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Wire Map Testers


A wire map tester is a device that transmits signals through each wire in a copper twisted-pair cable to determine if it is connected to the correct pin at the other end. Wire mapping is the most basic test for twisted-pair cables because the eight separate wire connections involved in each cable run are a common source of installation errors. Wire map testers detect transposed wires, opens (broken or unconnected wires), and shorts (wires or pins improperly connected to each other)—all problems that can render a cable run inoperable.


Wire map testing is nearly always included in multifunction cable testers, but in some cases it may not be worth the expense to spend thousands of dollars on a comprehensive device. Dedicated wire map testers are relatively inexpensive (from $200 to $300) and enable you to test your installation for the most common faults that occur during installations and afterward. If you are installing voice-grade cable, for example, a simple wire mapping test may be all that’s needed. There are also slightly more expensive (under $500) devices that do wire map testing in addition to other basic functions, such as TDR length testing.


A wire map tester consists of a remote unit that you attach to the far end of a connection and the battery-operated, hand-held main unit that displays the results. Typically, the tester displays various codes to describe the type of faults that it finds. In some cases, you can purchase a tester with multiple remote units that are numbered, so that one person can test several connections without constantly traveling back and forth from one end of the connections to the other to move the remote unit.

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