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Cost of Twisted Pair Cables

There are two types of twisted pair cables, shielded twisted-pair (STP) and unshielded twisted-pair (UTP). Both rely on the same principle where two copper wires, twisted together, create a circuit that can transmit data. The magnetic effect created by a twisted pair cancels out any electrical noise or crosstalk. Placing a number of these twisted pairs together into a single cable only magnifies this canceling effect. The main use of twisted pair cables is for telecommunications and Ethernet based networks.

Shielded twisted pair cable (STP)

Shielded twisted pair cable (STP) uses the basic principle of wire twisting combined with shielding. Each pair is wrapped in metallic foil. The pairs of twisted wire are then wrapped in an additional metallic braid or foil. The cable is typically 150-ohm. STP used in telecommunications and Ethernet networks reduce the amount of electrical noise from within the cable (thanks to twisted pairs with foil shielding) and from outside influences like electromagnetic interference (EMI) and radio frequency interference (RFI). Special connectors are typically installed with STP; however, RJ connectors are also used. Although STP offers better fidelity compared to UTP, STP is often expensive and difficult to install. Special connectors are required, and proper grounding of the metallic shielding is also required making it unsuitable for Ethernet networks.

Unshielded twisted pair cable (UTP)

UTP is the typical networking cable of choice. UTP relies only on the canceling effect of two twisted wires. Placing this twisted pair with other twisted pairs only magnifies this effect. There are certain guidelines that you should follow in relation to the length of cable run from one point to another. The signal degrades if the cable length is too long. Most UTP cable uses a Registered Jack 45 (RJ-45). The RJ-45 has eight connectors and is used in various applications from telecommunications to networks. The thinner profile of UTP allows for easy installation without the need for grounding. Comparing cost versus STP, UTP is typically the most inexpensive solution for telecommunications and networking.

Comparing STP and UTP

The obvious advantage STP has over UTP is the fact it adds an additional level of protection against EMI and RFI. Special connectors are required for STP but not necessary. Additional attention to proper grounding of STP cable is also important since improper grounding of STP cable may in fact create unwanted EMI and RFI. Comparing cost, UTP is cost effective. Fewer special considerations are needed when deploying UTP, so fewer problems may arise in the initial installation. Expect UTP cable to cost around $50 cheaper per 1000 feet; inexpensive RJ-45 connectors make installation easy as well.

You must always consider how important your data is but you must also temper that concern with practicality. If you are working in a hostile environment where you run the chance of EMI or RFI, then STP is your obvious choice. It offers the best protection and reliable data transmission. However, if cost is a huge consideration, UTP is the more prudent choice. Whichever type of cable you decide to use, the final decision must always factor in the cost per foot for the installation.