The '568-C Family of Standards: An Update and an Overview
The ANSI/TIA-568 family of Telecommunications Standards contains the requirements for balanced twisted-pair and optical fiber cabling, which provide the foundation for the design, installation, and maintenance best practices described in BICSI's Telecommunications Distribution Methods Manual (TDMM). With the recently published '568-C.0, '568-C.1, '568-C.2, and '568-C.3 Standards encompassing 305 pages of detailed information and containing 151 tables and 121 figures, it can be challenging to remain up to date with the latest TIA telecommunications cabling specifications. This article will help to summarize the content, enhancements, and critical revisions of this important series of Standards.
The American National Standards Institute (ANSI) mandates that subcommittees responsible for the publication of standards reaffirm, revise, or rescind their document every 5 years. As a result, the ANSI/TIA-568 family of Standards has undergone 3 sets of revisions since the original document was published in 1991. This mandate provides an opportunity for TIA subcommittees to evaluate the document content to ensure that material is up-to-date, information is centralized, and duplication is reduced or eliminated.
A key outcome of the last ANSI review process was the decision to divide the three main documents that comprised the previous edition ANSI/TIA-568-B ('568-B) family of Standards into four main documents. This decision was driven by the need to have one common standard that could be used to address generic cabling needs when a specific premise standard, such as the commercial building, data center, residential, or industrial standard, does not exist. This common content applies to previously unsupported environments such as non office areas of an airport or stadium and also serves as a repository of generic requirements that are applicable to all specific premise and component Standards.
The new ANSI/TIA-568-C ('568-C) family of Standards contains the following main documents:
- "Generic Telecommunications Cabling for Customer Premises", published 2009
- "Commercial Building Telecommunications Cabling Standard", published 2009
- "Balanced Twisted-Pair Telecommunication Cabling and Components Standard", published 2009
- "Optical Fiber Cabling Components Standard", published 2008, errata issued in October, 2008
The '568-C series incorporates material from '568 B.1, '568-B.2, '568-B.3, the 18 addenda to the '568 B series, as well as necessary updates and revisions. Table 1 provides a summary of the content appearing in the four main '568-C documents. Figure 1 shows how the '568 C documents interrelate with each other and other important TIA cabling Standards.
Key updates and changes to the '568-C documents include:
- Generic terminology has been introduced to describe cabling segments and connection points
- Category 6A has been added as a recognized media
- Optical fiber link test requirements were moved to this document
- Optical fiber link performance requirements were moved to this document
- The installation bend radius requirement for UTP and F/UTP cables has changed to "4x cable o.d." and the patch cord bend radius requirement has changed to "1x cable o.d." to accommodate larger diameter cables
- Stewardship text has been added recognizing the need to support sustainable environments and conserve fossil fuels
- Category 6A has been added as a recognized media
- 850nm laser-optimized 50/125µm optical fiber is recommended if multimode optical fiber is used for backbone cabling
- Category 5, 150 Ohm STP, and 50 Ohm and 75 Ohm coaxial cabling have been removed from the list of recognized media
- Category 5e cabling is recommended for support of 100 MHz applications
- Category 5 channel performance values have been preserved in an informative annex
- Balanced twisted-pair channel and permanent performance requirements were moved to this document
- Performance equations for individual transmission parameters are listed in a single table for all categories
- Coupling attenuation has been introduced as a parameter that is under study for characterizing radiated peak power generated by common mode currents for screened cables
- One laboratory test method has been defined for all categories of connecting hardware
- ISO nomenclature for optical fiber cable type (i.e. OM1, OM2, OM3, OS1, and OS2) has been added to transmission performance tables
- Recommended connector strain relief, housing, and adapter color coding has been added to support installations when color is used to identify fiber type
- Minimum OFL bandwidth for 62.5/125 mm optical fiber cable has been increased from 160 MHz·km at 850 nm to 200 MHz·km at 850 nm.
Figure 2: Comparison of '568-C.0 and '568-C.1 Terminology
An initial cause of concern and confusion for those reviewing the '568 C.0 Standard for the first time is the new terminology introduced for the functional elements that describe generic infrastructures. It's important to remember that the '568 C.0 terminology is only to be used when a specific customer premise standard defining terminology does not exist. As shown in figure 2, the generic infrastructure topology is actually fully consistent with the commercial building topology specified in '568 C.1.
It is interesting to note that optical fiber link performance specifications are contained in '568-C.0, while balanced twisted-pair channel and permanent link specifications are contained in '568-C.2. This represents a deviation from the original '568-C series planning outline and was a cause of considerable debate in the TIA subcommittees. Ultimately, it was agreed that, since the balanced twisted-pair channel and permanent link specifications are so dependent upon the modeling configurations described in annex J of '568-C.2, it was most logical to move the cabling specifications into '568-C.2 and keep this interdependent information together.
Another deviation from the original '568-C series planning outline was the agreement to move balanced twisted-pair field tester and field testing requirements from the '568-C.2 Standard into a standalone document (pending ANSI/TIA 1152). This carefully weighed decision supported reducing the overall page count of '568 C.2, as well as ensuring that updates or even simple reaffirmations of future revisions of the proposed ANSI/TIA-1152 Standard could be quickly addressed without the need to open the entire balanced twisted-pair cabling content of '568-C.2 for review.
Although there is always an understandable degree of trepidation and resistance to change when something new comes along, the '568-C family of Standards is a user-friendly and well-organized compilation of the critical information that RCDDs and other cabling professionals need to know to excel in their areas of expertise. Since there are 5 years to go until the next ANSI review cycle, now is the time to familiarize yourself with the content of these important Standards!
Copies of the standard references in this article may be purchased through the IHS Standards Store (www.global.ihs.com).
Table 1 – Content Overview of the ‘568-C Series of Telecommunication Standards
Cabling System Structure
Optical Fiber Transmission/Test Requirements
Annex A: Centralized Optical Fiber Cabling
Annex C: Multi-Tenant Cabling
Telecommunications Rooms and Enclosures
Annex A: Connector Reliability
Optical Fiber Cable
Connecting hardware and adapters
Patch Cords and Fiber Transitions
Annex A: Connector performance specifications
Valerie Maguire is Global Sales Engineer for Siemon, Chair of the TIA TR-42.7 Copper Cabling Subcommittee, and 2008 Recipient of the Harry J. Pfister Award for Excellence in the Telecommunications Industry.