Fluke Networks CertiFiber Pro Users Manual - Manual (Page 155)

Chapter 5: How to Diagnose Copper Test Failures
Causes of Twisted Pair Test Failures
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Insertion loss gives FAIL, FAIL*, or PASS* result
 Link is too long (may need to remove coiled service loops)
 Poor quality patch cord
 Bad connection (possibly shows insertion loss failure on only one or two
pairs)
 Wrong cable type in the installation
 Wrong test standard selected
 Wet lubricant in a conduit with unshielded cable. Possibly, the test will
pass after the lubricant dries.
Characteristic impedance exceeds the limit or an anomaly is detected
 Bad connection
 Cable compression (tight cable ties, pinches, kinks, etc.)
 Mismatch of cable types
 Water in cable jacket
Return loss gives FAIL, FAIL*, or PASS* result
 Patch cord or cable impedance not 100 
 Patch cord handling causing changes in impedance
 Excessive amount of cable jammed into outlet box
 Tight service loops in telecommunications closet
 Excessive untwisting of pairs at connector
 Poor quality connectors
 Cable impedance not uniform (poor quality cable)
 Mismatches in cable construction (such as cable from different
manufacturers)
 Water in the cable jacket (typically causes failures on all pairs at lower
frequencies)
-continued-
Table 7. Causes of Twisted Pair Test Failures (continued)