New testing indicates that a majority of Cat 6 and 6a patch cords are marginal or failing — 18 years after original testing showed the same result.
Quabbin Wire & Cable repeats a 2003 study and the results may surprise you
By Jim Rivernider, Chief Technology Officer at Quabbin Wire & Cable Co., Inc.
Abstract
Quabbin Wire & Cable recently evaluated the electrical performance of 56 different Cat 6 and 6a patch cords from various sources on the open market. Upon examination, Quabbin found that 60% of the cords failed to meet TIA’s critical performance requirements. Our 2003 study of Cat 5e and Cat 6 patch cords, “Most Patch Cords Fail Testing,” proved that 70% of the patch cords failed to meet return loss and/or crosstalk specifications. These two market surveys clearly demonstrate the importance of specifying high quality components in the assembly.
Reason for Market Testing
The increased speeds of Ethernet protocols in home and office settings require improved patch cord performance. In addition, higher performance Ethernet categories demand higher quality components and precise assembly techniques. Given these changes, we decided to revisit our 2003 study.
Many end users are unaware of the importance of patch cords to their network’s performance. At higher data rates, cords have a significant impact on network performance, error rates, and channel throughput. Poor network performance can negatively impact a company’s productivity; therefore, consistent and reliable network performance is paramount. Additionally, in the event of a network issue the Telecommunications Industry Association (TIA) recommends swapping out the patch cords early in the troubleshooting process. In some instances, users opt to purchase and install a new cable rather than troubleshooting the existing one. Many consumers focus solely on price while overlooking cord performance. And while testing patch cords was difficult in the past, today’s handheld testers provide users with a simple patch cord verification process.
In 2002 the TIA issued the industry’s first patch cord test procedure (TIA/EIA-568-B.2-1, Annex J). The procedure required expensive equipment and highly trained technicians, making testing costly. It wasn’t until 2003, when Fluke Networks introduced a patch cord adapter, that patch cord testing became more prevalent. While these adapters made testing simple and fast, many assemblers elected to omit testing assemblies’ performance. In 2003 we doubted the quality and consistency of many low-priced cords, even with the new easy testing ability – and it turns out we were right.
When revisiting the topic almost 20 years later we applied the most recent standard revision, ANSI/TIA-568.2-D, published in 2018 and which includes new specifications for Cat 6a and Cat 8 assemblies. With the availability of established specifications for Cat 6a and Cat 8 assemblies and affordable handheld testers from a variety of vendors, we expected to observe improved patch cord performance.
Patch Cord Selection
Consistent with the 2003 testing, we investigated cord “interoperability.” Simply put, if one uses and installs compliant components from different vendors, the system will comply. The TIA patch cord test ensures that a passing cord installed in a passing link will result in a passing channel. Since we concluded in 2003 that almost all Cat 5e components and cords are interoperable, our most recent study evaluated Cat 6 and 6a cables. Additionally, some Cat 6 and 6a hardware manufacturers’ system warranties are contingent upon installation of their proprietary cords. Since the TIA’s specifications pertain to component interoperability, we analyzed cords available on the open market and excluded system-proprietary cordage from the study.
Cat 6 and 6a cordage was also selected for the study after considering modernized industry protocols. The wide spectrum of emerging technologies precludes the installation and testing of cordage lower than Cat 6a. Many companies are utilizing 2.5G Base-T, 5G Base-T and 10G Base-T to support wireless applications such as WiFi 6. For these reasons the TIA is recommending Cat 6a, rather than Cat 5e or 6, to give new installations maximum headroom.
Previously, Cat 6 cordage was often used when the electrical performance exceeded actual network requirements, essentially enabling failing cords to work in network applications. No such fail-safe exists with Cat 6a. Simply put, the cord must meet TIA specifications in order for the channel to work. Thus, we sought to assess the performance of Cat 6 and Cat 6a cords since the new protocols were adopted.
We tested twenty-six Cat 6 and thirty Cat 6a rated cords. These 56 cords were purchased on the open market from 8 unique domestic vendors (including distributors, retail outlets, and assemblers). Most cords were either 2m (or 7ft) in length. Each cord was specifically identified by vendor and performance category.
Testing Procedure
Patch cord testing consisted of physical and electrical tests in order to obtain adequate data from which to draw a conclusion. We inspected packaging upon receipt and assigned each a score of poor, fair, or good, and recorded any damage to the patch cord caused by the packaging. Next, we removed the cord from the packaging and inspected it for any visible damage, type/connector quality, cable labeling, color, and length. We compared our inspection results with manufacturers’ marketing information. Next, we evaluated cord electricals using WireXpert handheld testers by attaching a tester to each end of the patch cord sample with the Cat 6a adapters and tested to Cat 6 or 6a TIA-Patch Cord 2M test. To ensure test data accuracy, each cord was tested twice. Upon completion of one test cycle, the cord was removed from the tester, reinserted, and tested in the opposite direction. Finally, we analyzed electrical performance, measuring return loss (RL) and near-end crosstalk (NEXT) per the TIA patch cord requirements. (See “What is Return Loss? Why is it Important?”“Effect of Return Loss and Impedance Stability on Premise Wiring Systems at Extended Frequencies,” and “Return Loss and Data Transmission” at Tech Briefs.)
