By Susan Feldman on January 24 2018 16:16:51
In a typical electrical code, some colour-coding of wires is mandatory. Many local rules and exceptions exist per country, state or region. Older installations vary in colour codes, and colours may fade with insulation exposure to heat, light and ageing.
Cables for industrial, commercial and apartment buildings may contain many insulated conductors in an overall jacket, with helical tape steel or aluminium armour, or steel wire armour, and perhaps as well an overall PVC or lead jacket for protection from moisture and physical damage. Cables intended for very flexible service or in marine applications may be protected by woven bronze wires. Power or communications cables (e.g., computer networking) that are routed in or through air-handling spaces (plenums) of office buildings are required under the model building code to be either encased in metal conduit, or rated for low flame and smoke production.
Copper sheathed mineral insulated cables at a panel board. For some industrial uses in steel mills and similar hot environments, no organic material gives satisfactory service. Cables insulated with compressed mica flakes are sometimes used. Another form of high-temperature cable is a mineral insulated cable, with individual conductors placed within a copper tube and the space filled with magnesium oxide powder. The whole assembly is drawn down to smaller sizes, thereby compressing the powder. Such cables have a certified fire resistance rating and are more costly than non-fire rated cable. They have little flexibility and behave more like rigid conduit rather than flexible cables.
A wiring diagram is a simplified conventional pictorial representation of an electrical circuit. It shows the components of the circuit as simplified shapes, and the power and signal connections between the devices. A wiring diagram is often used to troubleshoot problems and to make sure that all the connections have been made and that everything is present.