Overhead cabling system for telecommunication switching center

An overhead cabling system for a telecommunications switching center including one or more cable chute assemblies, a plurality of cable tray assemblies, and one or more cable ladder assemblies. The cable chute assemblies are mounted to the floor adjacent the ends of the cabinet suites. The cable ladder assemblies are supported by the cable chute assemblies and extend cross aisle between two or more cabinet suites. The cable tray assemblies are mounted to the tops of the cabinets which provide the sole support for the cable tray assemblies. The cable tray assemblies are modular and designed to fit on top of a single cabinet. The overhead cabling system does not require support from the walls or ceiling of the telecommunications center.

FIELD OF THE INVENTION 
The present invention relates generally to cabling systems for a 
telecommunications switching center, and more particularly, to an overhead 
cabling system for a telecommunications switching center which is 
supported independently of the walls and ceiling of the switching center. 
BACKGROUND OF THE INVENTION 
In a telecommunications switching center, the telecommunications switching 
cabinets are typically arranged in a plurality of rows which are separated 
by aisles. Cabling between cabinets is typically routed either below the 
floor or through overhead raceways. Overhead raceways for 
telecommunications switching centers are typically supported from the 
ceiling of the telecommunications switching center by threaded rods or by 
a metal framework which itself is supported by threaded rods from the 
ceiling. 
The overhead cabling systems used in the past have numerous shortcomings. 
One major disadvantage is that the overhead support structure is dependent 
upon the building structure in which it is installed. It is not unusual, 
and in fact to be expected, that the building structure will vary from one 
installation to the next. This variation means that each installation must 
be customized to work with the particular building structure in which it 
is installed. The lack of standardization leads to longer engineering and 
installation time, increased warehouse inventory to maintain parts for all 
possible installation scenarios, and increased documentation. 
Other problems which have been encountered in the past include raceway 
congestion, inadequate heat dissipation, inconvenient cable transitions 
from the cable raceway to the switching cabinet, difficulty of 
installation, and failure to meet structural requirements for seismically 
active regions. 
SUMMARY OF THE INVENTION 
The present invention is an overhead cabling system for a 
telecommunications switching center. The overhead cabling system is 
designed to be self-supporting, i.e., supported independently of the walls 
or ceiling of the switching center. Since supports or braces from ceiling 
structures or walls are not required, installation procedures can be 
standardized. The use of modular components further reduces installation 
time. 
The overhead cabling system comprises three main assemblies--one or more 
chute assemblies, a plurality of cable tray assemblies, and one or more 
cable ladder assemblies. The cable chute assemblies are mounted to the 
floor adjacent the ends of the cabinet suites. The cable ladder assemblies 
are supported by the cable chute assemblies and extend cross aisle between 
two or more cabinet suites. The cable chute assemblies and cable ladder 
assemblies provide a raceway to route cabling cross aisle between suites. 
The cable tray assemblies are mounted to the tops of the cabinets which 
provide the sole support for the cable tray assemblies. The cable tray 
assemblies route cables from the cable chute assembly to the individual 
cabinets in a suite. The cable tray assemblies are also used to route 
cabling between cabinets in the same suite. 
The cable tray assemblies are modular and designed to fit on top of a 
single cabinet. Thus, there is one cable tray assembly for each cabinet in 
a suite. One advantage of using modular cable tray assemblies is that the 
cable tray assemblies can be assembled on the switching cabinets at the 
factory before the cabinets are shipped to the installation site. By 
pre-installing the cable tray assemblies at the factory, installation time 
is significantly reduced. 
Other objects and advantages of the present invention will become apparent 
and obvious from a study of the following description and the accompanying 
drawings which are merely illustrative of such invention.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to the drawings, the overhead cabling system of the present 
invention is shown therein and indicated generally by the numeral 10. The 
overhead cabling system 10 is designed to provide an overhead cable way 
for suites of telecommunications switching cabinets 12. For example, the 
overhead cabling system may be used with the AXE series cabinets 
manufactured by Ericsson. The switching cabinets 12 are typically arranged 
in rows with aisles between the rows. A row of side by side cabinets is 
referred to in the industry as a suite. The most common installation of 
suites is in a back-to-back configuration. A suite consisting of a single 
line of cabinets will be referred to herein as a single suite. Two suites 
in a back-to-back configuration will be referred to as double suites. 
