Preventive Maintenance for Fiber-optic Connectivity _ HYPERLINE

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Video microscopes, like this

one offered by Fluke

Networks, let technicians in thefield inspect a fiber-optic

connector's cleanliness

without assuming the risks

associated with looking directly

into a fiber.

Preventive maintenance for fiber-opticconnectivity

Avoid having to take down a live circuit by properly cleaning and handling optical components

during termination.

by Patrick McLaughlin Courtesy of Cabling Installation & Maintenance Magazine

The growing use of fiber-optic cabling in environments in which the medium had previously been used

infrequently, if at all, has justifiably given bragging rights to those who view fiber as a preferred medium totwisted-pair copper. Yet that increased deployment has also raisedissues of termination best practices,

which can have long-term effects on the system's performance and reliability.

This article will focus specifically on the cleanliness of fiber endfaces, andcleanliness' impact on the long-term maintenance of an installed fiber

system.

"We are seeing some trends with what can be called the convergence of

LAN infrastructure, including applications such as security and industrial

networks," says Marcus Sullivan, LAN market manager with Corning

Cable Systems (www.corningcablesystems.com). "Today, fiber-optic

cabling is being run to some peri-pheral devices in locations that arenotnecessarily clean."

Furthermore, there are more termination options for optical circuits than

there had been in years past, including traditional epoxy/polish, anaerobic

epoxies, no-epoxy/no-polish, and even splicing. System installers willchoose one termination style over others for any number of reasons, from

technician skill-level, to insertion-loss requirements, to the physicalenvironment in which connections are being made.

Rugged environments

"On a factory floor, for example, a technician probably would not want to

set up a polishing station," Sullivan notes. "So, in that type of an

environment, pretermi-nated connectors will be a popular choice. In other

extreme-type environments, such as in the oil and gas industry, often the

objective is to terminate the fiber quickly. So, preterminated connectors are popular in those cases as well."

Regardless of the termination style deployed, and the location of that deployment, ensuring a fiber endface is

clean at the point of mating is critical to long-term system performance. In fact, mating a dirty endface to

another may permanentlydamage one or both of them.

"Often, we discover contaminated connectors during testing or troubleshooting," explains Harley Lang,

product manager for fiber-optic tools with Fluke Networks (www.flukenetworks.com). "Research we

have conducted with network owners and installers has pointed to contamination as the number-one reason

http://cim.pennnet.com/home.cfm



fiber links fail."

"We recommend cleaning and inspection as a preventive measure during installation," adds Mara White,

Fluke Networks' fiber-optic marketing manager. The potential for contamination in a terminationenvironment is significant, she also points out: "There are many different types of contamination, including

body oils, dust in the air, buffer gels, and even pulling lubricants. All can get onto the fiber endface during

installation."

Dirty fibers (left), the most common culprit in optical-circuit performance degradation, are easily identifiable,

especially when compared to clean fibers. (Images provided by Fluke Networks)

Randy Harris, Corning Cable Systems' product specialist for field-installable connectors and a fiber-systeminstaller for many years, recalls some other common cleanliness hazards. "Dustcaps can be key," he says. "It

is important to keep dustcaps on connectors before plugging them in. As a contractor, I saw my share ofempty adapter panels and connectors lying on a table, uncovered by dustcaps."

Fluke Networks' Lang says the issue even goes beyond the use of dustcaps. "Use dustcaps, but don't

assume they are protecting against contamination; the ferrule must be cleaned every time the cap comes off."Similarly, he adds, do not assume a patch cord is clean when it comes out of the bag. Clean it before

plugging it in.

Keep circuits live

Taking a circuit down to clean it can and should be avoided. According to Jim Hayes, founder of the formerFOTEC (Fiber Optic Test Equipment Company) and also founder of The Fiber Optic Association(www.thefoa.org), taking down a live fiber circuit is a last-resort option. "Phone companies simply do not

conduct maintenance on fiber-optic networks," he says. Citing the Bernstein-Telcordia report issued earlierthis decade, Hayes says a fiber-to-the-home network will pay for itself in 20 years by reducingor

essentially eliminatingthe cost of maintenance.



This rendering shows a handheld fiber-cleaning tool that lets technicians in the field clean fiber endfaces quickly. (Image provided by USConec)

"Verizon will invest $22.9 billion on its FiOS network over four years," he says. "And they will save $4.9

billion in maintenance. The secret to maintaining a fiber-optic network is to install it properlyclean it, plugit together, and lock it up."

Equipment is available, and evolving, that will help installers and technicians in the field check on thecleanliness of fiber endfaces and clean them before termination. Fluke Networks' Mara says, "For several

years, the most effective means of inspection has been the optical microscope, which allows you to lookdirectly at the endface. The scope is economical, but does not allow you to look inside ports. A high-level

product is the video microscope, which allows inspection without having to hold anything up to your eye.The video microscope allowsaccess to high-density populated patch panels."

In addition to the video scope, a number of cleaning products have been developed over the past few years

that improve the quality of the cleaning process, and allow access to endfaces that previously were difficult

to clean effectively.

"A few products exist that allow technicians to clean a connector in their hand," explains Brian Teague,

product manager, cleaners, with USConec (www.usconec.com). These lever-activated cleaners dispense a

swath of cloth, making it easyto clean a connector that is in your hand.

"It is more difficult to clean the connectors in the back of a panel," he adds. "Behind-the-bulkhead cleaners

are also available that similarly use a precision-designed cloth to clean the connector." The device, he

explains, is inserted into thepanel's front, the user presses a lever, and a cloth advances to the connector inthe back of the panel.

Standards bodies have taken note of fiber cleaning's continued importance, and have written specificationscovering the practice. For example, the former FO-4 group within the Telecommunications Industry

Association's standards-making groupnow part of the TR-42 Engineering Committeehas sent to

publication a set of guidelines for evaluating connector-cleaning systems.

"The FOTP 240 specification is not a performance standard; it will not tell you how clean connectors need

to be," explains USConec's Mike Hughes.



"The informative annex at the end of the document may be the most valuable for many people," he

continues. "It talks about cleaning systems and the products availablewhat works and doesn't work, and

what to look for in certain environments. For example, an outside-plant environment is different from a datacenter, the fiber-cleaning needs of each will be different accordingly."

He further explains that a forthcoming standard from the International Electrotechnical Commission will

focus on how clean a connector should be. That standard will also discuss microscope characteristics suchas magnification and resolution, as well as image analysis.

Additionally, the International Electronics Manufacturing Initiative published a document of specifications onfiber-connector endface inspections.

Endface about-face

The best practice is that fiber-endface cleaning is gaining recognition as a critical step in fiber-system

deployment. For some network users, the lesson of endface-cleaning is learned the hard way, by

experiencing network sluggishness and ultimately having to take a circuit down before taking corrective

action.

But standards and an increased emphasis on cleaning by providers of optical-connectivity equipment may

make those tough lessons fewer in frequency and severity.

PATRICK McLAUGHLIN is chief editor of Cabling Installation & Maintenance.

Cabling Installation & Maintenance July, 2008

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Preventive Maintenance for Fiber-optic Connectivity _ HYPERLINE