Abstract:
A hollow-spine ladder-type cable tray with cable arms has a hollow channel within one of the two body spines which is adapted for running and holding electrical wiring. This is achieved by enlarging at least one of the spines, and thus its hollow channel, and by molding one side face of the spine so as to open outwardly except when covered by one or more snap-on cover plates. The cover plates may include mounts suitable for holding standard 110 or 220 volt electrical outlets, modular telephone jacks, or the like. Preferably, however, separate outlet plates bearing or adapted to bear the outlets are configured to snap on over the open face of at least one spine between adjacent cover plates.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation in part of U.S. application Ser. No. 09/246,683, filed Feb. 8, 1999. 
    
    
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     FIELD OF THE INVENTION 
     This invention relates to cable trays—more particularly, to a ladder-type cable tray having a pair of parallel spines with at least one open side face on at least one of the spines, through which open face may be passed electrical wiring, or data networking or telephone cabling, for ducting through the hollow interior of the open-faced spine. 
     BACKGROUND OF THE INVENTION 
     Ladder-type cable trays comprise pairs of beamed or spined members having regularly spaced transverse arms between said spines for cradling cables, wiring, tubes and the like, such as for computer networks, telecommunications and the like. Ladder-type cable trays normally are suspended from ceilings on rods. In computer network installations, ladder-type cable trays are used for routing network cables along the ceiling of a dedicated room to upright components known as racks. Occasionally, the ladder-type cable trays might be laid out on top of the racks. Ladder-type cable trays are often found in large installations where they may travel great distances, both indoors and outdoors, such as at petroleum refineries and the like. 
     It is also necessary, however, to run electrical power into and around the area to the racks and to other related equipment served by the cable trays. For purposes of isolating the electrical power wiring from interference with communication signals in the network cables, and for reasons of safety, electrical power wiring typically is carried within the hollows of separately mounted ducts called raceways. Prior art ladder-type cable trays, which are limited to carrying externally exposed cabling, therefore are not suitable for electrical wiring. To run electrical wiring along the cable arms thereof would not be in compliance with building code requirements. In order to meet building code requirements and the IEEE specifications, a metallic barrier must separate electrical wiring and low voltage cabling. 
     Prior developments in this field may be generally illustrated by reference to the following information disclosure statement: 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 U.S. Patent Documents 
               
             
          
           
               
                 U.S. Pat. No. 
                 Patentee 
                 Issue Date 
               
               
                   
               
               
                 5,629,496 
                 J. Navazo 
                 May 13, 1997 
               
               
                 5,659,151 
                 J. Dale 
                 Aug. 19, 1997 
               
               
                 5.123,618 
                 D. Geterman et al. 
                 Jun. 23, 1992 
               
               
                 5,323,988 
                 I. Handler 
                 Jun. 28, 1994 
               
               
                 5,131,860 
                 S. Bogiel 
                 Jul. 21, 1992 
               
               
                 4,166,195 
                 A. Schwab 
                 Aug. 28, 1979 
               
               
                 4,017,137 
                 W. Parks 
                 Apr. 12, 1977 
               
               
                 5,614,695 
                 J. Benito Navazo 
                 Mar. 25, 1997 
               
               
                   
               
             
          
         
       
     
