11
Shield Integrity Test
Wire Map testers use DC Resistance measurements to ensure the shield is correctly
terminated and presented in a cabling system. In Data Centers, where the shield is
typically grounded at both ends, any wire map tester will report the shield as connected,
even if one of the ends is not. That’s because the shield test is a simple DC Resistance
measurement. If the shield is open, it will find the remote unit using the building ground
(earth) or the shields of other cables. See Figure 5. This can result in a false PASS and
poor Alien Crosstalk performance.
Figure 5
Alternate electrical paths, such as through the building ground (earth) can
cause some testers incorrectly report the shield is properly connected
