77
CHAPTER 8: Testing Twisted-Pair Cable
8. Testing Twisted-Pair Cable
This chapter contains information about the fundamentals of testing
twisted-pair cables. It also discusses common wiring problems and reasons
that cables fail. Tables of troubleshooting tips are provided throughout the
chapter; use them for quick reference when troubleshooting a cable
segment.
8.1 Types of Twisted-Pair Cable
Twisted-pair cable is so called because of the physical make-up of the cable.
Two wires are physically twisted together along the length of the cable to
form a pair.
There are three basic kinds of twisted-pair cable: Unshielded Twisted Pair
(UTP), Shielded Twisted Pair (STP), and Screened Twisted Pair (ScTP).
Figure 8-1 illustrates the differences in the construction of twisted-pair
cables.
Figure 8-1. Twisted-Pair Cable Construction.
Although UTP is one of the most popular cable test standards to install, it
is also highly susceptible to a variety of failures if the cable is not properly
installed. The SCAN-LAN VI checks for these possible failures. The test or
tests you choose to run depend on whether you are performing a complete
check of cable characteristics compared to a standard (cable certification)
or troubleshooting a specific cable problem. See
Appendix A, Test
Standards
, for an explanation of various test standards.
The TSB-67 UTP Link Performance specification is becoming the
benchmark for installed UTP links and is the specification that the
SCAN-LAN VI design is primarily based on.
Unshielded Twisted Pair (UTP)
Shielded Twisted Pair (STP)
Screened Twisted Pair (ScTP)
or Foil Twisted Pair (FTP)
drain
Summary of Contents for SCAN-LAN VI
Page 2: ......