MAKING A CASE FOR 3-CABLE STATION RUNS
By Larry Smith, President, ABR Consulting
In the past
several years, it has been a standard to run 2 voice and 2 data cables to each
end-user outlet. The reason is that voice cables were placed on the
backboard and the data cables were placed on rack-mounted patch panels.
With the cabling design being changed because of voice-over-IP telephone systems
(see Designing Cabling Rooms (IDFs) for
Voice-Over-IP Telephone), we now recommend that you
specify 3 cables to each end-user outlet instead of 4.
story. The term 2 + 2 cabling implies that 2 cables will be for voice and
2 cables will be for data. This is
an older concept that was in use when the voice cables terminated on the wall
and the data cables terminated on the data racks.
It was also a time when the voice cables were Category 3 and the data
cables were no less that Category 5. The
cable jackets were often of different colors to distinguish between the cables.
Because it couldn’t be projected where more than one phone line or more
than one data line was needed, the 2 + 2 cabling concept evolved.
It has become an accepted standard.
Today’s cabling architecture is changing and is being driven by impending
installations of voice-over-IP equipment. VoIP
requires a cable rated at no less
than Category 5. With VoIP equipment
installed on a rack in a manner similar to data switches, all voice and data
station cables are terminated on the data racks.
Voice cables are no longer terminated on the backboard but there is a
connection to the backboard from the data racks to pick up the riser copper
backbone which is still terminated on the backboard.
With all station cables
terminated together on the data racks, the question becomes – “Why do we
need 4 cables?”. Except for rare
circumstances in a building installation, we never did need 4 cables; it was the
reasons above that dictated the 4 cables. With
the ability to now place 3 identical cables together than can be used for either
voice or data, where is the business requirement for 4 cables to each
workstation? it is our opinion that
3 cables for voice and data will serve your installation well. Should
there be an area that needs more, simply add another outlet.
This is far less expensive that providing the fourth cable to each
Contact us at www.abrconsulting.com