There are many cheapo cable testers on the market that will check for continuity, polarity, and length. However, if you are installing Category 5 or above cable and want to verify that the cabling and termination devices are adequate to support 100MB or faster service, then you will need to use a more expensive cable scanner such as a Microtest Penta or Fluke DSP4000. These scanners not only check cable continuity, polarity and length, but also test Near and Far end Cross Talk, Attenuation, and other parameters that are necessary to verify that your cables are performing at their specified levels. There are alot of factors that can contribute to the degredation of UTP cable links. Kinks in the cable, excessive bends, untwisting of pairs at termination points, improper pin-outs, to name a few, can prevent the transmission of higher speeds on cables that test "Good" on a low end cable tester.
