R&M Data Center Handbook

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Grounding System as a Tree Structure
A tree or star configuration was traditionally the
preferred configuration for the grounding system in
the telecommunications sector.
In a tree structure, the individual grounding
conductors are only connected with one another at
a central grounding point. This method avoids
ground loops and reduces the interference from
low-frequency interference volages (humming).
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Building Structural Steel
Horizontal cable
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TGBB
TGBB: Telecommunications
Ground Bonding Backbone
MET: Main Earthing Terminal
MET
Note: power outlets connections shown are logical,
not physical.
Grounding System as a Mesh Structure
The basic concept of a meshed system is not to
avoid ground loops, but to minimize these loops to
the greatest extent possible, and to distribute the
currents flowing into them as evenly as possible.
Meshed structures are almost always used today to
ground high-frequency data transfer systems, since
it is extremely difficult to achieve a proper tree
structure in modern building environments. The
building as a whole must have as many suitable
grounding points as possible if this type of grounding
is to be used. All metallic building components must
always be connected to the grounding system using
appropriate connection components. The conductive
surfaces and cross-sections of these connection
elements (e.g. metal strips and bars, bus
connections, etc.) must be as large as possible so
that they can draw off high-frequency currents with
little resistance.
R&M Data Center Handbook V2.0 © 08/2011 Reichle & De-Massari AG Page 67 of 156