Fiber optic cable not only gives you immunity to interference and greater signal security, but it’s also constructed to insulate the fiber’s core from the stress associated with use in harsh environments.

The core is a very delicate channel that’s used to transport data signals from an optical transmitter to an optical receiver. To help reinforce the core, absorb shock, and provide extra protection against cable bends, fiber cable contains a coating of acrylate plastic.

In an environment free from the stress of external forces such as temperature, bends, and splices, fiber optic cable can transmit light pulses with minimal attenuation. And although there will always be some attenuation from external forces and other conditions, there are two methods of cable construction to help isolate the core: loose-tube and tight-buffer construction.

In a loose-tube construction, the fiber core literally floats within a plastic gel-filled sleeve. Surrounded by this protective layer, the core is insulated from temperature extremes, as well as from damaging external forces such as cutting and crushing.

In a tight-core construction, the plastic extrusion method is used to apply a protective coating directly over the fiber coating. This helps the cable withstand even greater crushing forces. But while the tight-buffer design offers greater protection from core breakage, it’s more susceptible to stress from temperature variations. Conversely, while it’s more flexible than loose-tube cable, the tight-buffer design offers less protection from sharp bends or twists.

Resources:

White Paper - Fiber Optic Technology

Fiber Cable Selector

Multicolor Fiber Optic Patch Cables Data Sheet

1. UL® number and hologram: None, fake, or illegitimate. If there is no UL® number or hologram, that's an instant tip-off. Even if there is a number or hologram, you can look up the cable on-line at UL® to see if it's verified. Sometimes, even if there is a legit UL® number, it's possible that it was copied from "good" cable. UL also posts alerts on unauthorized numbers on its website.

2. ETL logos. Counterfeiters use them whether they are earned or not. Ask the seller for the ETL test results. You can also check the ETL website for a directory of verified cables.

3. Printing/Legend. Is the printing poorly done on the box and the cable? Are there any typographical or grammatical errors?  Check the UL® logo. It should have the letters UL arranged diagonally (descending left to right) with a circle with a small ® symbol directly below the U. Does the cable legend also have the proper markings?

4. Color. Does the color match previously bought cable?

5. Jacket/construction. Does the cable look like previously purchased cable? Are the conductors straight or oddly "twisty"? Does the jacket feel like a riser or plenum cable? Use a magnet to check that you're getting copper conductors instead of aluminum conductors. Just cut a few pieces of cable and see if a magnet picks them up. If it does, your cable is copper, not aluminum.

6. Weight. If the cable box/spool feels light, compare its weight to cable you know performs up to standard. Counterfeit cable and substandard cable often have undersized copper conductors or copper-clad aluminum conductors that weigh half as much as genuine cable.

One of the hottest topics during the past year has been the legal wrangling over counterfeit cable. Last year, Anixter sued Commodity Cables, Inc. The suit alleges that Commodity Cables sold substandard off-shore-manufactured cable that did not meet flame- and fire-resistance standards established by UL® and the National Fire Protection Association. Some of the cable in question was marked as being UL® certified or ETL Verified. Anixter is seeking $1 million in damages plus punitive damages for false advertising, unfair competition, breach of contact, and deceptive trade practices.

The basis of the suit stems from when Anixter said it discovered numerous boxes of cable with apparently fraudulent UL marks. Anixter sent the cables to UL for burn testing, which they failed. In December 2010, Anixter recalled all its Commodity Cables products from customers. Anixter has also worked with many customers to remove and replace the substandard cable.

In June 2011, Commodity Cables countersued Anixter. The counterclaim is a defamation allegation.

More information on the history of the suits can be found at Cabling, Installation & Maintenance. Or, read more about how to avoid unsafe, unapproved, or counterfeit cable.

Most cables are constructed with standard polymer jackets, which are combustible. Copper and aluminum are the most common metals used as conductors. Unfortunately, they’re good conductors of heat. The conductors can spread a fire by igniting surrounding flammable materials, such as the cable jacket. Then the jacket burns away, the conductors melt together, and the size of the cable bundle shrinks and causes gaps to develop within the cabling opening. This can be a major fire risk.

