Wiring

Several types of wire conductors are used to connect electrical systems. Common ones include single wires, twisted pairs, coaxial cable, flexible flat cable, and bundled wires. Single or multiconductor cables are feasible when few connections are needed. However, as product complexity increases, direct wiring becomes costly and unwieldy and other interconnection systems become necessary. Flat cables, sometimes called ribbon cables, contain numerous conductors embedded side by side in flexible strips of plastic insulation. These cables can be mass terminated at low cost. Flat cables carry more current and usually weigh less than round cables having conductors of corresponding size. Nevertheless, flat cables are more commonly used to carry digital signals rather than power. In digital applications, cable qualities that affect signal degradation are more important than current ratings. Cable surge impedance, for example, should match that of connected circuits. Also, if cable capacitance is too high, it can cause crosstalk that garbles data. High-speed signals call for flat cables with low transmission loss. Conductors in flat cable can be round or rectangular. But rectangular-wire cable costs more, so it is generally used only where cables