When it comes to the testing of installed copper and fiber cabling, many factors can influence the outcome.

Successful testing can be accomplished by following appropriate industry and manufacturer guidelines along with some common practices and tips from the field. The information provided is not all-encompassing but is intended help mitigate common issues faced when testing installed copper and fiber cabling systems.

Test Equipment

Certification test equipment should be well maintained, paying particular attention to the condition of all test adapters and associated cords, these should be inspected regularly. Look for things like worn connectors/cables and any obvious damage or debris in the connector interface between the test adapter and tester mainframe.

Ensure you are always running the latest firmware/software from the manufacturer on your test equipment, so you have the latest features and test limits.

Ensure your test equipment is within the recommended calibration interval, typically 12 months.

Proper training of all technicians using the equipment is a must. Contact the manufacturer for training.

“Successful certification testing begins with the right setup — from correct test limits and adapters to well-maintained equipment and trained technicians.”

Test Setup

Always use the correct test setup in the tester (test limits, cable, connectors, labeling scheme, etc.) and the appropriate test adapters for the test to be performed.

Common test types and adapters for copper:

• Permanent Link Testing – Typically a patch panel at one end and telecommunications outlet (jack) at the other end, use Permanent Link adapters.
• Channel Testing – When patch cords/equipment cords are connected to the link at each end and are to be included in the test, use Channel adapters.
• MPTL Testing – Patch panel at one end and a 8P8C (RJ45) modular plug at the field end, commonly used for connecting wireless access points, cameras and other devices. Use Permanent Link adapter on the Main unit at the panel and Patch Cord adapter rated for the category (Cat5e, Cat6 or Cat6A) of installed cabling at the field end. A common mistake here is using a Channel test adapter instead of a Patch Cord adapter.

For fiber, some additional considerations:

• Use appropriate test connector interfaces and test reference cords for the type of connector on the fiber under test. Most manufacturers provide interfaces and test reference cords to accommodate the most common types, such as LC, SC and ST terminated fiber, minimizing the need to use between-series cords.
• Before each testing day, inspect all optical test reference cords, both a visual examination for damage/wear but also examine the connector end faces using a fiber inspection microscope to check for contamination or damage. Damaged or dirty connector endings result in excessive loss and can contribute to test failure. Clean/replace as needed.
• Periodically inspect the light source/Transmit/Tx ports of both the Main and Remote units so ensure they are clean and free of damage. This should be performed using a fiber inspection scope.
• Periodically inspect the optical power meter/Receive/Rx port interface for dirt/damage. This is a visual inspection, remove and clean the interface adapter if necessary. Unlike the light source port, there is no connector end face to inspect.
• Use the correct fiber test reference cords for the fiber under test. A common error which will result in a call to technical support is using a singlemode test reference cord for a multimode test and vice versa. With multimode testing, ensure your test setup is Encircled Flux compliant and that the core diameter of your test reference cords is the same as the fiber under test, for example don’t use 50/125 OM4 test reference cords when testing OM1 62.5/125 OM1 installed fiber.
• Always follow the appropriate set reference procedure prior to testing. The most common, and recommended, set reference procedure is the “One Jumper” method, where a single test reference cord is connected between the Main light source and Remote power meter and a second cord is connected between the Remote light source and Main power meter of the Optical Loss Test Set. The One Jumper method is recommended for testing between fiber distribution panels on opposite ends of the link or from a panel to a fiber end point. Two Jumper and Three Jumper set reference methods are for testing situations where there is a patch cord or equipment cord to be included/considered as part of the fiber under test at one or both ends of the link. Allow your OLTS warm up after powering on before setting reference, based on manufacturer’s specifications.
• Use a fiber optic inspection scope to examine the connector end faces of the installed fiber. Clean if necessary and inspect again to ensure the cleaning was successful. Cross-contamination due to dirty connectors on installed fiber is the most common cause of test failure due to excessive loss.

“For fibre testing, clean connectors are not a minor detail — they are often the difference between a valid pass and an avoidable failure.”

Best Practices and Tips From the Field

• Do not place your tester on a known source of electromagnetic interference (EMI), such as a power transformer. This can interfere with the measurements and cause test failures.
• Select the correct cable from the cable library on your test equipment. This is not only a record-keeping detail for your test results but will ensure the correct NVP (nominal velocity of propagation) is set for the cable under test. The NVP value directly relates to accuracy of length measurement for copper cabling.
• The most common copper certification test failure is NEXT (Near-End Crosstalk). Testers typically include a TDR trace function to help isolate where the problem is worst along the length of the cable. Visual inspection is also required. Common causes of NEXT failure include:
  • Mixed categories of cabling/termination hardware
  • Improper termination – check that pair twist was maintained properly up to the point of termination, or bare conductors with damaged insulation.
  • Split pairs
  • Incorrect/substandard components
  • Incorrect/defective test cables or test adapters
  • Excessive EMI in the environment
  • Too much compression by cable ties or supports on bundles
  • Cable kinked during installation or damaged by excessive force used when installing cable
• For fiber optic certification, some equipment, other than the OLTS, is recommended for all technicians testing fiber:
  • Connector cleaning system for cleaning fiber connector end faces
  • Visual Fault Locator (VFL) to assist in finding breaks at one end or the other
  • Visual Inspection scope/probe to allow technicians to inspect connector end faces
  • Spare test reference cords.
  • OTDR for pinpointing events causing fiber loss and finding breaks along the installed fiber
• Fiber optic connector cleaning. This is mentioned again, as it is SO important. This applies to both connectors to be mated during the testing. Inspect, clean if needed, inspect again. Example of before and after cleaning:

Test Results

Correct test results are the ultimate goal of successful certification testing of installed copper and fiber cabling systems and are commonly required by the end customer, the specifier and/or the cabling system manufacturer providing the extended warranty.

By following the proper procedures and guidelines, you will be able to provide the test results your clients require. Test reports:

• Provide to the end customer proof of quality
• Protect the installer
• Support manufacturer extended warranty
• Include the following:
  • Complete test results
  • Details about the equipment used, including calibration date
  • Test configuration
  • Application compatibility information based on the test results