Cim 20071101 nov_2007

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Installation 7Maintenance
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Exceptional optical performance comes naturally.
Nothing is more treasured in field termination than exceptional optical performance. The secret to UniCam® Pretium™-
Performance Connectors is inside – a laser-cleaved, factory-polished fiber stub that ensures outstanding connectivity in
a no-epoxy/no-polish (NENP) connector. UniCam Pretium-Performance Multimode Connectors offer 0.1 dB insertion loss.
And UniCam Pretium-Performance Single-Mode Connectors enable 0.2 dB insertion loss. That’s exceptional optical
performance in less than a minute per fiber, from the most widely deployed NENP connector on the market. Naturally ...
Customer-focused innovation is second nature at Corning.
www.corning.com/cablesystems/cimls

© 2007 Corning Cable Systems LLC / LS-02413

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Contents Zoom In Zoom Out Front Cover Search Issue Next Page EMaGS
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Turn your cable tester into an OTDR
and watch the transformation begin.

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N E T W O R K S U P E R V I S I O N ©2007 Fluke Corporation. All rights reserved. 02152

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Our U.S. area of expertise.

No matter where you’re located, our fiber optic cable products are there. Optical Cable Corporation
has built a network of reliable stocking distributors and a dedicated sales team committed to
getting you the best fiber optic cables for your requirements when you need them...where you
need them. For over 20 years, we have been manufacturing the broadest range of top-performing
tight-buffered fiber optic cables for most applications in the government, military, and commercial
markets. Your order is our top priority. Contact Optical Cable Corporation for a stocking
distributor nearest you. We are where you are.

1-800-622-7711
5290 Concourse Drive • Roanoke, Virginia 24019 • Phone 540-265-0690 • www.occfiber.com

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PHOTO BY JANA STOW

NOVEMBER 2007 VOL. 15, NO. 11

ABOUT THE COVER
While Wi-Fi deployments
have had mixed results in
many cities, Minneapolis’
features
partially built network
proved vital in coordinating
rescue and relief efforts 9 6A’s final hurdle: testing
(But not the kind you think)
following a highway bridge
collapse this summer. Committee members optimistically look at December as
TO LEARN MORE, a potential publish date. PATRICK McLAUGHLIN
SEE PAGE 39.

15 Making the right connection:
Bonding a shielded system
Bonding the system to ground helps ensure optimum performance
for your shielded system. TOM TURNER & ROBERT DENNELLY

25 The verdict is in:
Court chooses fiber-to-the-desk
Texas U.S. District Court rules in favor of an optical
cabling solution—for itself. BOB BALLARD, RCDD

33 Energy consumption an overriding issue
Federal government involvement is driving improved practices
for more efficient operation. PATRICK McLAUGHLIN

39 Wi-Fi trials, tribulations—
What’s working, what’s not
Many failures and some successes mark cities’ efforts
departments
to deploy wide scale Wi-Fi. BETSY ZIOBRON 4 Editorial
An insider’s take on
cable-removal definition
49 INDUSTRY SPOTLIGHT
■ Mini Max cabinets boost school district’s IT upgrade 6 Letters
■ Prysmian unveils high-rise FTTx cable 53 New Products
55 Product Focus:
MARKING & LABELING
EQUIPMENT

CABLING INSTALLATION & MAINTENANCE (ISSN 1073-3108), a trademark, is published 12 times a year, Novemberly, by PennWell Corporation, 1421 South Sheridan
Road, Tulsa, OK 74112; telephone (918) 835-3161; fax (918) 831-9497; Web address www.pennwell.com. Editorial offices: 98 Spit Brook Road, Nashua, NH 03062-
5737; telephone (603) 891-0123. © 2007 CABLING INSTALLATION & MAINTENANCE. All rights reserved. Authorization to photocopy items for internal or personal use,
or the internal or personal use of specific clients, is granted by CABLING INSTALLATION & MAINTENANCE (ISSN 1073-3108), provided that the appropriate fee is paid
directly to Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923 USA; (978) 750-8400. Prior to photocopying items for educational classroom use,
please contact Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923 USA; (978) 750-8400. For further information, check CCC Online at the fol-
lowing address: http://www.copyright.com/. All rights reserved. No material may be reprinted. Bulk reprints can be ordered from Diane Troyer, telephone (603) 891-9135.
Corporate officers: Frank T. Lauinger, Chairman; Robert F. Biolchini, President and CEO.

