As first reported in the very first edition of Connected Home Australia (then Connected Home Solutions, April/May 2004), AS/NZS ISO/IEC 15018:2005, the generic cabling standard for homes, was first published by Standards Australia on 4 February 2005.

Originally published as an international standard in 2004, ISO/IEC 15018 was a home-specific implementation of ISO/IEC 11801 Edn.2.0:2002 – the ubiquitous generic cabling standard known here as AS/NZS 3080:2003.

But such were the difficulties in its creation, that it was torn up and completely re-written twice along the way.

Initially, ISO/IEC 15018 started life as the small office/home office (SOHO) standard under the author of this article’s hand in a coffee shop in Berlin in 1995. Over the subsequent nine years, while I was the chair of the home cabling standard sub-committee, and with input from some of the ‘best brains’ in international standardisation, the document transformed into the all-encompassing home cabling standard that we are all familiar with.

After 15018 was published, however, several derivatives of the Standard with ‘catchy’ names were marketed by carriers, homebuilders and industry associations, as definitive home wiring systems.

Sadly, none of these systems fully embraced the 15018 concept of a truly universal home cabling system supporting all home information and communications technologies (ICT), broadcast and communications technologies (BCT) and commands, controls and communications in buildings (CCCB).

Now, with the advent of the National Broadband Network (NBN), for the first time we have a situation where the potential of 15108 will be matched by a true broadband signal coming into the home.

It is in this light that it is timely to re-examine 15108 and its progress since 2004.

THE FIRST AMENDMENT
In 2009, 15018 Amendment 1 added an Annex E to the Standard, called Reference implementation of TV and radio applications – Usage of baluns.

The first amendment (in five years) dealt with the long-awaited addition of balanced to unbalanced transformers (baluns), which allow the interconnection of coaxial cable input/outputs on RF devices with the twisted pair cabling prescribed in 15018 and present in all of the commercial solutions being offered.

While the reticulation of BCT using coaxial cabling (BCT-C) is in the 15018 standard, coax has not been as widely installed as the cheaper balanced twisted pair cabling. The introduction of baluns, then, potentially brings sound, radio and TV into every room pre-wired with balanced cabling outlets (BCT-B).

The connection of a BCT-B channel to equipment that has a 75Ω coaxial connection requires the use of a balun. Likewise, the connection of a balanced BCT-B channel to a CATV network, or any feeder coaxial system, requires the use of a balun at the home network interface (HNI).

Amendment 1 also contains illustrations showing where baluns could be used in a home (single dwelling). So, by using baluns, in accordance with the manufacturer’s instructions, it is also possible to run BCT applications via the ICT balanced cabling permanent links/outlets.

At the external network interface (ENI), a configuration is shown where the home is fed with a coaxial system. A balun is used to connect this coaxial system to balanced cabling, including the primary home distributor (PHD).

An illustration is also given where a balun is built into the wall outlet of the broadcast outlet (BO). In this case the unbalanced connector at the BO no longer exists, though the permanent link must still meet the performance specified in Clause 9.

Finally, a balun is shown in the equipment cord between a BO and the terminal input (TI) of some terminal equipment.

To ensure transmission efficiency the input impedance of the coaxial port of the balun/equipment cord combination must be 75Ω ±3Ω and the return loss must start at 14dB and not go below 10dB in the range 5MHz to 862MHz.

Tables are provided for the minimum performance of BCT-B channels.

The insertion of the balun/equipment cord combination must not affect the carrier-to-noise ratio, and the carrier-to-composite beat shall comply with IEC 60728-1. It must not induce a total sectional longitudinal slope (from the HNI to the coaxial port of the balun) larger than the value given in a further Table for that purpose.

Amendment 1 states that in each of the above four cases, if the balun cannot cover the frequency range of the forward (47MHz to 862MHz) and return path (5MHz to 65MHz), two types of baluns should be used, each one in the appropriate path.

All in all, Amendment 1 is a worthy addition to the original 15018 standard, providing further flexibility with regards to the reticulation of RF signals in a universal cabling environment.

THE SECOND AMENDMENT
This year, 2010, will see Amendment 2 add a further sub-section to the existing performance clause (7) in 15018. This will, at last, bring optical fibre to the home cabling standard.

Along with the existing sections (mentioned previously) – 7.2 ICT channel performance, 7.3 BCT channel performance and 7.4 CCCB channel performance – there will now be a 7.5 Optical channel performance.

As 15018 is a subset of ISO/IEC 11801 Ed.2 (2002), the Amendment will have the same optical fibre cabling channel ‘class’ as that in Clause 8 of 11801.

The addition of Amendment 2 to the standard also brings:
• Class OF-300 channels that support applications listed in Annex E (of 11801) using optical fibre cable in accordance with clause 9.5.1 of 11801 to a minimum of 300m;
• Class OF-50 channels that support applications listed in Annex E using optical fibre cable in accordance with clause 9.5.1 to a minimum of 50m; and,
• Class OF-100 channels which support applications listed in Annex E using optical fibre cable in accordance with clause 9.5.1 to a minimum of 100m.