Test Results and Evaluation
Approximately 65% of Cat 6 patch cords tested failed to meet the TIA requirements, with 16% of those either passing or failing marginally (<1dB margin). Surprisingly, these results are nearly identical to those from our 2003 study – suggesting that very little has changed in nearly 20 years! One unfortunate constant is that consumers continue to purchase cords that are likely to fail testing. While one would expect Cat 6a cords to perform better as a result of new and stricter requirements, we found that nearly 40% failed and an additional 40% marginally passed or marginally failed. While somewhat more promising than the 60% failing Cat 6 data, both groups of assemblies had about 80% marginal or failing cords.
NEXT accounted for most of the test failures; Cat 6 exhibited predominantly NEXT failures, while Cat 6a exhibited both NEXT and RL failures. Figure 1 below, which represents four unique Cat 6a patch cords (two UTP and two shielded), illustrates NEXT results for the 36-45 pair combination – generally the most likely to fail. Sample D (light blue) failed throughout the frequency range, whereas sample A (red) failed at low and high frequencies. These two sample results illustrate the difference between a failure (sample D) and a marginal failure (sample A).
Figure 2 below, which represents Cat 6 36-45 NEXT data, clearly illustrates sample A’s failure margin, with the worst result at almost 8 dB over the limit. It should be noted that a failure of this magnitude would also likely fail the less demanding Cat 5e test.
Figure 3 below, which represents the Cat 6a RL for the worst pair (brown), shows a decrease in margin when frequency increases and most RL failures occurring at low or high frequencies.
We also analyzed the correlation between Cat 6a cord price and electrical performance. Slightly more than half of cords (16 of 30) were purchased for under $10. Of those 16, only half passed. The remaining 14 cords were purchased for over $10. Unlike the less costly samples, almost all passed, seeming to justify the higher purchase price. For Cat 6, patch cord failures were evenly distributed regardless of price.
Although we obtained cords from a variety of domestic vendors, many samples came from one overseas manufacturer and underscored its marketplace prevalence. Also of note is that cords manufactured in the United States demonstrated a higher pass rate than similarly priced cords manufactured overseas.
When available, we compared customer reviews to test results. While most patch cords were rated 4.5 out of 5 or higher, suggesting most should pass electrical testing, we discovered that failing cords – even those rated favorably – had been subject to packaging complaints. We reasoned that buyers are not performing incoming testing or requiring vendor-supplied data. Most networks perform network “learning” and decrease network speed to accommodate poor channel performance. Thus, while poorly performing patch cords may “work” they don’t allow the network to work to its full capability. This underscores that a significant portion of the market is unaware that cords are failing and in fact assume they are working.
Conclusion
We assumed that the patch cords available on the market had improved since the results of our initial study were published. We were wrong. Once again, our study proved that most open-market cords labeled Cat 6 and 6a fail to meet the TIA’s published requirements. Despite the release of additional requirements and testing of twisted pairs over the past 20 years, some manufacturers still claim electrical performance that substandard cable and connectors are unable to deliver.
Based on the results of our study, network engineers and IT professionals should specify the highest quality cable and connectors for their patch cords. End users typically spend between $500-1000 per network drop, not including the patch cord cost, yet they risk their network’s performance by skimping on patch cords. Visit www.quabbin.com to view our patch cord selection and Patch Cable Part Number and Connector Reference Guide for a listing of superior connectors, suppliers, and Quabbin part numbers. Watch for our next white paper which will provide our unique and technical insight into specifying patch cords to assemblers.
About Quabbin Wire & Cable Co., Inc.
Quabbin is a high-quality manufacturer of electronic cables for numerous industrial, commercial, audio/visual/lighting and general purpose applications. These cables are manufactured in the U.S.A. and constructed to your exact specifications with proprietary, high speed equipment resulting in the right cable at the right price. Our capability of long, continuous lengths provides superior lot traceability and consistency. Advanced, real-time process controls monitor quality and consistency throughout the manufacturing cycle. This establishes a foundation of quality at the beginning of the cable supply chain and contributes to cost control by increasing assembly yield and reducing rework and scrap. Quabbin remains the trusted choice of Assemblers, OEMs, and Cable Distributors for 4 decades and counting.