use：
A cable is a cable that carries telephone, telegraph, fax files, television and radio programs, data and other electrical signals. It is formed by twisting a pair of mutually insulated wires. It is a communication line composed of a plurality of mutually insulated wires or conductors and an outer sheath that protects the cable from moisture and mechanical damage.
Use characteristics：
1. Long-distance cable: The transmission distance is long, and it is generally reused. Most of them are buried directly in the ground. In a few cases, it is installed by overhead or installed in the pipeline. 2. Cables in the city: The wires in the cable are “paired in pairs” and have many logarithms. Generally installed in the pipeline, a small number of city cables are attached to the building or installed overhead. 3. Local office cable: mainly refers to the communication cable used in the telecommunications bureau, generally installed on the distribution frame, and some are installed in the cable trough; the local cable is used between the transmission equipment and the switching equipment in the telecommunication office, and other The inside of the in-house equipment. In order to prevent fire inside the telecommunications bureau, it is sometimes necessary to add a flame-retardant jacket to the office cable.
