BY HERB CONGDON
Few documents have as much effect on the structured cabling and connectivity industry than the ANSI/EIA/TIA-568-B series. So, when the TIA TR-42 User Premises Telecommunications Cabling Requirements Engineering Committee says that the release of the 568-C series revisions will be released in the very near future, substantial interest is generated
The most common question on the 568-C crusade is, “Why are you revising the 568-B series?” The simple answer is the maximum 5-year lifespan established by the American National Standards Institute (ANSI) for standards recognized by ANSI. The first 568-C series document that was published, 568-B.3 Optical Fiber Cabling Components Standard was published in March 2000.
An additional consideration is the numerous addenda that have already been published to supplement the 568-B series (for the record, six addenda to 568-B.1, 10 addenda to 568-B.2, and one addendum to 568-B.3). A revision allows these addenda to be assimilated into one document as well as to address other advancements worthy of consideration.
A better way
TR-42 took the opportunity presented by the 568-C revision to establish a better way to develop and maintain standards. Recognizing the complications of updating several documents due to one change (for example, the release of a new Ethernet application), it makes sense to have a single repository of common information rather than duplicating that information in multiple documents.
Additionally, a recurring problem is the lengthy development process for creating a new standard; much of this time is consumed by recreating and debating information that is already well-established in other documents (for example, the data center standard had to include text on hierarchal star networks that was already established in 568-B.1).
Finally, the 568-B.1 standard, which was created to address office-oriented commercial buildings, has been widely used to cover other types of commercial buildings, such as airports, schools and stadiums. While this is akin to forcing a square peg into a round hole, there just was no round peg for these other types of premises—so, 568-B.1 became a de facto standard.
The solution to all of these problems was solved by creating the 568-C.0 Generic Telecommunications Cabling for Customer Premises standard. It was drafted to become the generic document for use when a specific standard is not available (for example, health care facilities), to become a single repository for common information to simplify the process of keeping standards up to date, and also to simplify and speed up the development of new standards, which can focus on the exceptions and allowances to the generic document rather than repeating generic information (this should also reduce the size and cost of new standards as well). The “568-C.0” nomenclature was chosen due to the familiarity of this nomenclature in the industry.
Foundation for future standards
The process of creating 568-C.0 started with a complete review of all documents controlled by TR-42, which focused on extracting the repetitive and universally-applicable requirements and guidelines and moving that information into the new document (information such as choosing media, cabling lengths, polarity, installation requirements, application support tables, optical fiber testing and limits, etc.). Generally speaking, if the information was in two documents, it was considered for inclusion.
As you may expect, much of that information was in the existing 568-B.1 document and its addenda. In fact, the current 568-B.1 document is 94 pages (not including addenda) and the draft 568-C.0 document is 60 pages with 25 pages in the draft 568-C.1 document. So, you can see this is almost an even trade as far as the numbers of pages are concerned, and even a reduction when the addenda pages are considered.
The 568-C.0 document is now poised to become the foundation for the other standards and for new standards that may be developed. Standards that apply to other premises, such as data centers, can focus the content on the exceptions to and additional allowances to the generic standard, 568-C.0. This should make for shorter documents, focused documents, and documents than can be developed in a faster time.
Additional effort was applied to get the 568-C.0 document caught up with modern times. Here are a few technical changes that are in the draft of the 568-C.0 document:
- Installation minimum bend radius for balanced twisted-pair cable has been changed to 4x cable OD for both shielded and unshielded cable (Note: with the maximum size of 0.354 inches from 568-B.2 Addendum 11, this means the worst case minimum bend radius is now 1.5 inches for balanced twisted-pair cable, not 1.0 inch).
- Patch cable bend radius for balanced twisted-pair cabling has been changed to “1x cable OD” from “0.25 inches” to accommodate these larger cable diameters.
- Maximum untwist for Category 6A cable termination was added and set to 13 mm (the same as Category 6).
- Augmented Category 6 (Category 6A) has been added as a recognized media type.
- Optical fiber cabling performance and testing requirements were moved to this document. Note, however, that the copper cabling and testing requirements were moved into the draft 568-C.2 document.
At this point, it is probably worth addressing the issue of nomenclature. Since the 568-C.0 standard is a new document, some new nomenclature was required; existing nomenclature couldn’t be used for a generic case. Although it seems like a simple concept, there was considerable debate over what nomenclature to use for the points of connection and the cabling segments. At the end of the day, “Cabling Subsystem” was used for the cabling segments, “Distributor” was chosen for the points of connection and “Equipment Outlet” was chosen for the Distributor at the end.
To address your next question, “no”, the existing nomenclature in the other standards will not be changed—this nomenclature is new for a new standard.
