Nearly-electrocuted copper-cable thief speaks remorsefully

Several UK-based news sources have reported on the fate of 22-year-old James Sorby, who was nearly electrocuted by 22,000 volts of electricity while trying to steal copper cable from an electrical substation.

One of those sources, The Daily Mail, ran a story that includes graphic photos of Sorby shortly after his ill-fated theft attempt. The story also includes an image of Sorby's scarred hands. You can see the story here, but please be aware that you may find the images disturbing.

In remorseful comments, Sorby told legal magistrates, "My message is, 'Don't do it.' Before I did this, it was just an idea and there was no danger to it. Everyone thinks it's so easy and they have no idea how stupid they're being. When you think of getting involved in something like this, you don't think of the danger."

Sorby's plight was in the news because he was due to be sentenced for his crime. The Yorkshire Evening Post reports his sentence was a 12-month supervision order.

Encircled flux: A practical view

by Eric Pearson, CFOS

I have been following the encircled flux (EF) standard from the sidelines. From this position I do not have the entire picture. With that understanding, I offer the following information.

Any measurement method has three objectives. First, the measured loss should indicate that the link will or will not work. Second, a subtle objective, the measured loss should indicate proper installation of the link components. Third, the measured loss should be the same with test equipment from different manufacturers.

Let's look at the first objective: The measured loss should indicate that the link will or will not work. The EF method of defining launch power distribution is a compromise of the distribution for the two types of multimode light sources: LEDs and VCSELs. In this characteristic, compromise, the EF method is no different from the coupled power ratio (CPR) method required by TIA/EIA-568-B. However, the EF method is a compromise that is different from that of the CPR method of TIA/EIA-568-B.

There are two consequences of this compromise. The first consequence is that the measured loss will be less than the loss experienced with an LED transmitter (100Base-F or 100Base-SX). The risk with testing for loss from LED transmitters is that an acceptable measured loss may not result in proper operation. Thus, troubleshooting and installation costs can increase.

The second consequence is that the measured loss will be greater than the loss experienced with a VCSEL transmitter (1000Base-SX or 10GBase-SX). The risk with testing for loss from VCSEL transmitters is that an unacceptable measured loss may not result in improper operation. Thus, installation or rework costs can increase unnecessarily.

Of course, if the link components (cable, connectors and splices) are properly installed, the measured loss is likely to indicate proper operation for either type of light source. But it is this objective -- determination of proper installation -- that is the second objective of any test method.

Let's look at the second objective: The measured loss should indicate proper installation of the link components. Both the EF and CPR methods have the same difficulty with indicating proper installation. This difficulty results not from the test method, but from the TIA/EIA-568 standard. The TIA/EIA-568 standard recommends a method of calculation of the loss acceptance value. This method uses the maximum attenuation rate and connector loss values. This method conflicts with the reality of proper product installation. Properly installed cables, connectors and splices will have actual losses that are closer to the typical losses than they are to the maximum losses. Thus, neither EF nor CPR test methods can fulfill the second objective of a test method.

Such fulfillment requires the designer and installer to establish their own method. In our fiber-optic installation and design training programs and texts, including Successful Fiber Optic Installation - The Essentials, we at Pearson Technologies recommend a method to resolve this difficulty.

For now, let's look at the third objective: The measured loss should be the same with test sources from different manufacturers. While writing about encircled flux recently you stated, "In the meantime, there was poor correlation among labs when international round-robin testing was initially conducted. Another round-robin test is now underway." Obviously, the EF method does not yet meet this objective.

What are the network designer and installer to do? Because, apparently, losses measured with test equipment from different manufacturers do not yet agree, designers and installers should reference the TIA/EIA-568-B test method (CPR). When the EF test method is shown to create no problems for the installer and tester, the designer and installer can reference the TIA/EIA-568-C test method (EF). Of course, doing so may require purchase of new test sources and/or equipment.

We justify this recommendation with two facts. First, the CPR method of TIA/EIA-568-B does result in the same measured losses with test sources from different manufacturers. Our testing indicates that losses are with 0.05 dB of one another. this value is less than the repeatability value of 0.2 dB stated on many connector data sheets. Second, the CPR method results in the same measured loss with test sources that have a CPR ratio that is slightly outside of that defined in TIA/EIA-568-B. In 2003, testing conducted by Pearson Technologies demonstrated these two facts.

Eric R. Pearson, CFOS is president of Pearson Technologies Inc. You can reach him via email at fiberguru@ptnowire.com.

Cisco's PoE Passthrough switch powers itself

Cisco Systems has developed a Power over Ethernet Passthrough switch, which powers itself. In a video Narayanan Krishnamoorthy, a technical marketing engineer with Cisco, explains that the concept of PoE Passthrough is power coming into the switch from uplink ports that are PoE and PoE-Plus-capable. The switch uses that power to power itself, and if excess power is available, the switch allocates that power on the downlink ports.

The switch has no power supply and is cooled by convection, as is pointed out in the video. As a result, the switch is fanless and therefore quiet. Krishnamoorthy says Cisco put its best engineers on the project of developing the PoE Passthrough. A key technological breakthrough was the development of a chip to accept PoE coming through the uplink.

The in-house Cisco video, as we might expect, gushes over the switch's capability.

Take a look.

