Ethernet Cable Testing Explained: Verification, Qualification, & Certification

Written by Don Schultz, Senior Technical Marketing Specialist, Fluke Networks Certified Copper/Fiber CCTT, BICSI TECH, INSTC, INSTF Certified

What level of testing does your Ethernet cable actually need to be considered good quality? If you are a professional installer with a contractual requirement to certify the installation then the level of testing is clear--you will require a Fluke DSX-8000 or similar expensive test instrument to certify to the relevant standard. How can you be sure your cable installation is “good” if you have only an inexpensive wire map tester at your disposal? Is simply wire map testing sufficient or do you need to qualify that the cabling can reach certain speeds? We will cover all of this and more! First, please watch the video and then return here for more information.

Why Testing Matters Before Sign-Off

Testing is a “must do” step after cable installation, and is often underestimated by installers who don’t install structured cabling systems for a living.

• Testing prior to job completion is often a warranty requirement — from cable manufacturers, equipment manufacturers, or the installation contract itself
• Customers frequently require proof of a working system before final payment or sign-off
• Testing imparts confidence that the cable plant works correctly, removing one variable from the mix of myriad issues an operational (live) LAN may experience now or in the future
• Testing before leaving the site provides the installer (and your customer) with proof the system works — minimizing costly rework or return trips if a problem surfaces later

Verification — "Is It Connected?"

Verification is a visual inspection of your installation in addition to basic wiremap testing. Wiremap testing is confirming continuity and correct pin-to-pin connections across the cable.

When it's needed

• As a quick check before more comprehensive testing revealing opens, shorts, reversed pairs, crossed/miswired pairs, and split pairs
• When used in conjunction with link negotiated application speed testing with live LAN equipment or more advanced testing post-installation

Strengths

• Easy to use
• Low-cost test device
• No formal training required

Weaknesses

• Provides no performance data whatsoever — a cable can be "connected correctly" and still perform poorly (or not at all)
• Won’t reveal defective cable unless a conductor wire is literally broken (not a very common situation)
• Cannot save or export test results for later printing

The "Pass" Trap

A cable can fully pass a continuity/wiremap test — every pin connected correctly — and still fail to negotiate a reliable 1Gbps link due to noise, excessive length, or other performance issues that a wiremap test simply cannot detect. Wiremapping confirms the cable is terminated to the correct TIA color code pattern (T568A or T568B); it says nothing about whether the cable will actually perform.

If this is the only tester you can afford or you are simply a “one and done DIY” person, then trueCABLE recommends using wiremap testing in conjunction with link speed application testing in a live LAN environment (with routers and switches, etc.) to confirm speeds attained. Troubleshooting will be trial and error.

Qualification — "Can It Do XX Gbps?"

Qualification takes wiremap testing and adds application speed testing — historically known as BERT (Bit Error Rate Testing).

When it's needed

• When full TIA certification isn't required, but you (or a customer) need actual performance data confirming the link or channel supports a specific or range of application speeds with a PASS or FAIL test result
• A customer is willing to accept qualification test set results, but demands printed test reports as proof of system performance

Strengths

• Good for application speed confirmation, cable length measurement, and more advanced troubleshooting beyond simple wiremapping
• Best suited for channel testing (the full channel including patch cords), but may be used for permanent link testing as well
• 1/10 the price of typical certification test sets
• Ability to store and export reports you may provide to a customer
• Qualification testers typically also offer advanced logical network testing, being of great use for IT administrators

Weaknesses

• Limited help in isolating highly advanced issues such as defective cable, water intrusion, or similar difficult to diagnose problems
• Qualification test results won’t be accepted by customers that demand true certification

Typically you will see qualification test sets as standalone testers with a device like the Fluke LinkIQ (no live LAN required), or live-system testing using a switch plus a more advanced field tester with switch link speed qualification features. There are a number of options available. The nod for versatility goes to testers that can provide application speed testing with no installed LAN equipment, as cable installers typically install a structured cabling system well before any LAN equipment is available.

If you or your customer does not require actual certification and you install cabling more than once a year then trueCABLE recommends a qualification test set as the ideal low(er) cost way of testing.

Certification — "Does It Meet TIA Standards?"

Certification is true physics level testing — measuring Return Loss, NEXT (Near-End Crosstalk), and other electrical parameters in dB, evaluated against the specific thresholds defined by TIA standards for a specific Category of cable.

When it's needed

• Certification test set test results are typically required for manufacturer warranties on structured cabling systems
• Professional/commercial installations where certification is contractually specified

Strengths

• Provides hyper-accurate test results with signal plots which leaves no doubt about test results
• Enables highly advanced troubleshooting of the most difficult issues with signal plots to determine precisely what is wrong and often the approach to solving the problem
• Provides an incredible level of granularity in test reporting
• Allows the technician to characterize the quality of a link or channel in relative terms like “passes, but could be better” or if the link or channel fails the ability to determine how serious the failure is as opposed to simple PASS/FAIL

Weaknesses

• Very expensive (as in brand new small car expensive) to buy, especially with accessories beyond the basic tester
• High TCO (total cost of ownership) due to yearly requirement for calibration and expensive replacement parts
• Significant learning curve to operate the equipment and interpret results correctly

trueCABLE recommends certification test sets for any installer that requires advanced troubleshooting and iron clad proof that a structured cabling system meets the TIA standard for performance and reliability. This assumes, of course, you can afford one!

Quick Comparison — All Three Tiers Side by Side

Here is a quick tester comparison table:

Which Level of Testing Do You Actually Need?

Well, does your project contractually or by warranty require certification? If yes, certification is non-negotiable. Be prepared to open your wallet and keep it open, or hire out the certification phase. For all other scenarios the selection of tester type will depend upon what you are doing and potentially how much money you have to spend.
If certification isn't required, qualification with either standalone equipment (like a Fluke LinkIQ) or an advanced field tester with IT/switch speed testing functions is the right level for most professional and “well heeled” prosumers. At minimum, confirm the switch link speed negotiated on each run.

As a last resort, or if your budget is extremely limited, then wiremap verification with no live system, followed by connecting live equipment (PCs, switches) and checking bandwidth performance after the LAN is installed is better than nothing, but it's the least rigorous approach and leaves you exposed to the "pass trap" described above.

For a more detailed description of the type of testers available (including fiber optical cable testers), please refer to Ethernet Cable Testers: Which Is Best for My Application?

Conclusion

Testing at some level is important to do, but the cost of the testers goes from inexpensive to expensive (but still affordable) to very expensive. This can put many in a “Catch-22” situation, unfortunately. Keep in mind these three tiers aren't interchangeable, and picking the wrong one either wastes money (like overtesting when qualification would do) or leaves you exposed (under testing when a customer or warranty actually requires certification). Match your testing level to your actual requirement, and you'll never be caught without the proof you need.

HAPPY NETWORKING!!

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