2-Pair vs 4-Pair Cabling
I would like to respond to Scott's comment on 2-pair vs 4-pair cabling.
Clearly, this is an important factor for remote powering.
I presented an analysis on installed twisted pair cabling as input to the
100BASE-VG project a few years ago. I found that the vast majority of
horizontal cabling was laid as 4-pair and terminated as 4-pair at the
60603-7 (RJ-45) outlet. The only notable exception to this was found in
Germany, where cabling is generally laid as 4-pair but some is terminated
as 2-pair in each of 2 outlets. This practice continues however some
outlets are re-configurable as 4-pair at a later date. The presence of
2-pair configured outlets is quite small in the scheme of things.
The US and the rest of the world has either followed the requirements of
TIA 568/568A or the recommendation of ISO/IEC 11801 and
installed/terminated 4-pairs at the outlet. I'm sure that BICSI will
I have conducted a number of surveys on installed cabling and am closely
involved in cabling standards, so would be happy to answer any other
questions in this area.