The overhead cabling system of the present invention provides an overhead 
cable way for running cable between cabinets. Using the overhead cable way 
of the present invention, cabling can be run between cabinets in the same 
suite or between cabinets in different suites. The overhead cabling system 
includes three main assemblies--the cable chute assemblies 100, cable tray 
assemblies 200, and cable ladder assemblies 300. The cable chute 
assemblies 100 are disposed at the end of each suite of cabinets and 
extend vertically. The cable chute assemblies are anchored to the floor. 
The ladder assemblies 300 are supported by the cable chute assemblies 100 
and extend across the aisles between cabinet suites. The main purpose of 
the cable ladder assemblies 300 is to allow cabling to be run cross-aisle 
between cabinet suites. The cable tray assemblies 200 are mounted to the 
tops of the cabinets 12 which provide the sole support for the cable tray 
assemblies 200. The cable tray assemblies 200 are used for running cable 
lengthwise over a suite of cabinets. 
Referring now to FIGS. 2 through 5, the cable chute assembly 100 is shown 
in more detail. FIGS. 2 and 4 show a cable chute assembly 100 for a double 
suites while FIG. 3 shows a cable chute assembly 100 for a single suite. 
In each case, the construction of the cable chute assembly 100 is 
essentially the same, the primary difference being the difference in width 
of the cable chute assembly 100. 
The main components of the chute assembly 100 include the vertical support 
columns 102, support feet 110, cross braces 116, ladder rungs 118, and 
cable ladder supports 120. The support columns 102 have an I-shaped cross 
section as seen in FIG. 5. A central web 106 extends between two opposing 
flanges 104. The edges of the flanges 104 are turned inward to form a lip 
108. The edge of the lip 108 is serrated for reasons which will be 
explained below. 
The lower end of the support columns 102 are anchored by the support feet 
110. Each support foot 110 comprises a base plate 112 and a channel member 
114. Each support foot 110 is secured in place by an anchor bolt (not 
shown) which extends through anchor holes 112a in the base plate 112 into 
a structural concrete floor. For most applications, two anchor holes 112a 
are sufficient. More anchor holes 112a can be provided to give some 
flexibility in case one hole is not usable. 
The channel member 114 has a generally c-shaped configuration. The walls of 
the channel member 114 include one or more securing holes 114a for 
releasably securing the lower end of the support columns 102 and the 
support foot 110. 
The support columns 102 are secured in the channel member 114 by a nut and 
bolt type fastener. Preferably, a nut and bolt fastener known as a 
push-button manufactured by Hilti Installation Systems of Farmers Branch, 
Tex. is used. To briefly describe, a push-button comprises a strut nut and 
bolt which are held together by a spring member. The strut nut is inserted 
through the openings in the channel member 114 and rotated to engage the 
serrated lip 108 of the support column 102. The plastic spring member 
holds the strut nut in contact with the lip 108 of the support column 102 
while the bolt is tightened. 
Cross braces 116 and ladder rungs 118 are used to brace the support columns 
102. The cross braces 116 are relatively long members that extend 
angularly between support columns 102. The ladder rungs 118 extend 
perpendicularly between support columns 102 on the side of the chute 
assembly 100 which butts against the cabinet suite. Both the cross braces 
116 and ladder rungs 118 can be secured to the support columns 102 by 
using push-button fasteners as previously described. 
