ipment and cabling is grounding. A ground is a common elec- trical reference point which serves two primary purposes. The first, a power ground, is a matter of safety. Metal cabinets and racks housing equipment and cabling should be properly grounded to minimize the possibility of electrical shock to anyone coming into contact with them. This is done through grounding (con- necting with a wire) to cold water pipes or building steel. The second, a signal ground, is to ground the cable in order to enable proper transmission and reception of the signal with a minimum of distortion. As mentioned above, in many buildings, the cold water pipes are used for grounding. You may also ground to your UPS (uninterruptible power supply or battery backup) Grounding is really "completing the electrical circuit." A com- plete circuit ensures high-quality transmission. On the matter of safety, however, a person does not want to inadvertently become the object that completes the circuit! Advantages and Disadvantages of Twisted Pair Copper Cabling Some advantages of twisted pair cabling include the following: Many developments of new applications call for twisted pair. It is a flexible system. Distribution cables (feeder cables) are easily used and it is not necessary to home run all cables. The Telecom Handbook as 255 CABLE The same cabling can be used for voice and data communica- tions, saving on materials and labor, and therefore on expense. Many technicians are available for performing high-quality installations. It is often already in place, SO it may make sense to reuse it. Disadvantages of twisted pair include the following: It has limitations in terms of the speed (bandwidth) with which data can be carried. It is more likely to have crosstalk interference than other types of cable. It may be less secure than coax or fiber cable in terms of someone being able to tap into it. Coaxial Cable Another type of cable, more commonly used for data com- munications rather than voice, is coaxial cable, also known as coax. It is made up