     U.S. Pat. Nos. 5,123,618 and 5,323,988 teach typical cable trays having arms that are designed to hold multiple strands of cable in a distribution system. 
     U.S. Pat. Nos. 5,131,860, 4,166,195, 4,017,137 and 5,614,695 teach electrical wiring raceways comprising hollow ducts with snap-on covers. Some of these covers feature knockout or punch-out tabs for accepting electrical outlets. 
     U.S. Pat. Nos. 5,629,496 and 5,659,151 teach other box-like hollow mechanisms having provisions for electrical outlets and wiring. 
     It is possible to find ladder-type cable trays and electrical raceways mounted side-by-side in a single installation, resulting in a great deal of duplication of effort, materials and the like—not to mention the amount of space wasted in rooms, corridors, and the like—which often are no larger than closets. There has been no suggestion in the art that such unnecessary duplication could be eliminated were a single device to be designed to perform both functions safely. 
     Accordingly, there continues to be a need for a new and improved ladder-type cable tray which addresses the problems of construction, effectiveness and ease of use that are attendant in the prior art. In this respect, the present invention substantially fulfills this need. 
     SUMMARY OF THE INVENTION 
     In view of the disadvantages inherent in the known art, the general purpose of the present invention, which will be described subsequently in greater detail, is to teach a new and improved ladder-type cable tray with power channel which has all of the important advantages of the prior art and few, if any, of the disadvantages. 
     The present invention is a dual-hollow-spine ladder-type cable tray having cable arms wherein the hollow channel of at least one body spine (presently unused in the art) is adapted for running and holding electrical wiring. This is achieved by enlarging at least one spine, and thus its hollow channel, and by molding one side face of said spine (or both spines) so as to open outwardly except when covered by one or more snap-on cover plates. 
     The cover plates may include mounts suitable for holding standard 110 volt, 220 volt or NEMA outlets. Preferably, however, separate fixtures (herein “outlet plates”) bearing or adapted to bear the outlets are configured to snap on over the open face of one or both spines between adjacent cover plates. 
     FEATURES AND ADVANTAGES 
     It is therefore an object of the present invention to provide a new and improved ladder-type cable tray with power channel which has all, or nearly all, of the advantages of the prior art, while simultaneously overcoming most of the disadvantages normally associated therewith. 
     It is another object of the present invention to provide a new and improved ladder-type cable tray with power channel which may be easily and efficiently manufactured and marketed. 
     A further object or feature of the present invention is a new and improved ladder-type cable tray with power channel which is of a durable and reliable construction. 
     An even further object of the present invention is to provide a novel ladder-type cable tray with power channel which is susceptible of a low cost of manufacture with regard to both materials and labor, and which accordingly is then susceptible of low prices of sale to the public, thereby making the ladder-type cable tray with power channel economically available to the trade. 
     Still another object of the present invention is to provide a novel ladder-type cable tray with power channel wherein an increased ease of assembly is permitted relative to the art. 
     Another object or feature is a new and improved ladder-type cable tray with power channel that is easy to use, tidy in function and appearance, and suitable for mass production. 
     Accordingly, a feature of this invention is a ladder-type cable tray including: first and second parallel hollow spines elongated along first and second longitudinal axes; a first top wall of said first spine; a first bottom wall of said first spine; at least one first open side face of said first spine between said first top and first bottom walls, said first open side face forming an elongated first opening parallel to said first longitudinal axis; a plurality of cable arms mounted through said first and second spines perpendicular thereto and perpendicular to said longitudinal axes; and means for mounting at least one type of electrical outlet, said mounting means releasably engaged with said first opening. 
     A further feature is such an apparatus wherein said cable arms are straight beams, and further including at least one snap-on cover plate releasably engaged with at least said first opening. 
     Still another feature is disclosed wherein said at least one snap-on cover plate includes said mounting means. 