Firestopping is a term used to describe sealing and protecting openings and other joints between the cable and edges of the floor, wall, or ceiling. Firestopping was first practiced on U.S. combat ships in the 1960s. The walls and floors of the ships had steel tubes, which allowed conduits to pass through. Then, non-burning material was stuffed between the gaps, preventing the spread of fire and smoke. It wasn’t until the 1970s when larger companies began producing firestopping materials.

A successful firestop plan requires careful planning. Here are three tips to help you meet the needs of future cabling requirements and fire protection:

#1. Think long term

Most people tend to underestimate the size of the openings required for cabling and often forget about future expansion. When planning on how large to make the opening to run your cable, you must consider the diameter of the cable itself, how much room you need for firestopping materials, and whether you’ll be adding more cables in the future.

#2.  Different cabling systems require different firestops
There are two basic types of cabling systems: permanent and retrofittable. Permanent cabling systems, such as electrical cables, do not change. But most cabling systems, such as data and voice, have to accommodate moves, adds, and changes so they need to be retrofittable. You use different firestops with each system.

In permanent installations, a sealant is used in and around the cables. This is also appropriate for external areas, including conduits and sleeves.

In retrofittable systems, firestops need to be removed and reinstalled easily as cable needs change. Common firestops include pillows, putty, and fire-rated pathways. These products are packed in and around a cable bundle rather than being injected the way sealant is. The product to use often depends on the size of the cable opening and the frequency of changes.

#3. Use the proper materials

There are two basic types of materials used in firestopping: Passive firestopping uses nonintumescent materials, which draw heat away or insulate the cables. Passive materials include mortars, silicone sealants, foam, and grout. Cabling runs with passive firestopping are generally thicker and are more limited in the types of cables they can protect.

Intumescent materials expand when exposed to heat or fire and compensate for the loss of mass in cable bundles. They’re a good choice for sealing and surrounding cable holes and runs.

There are two primary organizations dedicated to developing and setting structured cabling standards. In North America, standards are issued by the Telecommunications Industry Association (TIA), which is accredited by the American National Standards Institute (ANSI). The TIA was formed in April 1988 after a merger with the Electronics Industry Association (EIA). That’s why its standards are commonly known as ANSI/TIA/EIA, TIA/EIA, or TIA.

Globally, the organizations that issue standards are the International Electrotechnical Commission (IEC) and the International Organization for Standardization (ISO). Standards are often listed as ISO/IEC. Other organizations include the Canadian Standards Association (CSA), CENELEC (European Committee for Electrotechnical Standardizations), and the Japanese Standards Association (JSA/JSI).

The committees of all these organizations work together and the performance requirements of the standards are very similar. But there is some confusion in terminology.

The TIA cabling components (cables, connecting hardware, and patch cords) are labeled with a “category.” These components together form a permanent link or channel that is also called a “category.” The ISO/IEC defines the link and channel requirements with a “class” designation. But the components are called a “category.” Follow?

The Standards
Category 5 (CAT5), ratified in 1991, was the de facto standard for 100-Mbps networks during the 1990s. It is no longer recognized by the TIA/EIA for use in data networking.

Category 5e (CAT5e)–ISO/IEC 11801 Class D, ratified in 1999, is designed to enable twisted-pair cabling to support full-duplex, 4-pair transmission in 100-MHz applications. The CAT5e standard added more headroom and established new requirements to support Gigabit Ethernet over a worst case four-connector channel. These include stricter specs for Near-End Crosstalk (NEXT) and Return Loss (RL). The standard also introduced the required measurements for Power Sum Near-End Crosstalk (PS-NEXT), Equal-Level Far-End Crosstalk (EL-FEXT), and Power Sum Equal-Level Far-End Crosstalk (PS-ELFEXT). CAT5e is still used in many organizations, although it is no longer recognized for new installations.

