R&M Data Center Handbook

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A maximum filling level of 40% should be estimated when dimensioning the cable tray. The use of low diameter
cables can be important in this regard. These significantly reduce the volume required in the cross-section of the
cable routing system, as well as weight. The AWG26 installation cable (Ø: 0,40 mm) from R&M is one example of
this cable type; it complies with all defined cabling standards up to a maximum cable length of 55 m, and only
takes up about 60% of the volume of a standard AWG22 cable (Ø: 0,64 mm).
Mixed cable routing systems
are increasingly gaining in
popularity, when basic data
center conditions permit this
method to be used. Data
cables in this setup are
routed in a cable routing
system under the ceiling,
and the power supply routed
in the raised floor.
Max. filling Füllgrad level 40% 40%
Metallene cabling Kabelführung routing
für for Kupfer-Verkabelung
copper cabling
Kabelführungen Plastic cabling routing
aus
Kunststoff for fiber optic
für FO
This ensures the necessary
distance between data
cabling and the power
supply in an elegant way
that does not require
extensive planning, and
cooling capacity is not
impaired. All other
requirements already mentioned
must be fulfilled here
as well.
2,6 2.6 m min. min.
Metallene cabling Kabelführungen routing
für for Stromversorgung
power supply
Mixed cable routing under ceiling and in hollow floor
3.5.4. Cable Runs and Routing
The cable routing system in the data center must fulfill the following demands.
• It must satisfy cabling requirements so no losses in performance occur
• It must not obstruct the cooling of active components
• If must fulfil requirements of electromagnetic compatibility (EMC)
• It must support maintenance, changes and upgrades
Depending upon building conditions, possible solutions for cable routing in the data center are the raised floor,
cable trays suspended from the ceiling or a combination of these two solutions, as already described in the preceding
section.
The cable routing in many “historically developed” data centers and server rooms may be described as catastrophic.
This is based on a lack of two things:
• In principle, installation of a “structured cabling” system in the data center is an “modern” concept. For a
long time, server connections were created using patch cords routed spontaneously in the raised floor
between the servers and switches. An infrastructure of cable routing systems did or does not exist in the
raised floor, and a “criss-cross cabling” is the result.
• In many cases, the patch cords that were laid were documented only poorly or not at all, so it was impossible
to remove connecting cords that were no longer needed or defective.
The result is very often raised floors that are completely overfilled, though cable routing is in principle only an
additional function of the raised floor in the data center. In most data centers these raised floors are also required
for server cabinet ventilation/cooling. An air flow system in the raised floor with as few obstructions as possible is
rising in importance, if only in view of the increasingly greater cooling capacities required for systems. Any kind of
chaotic cabling interferes with this. Considering that cabling systems are constantly changing, it is very difficult for
air conditioning technicians to dimension the air flow. Avoiding doing this is a point in favor of cabling technologies
like glass fibers or “multi-core cables” which save on cable volume, but also force one to use cable routing
systems like trays or grids. These systems ensure that cable routing is orderly, they prevent the proliferation of
cables, and also protect cables that were laid.
What system provides which advantages
R&M Data Center Handbook V2.0 © 08/2011 Reichle & De-Massari AG Page 73 of 156