Reader lambastes shielded-cabling coverage

In a guest-commentary article that will be published in Cabling Installation & Maintenance's June issue, magazine reader Gautier Humbert takes the magazine's editor to task for authoring an article that Humbert believes tells only one side of a technical story. Humbert is a business development manager for Legrand in East and Central Europe. The article with which Humbert takes issue is The technical realities of twisted-pair beyond 10G, published in the magazine's April 2011 issue. That article, authored by magazine editor Patrick McLaughlin (OK, I'll admit it, that's me), was derived in large part from a Web-delivered seminar that took place in January. That seminar was entitled Twisted-Pair Cabling and Higher-Than-10G Transmission, and can be seen and heard here. During the seminar, presenters told of the then-current state of affairs within standards bodies to establish bona fide cabling and/or networking standards through which twisted-pair cabling systems would support Ethernet transmission at 40 Gbits/sec. The seminar also included discussion of the reasons such standards efforts are being proposed -- or, said differently, the seminar included advocacy for such standards proposals.

In his commentary article, Humbert makes the argument that foiled/unshielded twisted-pair (F/UTP) cabling, not shielded/foiled twisted-pair (S/FTP) cabling, is likely to be the medium of the future. The article and corresponding seminar included significant information about the characteristics of S/FTP cabling. In addition to making an argument based on a combination of technical and market factors, Humbert chastises McLaughlin (me) for penning an article that told just a single side of the story. He says, "The fact that some manufacturers use tools like one-viewpoint white papers to push their solutions is not new. If any company wants to do this, I think they have the right to. But for this magazine to support it, I believe, is a mistake."

Cabling Installation & Maintenance's June issue will be mailed to subscribers in the middle of the month and will be available online at approximately the same time.

Rather than take a defensive posture and develop creative ways to challenge Gautier Humbert's stance, I'll recall one of the more famous lines from U.S. Senator Scott Brown's campaign, in which he won the Senate seat that had been vacated with the passing of the late Senator Edward Kennedy. During one of Brown's debates with Massachusetts's Attorney General Martha Coakley, Brown stated (and I'm paraphrasing here but you can watch it on YouTube), "It's not Kennedy's seat. It's the people's seat." In a similar vein, Cabling Installation & Maintenance is not my magazine. I'm privileged to serve as its editor and I hope that in doing so, I'm actually serving you. My own inherently biased opinion about the value of that article in our April issue is not what matters. Your opinion is what matters.

Young cabling professionals compete at WorldSkills

The profession we know and love, cabling, is part of the annual WorldSkills Competition. Described by WikiPedia as a competition for youth from 17 to 22 years of age to demonstrate their excellence in skilled professions, WorldSkills is held every two years in a member country. The 2009 competition took place in Calgary, Canada and this year's event will be held in London in October.

WorldSkillsTV has posted a few cabling-specific videos from Calgary on YouTube. In the 90-second video embedded here, competitor Rounnachai Ampaipoka of Thailand reflects on his first day of participation in the event.



In a separate video from 2009, which you can see here, Fluke Networks' David Coffin discusses his company's participation as a sponsor of the 2009 competition.

You can visit the WorldSkills website here.

Oh, flux. There's more to the story.

Recently in some online postings as well as an article that appeared in the April issue of Cabling Installation & Maintenance magazine, we have brought you information about the recently adopted TIA-526-14-B standard that specifies encircled flux as the launch condition for installed multimode fiber cable. The TIA TR-42 Committee approved TIA-526-14-B in October 2010.

After seeing the article in our April issue, Jim Hayes, founder of The Fiber Optic Association and VDV Works, wrote to me. Within his letter, Hayes noted that the International Organization for Standardization (ISO), which first standardized the encircled-flux launch condition, did so based on research conducted by a single individual. Additionally, the research "only looked at multimode loss up to 2 dB." Hayes added that based on tests he (Hayes) conducted with another individual, at loss values higher than 2 dB, the technology used to achieve the EF launch condition "failed to even make two OTDRs agree, and the results were vastly different depending on the configurations of the cable plant."

Hayes also said that much of the EF analysis conducted when the TIA was considering adopting the EF specifications, was done using simulations of cable plants. "Real world data was scarce," he said. In the meantime, there was poor correlation among labs when international round-robin testing was initially conducted. Another round-robin test is now underway.

In his letter, Hayes noted CI&M's recent coverage of bend-insensitive fiber (pro and con), commending the magazine for "noting that there was still controversy in the marketplace." He added, "I think you should have treated encircled flux with the same skepticism."

The Fiber Optic Association has published and maintains a Reference Guide to Fiber Optics. The guide's section on Modal Effects on Multimode Fiber Loss Measurements includes information on encircled flux and its adoption by the TIA. That section describes EF as "a more precise method of defining mode fill," and "a more sensitive way of defining power." That section of the guide later explains that EF has been incorporated into several multimode testing standards, adding, "It is intended to create a more reproducible modal condition for testing that is similar to the CPR/mandrel wrap method ... Since EF is new (as of 2/2011), testing sources for EF [have] not been demonstrated to be well correlated between labs or manufacturers, so using it is not yet widely accepted. It will probably not be a widely used method before 2012."

You can read that section of the Reference Guide to Fiber Optics here.

This take on encircled flux differs from information we have published in the past, including this article from a year ago. Despite the questions that Hayes raises about the validity of EF across a range of loss values, it remains the specified launch condition in TIA-526-14-B as well as IEC 61280-4-1 edition 2, from which the TIA adopted it. We intend to follow the practical application of encircled flux, and describe its real-world use for testing installed multimode fiber plants.

Fiber installers, splicers needed in U.S. Southeast

Eric Pearson of Pearson Technologies Inc. is recruiting professionals experienced in fiber-optic installation and splicing to help restore the many telephone lines that were damaged by the storms that recently ravaged the U.S. Southeast region.

Pearson is looking for experienced outside-plant contractors and installers for a project that will begin promptly and is expected to take approximately 90 days. Applicants are expected to have their own equipment.

Pearson can be reached by telephone at 770-490-9991 or by email at fiberguru@ptnowire.com.