Monthly Archives: December 2016

Horizontal Cabling: Choose the Right Copper Cable

Copper-based cabling has held the dominate position as the most prevalent horizontal cable medium for years. The reason of this can be partly explained by the fact that copper cable is inexpensive and easy to install. Additionally, the networking devices associated with copper cabling are less costly compared with their fiber optic counterparts. Copper cable comes in a dazzling array of types, and since cable type determines the network’s topology, protocol, and size, understanding the features of each copper cable is necessary for the installation of a successful and robust network.

Copper Cable Types at First Glance

By far the widely installed and most economical copper cable today is twisted-pair wiring. In this form of wiring, two conductors are wound together (“twisted”) for the purposes of canceling out electromagnetic interference (EMI) from external sources, and crosstalk from neighboring conductors. Unshielded twisted pair (UTP) and shielded or screened twisted pair (STP or ScTP) are the two primary varieties of twisted pair on the market today. Screened twisted pair (ScTP) is a variant of STP. Next, we will focus on the characteristics and possible applications of them.

Unshielded Twisted Pair (UTP)

Unshielded twisted pair (UTP) copper cable has been used in telephone systems for many years. And it was also intensively applied in local area networks (LANs) since late 1980s. UTP cabling typically has only an outer covering (jacket), which covers one or more pairs of wire that are twisted together. The lack of shielding enables a high degree of flexibility and durability, lower cost and simpler installation of UTP. During the past years, the bandwidth capabilities of UTP are consistently being improved, making it popular especially in computer networking. Four-pair UTP cables are often used for horizontal cabling, while multi-pair (25-,50-, or 100-pair) UTP cable is more commonly seen in backbone cabling.

UTP copper cable

Features of UTP are listed below:

  • Four-pair cables are typically used for horizontal cabling. Higher pair counts are often used for backbone cabling.
  • Its conductors are not surrounded by a metallic shield to prevent electrostatic or electromagnetic coupling.

UTP cable

Shielded Twisted Pair (STP)

Shielded twisted-pair copper cable has a metallic shield which significantly reduces the instances of interference-related network problems. Though more expensive to purchase and install than UTP, STP offers some distinct advantages: it is less susceptible to outside electromagnetic interference (EMI) than UTP cabling since all cable pairs are well shielded. As with UTP, four-pair cables are typically used for horizontal cabling. When it comes to STP, four-pair cables are offered in two versions:

STP and ScTP copper cable

Four-Pair Screened Twisted-Pair (F/UTP)

F/UTP (also referred to as ScTP) copper cable has an outer metal shielding covering the entire group of copper pairs. This type of shielding protects the cable from external EMI; however, the shield and drain wire add cost as well as size. The shield and drain wire also require bonding and grounding. F/UTP is recommended for use in hospitals, airports, or government/military communications centers.

F/UTP

Four-Pair Shielded Twisted-Pair (U/FTP)

U/FTP (also referred to as STP) copper cable includes metal shielding over each individual pair of copper wires. Besides protecting the cable from external EMI, U/FTP provides better near end crosstalk performance than F/UTP. However, the multiple shields also add more cost and size. Like F/UTP, the shield and drain wire require bonding and grounding.

U/FTP

Should I Choose Unshielded, Shielded, or Screened Copper Cable for Horizontal Cabling?

Network managers and cabling infrastructure designers are constantly in the dilemma to choose between these copper cables. Here we offer a solution for your reference.

For typical office environments, UTP cable always serves as the best choice (until fiber network components drop in price). Most offices don’t experience anywhere near the amount of electromagnetic interference (EMI) necessary to justify the additional expense of installing shielded twisted-pair cabling.

As for environments like hospitals and airports, it would be more beneficial to apply a shielded or screened cabling system. The deciding factor seems to be the external field strength. If the external field strength does not exceed three volts per meter (V/m), good-quality UTP cabling should work fine. If the field strength exceeds three V/m, shielded cable will be a better choice.

Conclusion

We have illustrated the characteristics and possible uses of different types of copper cable in this article. When it comes to horizontal cabling, your choice should base on the specific cabling environment and condition. Hope what we discussed here could help you to make the right decision.

Knowing Cable Ratings: Plenum and Riser Rated Cable

When doing data and voice cabling in premise environment, there is a common question that every installer may confront: Should I use plenum or riser rated cable? Plenum and riser here indicate flame ratings for cables which are defined by National Electric Code (NEC), with the purpose of preventing the spread of fire and smoke in commercial and residential buildings. Then, what is the difference between plenum and riser rated cable? This article will explain to you by making a comparison between them.

What are Plenum and Riser Cable?

The flame rating of cables differs according to various installation situations. Thus to decide which rating is appropriate for your installation environment is critical. So let’s just begin with the basic definition of the plenum and riser cable.

Plenum Cable: A plenum refers to any enclosed area that facilitates environmental air handling. Such as an air conditioning duct or an air routing drop ceiling. It can be any air space between walls, under floors, or dropped ceilings. Plenum cable is designed with a fire-retardant plastic jacket, that is laid in the plenum spaces of buildings. It is held to the most stringent testing of the cables rated by the NEC, rated for both flammability and smoke generation.

plenum rated cable

Riser Cable: Riser cables do what their name indicates—they rise between non-plenum vertical applications like floors of multi-story buildings. Riser cables may also penetrate either fire rated floors or walls. Described as backbone cables, riser cables serve as the main conduit of a distribution system for data, voice or video. The cables are only subjected to flame tests.

riser rated cable

Difference Between Plenum and Riser Cable in Application

In this part, we will illustrate the difference between plenum rated cable and riser rated cable from the perspective of their common application situations.

Plenum rated cable is usually made with strict standards required by a plenum space. It is installed to prevent contamination of the air. Requirements for plenum cables dictate the rate at which a flame spreads, as well as the maximum amount of smoke a burning cable may produce. This kind of cable can be applied to commercial and multi-family residential buildings. Plenum rated cables may substitute for riser and general purpose rated cables.

plenum and riser cable application

Riser rated cable is typically run between multiple floors of a building through open vertical shafts. Although these pathways do not handle environmental air, they can easily conduct a fire from one floor to the next if the cable is not properly rated. And the vertical spread of flame would pose a big threat to the safety. To minimize the spread of fire, riser rated cable is required for carrying a minimum of a riser rating. Riser cables may be used for different forms of data communications which also include CCTV video access. It is ideal as well for voice communications.

Plenum and Riser Cable in Cabling Design

When deploying cable for indoor applications, to plan and design beforehand is definitely critical yet beneficial. If the cables must be deployed in the plenum, it is important to remember that cables that will be deployed there must reach several standards on flammability, heat resistance, and amount of smoke cable generates when burning. Another essential part of installing cable within a building is riser cable deployment. Since riser cable should go through the whole building, it is rather vulnerable in case of fire. This is why riser cable has even more strict fireproof standards than the plenum one. The picture below illustrates the common design of the plenum and riser rated cable in the building.

plenum and riser cable design

Conclusion

Although cable rating is sometimes overlooked by system designers when selecting cables, it is rather vital to the whole installing environment. We have explained the difference between the plenum and riser cable from the perspective of the common application and cabling design, hope that would be informative enough.