What about 568-C.1?
568-C.1 is the revision to the existing 568-B.1 document with a few important differences. First, the 568-C.1 standard is not a stand-alone document as is 568-B.1. Commercial building cabling will be covered by the 568-C.0 (generic) standard, supplemented by the 568-C.1 standard (commercial building). The guidelines and requirements of 568-C.0 apply in commercial buildings subject to the exceptions and allowances detailed in 568-C.1. This allows 568-C.1 to be a focused document for office-oriented commercial buildings. Accordingly, it becomes less applicable to other premises, like schools.
As mentioned previously, the nomenclature in 568-C.1 does not change from 568-B.1. To tie in the 568-C.0 document with the 568-C.1 document, the following may be helpful:
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It is important to note, as an example, that the requirements in 568-C.0 for the Equipment Outlet apply to the requirements for the Telecommunications Outlet in 568-C.1, as do the exceptions and allowances listed in 568-C.1. So, the two documents are necessary for office-oriented commercial building cabling. While this may seem a bit cumbersome compared to the single document of 568-B.1, it is more efficient when you realize that the 568-C.0 will apply for all other premises as well.
Some technical changes to 568-C.1 were also implemented and should be noted:
- Augmented Category 6 (Category 6A) balanced twisted-pair cabling was added as a recognized media (by reference to 568-C.0).
- A recommendation to select 850- nm laser-optimized 50/125-µm as the multimode fiber for commercial buildings is included.
- Common information was transferred to 568-C.0.
- 150-Ω STP cabling, category 5 cabling and 50-Ω and 75-Ω coaxial cabling was removed as a recognized media.
- Balanced twisted-pair cabling performance and test requirements were removed and are to be placed in the ANSI/TIA-568-C.2 document.
The component standards
Because of the similar publication dates, the component standards, 568-B.2 (copper) and 568-B.3 (optical fiber) are also due for revision. These documents, due to the development of the 568-C.0 document), were modified to become manufacturer-focused documents.
The 568-C.3 Standard has been completed and released for publication. The revision process did allow the incorporation of several changes worth noting:
- ISO 11801 nomenclature (OM-1, OM-2, etc.) has been added as a parenthetical in the table of recognized fiber types.
- Connector strain relief, housing and adapter color coding has been refined for situations when color is used to identify fiber type, but the color codes are not mandatory in order to allow for the use of color for other purposes.
- The minimum OFL bandwidth for 62.5/125-µm fiber was raised to 200/500 MHz•km (from 160/500). Note: this applies to 62.5-µm fibers in patch cords as well.
- Annex A connector test parameters have been aligned with the same parameters in the IEC 61753-1, Category C document. This means that connectors compliant to IEC would be compliant to 568-C.3. Note: the reverse is not true, as the IEC standard includes some additional testing not covered in 568-C.3; the IEC is the more stringent document.
The 568-C.2 effort was competing with the 568-B.2 Addendum 10 (Augmented Category 6) effort, so it got off to a slower start. Now that the addendum has been published, the TR-42.7 committee has turned its attention to the 568-C.2 standard, with plans to publish in 2009. The first draft balloted consisted of more than 400 pages (remember that the performance and test requirements were moved into this document), but some resolved comments resulted in reducing the size down to nearly 250 pages, as some material will be moved to stand-alone documents. Interestingly enough, the TR-42.7 has already started a project to create the first addendum to the 568-C.2 standard.
By the time this article is published, this information may be overcome by more recent events, since the release of some of these documents may be only weeks away. As mentioned previously, 568-C.3 has been released for publication, so it should be available by the time you read this paragraph. 568-C.2 is targeting a release near the end of 2009.
The draft 568-C.0 document was issued for its second default (limited content) ballot in June, with a ballot closing date in early August—and that could have allowed for a release by late August if there were no technical changes resulting from the ballot comment resolution. Similarly, the draft 568-C.1 document is out for its second default ballot, which could have allowed a release in late August as well. If not, the next scheduled meeting of TR-42 is in early October.
Just like 568-C.1 was constructed to utilize the 568-C.0 document, the remaining premise standards (residential, outside plant, data centers, etc.) will need to be revised to utilize the 568-C.0 document, too. Similarly, the other “common” standards (administration, pathways and spaces, etc.) will need to be revised to broaden their scope beyond office-oriented commercial building cabling and make them more “generic”. This process has already started in some cases, and will be accomplished as these documents begin to reach their 5-year limit.
At the end of the day, probably within the next four years, the entire suite of TR-42 documents should be a complete, neat package.
HERB CONGDON is systems market manager at Tyco Electronics/AMP Netconnect (www.ampnetconnect.com), and chairman of the TIA’s TR-42 committee.