The document will introduce a new Table 1 showing maximum attenuation of optical fibre cabling channels. It will state that the attenuation of a channel must be measured according to ISO/IEC 14763-3 (the FO testing standard) and that the attenuation of channels at a specified wavelength must not exceed the sum of the specified attenuation values for the components at that wavelength. (In other words, it is so that there is no (light) power gain in these passive channels.)

Amendment 2 will add assumptions regarding total connecting hardware attenuation within channels, such as those for OF-50 and OF-100 where the values are based on a total allocation of 3.0dB for connections. (Additional connectors and splices may be used if the power budget of the application allows.)

In the case of the channel attenuation for OF-300, it will state that it must not exceed the values specified in ISO/IEC 11801Ed.2.

The new amendment will also state that the components of one optical class shall be interoperable and that components of different optical classes, especially fibre types, must not be mixed within one installation.

Reference implementations of optical channels will also be added whereby optical fibre channels will be comprised of components that comply with Clauses 9.5 and 10.3 of 11801.

These clauses specify physical construction (core/cladding diameter and numerical aperture) and transmission performance. Within the reference implementations of this clause, the optical fibres used in each cabling channel shall have the same specification.

It will state that the selection of optical fibre components will be determined by the channel lengths required and the applications to be supported. It will refer the reader to Annex E for guidance.

Maximum channel lengths will be determined using the cables of Clause 9.5 and mated connections in accordance with Clause 10.3. Where the number of mated connections within the channel exceeds two, the channel length shall be reduced by the length differentials of 20m for each additional connection. For a given length of channel, additional connections may be used if the optical power budget of the application allows (see Annex E).

Requirements for optical fibre cables will be multimode, graded or step-index optical fibre waveguide complying with a new Table 2, which will set out whether it is indoor or outdoor fibre, the category (e.g. A4g), the relevant IEC standard, and the 11801 class (e.g. OF-100). Amendment 2 will state that the mechanical and environmental requirements for indoor and outdoor optical fibre cables are defined in accordance with IEC60794-1-1, IEC 60794-1-2 and IEC 60794-2. It will also point out that the category and polarity of the optical fibre(s) within the cable shall be marked upon the cable sheath.

Optical fibre connecting hardware will draw on the requirements of Clauses 10.3.2 to 10.3.4 and will apply to all connecting hardware used to provide connections between optical fibre cables described in 9.5. These requirements apply to the connecting hardware for both horizontal and backbone cabling. Additionally, for safety reasons, all optical ports will need to comply with the requirements of IEC 60825-2.

The new amendment will also suggest that coding of connectors and adapters, for example by colour, should be used to prevent accidental connection of different fibre types (i.e. 50/125μm glass optical fibre (GOF), 62.5/125μm GOF, 62.5/125μm plastic optical fibre (POF)) and/or fibre categories.

It calls for consistent polarisation of duplex optical fibre connections to be maintained throughout the home cabling system by means of physical keying, administration (i.e. labelling) or both. Also, keying and the identification of fibre types shall be used to prevent from mixing fibres types within an optical link.

Amendment 2 states that the following colour code will apply for connectors:
• Multimode (GOF): Beige/Black;
• Multimode (POF): White.

These markings and colour codes are in addition to, and will not replace, other markings specified in IS 14763-1, or those required by local codes or regulations.

Amendment 2 will introduce a new Table 3 that sets out the required mechanical and optical characteristics of optical fibre connecting hardware.

At the telecommunications outlet (TO), the optical fibre cables shall be terminated with a duplex LC-connector (LC-D) that complies with the detail mating interface specification IEC 61754-20. The optical fibre connector used at the TO shall meet the requirements of the new Table 3.

The performance of optical channels is dependent upon the performance of optical cords and jumper cables. The moves, additions and changes made using cords and jumpers in a home represent a greater risk to operational channel performance than that of installed horizontal or backbone cables. Thus a new clause defining the requirements for terminated cables used as work area cords, CP cords, equipment cords and patch cords within horizontal and backbone cabling was added in Amendment 2.

Further, optical cords must now comply with the relevant part of IEC 61753-12. POF cables used for cords must meet the generic specification IEC 60794-1-1, the test methods IEC 60794-1-2 and the sectional specifications as defined in 9.5.1.

Connecting hardware used must meet the requirements of Clause 10.3. The connecting hardware and the means of maintaining polarity within the cord must be in accordance with the intended use of the cord and shall be a logical extension to the cabling interface(s) to which it is to be connected.

A new sub-section was added to Annex E that supports applications and maximum channel lengths with plastic optical fibres. Optical fibre cabling specified in this international standard is intended to support the applications detailed in this annex; other applications not listed may also be supported. Optical fibre cabling applications are correlated to channel performance classes specified in Clause 6 of the standard.

Finally, a new Table E.1 was added, containing established and emerging applications defined by the relevant application committees or industrial available solutions for the supported applications and maximum channel lengths with plastic optical fibres.

John Ward, B.Eng. (UTS) Dipl. Electronic Eng. (NSWIT) is CEO of Jamsam Pty Ltd. He has spent 31 years as a telecommunications engineer/consultant and now specialises in network design audit and troubleshooting, test equipment sales and corporate cabling solutions training.