How to: Dressing Ethernet Cables into Patch Panels
Written by Dave Harris, trueCABLE Technical Specialist, BICSI INST1 Certified
When customers come to us with questions about designing an Ethernet cable installation for their home or small business, we advise them that the best performance, reliability, and flexibility result from installations consisting of “permanent links.”
Each permanent link consists of an Ethernet cable running from the location of the network router or switch to the location of a network device. Both ends of the Ethernet cable are terminated with a keystone jack. Then factory-produced patch cords are used at each end to connect the devices to the jacks. Cables are routed through walls and ceilings so that they are concealed from view, and also protected from physical damage.
Figure 1. Diagram of a permanent link in a jack-to-jack configuration. This is just a diagram. A permanent link is installed with the jacks mounted in either a patch panel or wall faceplate.
At the device end, the keystone jacks are supported by faceplates mounted to the walls in the workspaces. Instructions for mounting a jack and faceplate in a wall are provided in our Cable Academy blog, “How Do You Install a Keystone Jack Into a Wall”?
In this article, we’ll explore solutions for finishing the other ends of the permanent links, at a patch panel located close to the switch (or router). If there are only a few cable runs (say up to three or four), the keystone jacks can be mounted in the wall using a multi-port faceplate, with patch cords finishing the connections to the switch or router.
If more than a few runs are installed, then the keystone jacks should be mounted in a patch panel, with patch cords finishing the connections to the switch. If you are running shielded cable, then a patch panel is necessary no matter how many cables are installed. This is because the cable shields must be grounded. A patch panel made for shielded keystone jacks provides a bonding wire for this purpose. It is very difficult to achieve this connection to ground, especially in a residential structure, without using a shielded patch panel.
Figure 2. A shielded patch panel with openings for keystone jacks. This panel is designed to be mounted in a telecommunications rack. Some ideas for grounding shielded cable can be found in our blog, “Residential Bonding and Grounding of Shielded Ethernet Cable Systems.” Note the green wire for bonding the panel and fitted keystone jacks to ground. Both shielded and unshielded jacks can be used in this panel, as well as keystone couplers, and modules for multimedia and/or optical fiber. The lacing bar on the rear of the panel provides a secure attachment point for the cable, and protects the connections from physical strain. Brackets are available for mounting this type of patch panel on a wall.
Not all patch panels are made to accommodate keystone jacks. Some patch panels already have jacks permanently installed, with connections made by “punching down” the conductors directly to IDC contacts located on the rear of the patch panel. In commercial settings with a lot of cable runs, punch-down patch panels can save installation time. Skill and experience is required to terminate punch-down patch panels while avoiding excessive crosstalk and insertion loss. Because of this, and the ability of the keystone patch panels to accommodate a variety of different types of modules, punch-down patch panels are being deployed in fewer and fewer new installations.
Figure 3. Front view of a wall mounted punch-down shielded patch panel.
Figure 4. Rear view of a wall mounted punch-down shielded patch panel. Note the grounding wire and the IDC contacts for connecting the conductors. Both shielded and unshielded cable can be accommodated by this panel.
Figure 5. A view of the rear of a telecommunications rack in a commercial setting equipped with multiple punch-down patch panels. This rack uses horizontal cable managers between panels instead of lacing bars attached behind the panels. This picture was taken as part of a survey of a site’s network infrastructure prior to an upgrade. There are several clues that this is an older installation, such as the large amount of conductor that is untwisted at the punch-down locations, the large, combed cable bundles, and the lack of labels on the cables.
If you are installing a patch panel into a residence or small business, it is often more efficient to mount the patch panel on a wall so that purchase and installation of a rack or cabinet is not necessary. When mounting a patch panel or any other equipment on a wall, it is best to mount a plywood back board first. Use ¾ inch plywood, and size the board to allow mounting of future devices and cable service loops. Once the back board is mounted on the wall, equipment can be screwed directly to the board, eliminating the need for wall anchors (unless they were needed to mount the board). It is normally a good idea to paint the backboard, just so it looks better.
