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  • Classification of Low Voltage Cables

    Low voltage data transmission wires are normally referred to as LAN cables or networking wires. However, their generic name is Unshielded Twisted Pair or UTP. Low voltage wires have many applications such as telephone lines, interconnecting computers on a network, and DSS.

    ISO / IEC have divided low voltage wires into different categories based on how much shielding they can provide from outside interferences. The higher the category number, the greater the shielding level and data transfer rate.

    The categories of low voltage wires are as follows:

    • Grade 1, Grade 2, Category 3 and Category 4: These wires are now obsolete, so no discussion is necessary.
    • Category 5:  This category comprises of unshielded twisted pairs of wires which offer an impedance of 100 Ohm and support frequencies less than 100 MHz.
    • Category 5e or Enhanced Category 5: This category is better than Category 5 in terms of performance. The specifications have also been improved for Near End Cross Talk (NEXT), Power Sum Equal Level Far End Cross Talk (PSELFEXT) and attenuation.
    • Category 6: This class is similar to Category 5e because it supports the same networking standards. Its advantage lies in the fact that it is compatible with lower category grades.
    • Category 7: This category supports frequencies up to 600 MHz and offers an impedance of 100 Ohm.
    • 10 Gig: This type has not been classified officially. It supports up to 10 GB transmission speeds.

    The standard wires used in computer and telecom applications belong to category 5, 5E and 6 because they reject more interference and support faster data transmission equipments. Each cable consists of four twisted pairs of insulated copper wire which is further enclosed in thick plastic. One cable can support 4 telephone lines or a single network connection. The ratings of category 5, 5E and 6 wires are 100 MHz, 350 MHz and 550 MHz, respectively.

    A few standards have been set with low voltage wires. These are:

    • The cabling has been restricted to 100 meters or 328 feet.
    • The minimum grade for structured wiring is Category 5e.
    • When installing, all components used must be compatible with that category to achieve optimal performance.