R&M Data Center Handbook

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3.5. Data Center Infrastructure
An enormous savings potential in the area of energy demand and CO2 reduction can result from properly
designing a data center and installing servers and racks. This especially applies for the layout of rack rows and
conduction of heated and cooled air. Even small changes in arranging the alignment of supply and return air can
lead to dramatic improvements and higher energy efficiency. This in turn assumes an “intelligent” room concept,
which saves space yet at the same time allows for expansion, saves energy and is cost-effective.
In addition to expandability, one must make sure, when equipping a data center, that the facility is easy to
maintain. Data center accesses (doors) and structural engineering must be designed in such a way that large,
heavy active components and machines can be installed, maintained and replaced. Access doors must therefore
be at least 1 meter wide and 2.1 meters high, lockable and have no thresholds.
The room must have a headroom of at least 2.6 meters from the floor to the lowest installations, and a floor
loading capacity of more than 750 kg/m 2 (2.75 meters and 1,200 kg/m 2 is better still).
Placing cabinets in rows makes for arrangements that are advantageous for cooling active components. One must
make sure that aisles have sufficient space to allow for installing and dismantling active components. Since active
components in recent years are having continuously larger installation depths, an aisle width of at least 1.2 meters
must be provided. If aisles cannot be made equally wide, the planner should choose to make the aisle at the front
of the cabinet row larger. If a raised floor is used, cabinet rows should be placed so that at least one side of the
cabinets is flush with the grid of the base tiles, and that at least one row of base tiles per passageway can be
opened.
3.5.1. Power Supply, Shielding and Grounding
Proper grounding is a key factor in any building. It protects people within the building from dangers that originate
from electricity. Regulations for grounding systems in individual countries are established locally, and installation
companies are generally well-known.
With the introduction of 10 gigabit Ethernet, shielded cabling systems have been gaining in popularity around the
world. However, since unshielded data cabling systems have been installed for the most part in most of the world
up to this point, it is important to have exact knowledge about the grounding of shielded patch panels and the
options available for this.
Importance of Grounding
Every building in which electrical devices are operated requires an appropriate grounding concept. Grounding and
the ground connection affect safety, functionality and electromagnetic interference resistance (EMC: electromagnetic
compatibility).
By definition, electromagnetic compatibility is the ability of an electrical installation to operate in a satisfactory
manner in its electromagnetic environment, without improperly affecting this environment in which other installations
operate. The grounding system of buildings in which IT devices are operated must therefore satisfy the
following requirements:
• Safety from electrical hazards
• Reliable signal reference within the entire installation
• Satisfactory EMC behavior, so all electronic devices work together without trouble
In additional to current local regulations, the following international standards provide valuable aid in this area: IEC
60364-5-548, EN 50310, ITU-T K.31, EN 50174-2, EN 60950, TIA-607-A.
Ideally, low- and high-frequency potential equalization for EMC is meshed as tightly as possible between all metal
masses, housings (racks), machine and system components.
Alternating Current Distribution System
A TN-S system should always be used to separate the neutral conductor of the alternating current distribution
system from the grounding network. TN-C systems for internal installations with PEN conductors (protective earth
and neutral conductor combined) may not be used for IT devices.
There are essentially two possible configurations for building grounding systems, described as follows.
Page 66 of 156 © 08/2011 Reichle & De-Massari AG R&M Data Center Handbook V2.0