Voice and data wiring essentially involves installing cable and connecting equipment: the same things most of us have been doing for decades. But there are some significant differences related to system performance and required installation methods.

It's not difficult work, and it usually pays well." That's what we typically hear about wiring offices for voice and data. To become successful, you must first learn basic installation mechanics. Let's look at a few diagrams describing the basic system structure and talk about some of these special areas of concern.

EIA/TIA standards: your guides to cabling layout. Your primary source of information is the general standard for structured cabling systems. This is EIA/TIA 568 (Commercial Building Telecommunications Wiring Standard). It includes later revisions, such as 568A and 568B. There are other associated standards, such as EIA/TIA 569 (Commercial Building Standard for Telecommunications Pathways and Spaces) and TIA/EIA 606 (Administration Standard for the Telecommunications Infrastructure of Commercial Buildings). Note: These standards are not codes. Therefore, you're not required to follow them when you install communication cabling. But if you want to install structured cabling properly, you should follow them.

The main cross-connect is where the entire building network connects to outside telephone lines or some other type of long-distance circuit.

The horizontal runs are similar to branch circuits, running from a patchpanel in the telecom closet to the wall outlet. A patch cord runs from the outlet to the computer.

Voice cabling basics. While voice circuits don't require the same high-quality cabling as computer networks, installers frequently wire them with Cat. 5 cables. This is because most contractors find it easier to standardize on one type of cable for both voice and data, rather than keeping track of two types. The cost difference is minimal.

"UTP" stands for unshielded twisted pair cable. "PBX" stands for private business exchange (the main telephone equipment). Without a PBX, customers would have to install a great number of outside telephone lines; one for each extension. Instead, the PBX switches several extensions on a few outside (trunk) telephone lines. It may also provide intercom, music-on-hold, and many other features.

Always use caution. When installing voice or data cabling, follow these guidelines:

  • Don't forget about fire stopping. Note where the fire barriers are in the structure, and make sure you make proper allowances for crossing them.

  • Make sure you protect your cables during the construction process (while you're not there). This is critical in situations where there'll be a long time between your cable installation and installing of jacks. In such instances, it's up to you to protect your cables any way you can. If you don't, they may pull away or twist by accident. You won't see this damage to the cables until you test them.

  • Leave enough extra cable at each outlet point. The recommended slack lengths are a minimum of 3 m (almost 10 ft) in the telecommunications closet for both twisted-pair and fiber cable, 1 m (a little over 3 ft, 3 in.) for fiber, and 30 cm (almost 1 ft) for twisted-pair cable at the outlet. (Notice when you move from power wiring to data cabling, the units of measurement switch from standard to metric.)

  • Trimming data cabling is essentially the same as trimming power wiring (strip the cables, install the devices and plates, etc.) except a lot more testing is required. When trimming power wiring, we generally test by flipping a switch or hitting the outlet with a voltage tester. Either power is present, or it's not. Testing data cabling is not so simple. Remember, you need to test not only for the presence of the signal, but also for its quality.