     Another feature is wherein said mounting means is a plurality of opposed pairs of knockout tabs adapted to form apertures within which to engage said at least one type of electrical outlet. 
     In one preferred embodiment, said at least one type of electrical outlet is 110 volt. 
     A further feature is wherein said mounting means is at least one aperture within which to engage said at least one type of electrical outlet. 
     As a preferred feature, there are at least two snap-on outlet plates, namely, at least one 110 volt outlet plate having a pair of said at least one apertures within which to engage a first said type of electrical outlet, namely, a 110 volt electrical outlet, and at least one 220 volt (or, alternatively, a NEMA) outlet plate having one of said at least one apertures within which to engage a second said type of electrical outlet, namely, a 220 volt electrical outlet. 
     Another featured apparatus is one further including a second open side face of said second spine between said second top and second bottom walls, said first and second open faces mounted parallel to each other along opposite longitudinal edges of said first and second spines; and said second open face forming an elongated second opening parallel to said second longitudinal axis, onto which second opening at least said snap-on cover plates may be snapped. 
     Yet another apparatus features at least one snap-on outlet plate, which said at least one outlet plate includes said mounting means, and features first and second interior reinforcement walls running parallel to said longitudinal axes inside said first and second spines. 
     Other novel features which are characteristic of the invention, as to organization and method of operation, together with further objects and advantages thereof will be better understood from the following description considered in connection with the accompanying drawing, in which preferred embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawing is for illustration and description only and is not intended as a definition of the limits of the invention. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming part of this disclosure. The invention resides not in any one of these features taken alone, but rather in the particular combination of all of its structures for the functions specified. 
     There has thus been broadly outlined the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form additional subject matter of the claims appended hereto. Those skilled in the art will appreciate that the conception upon which this disclosure is based readily may be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
     Further, the purpose of the Abstract is to enable the U.S. Patent and Trademark Office and the public generally, and especially the scientists, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The Abstract is neither intended to define the invention of this application, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way. 
     Certain terminology and derivations thereof may be used in the following description for convenience in reference only, and will not be limiting. For example, words such as “upward,” “downward,” “left,” and “right” would refer to directions in the drawings to which reference is made unless otherwise stated. Similarly, words such as “inward” and “outward” would refer to directions toward and away from, respectively, the geometric center of a device or area and designated parts thereof. References in the singular tense include the plural, and vice versa, unless otherwise noted. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawing wherein: 
     FIG. 1 is a broken exploded perspective view of a first preferred ladder-type cable tray with power channel of this invention; 
     FIG. 2 is a broken right side elevation of the device of FIG. 1; 
     FIG. 3 is a broken plan view of the device of FIG. 1; 
     FIG. 4 is an exploded cross sectional frontal elevation of the device of FIG. 1; 
     FIG. 5 is an exploded cross sectional frontal elevation of a second preferred ladder-type cable tray with power channel of this invention; 
     FIG. 6 is a broken cross sectional right side elevation showing the interconnection of a pair of the devices of FIG. 1; 
     FIG. 7 is a perspective view of an alternate embodiment of the cover plate of the device of FIG. 1; and 
     FIG. 8 is an exploded cross sectional frontal elevation of a third preferred ladder-type cable tray with power channel of this invention; 
     FIG. 9 is an exploded cross sectional frontal elevation of a fourth preferred ladder-type cable tray with power channel of this invention; and 
     FIG. 10 is an exploded cross sectional frontal elevation of a fifth preferred ladder-type cable tray with power channel of this invention. 
    
