Submittal

0711CIMinstallF5
An enterprise shielded cabling setup
Telecommunications
bonding
backbone
Ethernet
switch
Patch
panel
Shielded
patch cord
RJ-45
outlet
Patch
cord
Workstation
(UTP or
shielded)
Horizontal cabling
(shielded)
AC outlet
AC outlet
AC panel
Telecommunications
grounding busbar
GES
GESGES
WorkstationData center
3-prong
AC plug
Branch
circuit
ground
Power
distribution
ground
Branch
circuit
ground
leaving the cable link at the workstation area ungrounded. e
advantage of this option is that the risk of establishing a sub-
stantial ground loop current is greatly reduced.
is option, however, lowers the level of pro-
tection against external noise, such as alien
crosstalk, EMI, and RFI, across that link in the
channel, thus lowering system performance.
It commonly is used only when it is not pos-
sible to eliminate voltage dierences between
ground potentials.
Best practice 2: Ensuring path continuity
To optimize the performance of your shielded (or unshielded)
network, you should perform a visual inspection upon instal-
lation and on an annual or semi-annual ba-
sisthereaertocheckforproperbondingand
grounding, as well as the overall design of the
power and ground system. An inspection that
follows a line-by-line work order allows ear-
ly detection of potential problems, such as:
loosened or corroded connections; missing
labels; conductors that have been damaged,
cut, or removed; and new metallic elements
that require connections to the common bond-
ing network described in e Emerald Book.
To facilitate inspection of the grounding system, install con-
nectors, busbars, and conductors in such a way to allow visual
verication of the bond. ere should be a logical ow as you
follow the grounding busbar(s). For example,
follow the path(s) from the equipment chassis to the rack, from
the rack to the data center grounding infrastructure, then over
to the local TGB. e TGB connects to the tele-
communications backbone (TBB), or grounding
cable, that runs back to the telecommunica-
tions main grounding busbar (TMGB), which
is bonded to earth ground via the electrical en-
trance facility and links all the TBBs together.
Inspect all splices for proper crimping, and in-
spect labels to ensure that proper labeling proce-
dures have been followed.
Best practice 3: Testing at the workstation
Once the visual inspection of the data cen-
ter bonding and grounding system is complete,
attention can be turned to the cabling area
closest to the end user—the workstation. If a
potential dierence exists between these two
points, a ground loop will form and current may
ow within the loop.
A method for testing whether a ground loop
potential exists at a workstation is to use a true
RMS multimeter to measure the potential dierence between
the power outlet ground and the shielded module on the work-
station outlet. Position one multimeter probe on the face of the
shielded module on the workstation and the other in the ground-
ing prong of the electrical outlet, and check the voltage reading
on the meter. If the meter reads less than 1 volt of potential (as
described in ANSI J-STD-607-A Annex D) between the mod-
The typical shielded cabling channel deployed in an enterprise environment terminates in
the data center at one end, and at the other end terminates at the workstation.
Use a two-point
multimeter to measure
the potential difference
between the workstation
outlet module (left) and
the ground wire of the
electrical outlet (right).
If the IT equipment is grounded, then any shielded
cables used to connect equipment to patch panels,
or to other equipment, must be grounded.