TELECOM ACCESS STANDARDS NEWSLETTER NO. 166

April 2008

CONTENTS
1. PTC106 Amendment
2. Specification updates
3. Softcopy Telepermit Applications
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1. PTC106 Amendment

PTC106 (Telecom Code of Practice for Residential-Type generic cabling Systems) is being re-issued with a couple of amendments. The changes are relatively minor and are sumarised as follows:

Location of Home Distributor Cabinet
PTC106 originally recomended the Home Distributor Cabinet to be centrally located, to minimise cable runs. PTC106 now recomends that it is located as close as possible to the cable entry point (ETP). This is to allow for other forms of service delivery such as fibre to be retro fitted without having to install long runs of fibre within the house.

Disconnect Test Point (DTP)
The Home Distributor Cabinet requires a facility for isolating the network from the house wiring. This is known as a "Disconnect Test Point". This facilitates diagnosing whether faults are in the house wiring or network. It is located "electrically" at the point in the wiring where either ADSL splitters or residential gateways would be connected. The requirement for the DTP remains, but to allow it to be used for the connection of resdential gateways or splitters the method of implementing it has now been defined. Basically it is two RJ45 sockets, with one connected to the network and one connected to the house wiring. To connect the network to the house wiring a short RJ 45 plug terminated patch cable is plugged into each socket. In addition teh house wiring is also connected to pins 1 and 2 of the network socket. This allows the the "through" connection to be made with a single RJ45 plug with 2 links wired. PTC106 shows details of how splitters and gateways connect at the DTP.

In addition a facility for connecting a security alarm system is also required. While this is not strictly a part of the DTP function, it is important that the security system is connected on the house wiring side of the DTP, but before any other CPE is connected, so this is the logical place to do this.

It is proposed to include the use of a DTP for legacy wiring to PTC103, and PTC103 will be amended accordingly. In this scenario the DTP will be a small standalone unit inserted in the wiring between the ETP and the first jackpoint.


2. Specification updates

The definition of the Disconnect Test Point (DTP) has an effect on several other specifications which are being currently amended. These are:

PTC225 (Star wiring box/Home Distributor)

PTC103 (Code of practice for residential house wiring)

PTC227 (Disconnect Test Point) New Specification covering a standalone DTP

PTC285 (xDSL Splitters) New Specification covering self install splitters.


In addition to the above, PTC280 is being rewritten to cater for ADSL2+ frequencies, and to pick up a few other issues which have shown up since the original specification was published. It will probably be renumbered PTC281.


3. Softcopy Telepermit Applications

For the past 15 years or so, we have had to keep the majority of our Telepermit records off site due to the finite amount of office space we have available. We endevoured to keep the most recent two or three years of records, as these are the ones most likely to be referred to. However, electronic storage makes it far more economical, and far more convenient to store all records electronically. We would therefore encourage all Telepermit Applications and supporting information to be sent to us either on CD ROM, or as email attachments. One caveat however, email attachments which are too large can be blocked, and no notification is given to either the sender or or adressee that this has happened. Some years ago attachments of over 2 MByte were being blocked, although now it seems that anything up to about 12 MB seems to be ok. If there are a number of large attachments it is a good idea to send them separately, and limit the total attachments per email to about 12 MB. We are looking at getting a common email address for the group, so that all applications etc can be sent to one common email address.



Richard Brent
Access Standards