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Your office cabling system is costly and complicated investment. It's also a commitment to an office design and structure that is not easy to modify. If you add more workstations later, new cabling might be needed.

Most offices have a structured cabling topology that hardwires the cables from wallplate to patch panel. With this system, modifications are less likely because the initial installaiont includes a planning process that should anticipate some expansion. By pre-wiring potential locations in an existing or newly-constructed building, future moves, additions or alterations are avoided. You can just transfer patched cables in the wiring closet. Also, it is critical to number the wallplates to match the corresponding patch panel number. This will make it much easier to relocate a workstation or to troubleshoot a connectivity problem.

There are several sub-systems to consider:

• The Demark refers to the point where the Internet Service Provider's (ISP) data line comes to an end and hooks up with the cabling in the building.


• The equipment room serves as storage for all apparatus and wiring integration points.


• Backbone cabling are high-speed cables (typically Cat6 or fiber) that connect various floors or wall closets.


• The horizontal cabling for links up the network space to individual wallplates. These are done through conduits and ceiling spaces on every level.


• The telecommunications enclosures are wall or floor mounted cages that hold the network equipment; primarily the patch panels ands switches but also sometimes the server and Uninterruptible Power Supplies (UPS) too.

Installation and design of structured cabling is regulated by standards that identify the following:

• Network data switches


• Offices layout for voice & data communications for Cat5e or Cat6 cable


• Fiber Optic cables for backbones


• Modular connectors at the wallplate

These components will guide the layout of cables in order to fulfill the data access requirements of your office. All of the cables start at the patch panel on a mounted rack (about 19 inches wide) in the wall closet. From there, they traverse through the drop ceiling and down the walls to individual wallplates. Quite often a wallplate will host 2 or more connections. At the wallplate a short patch cable, usually 7 to 14 feet in length wil connect the computer, phone, printer or other networked device.

All cabling standards require that all of the eight conductors in Cat5, Cat5e and Cat6 cables are inter-connected in a precise color-coded pattern. The network cable connects each device but some devices can share a single cable. This is true for VoIP phones. Most VoIP phones have a jack for the network cable and then a jack on the phone for connecting the computer. This pass-thru enables the two devices to share one connection.

The Ethernet network cable connects devices on a LAN (local area network) such as personal computers, switches and routers. These cables are typically Cat5 and Cat6. These cables provide the infrastructure that connects the PCs, printers, router/modem and other peripherals to a switch. The cables are made up of stranded or solid copper wires. Stranded wires are not as susceptible to fractures but are more difficult to terminate. Solid Cat5/Cat6 also is less susceptible to electrical interference. These shielded cables are made up of braided strands of copper wrapped in a polymer layer and spiral copper tape. The shield is applied across the splices.

An Ethernet cable can be compared to an electrical power cord in that it can only extend a limited distances because of the electrical transmission properties. Meanwhile, wireless technologies (Bluetooth and Wi-Fi or local wireless technology) have enhanced the reach of Ethernet in residential and enterprise networks. The standard Ethernet cable consists of four coiled pairs that terminate at the eight pins of the clipped connector or "RJ45" at both ends of  a cable. At the wallplate is simply the female end of the same connector. The cable is made up of unshielded (UTP) or shielded twisted-pair (STP) cabling.

Shielding is not selected automatically during installations. The answer is, it affords the protection required for certain environments although there are also some downsides. One is mass. The single-shielded cable made of Ethernet weighs approximately 12 percent more than the unshielded cable. The double-shielded version is roughly 30 percent heavier. You may be putting together dozens or perhaps hundreds of individual shielded twisted-pair cables along  a  ladders tray above the ceiling, under a floor, or at the back of panels. The aggregate weight of these cables can collapse the mounting bracket.

Cable flexibility is also an important issue. Take care when you pull the cables through  conduits. The cable shielding can make installation more difficult. The sole foil shield can crack while the sharp boundaries of the shield can scrape the insulation of individual wires. This can cut the wire and cause data transmission issues.

What are the shielding options?

You have a number of shielding choices in for your Ethernet network. The single-shielded cable has the lightest protection. Double-shielded cables contain a foil and plate shield. It can ensure better protection against electromagnetic or radio frequency interference and reduce issues related to cable relocation. High-flex industrial cables are fabricated and protected for uninterrupted applications. These have special jacket materials to address industrial and outdoor concerns.

The plenum space is described as that section of the building that makes possible air movement for HVAC systems. It also provides the space for conduits of heated, conditioned and return air circulation. The distance between the structural ceiling and dropped ceiling tiles is regarded as the plenum space.

The plenum space houses communication cables for telephone and computer networks. However, increasing neglect of cables in plenum areas create a major risk in case of fire.