Category 6 (CAT6)–Class E has a specified frequency of 250 MHz, significantly improved bandwidth capacity over CAT5e, and easily handles Gigabit Ethernet transmissions. In recent years, it has been the cable of choice for new structured cabling systems. CAT6 supports 1000BASE-T and, depending on the installation, 10GBASE-T (10-GbE).

10-GbE over CAT6 introduces the problem of Alien Crosstalk (ANEXT), the unwanted coupling of signals between adjacent pairs and cables. Because ANEXT in CAT6 10-GbE networks is so dependent on installation practices, TSB-155 qualifies 10-GbE over CAT6 up to 55 meters and requires it to be 100% tested. To mitigate ANEXT in CAT6, it is recommended that you unbundle the cables and increase the separation between the cables.

Augmented Category 6 (CAT6a)–Class Ea was ratified in February 2008. This standard calls for 10-Gigabit Ethernet data transmission over a 4-pair copper cabling system up to 100 meters. CAT6a extends CAT6 electrical specifications from 250 MHz to 500 MHz. It introduces the ANEXT requirement. It also replaces the term Equal Level Far-End Crosstalk (ELFEXT) with Attenuation to Crosstalk Ratio, Far-End (ACRF) to mesh with ISO terminology. CAT6a provides improved insertion loss over CAT6. It is a good choice for noisy environments with lots of EMI. CAT6a is also well-suited for use with PoE+.

CAT6a UTP cable is significantly larger than CAT6 cable. It features larger conductors, usually 22 AWG, and is designed with more space between the pairs to minimize ANEXT. The outside diameter of CAT6a cable averages 0.29–0.35" compared to 0.21–0.24" for CAT6 cable. This reduces number of cables you can fit in a conduit. At a 40% fill ratio, you can run three CAT6a cables in a 3/4" conduit vs. five CAT6 cables.

There are two types of CAT6a cable, UTP and F/UTP. For a discussion of the differences, see the white paper in our Resources section.

Category 7 (CAT7)–Class F was published in 2002 by the ISO/IEC. It is not a TIA recognized standard. Class 7 specifies minimum performance standards for fully shielded cable (individually shielded pairs surrounded by an overall shield) transmitting data at rates up to 600 MHz. It offers greater capacity for demanding applications such as broadband video. It’s also well suited for applications where fiber optic cable would typically be used—but it costs less. Because each CAT7 pair is fully shielded, it's ideal for areas prone to EMI/RFI. Class 7 cable offers two connector styles: the standard RJ plug and a non-RJ-style plug and socket interface specified in IEC 61076-2-104:2.

Category 7a (CAT7a)–Class Fa is currently in ISO standards for channel performance in Amendment 1, recently component performance has been ratified in Amendment 2. The formal names are ISO 11801 Amendment 1 (2008) and ISO 11801 Amendment 2 (2010). Class Fa cable is a fully shielded cable that extends frequency from 600 MHz to 1000 MHz. It can easily handle 10-GbE and offers users a lifespan of 15 years or more. It has even been discussed that Class Fa cable is the future for 40GBASE-T or more.

Now that you’ve memorized the alphabet soup of cabling, how about a test? Just kidding. For a comparison chart of category performance standards, see the Buyer's Guide in the Resources section. Questions? E-mail info@blackbox.com.

If you’re accustomed to certifying copper cable, you’ll be pleasantly surprised at how easy it is to certify fiber optic cable because it’s immune to electrical interference. You only need to check a few measurements.

Attenuation (or decibel loss)—Measured in decibels/kilometer (dB/km), this is the decrease of signal strength as it travels through the fiber cable. Generally, attenuation problems are more common on multimode fiber optic cables.

Return loss—This is the amount of light reflected from the far end of the cable back to the source. The lower the number, the better. For example, a reading of -60 decibels is better than -20 decibels. Like attenuation, return loss is usually greater with multimode cable.

Graded refractive index—This measures how the light is sent down the fiber. This is commonly measured at wavelengths of 850 and 1300 nanometers. Compared to other operating frequencies, these two ranges yield the lowest intrinsic power loss (NOTE: This is valid for multimode fiber only.)

