the fitting  44  extends from the sidewall  52  at an oblique angle to the sidewall  52  and a projecting wall  76  extends from the flange  58  parallel to the sidewall  52 . The flange  58  extends over a top  80  of the sidewall  50 . The projecting wall  76  is configured to be coupled to a coupling feature  72  of the sidewall  50 . In particular, the feature  72  defines a T-shaped recess  74 . Referring to  FIG. 14 , an example fastener assembly  82  includes a knob  84 , a T-shaped engaging element  86  and a nut  88 . The nut  88  can be used to rotationally secure the knob  84  to the T-shaped engaging element  86 . For example, both the nut  88  and the T-shaped engaging element  86  can be complementarily threaded. The T-shaped engaging element  86  can be passed through a notch or fully enclosed hole defined by the projecting wall  76  and into the T-shaped recess  74 . Then, the knob  84  can be rotated (e.g., 90 degrees) such that the ends  92  of the of cross-member of the T-shaped engaging element  86  enter the complementarily shaped portions  90  of the T-shaped recess  74 , thereby securing the fitting  44  to the sidewall  50  of the trough  42 . 
     Referring again to  FIGS. 3-6 , the channel  68  can be used to support one type of cable, wire or fiber that is different from wires, fibers, or cables supported by the bottom surface  46  of the trough  42 . The fitting  44  is sized such that there is a gap  60  between the bottom surface  46  of the trough  42  and the bottom  96  of the fitting  44 , allowing fibers to pass underneath the fitting  44 . A depth D 1  of the channel  68  is defined as the distance between a top of the sidewall  54  (which is the shorter of the two sidewalls  52  and  54 ) and the curvature inflection point of the bottom cable support surface  56 . A depth D 2  of the channel is defined as the distance between the top  80  of the sidewall  50  and the lowest most point of the bottom cable support surface  46 . A ratio of D 1 :D 2  can be selected to, e.g., maximize the bulk of wire or fiber that can be supported by the bottom cable support surface  56  while ensuring a desirable gap  60  between the bottom cable support surface  46  and the fitting  44 . For example, a ratio of D 1 :D 2  can be in a range from about 19:20 to about 1:2, or outside of this range. 
     The maximum interior width W 1  of the fitting  44  is defined as a maximum interior distance between the sidewalls  52  and  54 . The maximum interior width W 2  of the trough  42  is defined as the maximum interior distance between the sidewalls  48  and  50  of the trough  42 . A ratio of W 1 :W 2  can be, e.g., 1:2 or smaller, such as 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, or anywhere in a range from 1:2 to 1:10, as well as ratios outside of this range. The ratio can be based on one or more parameters of a given trough system, such as a corresponding the number of optical fibers or potential number of optical fibers to be supported in the trough, and the number of cables or wires or potential number of cables or wires to be supported by the fitting. 
     An assembly kit for a trough system in accordance with the present disclosure can include fittings of different sizes to enhance customizability of pathway isolation for a given trough or for a plurality of differently configured or differently used troughs. 
     Still referring to  FIGS. 3-6 , projecting interiorly from the sidewalls  52 ,  54  are a pair of strap retainers  62  and  64 . A tie or strap  66  (depicted schematically) can be looped through slots defined by the retainers  62  and  64  and tightened to help stabilize the width W 1  between the sidewalls  52 ,  54  even when the fitting  44  is heavily loaded with cables, which may otherwise cause unwanted flexing or bending of the sidewall  54  away from the sidewall  52 . Thus, by using the strap  66 , the size and shape of the channel  68  can be substantially maintained regardless of the weight of cable, wire, or fiber supported by the bottom cable support surface  56 . 
     Referring now to  FIGS. 7-9  a further embodiment of a pathway isolation fitting  100  is depicted. The fitting  100  includes a concave bottom cable support surface  102  and two opposite sidewalls  104  and  106  extending from the support surface  102 . The concavity of the bottom cable support surface  102  faces away from the bottom  126  of the fitting  100 . Opposing strap retainers  108  and  110  defining slots  112  and  114  through which a tie or strap can be passed project interiorly and towards each other from the sidewalls  104  and  106 . A flange  116  extends obliquely (forming an oblique angle  124 ) from the sidewall  104  and a projecting wall  118  extends from the flange  116  parallel to the sidewall  104 . The interior contour formed by the flange  116  and projecting wall  118  ( FIG. 8 ) is configured to complement the general contour of a mounting lip  99  ( FIG. 4 ) protruding from the sidewall of a trough. The sidewalls  104  and  106  together with the bottom cable support surface  102  define an isolated pathway channel  122 , the purpose of which has been described above. The internal width W 3  of the channel  122  is less than the internal width W 1  of the channel  68  ( FIG. 6 ). The projecting wall  118  defines a notch  120  that is positioned to be in communication with the T-shaped recess  74  of a trough  42  ( FIG. 3 ). Thus, for example, the T-shaped engaging element  86  of the fastener assembly  82  ( FIG. 14 ) can be passed through the notch  120  and into the T-shaped recess  74  ( FIG. 4 ) in the manner described above to couple the fitting  100  to the trough  42  ( FIG. 3 ). 