    
     DRAWING REFERENCE NUMERALS 
       10  ladder-type cable tray with power channel 
       12  first spine 
       12 ′ second spine 
       14  first power channel 
       14 ′ second power channel 
       15  first bottom 
       15 ′ second bottom 
       16  first top 
       16 ′ second top 
       17  first opening 
       17 ′ second opening 
       18  first open face 
       18 ′ second open face 
       20  first closed face 
       20 ′ second closed face 
       21  cable arm 
       22  first rod aperture 
       22 ′ second rod aperture 
       24  connector 
       26  first cover plate 
       26 ′ second cover plate 
       27  cover plate 
       28  male flange 
       30  female flange 
       32  first upper stub wall 
       32 ′ second upper stub wall 
       33  first lower stub wall 
       33 ′ second lower stub wall 
       34  first ceiling rod 
       34 ′ second ceiling rod 
       36  first 110 V outlet plate 
       36 ′ second 110 V outlet plate 
       38  aperture 
       39  knockout tab 
       40  110 V outlet 
       41  screw hole 
       42  first 220 V outlet plate 
       42 ′ second 220 V outlet plate 
       43  knockout tab 
       44  aperture 
       46  220 V outlet 
       48  first ring 
       48 ′ second ring 
       50  first spacer 
       50 ′ second spacer 
       52  first washer 
       52 ′ second washer 
       54  first nut 
       54 ′ second nut 
       56  cables 
       58  electrical wiring 
       58 ′ electrical wiring 
       60  tie 
       110  ladder-type cable tray with power channel 
       112  first spine 
       112 ′ second spine 
       114  first power channel 
       114 ′ second power channel 
       116  first top 
       116 ′ second top 
       118  first open face 
       118 ′ second open face 
       121  cable arm 
       123  first reinforcement wall 
       123 ′ second reinforcement wall 
       126  first cover plate 
       126 ′ second cover plate 
       134  first ceiling rod 
       134 ′ second ceiling rod 
       136  outlet plate 
       148  first insulator 
       148 ′ second insulator 
       210  ladder-type cable tray with power channel 
       212  first spine 
       212 ′ second spine 
       214  power channel 
       214 ′ telephone channel 
       215  first bottom 
       215 ′ second bottom 
       216  first top 
       216 ′ second top 
       218  first open face 
       218 ′ second open face 
       221  cable arm 
       223  first reinforcement wall 
       223 ′ second reinforcement wall 
       226  first cover plate 
       226 ′ second cover plate 
       234  first ceiling rod 
       234 ′ second ceiling rod 
       236  power outlet plate 
       237  telephone outlet plate 
       256  cables 
       258  electrical wiring 
       259  telephone cabling 
       310  ladder-type cable tray with power channel 
       312  first spine 
       312 ′ second spine 
       315  first bottom 
       315 ′ second bottom 
       321  cable arm 
       323  first reinforcement wall 
       323 ′ second reinforcement wall 
       326  first cover plate 
       326 ′ second cover plate 
       334  first ceiling rod 
       334 ′ second ceiling rod 
       336  outlet plate 
       336 ′ outlet plate 
       410  ladder-type cable tray with power channel 
       412  first spine 
       412 ′ second spine 
       421  cable arm 
       426  first cover plate 
       426 ′ second cover plate 
       434  ceiling rod 
       436  outlet plate 
       436 ′ outlet plate 
       462  center hung support bracket 
     It is to be noted that, for convenience, the last two positions of the reference numerals of alternative embodiments of the invention duplicate those of the numerals of the embodiment of FIG. 1, where reference is made to similar or corresponding parts. However, it should not be concluded merely from this numbering convention that similarly numbered parts are equivalents. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG. 1, there is illustrated therein a first preferred ladder-type cable tray with power channel  10  of this invention. Ladder-type cable tray  10  principally comprises first and second hollow, longitudinally-extended, beam-like spines  12 ,  12 ′ which spines are pierced by a regularly spaced plurality of straight beam cable arms  21  arranged transversely with respect to the spines  12 ,  12 ′ (perpendicular to their longitudinal axes). Preferably, the spines are extruded aluminum, but they can be fabricated by standard means from plastic or any of a number of equivalent materials. Preferably, the cable arms  21  also are aluminum. The ladder-type cable tray  10  preferably is suspended from the ceiling of a room from a series of first and second ceiling rods  34 ,  34 ′, it may be laid on top of equipment or other horizontal surfaces, or it may be suspended from a single line of centrally located ceiling rods in the manner of the embodiment of FIG.  10 . The parallel rows of first and second ceiling rods  34 ,  34 ′ travel though rod apertures  22   22 ′ in both the first and second bottoms  15   15 ′ and the first and second tops  16 ,  16 ′ of the spines  12 ,  12 ′, respectively. Except for the apertures  22 ,  22 ′, the top and bottom walls of both spines are generally closed. Turning briefly to FIG. 4, it can be seen that bundles of cables  56  may be laid loosely along the tops of both sides of the cable arms  21  so as to run parallel to the longitudinal axes of the spines  12 ,  12 ′. This much is standard in the art. 
