bling Signals transmitted via copper react to electrical interference or "noise" on the line. Power lines, lights, and electric machinery can all inject noise into the line in the form of electric energy. This is why interference from signals such as copiers, magnetic sources, manufacturing devices, and even radio stations can introduce noise and static into telephone calls and data transmissions. One way to protect copper cabling from noise and crosstalk introduced by nearby wires is to twist each insulated copper wire of a two-wire pair. Noise induced into one wire of the twisted pair cancels an equal amount of noise induced in the other wire of the pair. Crosstalk occurs when electrons that carry the conversations or data along a copper pair cross over, or "leak," on to other nearby wire pairs. Another electrical property of copper wire is resistance. Resistance causes signals to weaken as they are transmitted. This is referred to as attenuation. Attenuation is the Computing and Enabling Technologies reason signals on copper cable in the outside network need to be boosted on cable runs of more than approximately 1.5 miles. In contrast, because signals are non-electrical, signal on a high-performance fiber-optic cabling can travel 80 miles before it needs to be strengthened. Thus, the dual inherent impairments of interference and resistance are the key factors that limit copper's performance. Using Structured Cabling Standards to Uniformly Support Higher Speeds on Copper Cabling Cabling standards have been created to support ever-higher speeds, carry multi-media traffic, and ensure that organizations can purchase cabling and connectors from diverse manufacturers without risk of incompatibility. Each cabling standard includes defined tests that should be performed when cables are installed to ensure that it and all of the connectors perform to their specifications. Every new standard needs to be compatible with all lower standards. This allows applications that operated over lower-category cabling systems to ope