POSTMASTER: Send address changes to: CABLING INSTALLATION & MAINTENANCE, Circulation Dept., P.O. Box 3280, Northbrook, Il 60065-3280.
Return undeliverable Canadian Addresses to: P.O. Box 1632, Windsor, ON N9A 7C9. Periodicals postage paid at Tulsa, OK 74101 and other additional
offices. Subscriptions: In the U.S.: one year $74; Canada/Int’l surface : one year $84; International via air: one year $100. If available, back issues can be purchased
for $16 in the U.S. and $21 elsewhere. We make portions of our subscriber list available to carefully screened companies that offer products and services that
may be important for your work. If you do not want to receive those offers and/or information, please let us know by contacting us at List Services, CABLING
INSTALLATION & MAINTENANCE, 98 Spit Brook Road, Nashua, NH 03062-5737-“Canada return address: PO Box 122, Niagara Falls, ON L2E 6S4”.

www.cablinginstall.com Cabling Installation & Maintenance ■ November 2007 ■ 3

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Chief Editor / Patrick McLaughlin
(603) 891-9222 • patrick@pennwell.com

Executive Editor / Steve Smith

An insider’s take on (603) 891-9139 • stevesm@pennwell.com

Senior Editor / Matt Vincent
(603) 891-9262 • mattv@pennwell.com

cable-removal definition Circulation Manager / Michelle Blake
(603) 891-9360 • michellb@pennwell.com

Y
eah, I know. I climb on the inal abandoned-cable requirements, Art Director / Kelli Mylchreest
abandoned-cable soapbox time he explained to me that those re-
Lead Illustrator / Dan Rodd
and again, and see no reason quirements were perfected over three
to apologize for it. So get ready (or revision cycles before they were Senior Vice President/Group Publishing Director
Mark Finkelstein
get flipping the page), because here I finally included in the NEC. At three (603) 891-9133 • mark@pennwell.com
go again. years per cycle, that’s as much as nine Associate Publisher/National Sales Manager
Not long after I years of work. In that time, Janeway Ed Murphy
(603) 891-9260 • edm@pennwell.com
wrote an article in explained, the wording was pondered
our July issue en- exhaustively. CABLING INSTALLATION & MAINTENANCE
titled “Abandoned Then he gave me his perspective on EXECUTIVE AND EDITORIAL OFFICES
cable removal a how to determine if a cable fits the PennWell ATD
98 Spit Brook Road
dogged challenge definition of “abandoned.” I had nev- Nashua, NH 03062-5737
Tel: (603) 891-0123, fax: (603) 891-9245
for all” (page 25), er heard it put this way before. Rather Internet: www.cablinginstall.com
I received a call than telling me when/if/why a cable
from a gentleman not currently in use would have to SUBSCRIPTION INQUIRIES:
For subscriptions or to change your format to print
who had just read my article and paid be removed from a building, Jane- or digital, please go to: www.cim-subscribe.com.
particular attention to the following way laid out the circumstances un- Subscriptions outside the USA are available in digital
format only.
line: “One potential reason for such der which such a cable can stay in a
unpredictable enforcement could be building. Quite simply, it has to meet
the sometimes-confounding wording two requirements: 1) It must be ter-
within the NEC in which abandoned minated at both ends; 2) It must be
CORPORATE OFFICERS
cable is referenced.” He suggested I tagged for future use.
Chairman / Frank T. Lauinger
might want to get in touch with Phil End of story. No need for debate
Janeway, who chairs BICSI’s Codes about a cable that’s terminated on President and Chief Executive Officer
Robert F. Biolchini
Committee ... before Phil read the one end but not the other. No get-
Chief Financial Officer / Mark C. Wilmoth
article and got in touch with me. ting away with tagging an untermi-
Mr. Janeway, I was informed, would nated cable for future use just so you ADVANCED TECHNOLOGY DIVISION
not use the word “confounding” to don’t have to rip it out. Senior Executive Assistant
Carol Woodward
describe those parts of the National As one who has been guilty of treat- Tel: (603) 891-9112, fax: (603) 891-9287
Electrical Code that deal with aban- ing NEC requirements for abandoned- carolw@pennwell.com
doned cable. cable removal like they’re the tax code, VP Audience Development / Gloria S. Adams
Shortly thereafter, I had the oppor- I found it enlightening to hear from
tunity to speak to Phil Janeway, and one of the men who helped craft those ATD PUBLISHING SERVICES DEPARTMENTS
discovered the assessment I was giv- requirements. Hopefully, you find it Art Director / Meg Fuschetti