     Novel to this invention is at least one open face, either first open face  18  or second open face  18 ′ (two such open faces being illustrated in the embodiment of FIGS. 1-4) on one side of at least one of the spines  12 ,  12 ′. Preferably, the opposite side of each spine will have a closed face  20 ,  20 ′. The tops  16 ,  16 ′ and bottoms  15 ,  15 ′ also are continuous panels, giving the spines  12 ,  12 ′ overall “C” shapes. Each open face  18 ,  18 ′ has an opening  17 ,  17 ′ formed between an upper stub wall  32 ,  32 ′ and a lower stub wall  33 ,  33 ′, which openings extend along the entire length of the spines  12 ,  12 ′, respectively. 
     At least one, and preferably a mixed plurality, of cover plates  26 ,  26 ′, 110 V outlet plates  36 ,  36 ′, and 220 V outlet plates  42 ,  42 ′ are configured to cover the first and second openings  17 ,  17 ′, respectively. These plates are identical and interchangeable whether used on the first spine  12  or the second spine  12 ′. Accordingly, they will be described in detail as follows only with respect to those affixed to the first spine  12 . 
     Cover plates  26  snap onto the stub walls by means of opposed pairs of male flanges  28  on the backs of the cover plates  26 , which male flanges  28  compress and mate with opposed pairs of female flanges  30  (or simple edges) found on the bottom of the upper stub wall  32  and the top of the lower stub wall  33 , respectively. Preferably, such snap-on cover plates are “closed,” i.e., they are continuous (without apertures) so as to be able to fully cover whatever portion of the opening  17  onto which they are snapped. 
     Additionally, electrical outlets are provided, or at least means for mounting at least one electrical outlet (preferably a variety of types of such outlets), such as apertures formed in outlet mounting plates therefor. A 110 V outlet plate  36  forms a pair of apertures  38  adapted to mount and hold a standard 110 V outlet  40  (schematically illustrated in FIG.  1 ). Apertures  38  comprise one form of means for mounting at least one type of electrical outlet to the apparatus. Because said apertures are formed on a releasable outlet plate  36 , the electrical outlet mounting means (i.e, the apertures) are releasably engaged, via the outlet plate  36 , with the opening  17 . Plate  36  has an opposed pair of male flanges  28  for snapping the 110 V outlet plate  36  onto the female flanges or edges of the upper stub wall  32  and lower stub wall  33 . The male flanges  28  may be said to comprise “plate mounting means” to distinguish them from the aforesaid outlet mounting means, namely, apertures in snap-on plates (or tabs for forming such apertures, as discussed below with reference to FIG.  7 ). 
     A 220 V outlet plate  42  forms an aperture  44  adapted to hold a standard 220 V outlet  46  (schematically illustrated in FIG. 1) and has an opposed pair of male flanges  28  for snapping the 220 V outlet plate  42  onto the female flanges  30  of the stub walls. Other types of outlet plates can be provided for standard outlets, such as the NEMA type (not illustrated). 
     As seen in FIG. 2, a suitable assortment of cover plates  26 , 110 V outlet plates  36 , and 220 V outlet plates  42  may be assembled together to allow the entire opening  17  of the open face  18  to be closed. Furthermore, individual cover plates  26  may be cut to size where necessary, so as to allow particular outlet plates  36 ,  42  to be precisely positioned wherever desired along any length of spine. 
     Screw holes  41  are positioned in the outlet plates as required to hold in the outlets  40 ,  46 . Holes may be provided, if desired, for screwing the outlet plates onto the stub walls, for added security. 
     Again, the construction, function and positioning of the second series of plates  26 ′,  36 ′, and  42 ′ are identical with respect to covering the second opening  17 ′ of the second spine  12 ′, as noted above. Indeed, the same plates may be used interchangeably for either opening  17 ,  17 ′. 
     The novel provision of the open faces  18 ,  18 ′ allows the hollow interior channels of the spines  12 ,  12 ′ to be used as power channels  14 ,  14 ′, i.e., suitable bundles of electrical wiring  58 ,  58 ′ may be stuffed through the openings  17 ,  17 ′ into the power channels  14 ,  14 ′, where they may run unimpeded throughout the longitudinal extent of the ladder-type cable tray with power channel  10  (FIG.  4 ). Therein, the electrical wiring  58 ,  58 ′ is sufficiently isolated as to prevent interference with the telecommunication cables  56  carried externally on the cable arms  21 . Furthermore, once the first and second openings  17 ,  17 ′ are fully closed by full lengths of cover plates  26 ,  26 ′, 110 V outlet plates  36 ,  36 ′, and 220 V outlet plates  42 ,  42 ′, the electrical wiring  58 ,  58 ′ is covered from view and touch. Provided proper insulation and grounding is provided to the spines  12 ,  12 ′ when required, storage of electrical wiring  58 ,  58 ′ in the power channels  14 ,  14 ′ should meet all applicable code requirements. 
