R&M Data Center Handbook

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Since old cable terms related to shielding were not standard, were inconsistent, and often led to confusion, a new
naming system in the form XX/YZZ was introduced with ISO/IEC 11801 (2002).
• XX stands for overall shielding
o U = no shielding (unshielded)
o F = foil shield
o S = braided shield
o SF = braid and foil shield
• Y stands for pair shielding
o U = no shielding (unshielded)
o F = foil shield
o S = braided shield
• ZZ always stands for TP = twisted pair
Twisted pair cables in the following shield variants are available on the market:
Shielding U/UTP F/UTP U/FTP S/FTP F/FTP SF/FTP
Overall shield
Foil ()
Wire mesh ()
Core pair shield Foil
The introduction of thin, lightweight AWG26 cables (with a wire diameter of 0.405 mm, as compared to 0.644 mm
for AWG22) as well as enormous advances in shielding and connection technology is making massive savings in
cabling costs possible, and at the same time increasing the performance and efficiency of passive infrastructures.
Up to 30 percent savings in cabling volume and weight is possible using these cables. However, some details
come into play with regard to planning, product selection and installation for achieving sufficient attenuation
reserves in the channel and permanent link, and in turn full operational reliability of the cabling system.
AWG stands for American Wire Gauge and is a wire diameter coding system used to characterize stranded
electrical lines as well as solid wires, and is primarily used in the field of electrical engineering. The following core
diameters are used for communication cabling:
• AWG22 / Ø 0.644 mm • AWG23 / Ø 0.573 mm • AWG24 / Ø 0.511 mm • AWG26 / Ø 0.405 mm
In addition to the actually transmitting data, a structured cabling system with twisted copper cables allows terminal
devices that are frequently used to be supplied with power from a remote location. Such a system based on the
IEEE 802.3af and IEEE 802.3at standards, better known by the names “Power over Ethernet” (PoE) and “Power
over Ethernet Plus” (PoEplus), can use data cables to supply terminal devices such as wireless access points,
VoIP telephones and IP cameras with the electrical energy they require. You can find detailed information on this
process in section 3.10.3.
Pre-Assembled Systems / Plug-and-Play Solutions
There are manufacturing concepts that will provide decided advantages when it is expected that a data center will
undergo dynamic changes. All installations described up to this point (copper and glass fiber cabling) require that
an installation cable be laid and be provided with plugs or jacks at both ends. The termination process requires a
high level of craftsmanship. Quick, spontaneous changes to the positions of connections in a data center are only
possible under certain conditions, and are therefore expensive. Most cabling system manufacturers provide
alternatives in the form of systems made up of the following individual components:
• Trunk cables consisting of multiple twisted-pair cables or multi-fiber cables, both ends terminated with
normal plug connectors or jacks or even a special unique manufacturer-specific connector.
Manufacturers also provide a measurement report for all connections, especially for glass fiber systems.
• Modular terminal blocks which can be mounted in the cabinet using 19” technology or even in special
double floor systems. Trunk cables can be connected to this block at the input side using the special
connector, and then completely normal RJ45 jacks or even glass fiber couplers are available on the output
side.
At this point we should again mention that the availability of data center applications can be increased by using
cabling systems pre-assembled at the factory. This is because these systems minimize the time spent by
installation personnel (third-party personnel) in the security area of the data center during both initial installation of
the cabling system as well as during any expansions or changes, which translates into an additional plus in terms
of operational reliability.
Page 112 of 156 © 08/2011 Reichle & De-Massari AG R&M Data Center Handbook V2.0