en was absolutely true. He does not interesting too. Production Director / Mari Rodriguez
(603) 891-9193 • marir@pennwell.com
believe the abandoned-cable-remov-
al requirements are vague, nor do Marketing Communication Manager
Kristen Jones
they provide loopholes that would al- (603) 891-9425 • kristenj@pennwell.com
low building owners to keep in place Ad Traffic Manager / Jackie Linker
cable that will never again be put to (918) 832-9314 • jackiel@pennwell.com

any practical use. As a member of PATRICK McLAUGHLIN
Mc
the National Fire Protection Associ- Chief Editor PRINTED IN THE USA GST NO. 126813153
ation group that developed the orig- patrick@pennwell.com
Publications Mail Agreement Number 40052420

4 ■ November 2007 ■ Cabling Installation & Maintenance www.cablinginstall.com

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THE
CUT-OVER.
THE MOMENT OF TRUTH.
OCCASIONALLY FOLLOWED BY THE MOMENTS
OF DREAD, BLAME AND CONFUSION.

There comes a moment in every project when each decision you’ve made is put
to the test. Success and failure hang in the balance, as the switch is made from
the old system to the new. At moments like these, your most crucial decision was
actually one of your ﬁrst: your distributor. If it’s Graybar, you’re not on your own. Our
nationwide supply chain, local support network and trusted suppliers like Berk-Tek
can stand up to any ‘moment of truth’ you may encounter. So take a deep breath;
we’ll be right there.

FOR MORE INFORMATION, VISIT GRAYBAR.COM/BERKTEK OR CALL 1-800-GRAYBAR(472-9227).
_____________

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Who’s dense?
The photo on page 37 of your Sep-
tember issue (right) is of a tele-
phone system, not a blade
server.
Attention to detail in the industry
is important. Good article, though. have thought that for a long time now.
If you look closely at the pictures
Randy Aldous in the article “Back to school with
Submitted via e-mail 10-Gbit Ethernet” (page 19), you
can see how bulky the cables are. I don’t think some
While the telephone system pictured on that page is dense, of the cables pictured will pass 10-Gbit either. Some
and a blade server also is dense, evidently neither one is as cable ties are too tight, some cables look like they are bent
dense as the author/editor who chose to include the photo in in a 90-degree turn going into the patch panel, no cable
the article.—Ed. management/support, too much length of twisted-pair
wire extended out from the end of the cable before it is
Fiber over copper punched down … just to name a few things I can see from
From your September issue, I have to agree with the arti- the pictures.
cle Doug Coleman of Corning Cable Systems wrote: “Opti- Ronnie Sugarek, RCDD/OSP/TPM
cal connectivity a good choice in the data center” (page 9). I Submitted via e-mail

___________


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trade name and trademark. All rights reserved. 1107

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®

Now. GigaLAN10 with reduced O.D.
Like the Mars Rover’s continuing leadership in the Conduit & Cable Tray Fill Comparison Chart
exploration of space, Mohawk’s new GigaLAN 10 Old OD .320” New OD .295
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UTP cable with reduced O.D. continues to lead 1.5” conduit 9 cables 10 cables
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The reduced .295” OD brings enhanced flexi-
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MOHAWK
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visit www.mohawk-cable.com.
Cabling Excellence for Open Architecture

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www.cablinginstall.com design

6A’s ﬁnal hurdle: testing
(But not the kind you think)

I f all goes according to
plan, the final chapter of the
Telecommunications Industry
Committee members optimistically look
at December as a potential publish date.