     While a pair of power channels, namely first and second power channels  14 ,  14 ′, are illustrated in FIGS. 1-4, only one need be provided for most applications wherein only electrical wiring  58 ,  58 ′ needs to be isolated. The other spine may have all its faces or walls permanently closed (not illustrated). However, a ladder-type cable tray with power channel  10  having two power channels, as illustrated, can allow for two discrete sets of electrical wiring  58 ,  58 ′ to be segregated from each other, as well as from the cables  56 . Furthermore, one power channel can be used to carry electrical wiring  58  and the other used to transport phone cabling (i.e., used as a “telephone channel”) in the manner of the embodiment of FIG. 8, essentially without modification. Different types of connector plates supporting telephone connections need only be provided, as in FIG.  8 . 
     FIG. 4 illustrates one means for electrically insulating the spines  12 ,  12 ′ of a ladder-type cable tray with power channel  10  from the ceiling rods  34 ,  34 ′, which rods connect the device  10  to the external environment. As noted above, each ceiling rod  34 ,  34 ′ passes through rod apertures  22 ,  22 ′ in the tops  16 ,  16 ′ and the bottoms  15 ,  15 ′ of the spines  12 ,  12 ′, respectively. Nuts  54 ,  54 ′ threaded on the end of each ceiling rod  34 ,  34 ′ bear the weight of the apparatus  10 , perhaps aided by washers  52 ,  52 ′ or the like. Where electrical insulation between the spines  12 ,  12 ′ and the ceiling rods  34 ,  34 ′ is desired, rubber or similar insulating rings  48 ,  48 ′ in the rod apertures  22 ,  22 ′ shield each ceiling rod  34 ,  34 ′ from electrical contact with its respective spine  12 ,  12 ′. Tubular insulating spacers  50 ,  50 ′ may be provided between the tops and bottoms of the spines. Spacers  50 ,  50 ′ could perform the dual function of insulating the ceiling rods  34 ,  34 ′ from electrical contact with the electrical wiring  58 ,  58 ′ while providing structural support between the tops  16 ,  16 ′ and the bottom  15 ,  15 ′ walls of the spines. 
     FIGS. 3 and 6 illustrate the manner in which abutting adjacent lengths of first spine  12  and first spine  12   a  may be interconnected by means of a C-shaped connector  24  to form a unitary ladder-type cable tray with power channel  10  of any desired length (adjacent lengths of second spines being interconnected in exactly the same manner). If desired, the two first ceiling rods  34  and  34   a  nearest the interconnected ends of first spine lengths may be tied together by a simple tie  60  (FIG. 6) or similar means, where desired to prevent longitudinal movement during earthquake, storm or the like. FIG. 6 also illustrates the fact that the insulating rings  48 ,  48 ′ of FIG. 4 possibly may be eliminated—for example, for use of the device  10  in applications wherein electrical insulation is not needed. For example, the channel  14  might be used to carry telephone cables rather than power wires. 
     FIG. 7 illustrates an alternate form of cover plate  27  for use on the device  10  of FIG. 1, namely, one which is designed to be used without separate outlet plates (such as outlet plates  36 ,  36 ′ and  42 ,  42 ′). In cover plate  27  a regularly spaced plurality of means for mounting at least one type of electrical outlet (preferably a variety thereof), is provided, namely, a large plurality of opposed pairs of knockout (punch-out) tabs  39  adapted to form apertures within which to engage 110 V outlets  40  and a large number of knockout tabs  43  adapted to form apertures within which to engage 220 V outlets  46 . As before, the back side of the cover plate  27  contains opposed pairs of male flanges  28  for snapping the cover plate  27  onto the open face  18  of a ladder-type cable tray with power channel  10 . A single cover plate  27  of standard length (matching the length of a standard spine  12 ,  12 ′) can be used to cover an open face  18 ,  18 ′. Alternatively, the cover plates  27  and spines  12 ,  12 ′ can be cut to length at the job site. 