The cable ladder supports 120 are mounted at the top of the support columns 
102. The cable ladder supports 120 provide support for the cable ladder 
assembly 300. There are a total of four cable ladder supports 120 per 
cable chute assembly 100. Each cable ladder support 120 includes a support 
bar 124 having a mounting plate 122 at one end thereof. The support bar 
124 is similar in cross-section to the support columns 102. Two of the 
cable ladder supports 120 are mounted to the front support columns 102 and 
extend forwardly therefrom in cantilever fashion. The remaining two cable 
ladder supports 120 are mounted to the rear site of the front support 
columns 102 and extend rearwardly over the top of the rear support columns 
102. For purposes of this application, the front of the cable chute means 
the side facing away from the cabinet suite. The back of the cable chute 
means the side which butts against the cabinet suite. Angle brackets 126 
are disposed between the mounting plate 122 of the cable ladder supports 
120 and the front support columns 102. The cable ladder support 120 and 
angle bracket 126 are secured to the front support columns 102 by 
push-button fasteners. A pair of L-brackets 128 are used to secure the 
rearwardly extending cable ladder supports 120 to the rear support columns 
102. The L-brackets 128 are secured to both the rear support columns 102 
and the cable ladder supports 120 by push-button fasteners. 
The cable chute assembly 100 may also include pre-installed alignment 
brackets 150 which are used during installation to align the chute 
assembly 100 with the cabinet suite 100. The alignment brackets 150 
include a mounting plate 152 and a spacer 154. The mounting plate 152 is 
secured to the rear support columns 102 of the chute assembly 100 by 
push-button fasteners. The spacer 154 resembles a tray made of sheet metal 
and projects from the rear of the chute assembly 100. The rear face of the 
spacer 154 includes a series of bolt holes which preferably align with 
pre-drilled holes in the mounting cabinet 12. Thus, the cable chute 
assembly 100 can be aligned with a cabinet by aligning the bolt holes in 
the spacer 154 with the corresponding holes in the cabinet 12. It will be 
apparent that different aligning brackets could be used for different 
cabinets. Alternatively, a series of bolt holes could be provided in the 
spacer 154 to match different models of cabinets 12. 
In the preferred embodiment of the invention, the chute assemblies 100 are 
enclosed by a series of dress panels. The dress panel support system 
includes lower side panel supports 130, upper side panel supports 132, a 
lower front panel support 134, and an upper front panel support 136. The 
panel supports 130, 132, 134 and 136 are secured to the support columns 
102 by any suitable fastening means. The dress panels mount to the panel 
supports 130, 132, 134 and 136 in a conventional manner. 
Referring now to FIGS. 6 and 7, the cable tray assemblies 200 are shown in 
greater detail. The cable tray assemblies are designed to mount on top of 
a switching cabinet 12. In the preferred embodiment of the invention, one 
cable tray assembly 200 is mounted on top of each switching cabinet 12. 
This allows the cable tray assemblies 200 to be pre-installed on the 
cabinets 12 before the cabinets 12 are shipped thereby greatly reducing 
installation time. 
The main components of the cable tray assemblies 200 include a pair of 
mounting rails 202, a pair of tie rails 204 and a cable tray 206. The 
mounting rails 202 are mounted on top of the switching cabinet and extend 
from front to back along each side of the cabinet 12. The mounting rails 
202 are preferably insulated from the cabinet 12 by a LEXAN insulator 
strip 203. The mounting rails 202 may be secured to the switching cabinet 
12 by any suitable means such as conventional nut and bolt fasteners. 
The tie rails 204 are mounted on top of the mounting rails 202 and extend 
perpendicular to the mounting rails 202. The tie rails 204 are disposed 
adjacent the front and back of the switching cabinet 12. The tie rails 204 
are secured to the mounting rails 202 by strut nut type fasteners as shown 
in FIG. 7. 
The cable tray 206 mounts on top of the tie rails 204. The cable tray 206 
includes a plurality of risers 208, tray 210, and divider 212. The risers 
208, tray 210 and divider 212 are preferably made from a sheet metal. The 
bottom edge of the risers 208 are secured by strut nut fasteners to the 
tie rails 204. Where the riser 208 aligns with the mounting rails 202, a 
single strut nut fastener is used to secure the riser 208 and tie rail 204 
to the mounting rail. (See FIG. 7). The tray 210 and divider 212 are 
secured by sheet metal screws to the top edge of the risers 206. The tray 
200 includes a front wall 210a, a button wall 210b, and a back wall 210c. 