Association’s (TIA; www.tiaonline.org) standardization of Electrical and Electronics Engineers’ (IEEE; www. ____

of Augmented Category 6 (Category 6A) specifications ieee.org) 10GBase-T specifications. Such high frequen-
will be written before this calendar year ends. The group cies have been new territory for the group, which has
has its sights set on a meeting the second week of Decem- been challenged to make some minute measurements of
ber, at which all outstanding issues may be resolved and connectors to 500 MHz without using ASTM
the standard approved for publication. International (www.astm.org) tests as references, be-
“The standard is in great shape,” says Val Rybinski, cause no such tests exist.
global sales engineer with Siemon (www.siemon.com) “We can make measurements with a certain amount of
and newly-re-elected chair of the TIA’s TR-42.7 Tele- inaccuracy—say 1 dB, for example,” Rybinski continues.
communications Copper Cabling Systems Committee. “What we’d like to do in the standard is get that inaccu-
“The transmission numbers have been firm for a long racy reduced, and the way to do that is to develop better
time; they have not changed in two years,” she adds. In test fi xturing. We believe the new measurement fi xture
addition to establishing link and channel performance made specifically for connecting hardware will allow us
requirements, TIA standards also specify the perfor- to make very accurate measurements.”
mance of components within those systems. And it’s Effectively isolating a connector and measuring that
some of those component specifications—for connect- connector’s performance presents numerous challenges
ing hardware, in particular—that TR-42.7 must fi nalize from technical and practical standpoints, and TR-
before the standard is complete. 42.7 formed a task group—headed by the committee’s
co-chair, Sterling Vaden—to develop and refine a test
Measuring component compliance? fi xture for the purpose.
From a standards-process viewpoint, the only part of the Among the technical challenges the group has faced
standard that is still under review—and, therefore, still are maintaining good impedance around 100 Ω at
has the potential to change—is the procedure for mea- 500 MHz, and one of the biggest practical challenge is
suring connecting-hardware component compliance. isolating the twisted pairs from the measurement. His-
“We froze the entire body of the document except a few torically, the characteristics of the test leads used in the
minor technical changes” related to the component-mea- process have been subject to change during the testing
surement procedure, Rybinski states. So, it is safe to say process, due at least in some part to the leads’ movement
the link and channel specifications are indeed final, as while testing is underway. The fixture recently developed
they have been for two years. and currently being used by the test-fi xture task group
The most recent category-rated TIA specification, Cat- keeps the test leads very precisely located, thereby allow-
egory 6, specified performance levels to 250 MHz. Cat- ing them to be subtracted from the measurement and
egory 6A doubles that frequency to 500 MHz, which is allowing as pure a connector measurement as possible.
in sync with the maximum frequency of the Institute
If the connector ﬁts…
PATRICK MCLAUGHLIN is chief editor of Cabling Installation & The next step, one that is set to be taken as this article is
Maintenance. going to press, is a series of round-robin testing in ➤


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which multiple manufacturers’ connectors are tested using group is close to a final document. “At some point, jacks and
a single fi xture. Hugo Draye, product manager for certifica- plugs need to be defined as components. Link and channel per-
tion products with Fluke Networks (www.flukenetworks.com),
________________ formance reports must be based on individual components.”
points out that such testing is critical to arguably the most im- Draye recalls that similar challenges faced Category 6, when
portant characteristics of standard-compliant products—in- early pre-standard plugs and jacks were not interoperable
teroperability and backward compatibility. among vendors, nor necessarily backward-compatible with
“Manufacturers of connecting hardware are ready to conduct lower-category hardware. Back then, technology progressed
round-robin testing of each component,” says Draye. “That and connecting-hardware manufacturers refined their compo-
happens late in the standards process,” and he notes that the nents to perform within the TIA-established parameters that
would ensure both interoperability and
backward compatibility. With Category 6A,
TIA is on the threshold of finalizing the
means for measuring connectors’ ability
Premise Wiring to perform within those parameters.
Somewhat ironically, it has been an-
CAT 6 • CAT 6a • CAT 7a
“The standards clearly de-
Modular Plugs & Jacks
ﬁne what to measure and
how to do it to ensure valid
results. But they do not
address sampling method.”
other form of Category 6A testing—alien
crosstalk and the means of field-testing for
it—that has generated about 99% of the
pre-standard buzz. On that topic, Rybinski
offers two facts that may surprise many:
• Everything related to field-testing proce-
dures for Category 6A have been closed.
The specifications are complete.
• Standards have never made field test-
Stewart Connector understands that specifying and sourcing quality modular ing mandatory. Category 6A is no
connectors for premise and campuswide communications systems can be exception.
a tough job. Especially as technology, standards, and products continue to
evolve. That is why we ve engineered our plugs and jacks to ensure your
networks superior performance... today and tomorrow. Sampling undeﬁned
To that end, Draye observes, “The TIA and
PLUGS-CAT 3 to 7a JACKS-CAT 3 to 7a IEEE have said, ‘Here’s how you measure,
• Shielded and Unshielded • Shielded and Unshielded here are limit lines, et cetera.’ The stan-
• For Solid & Stranded Cable • Horizontal, Vertical, and Angled dards clearly define what to measure and
• Polished Contacts for High Mounting Options how to do it to ensure valid results. But they
Insertion Life • Single and Multi-Port Designs do not address the sampling method.”
• Multiple Keying and Wire • PCB and Cable Mounted Designs In other words, the standards are silent
Management Options
and users are left to make their own deci-
sions about testing all, some, or no Cate-
Stewart Connector gory 6A circuits for alien crosstalk.
As Rybinski pointed out, this is noth-
www.stewartconnector.com • 717/235-7512
ing new.


