A solid wire is composed of a copper metal wire, which is either bare or surrounded by an insulator. Single stranded copper conductors are commonly used as enameled wires in motors and transformers. They are relatively rigid and not prone to bending, and are usually installed in xxx performance, infrequent handling, and low bending applications. Twisted wire has a set of copper wires woven or twisted together. Compared to large single stranded wires with the same cross-section, multi stranded wires are more flexible and easier to install. Twisting can improve the lifespan of wires in vibration applications. The specific cross-sectional area of stranded conductors gives them the same resistance characteristics as single stranded conductors, but increases flexibility. A copper cable consists of two or more copper wires running side by side and bonded, twisted, or woven together to form a single component. Twisting wires can make cables more flexible. The copper wire in the cable may be bare or coated with a thin layer of another metal (most commonly tin, but sometimes gold or silver) to reduce oxidation. Electroplating can extend the lifespan of wires and make welding easier. Twisted pair and coaxial cables are designed to suppress electromagnetic interference, prevent signal radiation, and provide clear characteristics for transmission lines. The shielded cable is wrapped in foil or wire mesh. Application of Copper Conductors: Electrolytic Toughened Pitch (ETP) Copper is a high-purity copper containing oxygen as an alloying agent. Due to its high conductivity and improved annealing ability, it represents the majority of electrical conductor applications. ETP copper is used for power transmission, distribution, and telecommunications. Common applications include building wires, motor windings, cables, and busbars. The use of oxygen free copper to resist hydrogen embrittlement during bulk cold processing is necessary and suitable for applications that require higher ductility (such as telecommunications cables). When hydrogen embrittlement is a problem and low resistivity is not required, phosphorus can be added to copper. For certain applications, copper alloy conductors are preferred over pure copper, especially when higher strength or improved wear and corrosion resistance are required. However, compared to pure copper, the higher strength and corrosion resistance advantages provided by copper alloys are offset by their lower conductivity. Design engineers weigh the advantages and disadvantages of various types of copper and copper alloy conductors when determining which type to specify for a specific electrical application. An example of copper alloy conductor is cadmium copper wire, used in railway electrification in North America. In the UK, BPO (later PostOffice Telecommunications) used cadmium copper overhead lines containing 1% cadmium to increase strength; 40 pounds per mile (1.3 mm diameter) for local routes and 70 pounds per mile (1.7 mm diameter) for toll routes