Considerations for zone cabling to serve multiple applications

March 24, 2020
When used in concert with Power over Ethernet, zone cabling can represent an efficient architecture.

By Patrick McLaughlin

As increasing numbers of devices in a building connect to the Internet Protocol network, and many of them receive power as well as data service via communications cabling, a zone cabling architecture can offer an efficient physical-layer setup.

“This cabling approach runs cables from the telecommunications room out to ceiling consolidation points located within specific building zones,” explains Daniel Charles, global product manager for copper connectivity with Belden. He made that statement in a post to Belden’s blog titled “Zone cabling: Building workplaces of the future.” “These zones are also reflected inside the telecommunications room,” Charles continued. “Consolidation points allow users to easily connect any system or device.

“In addition to ease of use and constant connection for employees, there are other important benefits to zone cabling. It streamlines cabling by replacing individual cables that run from the telecommunications room patch panels to multiple workstation outlets with shorter cables that run to the consolidation point enclosures. It improves flexibility by connecting various devices directly in the consolidation point with a patch cord or running from the consolidation point to a fixed workstation outlet with pigtails. And it reduces labor and material costs during reconfiguration because the cabling from the telecommunications room to the consolidation point stays intact.”

Charles points out that building owners can benefit from deploying zone cabling in space that will be leased out to tenants. “In these applications, zone cabling saves time, money, and hassle,” he says. “By taking this cabling approach, owners can be prepared for any tenant, regardless of how they may want to arrange their workforce when they move in.”

Think of the alternative, he points out: “Without zone cabling, the horizontal cable runs going out to each outlet may have to be moved or removed based upon tenant requests. With zone cabling, cable doesn’t need to be removed or taken back to the telecommunications room. Instead, you’re dealing with a cable run of 10 or 15 meters, which is more manageable. This also prevents you from having to access the fixed part of your infrastructure—the cable that runs from your data center or telecommunications room to the consolidation point.”

As the title of his blog post indicates, Charles asserts that a zone cabling architecture is worthwhile in the modern and future-looking workplace. “With smartphones, tablets, wearables and laptops, people are on the move all day, every day,” he notes. “They may spend 30 minutes at their workspace before dashing off to a meeting on another floor, probably checking email on their phone while they’re walking or waiting for the elevator.

“Then, on their way to the cafeteria, they stop in the hallway to chat with a coworker. After lunch, they’re ready to collaborate with a colleague on a future launch. Everyone brings their laptops to a collaboration table so they can take notes and follow along, and keep up with email, of course.

“With wireless access points installed throughout buildings, employees can stay connected wherever they go—at their desks or not. But this creates challenges for your behind-the-scenes cabling infrastructure that ultimately supports all of this mobile activity. That’s where zone cabling comes in.”

The PoE picture

Many wireless access points are powered via PoE, and in a recent issue of its CrossTalk newsletter, Leviton Network Solutions detailed why zone cabling is a sensible option for PoE applications. “To leverage the many capabilities of PoE, network designers are increasingly turning to zone cabling architectures as an alternative to traditional home-run cabling in digital buildings,” the company points out. “There is no one-size-fits-all topology for PoE, and each architecture offers advantages and disadvantages. However, for high-power PoE, passive and active zone architectures create some clear benefits.”

Leviton points out that a home-run architecture eases active equipment and power management because they are centralized in the telecommunications room, but the tradeoff is the cabling infrastructure’s relative inflexibility, making future modifications difficult.

“In the passive zone topology, all active equipment and power is also centralized in the telecommunications room. But unlike the home run, the added consolidation point creates the flexibility of not having to provide cabling all the way back to the TR. Instead, it includes a break point in the middle that allows for adjustments. This provides a big advantage in environments like open offices, where work spaces or cubicles are often reconfigured and moved around.”

The passive zone setup differs from the active zone setup, as Leviton further explains. “An active zone design reduces the size requirement for the telecommunications room (TR) by running optical fiber from the TR to zone enclosures, and copper cabling from the enclosures to the device outlets. Moving the PoE switch from the TR to the zone enclosure—and closer to the end device—reduces energy loss in cables. In addition, smaller PoE switches used in zone enclosures are generally most cost effective than larger switches housed in a TR.

“Zone cabling options also have a lower cost after installation—‘day-two cost,’” the company adds. “There are, however, several disadvantages to using zone cabling. These include a higher initial cost and fewer measurable benefits to fixed workspaces where moves/adds/changes are rare.”

Getting it right

When deploying a zone cabling architecture through which PoE will be delivered, Leviton advises, “It’s important to select cabling that will provide optimal performance for the bandwidth and power requirements of the system’s applications. In turn, high-quality connectivity must meet the PoE performance requirements for digital building applications.”