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Create Clear, Crisp Labels. Deliver a Professional Image.
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*Estimated street price www.brother.com

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BUSINESSLINK FROM DODGE,
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It’s the one resource business owners rely on. With extended hours, next bay priority
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2007, www.intellichoice.com™ Chrysler Financial is a business unit of DaimlerChrysler
Financial Services. Dodge and BusinessLink are registered trademarks of DaimlerChrysler.

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ERITECH® Grounding & A B

Bonding Products Enhance
Your Data Center Reliability ERITECH® Signal ERITECH® Signal
Reference Grid System Reference Grid System
• High frequency, low • Allows for easy field
impedance grounding construction of wire signal
system reference grids
ERICO® provides a comprehensive approach to grounding, • Prefabricated using 26ga. • Accepts up to 3 conductors
2” copper strip allowing for grid and pigtail
bonding, surge protection and lightning protection applications. • IEEE® 1100 recommended construction using only one
Trust ERICO products to enhance safety, reliability and prevent • Attach grid sections using connector
CADWELD® “TW” connections
damage to your datacenter equipment.
C D

ERITECH® ERITECH® Ground Bars
HAMMERLOCK • Provide a convenient, single-
• Connects the grounding point grounding and
conductor to the ground bonding location
rod with the swing of • Create an equipotential plane
a hammer between service grounds and
• Has greater current equipment during fault and
carrying capacity than transient conditions
most mechanical ground • TIA©/EIA© 607 Compliant
rod connectors

E F

ERITECH® EK16/EK17 ERITECH® RC70/RC100
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Clamps to Rebar Clamps
• Features a conductor lay-in • Meets code requirements
slot that reduces installation where AHJs (Authorities
time Having Jurisdiction) call for
• Designed to handle a range two connections between the
of conductors from #10 to rebar and the conductor
#2 AWG • Easy to install since all
attachment hardware is on
one side of the clamp
A B F
G H
E
C H

G ERITECH® Convenient ERITECH®
Ground Electrode Copper-bonded
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• Contain two 4-ft, 5/8-in. • Exceed the requirements
diameter, ERITECH® copper- of ANSI®/UL® 467, CSA© and
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Contact ERICO at 1-800-677-9089 drive sleeve, a compression 40+ years
or visit www.erico.com coupling and a grounding • ERICO also offers a
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• Easier to install from ground rods and accessories,
level and more convenient including stainless steel
to transport than 8-ft and galvanized
ANSI is a registered trademark of the American National Standards Institute. ground rods
CSA standards are a copyright of the Canadian Standards Association International.
IEEE standards are a copyright of the Institution of Electrical and Electronic Engineers
NEMA is a registered trademark of the National Electrical Manufacturers Association.
UL is a registered trademark of Underwriters Laboratories, Inc.
EIA is a copyright of the Electronic Industries Alliance
TIA is a copyright of the Telecommunications Industry Association

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www.cablinginstall.com installation

Make the right connection:
Bonding a shielded system

W ith the publica-
tion of the IEEE 802.3an
10GBase-T standard in 2006,
Bonding the system to ground helps ensure
optimum performance of your shielded system.