     Referring to FIG. 5, there is illustrated therein a second preferred ladder-type cable tray with power channel  110  of this invention. Ladder-type cable tray  110  principally comprises a pair of parallel spines, namely, hollow, longitudinally-extended, beam-like first and second spines  112 ,  112 ′, which spines are pierced by a regularly spaced plurality of straight beam cable arms  121 . Preferably, the ladder-type cable tray is extruded aluminum, but it can be fabricated by standard means from plastic or any of an number of equivalent materials. The ladder-type cable tray  110  preferably is suspended from the ceiling of a room from a series of ceiling rods  134 ,  134 ′ arranged in two parallel rows. In this embodiment, first and second horizontal interior reinforcement walls  123 ,  123 ′ have been added just below, and parallel to, the top walls  116 ,  116 ′ within the C-shaped spines  112 ,  112 ′. The ceiling rods  134 ,  134 ′ travel though rod apertures in both the tops  116 ,  116 ′ and the reinforcement  123 ,  123 ′ walls. This feature creates larger power (or telephone, etc.) channels  114 ,  114 ′ than the previous embodiment, but requires more material to construct. 
     At least one, and preferably a plurality, of cover plates  126 ,  126 ′ snap onto the open faces  118 ,  118 ′. A variety of electrical outlets, or at least mounting plates therefor, are provided for covering either open face—for example, outlet plate  136 . 
     FIG. 5 illustrates a second means for electrically insulating the spines  112 ,  112 ′ of a ladder-type cable tray with power channel  110  from the ceiling rods  134 ,  134 ′, which rods connect the device  110  to the external environment. Where electrical insulation between the spines  112 ,  112 ′ and the ceiling rods  134 ,  134 ′ is desired, one-piece insulating rings  148 ,  148 ′ travels from the top walls  116 ,  116 ′ to the interior walls  123 ,  123 ′ to shield each ceiling rod  134 ,  134 ′ from electrical contact with the spines  112 ,  112 ′. Essentially, the insulators  148 ,  148 ′ incorporate the tubular insulating spacer  50  of the previous embodiment shown in FIG.  1 . 
     The embodiment of FIG. 5 otherwise illustrates alternative cable arm heights well known in the art, namely, either placing cable arms low down on the spines near the bottoms thereof, as are cable arms  121 , or placing them higher up the spines, near the tops thereof, as are cable arms  121   a.  Typically, however, one will find only one type of positioning on any one set of cable trays (as in the embodiment shown in FIG.  1 ). Where solely bottom cable arms are desired, the walls  123 ,  123 ′ likely would be moved to positions just above cable arms  121 , and cable arms  121   a  would be removed (not illustrated—see, e.g., the embodiments of FIGS.  9  and  10 ). Where solely top cable arms  121   a  are desired, the cable arms  121  would be removed. 
     The variety of cable arms  121 ,  121   a  in FIG. 5 illustrate another alternate mode of construction possible with this invention. Note that cable arms  121  travel through only the two innermost facing walls of the spines  112 ,  112 ′, whereupon they are fastened by crimping, welding, riveting or the like. The longer cable arms  121   a,  on the other hand, travel through the spines  112 ,  112 ′ and abut against the two outermost walls (i.e., open faces  118 ,  118 ′) of the spines. Longer cable arms provide more structural stability; shorter ones provide more room in the power channels and require less material. 
     Referring to FIG. 8, there is illustrated therein a third preferred ladder-type cable tray with power channel  210  of this invention. Ladder-type cable tray  210  principally comprises hollow, longitudinally-extended, beam-like first and second spines  212 ,  212 ′, which spines are pierced by a regularly spaced plurality of cable arms  221  arranged transversely with respect to the spines  212 ,  212 ′ at right angles to their longitudinal axes. Preferable, the spines and cable arms  221  are extruded aluminum. The ladder-type cable tray  210  is suspended from the ceiling of a room from a series of ceiling rods  234 ,  234 ′, arranged in two parallel rows, or it may be laid on top of equipment or other horizontal surfaces. The ceiling rods  234  travel both the bottoms  215 ,  215 ′ and the tops  216 ,  216 ′ of the spines  212 ,  212 ′. Bundles of cables  256  may be laid loosely along the tops of either or both sides of the cable arms  221  so as to run parallel to the longitudinal axes of the spines  212 ,  212 ′. This much of FIG. 8 is, again, standard in the art. 
     Novel to this invention is an open face  218  on a first vertical side of the first spine  212  (the right side in FIG.  8 ). In this embodiment, as, optionally, in the others, the leftmost or second vertical side of the second spine  212 ′ also has a novel open face  218 ′. Vertical interior reinforcement walls  223 ,  223 ′ travel within the length of the hollow interiors of the spines  212 ,  212 ′, providing their two hollow interiors with two channels: on the left or second spine  212 ′ a telephone channel  214 ′, and, on the right or first spine  212  a power channel  214 . 
     As before, the second open face  218 ′ has an opening formed between an opposed pair of stub walls. At least one, and preferably a plurality, of cover plates  226 ′ snap or screw onto the stub walls by means of opposed pairs of male flanges on the backs of the cover plates  226 ′, which male flanges compress and mate with opposed pairs of female flanges found on the stub walls. A variety of telephone outlets or telephone outlet holders, such as outlet plate  237  for a modular phone jack, are provided for snapping or screwing onto the open face  218 ′. 