The company offers end-to-end twisted-pair cabling products—cable, jacks, patch cords, and patch panels—that are optimized for PoE transmission. Concerning a zone cabling setup, Leviton points out that its “zone cabling enclosures are the perfect solution for adding flexibility within an open-office architecture. Active zone enclosures, typically a tie-in to the ceiling grid, should be used when active equipment is included in the consolidation point. Passive enclosures can be used in open-air environments or unfinished ceilings, where only passive cabling is used in the consolidation point.”

The Siemon Company has produced several technical resources to help system designers and installers deploy a zone cabling architecture. The company’s Zone Cabling and Coverage Area Planning Guide explains, “The major benefit of zone cabling is its ability to provide an easily accessible intermediate connection point. Being able to locate zone enclosures in an access floor, ceiling, on the wall, or within modular furniture enables convenient access to these connections. The deployment of strategically placed zone enclosures throughout a building space creates flexible, futureproof infrastructure for data, voice, building devices, and wireless access points.”

The guide provides detailed technical information and how-to suggestions to ensure a building, including a highly automated building, has full connectivity using a zone approach.

Siemon produced a version of the guide for facilities implementing 60-watt PoE lighting applications. This document provides “guidance to infrastructure designers on the selection, design and deployment of a structured cabling system optimized to support a wide range of PoE lighting applications,” the company explains.

“PoE lighting systems rely on a well-designed infrastructure of high-performance balanced twisted-pair cabling, network electronics, and software connecting and communicating with IP addressable luminaires, dimmers, sensors, and controllers to deliver maximum performance, comfort, and energy-savings benefits,” said Valerie Maguire, global sales engineer with Siemon. “Zone cabling is a standards-based design approach that is highly suited to support arrangements of these PoE lighting devices logically distributed throughout a ceiling space.”

Zones in data centers

The zone concept can be beneficial beyond the open-office environment. The Telecommunications Industry Association’s (TIA) 942 series of standards addressing data center systems identifies and describes several distribution areas in a data center facility. The standard, which most recently was updated to its “B” version in 2017, illustrates a computer room that includes a single main distribution area (MDA) as well as multiple horizontal distribution areas (HDAs) and multiple equipment distribution areas (EDAs). In a typical scenario, the MDA includes routers, backbone local area network and storage area network switches, as well as multiplexing equipment. The horizontal distribution area contains LAN/SAN/KVM switches. And the equipment distribution area includes racks and cabinets.

So where, literally, does the zone concept fit in? The TIA-942-B standard, like its predecessors, identifies the zone distribution area (ZDA) as an optional space between the HDA and the EDA. The ZDA acts like a consolidation point within the data center, providing a termination point for areas that may require periodic revisions.

Siemon recently published a technical brief titled “Zone cabling in the colocation data center for rapid deployments and improved SLAs.” In that document, which directly addresses the colocation facility manager, the company explains, “Whether leasing space by the rack unit, cabinet, or cage, as a colocation facility, you need to provide the infrastructure for your tenants’ equipment, including power, cooling, physical security and high-bandwidth connections to access providers. Deploying high-bandwidth cabling from the meet-me room to the tenant space takes time, space and cost. Thankfully there is a design strategy colos can deploy that helps eliminate these challenges, delivering benefits for both the business and tenants alike.”

In a colocation facility, the meet-me room contains the MDA or HDA, the document explains, and each tenant space can be considered to be an EDA. Placing a ZDA between the meet-me room and tenant spaces can provide benefits, Siemon says. “ZDAs can be located to serve a specific area or number of tenants,” the document states, adding that ZDAs “can be fully cabled with permanent links from the meet-me room.” Furthermore, “short links from the ZDA deliver services to tenant spaces, and spare ports within the ZDA are allocated for future tenants.”

Siemon further notes that using a product like its Cable Tray Rack is a means of providing ZDA flexibility in a colocation facility. The rack mounts directly to overhead ladder rack or cable tray; as such, it can be mounted above tenant spaces and used to house fiber and/or copper patch panels for interconnection to the meet-me room.

In a typical example, the Cable Tray Rack houses a 48-port copper patch panel and a 1U high-density fiber enclosure, which are fully cabled from the meet-me room via 48 copper cables and 288 fiber strands. From the rack, short runs of copper and fiber deliver services to the tenant spaces, with spare ports allocated for future use. “Delivering new services requires only short links from the Cable Tray Rack in the ZDA for fast, easier deployment,” the document emphasizes. “Tenant connections can also be easily reconfigured at the Cable Tray Rack.”

Patrick McLaughlin is our chief editor.

About the Author

Patrick McLaughlin | Chief Editor

Patrick McLaughlin, chief editor of Cabling Installation & Maintenance, has covered the cabling industry for more than 20 years. He has authored hundreds of articles on technical and business topics related to the specification, design, installation, and management of information communications technology systems. McLaughlin has presented at live in-person and online events, and he has spearheaded cablinginstall.com's webcast seminar programs for 15 years.

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