Augmented Category 6 (i.e., Category 6A) cabling sys-
PSANEXT performance comparison
tems are being deployed in data centers. Due to the high
-20
electrical frequency needed to support 10-Gbit/sec
-30 Category 6
data rates over copper cabling, the mitigation of signal -40
coupling between cables in close proximity, known as PSANEXT -50 IEEE limit
alien crosstalk (alien near-end crosstalk or NEXT, and (db) -60
alien equal-level far-end crosstalk or ELFEXT, which -70 Category 6A UTP
is also called alien attenuation-to-crosstalk-ratio at -80 Category 6 ASTP
the far end, or AACRF), is critical to meet 10GBase-T -90
100 200 300 400 500 600
performance standards. Frequency (MHz)
Shielded Category 6A links offer clear performance
Power-sum alien near-end crosstalk performance characteristics
benefits at 10 Gbits/sec by reducing or eliminating the
of copper cabling systems over a 100-meter channel.
effect of alien crosstalk and providing superior immunity
to electromagnetic interference (EMI), such as radio-fre- links to the workstation due to its easy termination and
quency interference (RFI). But it is important that shielded installation in the field, and cost-effective electronics. Of
cabling systems be properly bonded and grounded to the available copper cabling types, unshielded twisted-
ensure the highest level of performance and to protect pair (UTP) Category 6A copper solutions are specifically
expensive IT equipment. If shielded cabling systems are designed to reduce the effect of alien crosstalk by incor-
not properly designed and/or installed, transmission porating innovative features into both the cable (such as
errors may occur due to unwanted additional noise. increased separation between cables and tighter twist
Let’s consider the performance benefits of shielded rates) and the connectors (such as crosstalk suppression
twisted-pair structured cabling, and answer the follow- within the printed circuit board).
ing top-of-mind user questions on bonding and ground- Shielded Category 6A systems offer a different tech-
ing best practices: nique to suppress alien crosstalk, using foil and/or
• Where, and how often, should the shielded cabling braided shielding within the cable to prevent signals
system be bonded? from coupling between cables. These screens provide
• How can I tell if my existing grounding system is significant margin over IEEE 802.3an specifications for
adequate for shielded cable? power-sum alien attenuation-to-crosstalk ratio at the far
• How can I tell if ground-loop problems exist at the end (PSAACRF), virtually eliminating the effect of alien
workstation, and what can be done about the loops? crosstalk and providing more than 20 dB of headroom
over comparable UTP systems. This impact is similar
Performance beneﬁts of 6A whether the cable contains individual shields around
Copper is the preferred structured cabling medium each pair or a single foil around all pairs.
for most connections in the data center and horizontal The increased suppression of ANEXT and AACRF by
TOM TURNER is business development manager and ROBERT shielded cables also eliminates the need for costly and
DENNELLY is product liner manager at Panduit Corp. (www.panduit.com). time-consuming field-testing of alien crosstalk. Fur- ➤


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Typical bonding and grounding

ther, the foil shields provide superior immunity to TGB (telecommunications
grounding busbar)
EMI/RFI and makes it difficult for unauthorized
TBB (telecommunications
users to “listen in” by providing a more-secure bonding backbone)
data environment for such markets as government
or such applications as gaming that require strong
levels of security.