In commercial installations, backboards are usually required on the walls of telecommunications rooms. These backboards are required to be ¾ inch, AC grade, fire-retardant plywood. They are often required to be painted with two coats of fire-retardant paint. The board(s) should be mounted with the bottom edge eight inches from the floor.
Figure 6. Example of a backboard in a small business setting. This is another example of an older installation observed during a network survey. There is a patch panel located near the center of the photo. Note that there are several service loops coiled and mounted on the board. The cable runs to the patch panel are the blue Ethernet cables routed down the right-hand side of the board and into the rear of the panel. It’s good that they bundled the cable neatly and followed an unobstructed route. It’s bad that they used zip ties to bundle their cable. Don’t do it! Use hook and loop straps to bundle the cable. The straps can then be mounted to the board.
Routing and Dressing Permanent Link Cables
At the device end of your permanent link, the cable is terminated to a keystone jack and installed into a wall faceplate. Leave a small service loop, about 12-18 inches, either coiled in the wall box, or above the ceiling. It’s best for these to be hidden to maintain the design and decor of the room. This is pretty much the same for both commercial and residential installations. However, a commercial installation might specify a longer service loop in the ceiling above the outlet.
At the service end of your permanent link (where the patch panel is), the cable is either punched down to the patch panel, or terminated to keystone jacks for installation into a keystone patch panel. Always leave a “service loop,” which is a coiled up length of slack cable in case the run ever needs to be serviced. You don’t want to run short of cable if you have to reterminate or move the patch panel in the future.
In the home or small business installation, you can bring the cables in through an opening in the wall or ceiling. Bundle the cables together and route them down or across the board toward the location of the patch panel. Use hook and loop straps to bundle the cable–not plastic zip ties. Leave a small portion of some of the straps unwound, so you can mount the strap to the backboard with a screw..
Before you cut the cables to length, remember the following:
- Leave a ten foot service loop for each permanent link cable. The service loops can be coiled and attached to the board using hook and loop straps.
- There should be an identifying mark on both ends of each cable. Make sure that you remark the cable at a spot where it will not be cut off and lost.
- If you have a patch panel that is hinged so it can swing out from the wall, make sure to leave the cables long enough to allow the panel to swing freely. Terminate the patch panel with the hinge open, making sure that it can also be closed.
If you are using a punch-down patch panel, bring the cable up to the connectors for its destination port on the panel. Mark the position on the cable where the cable jacket will be scored and removed. Before making any cuts, remark the cable with its identifier so it will not be lost. Punch down the conductors to the panel, following either the 568A or 568B color sequence. Do each cable one-at-a-time, so you can make sure that each cable ends up at the optimum length for a tidy installation.
If you are using a keystone patch panel with snap-in keystone jacks, the same procedure applies with just a couple of differences. The cables can actually be routed through the keystone holes before termination to help avoid tangles. Don’t mark the cable jacket to be snapped open right at the position of the patch panel. Instead, subtract off about an inch to allow for the depth of the jack. When you install the jack into the patch panel, insert the bottom of the jack first. With the bottom cleat in place, rotate the jack upwards so that the snap latch on top of the jack snaps into the panel. Do these one-at-a-time so slack is minimized and the cables look nice and orderly behind the patch panel. Finally, label the patch panel, wall faceplate and each end of each cable with a unique identifier.
For a commercial installation, there are more requirements and more challenges. There might be multiple patch panels and hundreds of permanent link cable runs. Imagine the work involved to bundle the cables neatly while making sure that each run ends up at its predetermined patch panel port. Tangles are a constant threat. Every run will have a service loop that must be stored someplace. Often they are neatly arranged on ladder racks or in cable trays above the racks. Finally, a commercial installation might require that you employ the ANSI / TIA 606-D standard for complete labeling of the cables.
Each site is different, and installations such as these require technicians with years of training and experience. For that reason, a full description of cable routing and dressing in a commercial installation is beyond the scope of this meager blog. Nevertheless, I hope this is helpful as an introduction to the topic.
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