All About Twisted Pair Cabling

It’s probably a stretch to compare twisted-pair cabling—the cable commonly used in telephone and Ethernet cords—to an acoustic guitar. However, in each case, you have an iconic product with a long history and a blue-blood pedigree: Alexander Graham Bell first used twisted-pair cable for telephony in 1881; C.F. Martin founded his guitar manufacturing company in 1833.

In each instance, technological innovations and cultural shifts have altered the product’s role: The data demands of the Internet, fiber-optic cable and wireless networks have changed the applications to which twisted-pair cable is well-suited; musical tastes, not to mention the advent of electric (and now digital) instruments, have changed the ways in which acoustic guitars are used. And in each situation, despite these cultural shifts and new technologies, the original product is still effective, is still in demand and is not going away anytime soon.

For electricians, this means that understanding and correctly installing twisted-pair cabling is still vital, despite the popularity of wireless networks and the efficacy of fiber optic cable in data transmission. Fiber optic cable may be used to send data to and from buildings, but it’s too expensive for widespread use within buildings. In residential, commercial and industrial building, twisted-pair cable is still king. Even wireless network hubs need to connect with fiber optic trunk lines somehow, and the first choice to bridge that gap is twisted-pair cable.      

Changing tides                                                                                                                                     For generations, twisted-pair cable was everywhere. The cable, which (as the name suggests) consists of pairs of wire twisted together, ferried voice data from place to place and formed the backbone of telephone systems. The wires are twisted to prevent the signals they carry from being vulnerable to interference, attenuation and cross-talk. (Cable with a higher twist rate also is more secure. Additionally, some twisted-pair cable types are shielded, but many are not—even in modern voice and data applications.)

Most U.S. homes have a phone jack in nearly every room, and most offices have phone and Ethernet jacks at every workstation, but the widespread adoption of wireless networks has decreased the use of twisted-pair cable. While the shift to less cabling simplifies installation, it doesn’t eliminate the challenges.

“Running regular electrical wire is both art and science, and it’s the same with twisted-pair cabling,” says Sevan Muradian, an adjunct Computer Information Systems professor at Northwestern University in Chicago, Ill. “The same concepts apply: lay the cable out beforehand, know how much you’ll be needing, and avoid certain types of environments—for example, you wouldn’t run twisted-pair wires overhead if you’ve got fluorescent lights there because the lights will give electromagnetic interference and cause data integrity issues. So you need to have a good structured wiring plan for twisted-pair cabling implementation.”
    
To master the finer points of twisted-pair installation, termination and testing (and other types of data transmission), electricians can pursue certifications such as the Information Transport Systems (ITS) installer credentials offered by BICSI, a Tampa, Fla.-based non-profit organization that serves the telecommunications infrastructure industry. Beyond ITS, BICSI also offers a higher credential, the Registered Communications Distribution Designer (RCDD).

In the field, “adding that RCDD to your title is almost like adding an MD-Ph.D.,” says John White, cable sales manager at Tripp Lite, a Chicago manufacturer. “It just adds so much to your credibility.”    

In addition to the BICSI programs, several cabling manufacturers such as Panduit and Ortronics offer product-specific certified installer programs, with certified installers gaining not only training but the ability to offer extended product warranties.

Twisted-pair cable isn’t new, but its enduring functionality and utility are a testament to its genius. It may not be as beautiful as a vintage Martin guitar, but both products are classics.