Importance of bonding, grounding
Although overall integrity of the power and
grounding system is crucial to ensure the reli-
ability of all networked equipment, there is often
confusion over how to properly ground and bond
shielded cabling solutions.
The primary purpose of the grounding and bond-
ing system is to create a robust path for equaliza-
MCBN (mesh common
tion of voltages and for resultant surge currents to bonding network)
return to their source. Lightning, power-system
fault currents, circuit switching (motors on and This example of a telecommunications bonding and grounding system exhibits the
off ), activation of surge-protection devices, and essential principles as well as the recommendations of the TIA-942, ANSI J-STD-607-A,
electrostatic discharge (ESD) are common causes and IEEE Std 1100-2005 speciﬁcations.
of transient voltages and electrical surges. Ground
loops are a potential disruption to data signals, and develop to standards TIA-942, ANSI J-STD-607-A, and IEEE Std 1100-
when a voltage difference occurs in the ground at each end of a 2005 (The Emerald Book), here are the principles of a properly
cable shield, causing a current to flow through the shield. designed grounding and bonding system in a data center:
To realize the full performance benefits of any structured • An intentional design—each connection must be engineered
cabling system, shielded or unshielded, the overall integrity of and installed to properly handle the anticipated currents;
the bonding and grounding system must be sound. According • Bonds all metallic components to the grounding system
(e.g., equipment, racks, cabinets, access floors,
Structured ground system ladder racks, cable trays, water pipes, conduit,
building steel);
• Visually verifiable and generally arranged for
1
ease of inspection and testing;
• Equalization paths and ports for ESD-protec-
3
tion wrist straps;
The system grounding
protection starts at the The patch panel is • Support for the proper operation of surge protec-
jack module with bonded to the rack tion device for IT equipment and power circuits;
360º shielding with bonding screws.
• Electromagnetic compatibility within the data
center environment;
2
• Adherence to all local electrical codes, and
listed with a nationally recognized test lab.
In addition, it is recommended that complete
4
system bonding be observed over the entire net-
Finally, the entire
The connector is then work to minimize any electrical potential dif-
system is bonded from
bonded to the
the rack to MCBN ferences. Complete system bonding for any
patch panel
located in the ﬂoor
structured cabling system exhibits the following
characteristics:
• Electrical continuity throughout the rack;
• Bonds equipment and patch panels to racks/
cabinets;
Following these four steps with the Structured Ground System provides robust connections • Bonds each rack/cabinet to the telecommunica-
that have low resistance, are easy to install, and are easily checked during inspections. tions grounding busbar (TGB); this may ➤


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YOUR COMPLETE SOURCE FOR GROUNDING PRODUCTS

Grounding • Exothermic • Lightning Protection

Grounding Busbars

• UL Listed
• Meets ANSI-J-STD-607-A
Requirements
• Kits Available

Harger Lightning & Grounding
301 Ziegler Drive, Grayslake, IL 60030
Phone: 847.548.8700 • 800.842.7437 • Fax: 847.548.8755
Website: www.harger.com • Email: hargersales@harger.com

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Shielded cable/jack

be done via a mesh common bonding network This shielded cable and jack
(MCBN); combination from Panduit pro-
• Bonds the telecommunications grounding vides 360° shielding termination.
system to the alternating-current (AC) ser-
vice panels serving the IT equipment in the We recommend a 4-step
room; such bonding promotes equivalent process to properly bond the
ground potential between the IT equipment shield at the patch panel:
grounding and the equipment ground of the Foil of 1. Bond all the shielding
shielded cable 360˚
power system(s) serving the IT equipment; termination (foil and/or braid) of the
• Proper bonding and grounding elements cap data cable to the shielded
(clear covers, ID labels, green-coded conduc- jack module, which provides
tors) to aid in visual verification of the system. 360° shielding termination.
2. Snap the jack module into an all-metal patch panel to
Best practices for shielded create a bond between the module and the unpainted tabs
For shielded cabling systems, the additional step of bonding the on the patch panel.
cable shield is essential to ensure proper system performance. 3. Attach the patch panel to the rack using thread-forming
The foil screen in Category 6A shielded cabling already pro- bonding screws; the thread on the screws removes paint
vides enhanced system performance by preventing unwanted from the thread holes on the rack, and the serrations on
cable-to-cable signal coupling (i.e., alien crosstalk). A proper- the head of the screws remove paint from the patch panel,
ly bonded and grounded shielded cabling system further pro- creating a high-performance electrical bond between the
tects twisted pairs from external noise by carrying induced patch panel and the rack.
current along the continuous foil shield of the cable to the 4. So long as electrical continuity exists throughout the rack,
transceivers at each end of the cable. the last step is to bond the rack to the main busbar or MCBN
located under the data center’s raised floor. 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 field 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: Grounding the cable shield
During installation, a frequently asked question is whether the
installer should ground one or both ends of a shielded cable
channel. 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.
The rack is tied to the telecommunications grounding system,
which in turn is bonded to the AC power system.
The other end of the channel terminates outside the data
_____________________________________
center at the workstation outlet. An issue to considere is wheth-
er a shielded cabling link at this outlet location can be ➤


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