The front wall 210a is perpendicular to the bottom wall 210b. The tray 210 
is open at both ends as indicated at 216. The back wall 210c is inclined 
so as to extend upward from the button wall 210b at an acute angle. The 
inclined back wall 210c helps direct heat away from the cabinet 12. In 
particular, when two cable tray assemblies 200 are placed on back-to-back 
cabinets 12, a "chimney effect" is created which promotes cooling of the 
cabinet 12 and the equipment contained therein. 
The divider 212 is secured the inclined back wall 210c and extends 
generally parallel to the front wall 210a of the tray 210. The divider 212 
divides the space within the tray 210 into two compartments. This allows 
power cables to be segregated from other cables. Straps 214 are attached 
to the front and back walls of the tray 210 as well as to the divider 212. 
The straps 214 help hold the front wall 210a and divider 212 in a vertical 
position. 
As previously mentioned, the cable tray assemblies 200 are mounted 
individually on the top of separate cabinets 12. The cable tray assemblies 
200 may be mounted at the factory or on site where the switching cabinets 
12 are installed. Once all the switching cabinets 12 and cable tray 
assemblies 200 in a cabinet suite are in place, the cable trays 210 are 
connected together with a bonding strap 216 to ensure that they are on the 
same electrical plane. The bonding strap 216 is simply a metal strap which 
is bolted or screwed to the rear edge of the risers 208. One end of the 
bonding strap 216 is connected to the end riser 208 of one cable tray 
assembly 200, while the opposite end of the bonding strap 216 is connected 
to the end riser 208 on the adjacent cable tray assembly 200. Each 
adjacent pair of cable tray assemblies 200 are connected in this manner 
using a bonding strap 216 until the entire line of cable tray assemblies 
200 are joined. 
The cable tray assemblies 200 adjacent the cable chute assemblies 100 are 
also secured to the cable chute assembly 100. One leg of an L-bracket 230 
is fastened to the tie rail 204 of the cable tray assembly 200, as shown 
in FIG. 7. The other leg is fastened to one of the rear support columns 
102 of the chute assembly 100, as shown best in FIG. 3. This ensures that 
the cable tray assemblies 200 and cable chute assemblies 100 are on the 
same ground plane. 
A dress panel 218 attaches to the front of the cable tray 206 to conceal 
the cabling and provide an improved aesthetic appearance. The dress panel 
218 is designed to hang on the front wall of the cable tray 206. Panel 
hangers 220 are also attached to the front edge of the end risers 208. 
Quarter-turn connectors can be inserted through openings in the dress 
panel 218 to engage the panel hangers 220. 
Referring now to FIG. 8, the cable ladder assembly 300 is shown. The cable 
ladder assembly 300 is supported by the chute assembly 100. The cable 
ladder assemblies 300 extend above the aisles between cabinet suites at 
one or both ends of the suite. Thus, the cable ladder assemblies 300 allow 
cross aisle cabling between cabinet suites. 
The cable ladder assembly 300 comprises two horizontal ladders 302 disposed 
in spaced relation to one another. Each ladder comprises two parallel 
rails 304 having a plurality of rungs 306 extending between the rails 304. 
The ladders 302 are held in spaced relation by vertical spacer bars 308 
which are joined with the rails 304 of the ladders 302. 
The cable ladder assembly 300 rests on top of the cable ladder supports 120 
of the cable chute assembly 100. The cable chute assembly 100 is secured 
to the cable ladders supports 120 by ladder clamps 310. The ladder clamps 
310 are secured by a bolt and strut nut to the cable ladder support 120. 
These ladder clamps 310 include a hook-like element which engages a ladder 
rail 304. 
The primary advantage of the overhead cabling system 10 of the present 
invention is that it does not require support from ceilings or walls. Both 
the cable chutes and cable tray assemblies are modular and can be 
completely assembled in a factory and shipped to the installation site. 
The ease of installation of supports and raceways coupled with the systems 
modularity significantly reduces engineering and installation time. 
The present invention may, of course, be carried out in other specific ways 
than those herein set forth without departing from the spirit and 
essential characteristics of the invention. The present embodiments are, 
therefore, to be considered in all respects as illustrative and not 
restrictive, and all changes coming within the meaning and equivalency 
range of the appended claims are intended to be embraced therein.