Propagation delay—This is the time it takes a signal to travel from one point to another over a transmission channel.

Optical time-domain reflectometry (OTDR)—This enables you to isolate cable faults by transmitting high-frequency pulses onto a cable and examining their reflections along the cable. With OTDR, you can also determine the length of a fiber optic cable because the OTDR value includes the distance the optic signal travels.

There are many fiber testers on the market today. Basic fiber optic testers function by shining a light down on end of the cable. At the other end, there’s a receiver calibrated to the strength of the light source. With this test, you can measure how much light is going to the other end of the cable. Generally these testers give you the results in dB lost, which you can then compare to the loss budget. If the measured loss is less than the number calculated by your loss budget, you installation is good.

Newer fiber optic testers have an even broader range of capabilities. They can test both 850- and 1300-nanometer signals at the same time and can even check your cable for compliance with specific standards.

Precautions to take when using fiber

Intrinsic power loss—As the optic signal travels through the fiber core, the signal inevitably loses some speed through absorption, reflection, and scattering. This problem is easy to manage by making sure your splices are good and your connections are clean.

Microbending—These are minute deviations in fiber caused by excessive bends, pinches, and kinks. Using cable with reinforcing fibers and other special manufacturing techniques minimizes this problem.

Connector loss—This occurs when two fiber segments are misaligned. This problem is commonly caused by poor splicing. Scratches and dirt introduced during the splicing process can also cause connector loss.

Coupling loss—Similar to connector loss, coupling loss results in reduced signal power and is from poorly terminated connector couplings. Remember to be careful and use common sense when installing fiber cable. Use clean components. Keep dirt and dust to a minimum. Don’t pull the cable excessively or bend it too sharply around corners.

These properties particular to fiber optic cable can cause problems if you aren’t careful during installation.

For more cabling tips visit our resources page.

It's estimated that up to 20% of the cable for sale is now unsafe, unapproved, or counterfeit. Chances are that you've bought illegitimate cable and haven't even realized it! Cheap cable can really hurt you (literally) in the long run. Let's take a trip back in time to 1980. Remember the MGM Grand fire in Las Vegas? The fire spread so rapidly that eighty-four people perished. An electrical ground fault was to blame. What if counterfeit cable causes an accident where you work?

Below we've listed a few pro-tips of what are the sure signs of counterfeit or cheap cable:

1. Look for the UL number. If there is no UL umber, that's an instant tip-off. Even if there is a UL number, look it up to see if it's legit.
2. Look for the ETL logo. Ask the seller for the ETL test results and check the ETL website.
3. How is the printing? Is it poorly done on the box and cable?
4. Check for product manuals. Legitimate products will always include brochures or manuals.
5. Does the color match previous bought cable?
6. Compare the weight to cable you know performs up to standard.

Use these tips when you shop around for your next batch of cable. The last thing we want is for you to get burned on counterfeit cable. For more information and tips on how to avoid unsafe cable, listen to our "Complete Cabling Solutions" podcast, coming soon.

Do you have any cable horror stories? Share it with us so we can pass your wisdom on to others!

Do you have tangled and unsightly hanging cables in conference rooms in lobbies? Tidy-up those cables with the new coiled HDMI and USB cables. These cables are designed to make neater equipment connections on walls, counters, display stands, and desks.

The Coiled HDMI Cable (EVHDMI05) is well-suited for use with wall-mounted TVs, displays, and monitors. The Coiled USB Cable (USB10) makes desktop peripheral connections much tidier. Both make much cleaner connections for point-of-sale displays, directional signage, informational displays, and even home theaters.

The HDMI cables feature male/male HDMI connectors and can be used with DVD players, set-top boxes, and other digital audio/visual equipment. The USB 2.0 cables feature one Type A male and one Type B male connector and can be used with USB hard drives, printers, consoles, and other peripherals. To learn more go to http://www.balckbox.com/go/HDMIcables and http://www.blackbox.com/go/usbcoiledcable.