     The first open face  220  has an opening formed between an opposed pair of stub walls. At least one, and preferably a plurality, of cover plates  226  snap onto the stub walls by means of opposed pairs of male flanges on the backs of the cover plates  226 . A plurality of means for mounting at least one electrical outlet, preferably a variety thereof, such as outlet plate  236 , are provided for snapping onto the open face  220 . 
     The novel provision of the open face  220  allows the hollow interior channel of the first or right spine  212  to be used as a power channel  214 , i.e., suitable bundles of electrical wiring  258  may be stuffed therein. On the left or second spine  212 ′, the telephone channel  214 ′ carries separate bundles (or a single cable) of telephone cabling  259 . 
     If insulation and grounding is required by applicable code requirements for storage of electrical wiring  258  in the power channel  214 , such may be provided to the spines  212 ,  212 ′. In FIG. 8, no special insulation is shown (being the configuration the invention will assume where no insulation is required). However, suitable insulating members, such as ring  48  of the embodiment of FIG. 1 or the insulator  148  of the embodiment of FIG. 5 may be provided. Furthermore, the ceiling rods  234 ,  234 ′ themselves may be made (or covered) with electrically insulating material. 
     FIG. 9 is an exploded cross sectional frontal elevation of a fourth preferred ladder-type cable tray with power channel  310  of this invention. The ladder-type cable tray with power channel  310  is similar to the embodiment of FIG. 5, except that the first and second interior reinforcement walls  323 ,  323 ′ traveling within the spines have been moved to cross the first and second spines  312 ,  312 ′ near the first and second bottoms  315 ,  315 ′, respectively. The cable arms  321  are the type which travel through the spines  312 ,  312 ′ and abut against the two outermost walls thereof. Ceiling rods  334 ,  334 ′ support the ladder-type cable tray with power channel  310 . As before, the open faces of the spines are covered with cover plates  326 ,  326 ′, and with outlet plates  336 ,  336 ′ adapted to receive electrical or telephone plugs. While no electrical insulation is shown in FIG. 9 between the spines and the ceiling rods, the types previously discussed can be provided, e.g., the insulators  148  of FIG.  5 . 
     FIG. 10 is an exploded cross sectional frontal elevation of a fifth preferred ladder-type cable tray with power channel  410  of this invention. 
     The ladder-type cable tray with power channel  410  is similar to the embodiment of FIG. 9, except that a single row of ceiling rods  434  travels down the center of the device, about midway between the first and second spines  412 ,  412 ′. Each attaches to a center hung support bracket  462  below the cable arms  421  to support the spines of the ladder-type cable tray with power channel  410 . Such center hung support brackets  462  are a standard alternative means of support for ladder-type cable trays in the art and are readily available. As before, the open faces of the spines are covered with cover plates  426 ,  426 ′, and with outlet plates  436 ,  436 ′ adapted to receive electrical or telephone plugs. 
     As to the manner of usage and operation of the instant invention, the same should be apparent from the above disclosure, and accordingly no further discussion relative to the manner of usage and operation of the instant invention need be provided. 
     The above disclosure is sufficient to enable one of ordinary skill in the art to practice the invention, and provides the best mode of practicing the invention presently contemplated by the inventor. While there is provided herein a full and complete disclosure of the preferred embodiments of this invention, it is not desired to limit the invention to the exact construction, dimensional relationships, and operation shown and described. Various modifications, alternative constructions, changes and equivalents will readily occur to those skilled in the art and may be employed, as suitable, without departing from the true spirit and scope of the invention. Such changes might involve alternative materials, components, structural arrangements, sizes, shapes, forms, functions, operational features or the like. 
     For example, the cover plates and/or outlet plates may be affixed to the open faces by alternate means—the snap-on flanges might be eliminated and replaced by a hinging arrangement or, where a more permanent arrangement is desired, perhaps simply by screws or rivets. The female flanges could be eliminated from the stub walls, whereby the male flanges of the cover plates and outlet plates would simply snap onto the edges of the stub walls. These types of releasable plates are equivalent to the snap-on plates described above. 
     Therefore, the above description and illustrations should not be construed as limiting the scope of the invention, which is defined by the appended claims.