7. DEVELOPMENTS IN AS/NZS BUILDING CABLING STANDARDS
The Australian (New Zealand) telecommunication cabling Standards for commercial building cabling systems, AS/NZS 3080, and AS3084, pathways and spaces are currently being revised.
From Telecom's viewpoint, any developments and improvements in building cabling practices will have a positive impact on supporting the modern high speed data services delivered from the public network. Service reliability is improved and installation problems are minimised if building cabling meets the latest performance standards. Above all, cabling is an essential part of getting network services to the desktop.
In view of these points, the following is re-printed from an article prepared by Brian Salt, a member of the CT/1 building cabling standards working group, to publicise their proposed developments. It should be of interest to all industry personnel dealing with commercial cabling systems, as it also outlines the background to the joint Australia/New Zealand standards setting processes for commercial building cabling systems and support infrastructure. In particular, it explains how and why New Zealand and Australia have gradually moved from the widely accepted US cabling standards to the international versions, despite the fact that US practices were well established here:-
"As signatories to the International GATT convention on trade, Australia and New Zealand are obliged to follow International Standards unless there are any compelling local reasons to do otherwise. AS/NZS 3080:1996 is thus based on the International Standard ISO/IEC 11801. Also published in 1996 was HB-27, the Australian/New Zealand copper cabling field testing handbook. HB-27 is based on the North American TIA/EIA TSB-67 because, at that time, there was no comparable International Standard. HB-27 differs from TSB-67 in that the test limits for the basic link and channel test configurations were modified due to differences between the ISO and TIA specifications.
AS/NZS 3080:1996 includes the full version of ISO/IEC11801:1995, but with a local preface and five local appendices. Three additional appendices, covering open-office cabling, centralised optical fibre cabling and EMC requirement, were added through publication of Amendment 1 to AS/NZS 3080 in 1998. The highest performing copper cabling links and channels in these Standards are Class D, which are specified up to 100 MHz. Similarly the highest performing 100 ( cabling components are Category 5, which again are specified up to 100 MHz.
The IEEE Standard for 1000BASE-T (Gigabit Ethernet on copper cabling) was published in 1999. Although 1000BASE-T is designed to run on cabling specified up to 100 MHz (Class D/Category 5), the IEEE Standard does include some transmission performance parameters, such as return loss and far-end-crosstalk, that were not originally specified in the cabling Standards. The IEEE Gigabit Ethernet committee expect the majority of installed Category 5 cabling will support 1000BASE-T, but they strongly recommend the cabling be re-tested prior to implementation with the new parameters included.
To ensure support for applications using all 4-pairs for bi-directional transmission, such as 1000BASE-T, both the TIA and ISO have introduced new cabling specifications. The TIA specification for Category 5e cabling was published in late 1999 and ISO published a revised first edition of ISO/IEC 11801 with a revised Class D specification in March this year (Edition 1.2). These specifications are similar in that both are still only specified up to 100 MHz and both include return loss and far-end-crosstalk. However, the near end-crosstalk requirements for TIA Category 5e marginally exceeds that of the revised Class D.
Edition 1.2 of ISO/IEC 11801 includes specifications for two alternative copper cabling models, the permanent link (fixed wiring in the wall) and the channel (end-to-end, including equipment and work area cables). An accompanying document on "Test Methods" to be published as IEC 61935-1 primarily specifies the performance of field testers for testing these configurations.
Shortly a revised edition of AS/NZS 3080:1996 will be made available for public comment (by Standards New Zealand) and it is expected that this will later be published as AS/NZS 3080: 2000. The revised edition will include edition 1.2 of ISO/IEC 11801, as well as revised versions of the local preface and the 8 local appendices (including those in Amendment 1). By inclusion of the test limits for permanent links and channels in the revised edition of AS/NZS 3080, and by adopting IEC 61935-1 as a local standard for test methods, the existing testing handbook HB-27 will become redundant.
In parallel, the ISO/IEC and TIA Standards committees are developing specifications up to 250 MHz for Class E/Category 6 cabling systems and components, with the eventual aim of achieving harmony. These specifications will be published in the second edition of ISO/IEC 11801. Also included in the second edition will be further changes to the Class D specification, bringing it even closer to the TIA Cartegory 5e specification, and new specifications, up to 600 MHz for Class F/Category 7. It is expected that the second edition will be ratified by mid 2001 and that AS/NZS 3080 will again be revised to incorporate this new Standard.
The current version of the pathways and spaces Standard AS3084:1993 is based on the North American EIA/TIA 569 Standard. The TIA Standard has since been revised and republished as TIA/EIA 569-A and is currently being used by ISO to develop an International pathways and spaces Standard. As it may be a year or more before an International Standard is ratified, the draft ISO pathways and spaces document is being used as the basis for a joint Australia/New Zealand Standard. In addition to the ISO material there will be a local preface and appendices. Some of the information, originally in the AUSTEL TS-009 Standard and not relating to safety or network integrity, is being included in AS/NZS 3084, a draft version of which will be available for public comment shortly."
Any readers wishing to obtain the draft standards or other publications referred to above are advised to contact Standards New Zealand (Derek Perry, telephone (04) 498 5909).
DOUG BURRUS
Manager
Access Standards
