Submittal

0711CIMinstallF4
Shielded cable/jack
Foil of
shielded cable
360˚
termination
cap
•Bonds each rack/cabinet to the telecommu-
nications grounding busbar (TGB); this may
be done via a mesh common bonding net-
work (MCBN);
•Bondsthetelecommunicationsgrounding
system to the alternating-current (AC) ser-
vice panels serving the IT equipment in the
room; such bonding promotes equivalent
ground potential between the IT equipment
grounding and the equipment ground of
the power system(s) serving the IT equip-
ment;
•Properbondingandgroundingelements(clearcovers,ID
labels, green-coded conductors) to aid in visual verication
of the system.
Best practices for shielded
For shielded cabling systems, the additional step of bonding the
cable shield is essential to ensure proper system performance.
e foil screen in Category 6A shielded cabling already pro-
vides enhanced system performance by preventing unwanted
cable-to-cable signal coupling (i.e., alien crosstalk). A proper-
ly bonded and grounded shielded cabling system further pro-
tects twisted pairs from external noise by carrying induced
current along the continuous foil shield of the cable to the
transceivers at each end of the cable.
Werecommenda4-stepprocesstoproperlybondtheshield
at the patch panel:
1. Bond all the shielding (foil and/or braid) of the
data cable to the shielded jack module, which provides
360° shielding termination.
2. Snap the jack module into an all-metal patch panel to
create a bond between the module and the unpainted tabs
on the patch panel.
3. Attach the patch panel to the rack using thread-forming
bonding screws; the thread on the screws removes paint
from the thread holes on the rack, and the serrations on
the head of the screws remove paint from the patch panel,
creating a high-performance electrical bond between the
patch panel and the rack.
4. So long as electrical continuity exists throughout the rack,
the last step is to bond the rack to the main busbar or MCBN
located under the data center’s raised oor. To ensure long-
term integrity of the system, always use compression con-
nectors (not mechanical) so the connection does not loosen
with vibration.
Once cabling to the patch eld has been bonded, atten-
tion can be turned to the rest of the bonding and grounding
system.Hereareseveral“bestpractices”thatmustbecon-
sidered during the design and installation of the rest of your
shielded structured cabling system:
Best Practice 1: Ground-
ing the cable shield
During installation, a fre-
quently asked question is
whether the installer should
ground one or both ends
of a shielded cable chan-
nel. Generally, the cable shield is bonded to the grounded
equipment chassis or rack at each access or patch location.
In other words, if the IT equipment is grounded, then any
shielded cables used to connect equipment to patch panels, or
to other equipment, must be grounded.
A typical shielded structured cabling channel runs from a
switch to the workstation and comprises two patch cord links
and the shielded horizontal link. One end of the channel starts
in the data center where the switch, patch panel, and shielded
patch cord linking them must be properly bonded to the rack.
e rack is tied to the telecommunications grounding system,
which in turn is bonded to the AC power system.
e other end of the channel terminates outside the data
center at the workstation outlet. An issue to consider is
whether a shielded cabling link at this outlet location can be
properly bonded to a grounding system without inducing a
ground loop. A cable shield that is terminated at the worksta-
tion may be bonded to the AC ground via connections within
the workstation itself, but the outlet AC ground must be at the
same potential as the telecommunications grounding system.
e recommended method for grounding the shielded link is to
use workstation-provided ground. Use of a shielded patch cord
grounds both ends of the shielded cable link and completes the
shieldedchannel.However,whenbothendsofashieldedlink
are grounded, there is the possibility for a ground current to be
conducted across the shielding if the grounds are not at the same
potential. In this example, a voltage dierence may exist on the
ground between the AC power source serving the workstation
and the telecommunication ground within the data center.
erefore, to reduce the magnitude of such ground currents,
all serving AC power systems must be bonded together to the
same grounding electrode system. (A building can have only
one grounding electrode system, as required by the National
Electrical Code.) is approach will reduce any ground voltage
dierences that may exist either between diering AC power
system grounds or between the AC power system ground and
the telecommunications ground.
An alternative industry practice is to use UTP patch cords
between the outlet and the workstation, eectively grounding
only one end of the shielded cable channel in the data center and
This shielded cable and jack
combination from Panduit pro-
vides 360° shielding termination.