     Referring now to  FIGS. 10-13 , a further embodiment of a pathway isolation fitting  200  is depicted. The fitting  200  includes a support surface  202  having a planar portion  203  and two opposite sidewalls  204  and  206  extending from the support surface  202 . The sidewall  206  extends perpendicularly from the support surface  202 , while the sidewall  204  extends obliquely from the support surface  202  forming an oblique angle  226 . The obliqueness of the sidewall  204  relative to the support surface  202  matches the obliqueness of the sidewall  50  relative to the support surface  46  of the trough  42  ( FIG. 4 ), such that when the fitting  200  is mounted to the trough  42  the planar portion  203  is parallel to the planar portion of the bottom cable support surface  46  of the trough  42  ( FIG. 4 ), i.e., the planar portion  203  is oriented horizontally and perpendicular to the force of gravity. This orientation relative to gravity can stabilize the cables supported by the support surface  202  and minimize lateral shifting thereof 
     Strap retainers  208  defining slots  210  through which ties or straps can be passed project interiorly from the bottom cable support surface  202 . Such ties or straps can be, e.g., wrapped around cables to secure the cables to the bottom cable support surface  202 . 
     A flange  216  extends obliquely (forming an oblique angle  224 ) from the sidewall  204  and a projecting wall  218  extends from the flange  216  parallel to the sidewall  204 . The interior contour formed by the flange  216  and projecting wall  218  ( FIG. 11 ) is configured to complement the general contour of a mounting lip  99  ( FIG. 4 ) protruding from the sidewall of a trough. The sidewalls  204  and  206  together with the bottom cable support surface  202  define an isolated pathway channel  222 , the purpose of which has been described above. The internal average width W 4  of the channel  222  is greater than the internal width W 1  of the channel  68  ( FIG. 6 ). The projecting wall  218  defines a pair of notches  220  that are positioned to be in communication with the T-shaped recess  74  of a trough  42  ( FIG. 3 ). Thus, for example, a pair of T-shaped engaging elements  86  of a pair of fastener assemblies  82  ( FIG. 14 ) can be passed through the notches  220  and into the T-shaped recess  74  ( FIG. 4 ) in the manner described above to couple the fitting  200  to the trough  42  ( FIG. 3 ). Due to the larger width W 4 , the fitting  200  can support a greater weight of cables such that two fastener assemblies  82  ( FIG. 14 ) may needed to stabilize the mounting of the fitting to a trough. 
     Referring now to  FIGS. 15-16 , a further embodiment of a pathway isolation fitting  300  is depicted. The fitting  300  is structurally and functionally identical to the fitting  44  described above ( FIG. 3 ) except for the coupling mechanism used to couple the fitting  300  to a trough. The fitting  300  includes a coupling mechanism  302  supported by the projecting wall  76  that extends from the flange  58 . The coupling mechanism  302  includes a latch  304  projecting from a cantilever arm  308  disposed in a window  310  defined by the projecting wall  76 . The cantilever arm can flex outward until the latch  304  finds the exterior opening  97  to the T-shaped recess  74  of the lip  99  of the trough  42  ( FIGS. 3-4 ), at which point the latch  304  can resiliently snap into the opening  97  thereby coupling the fitting  300  to the trough  42  ( FIG. 3 ). To decouple (i.e., release) the fitting  300  from the trough, a release tab  306  extending from the cantilever arm  308  can be urged upward, causing the cantilever arm  308  to flex outward and the latch  304  to disengage the opening  97  of the lip  99 . Thus, it should be appreciated, that the fitting  300  can be coupled to a trough without using a separate fastener, such as the fastener assembly  82  ( FIG. 14 ). 
     Referring now to  FIGS. 18-20 , a further embodiment of a pathway isolation fitting  400  is depicted. The fitting  400  includes a support surface  402  having a planar portion  403  and two opposite sidewalls  404  and  406  extending from the support surface  402 . The side walls  404  and  406  are parallel to each other and both extend from the support surface  402  at oblique angles  408 ,  410  relative to the planar portion  403 . A transition portion  412  between the wall  406  and the planar portion  403  has a curvature with a greater radius of curvature than a transition portion  414  between the wall  404  and the planar portion  403 . In some examples, the obliqueness of the sidewalls matches the obliqueness of the sidewall  50  relative to the support surface  46  of the trough  42  ( FIG. 4 ), such that when the fitting  400  is mounted to the trough  42  the planar portion  403  is parallel to the planar portion of the bottom cable support surface  46  of the trough  42  ( FIG. 4 ), i.e., the planar portion  403  is oriented horizontally and perpendicular to the force of gravity. This orientation relative to gravity can stabilize the cables supported by the support surface  402  and minimize lateral shifting thereof 
     Strap retainers  416  defining slots  418  through which ties or straps can be passed project interiorly from the sidewalls  404  and  406  to help hold the sidewalls in position even when the fitting  400  is loaded. 
     A flange  420  extends obliquely (forming an oblique angle  424 ) from the sidewall  404  and a projecting wall  428  extends from the flange  420  parallel to the sidewalls  404  and  406 . The interior contour formed by the flange  420  and projecting wall  428  is configured to complement the general contour of a mounting lip  99  ( FIG. 4 ) protruding from the sidewall of a trough. The sidewalls  404  and  406  together with the bottom cable support surface  402  define an isolated pathway channel  430 , the purpose of which has been described above. The projecting wall  428  defines a notch  432  that is positioned to be in communication with the T-shaped recess  74  of a trough  42  ( FIG. 3 ). 
     From the foregoing detailed description, it will be evident that modifications and variations can be made in the devices of the disclosure without departing from the spirit or scope of the invention.