By Alma Krause on February 27 2018 07:59:10
Wiring installation codes and regulations are intended to protect people and property from electrical shock and fire hazards. They are usually based on a model code (with or without local amendments) produced by a national or international standards organisation, such as the IEC.
In North American practice, an overhead cable from a transformer on a power pole to a residential electrical service usually consists of three twisted (triplexed) conductors, with one being a bare neutral conductor, with the other two being the insulated conductors for both of the two 180 degree out of phase 120 V line voltages normally supplied. The neutral conductor is often a supporting "messenger" steel wire, which is used to support the insulated Line conductors.
Essential for pre-study works, the wiring diagram allows the cable list to be produced. If the wiring diagram is useful during the pre-study phase, it is also an important tool for the design of the installation functional scheme. Starting with the wiring diagram, the user can start producing his installation as a pre-study, and then launch his study during the installation cabling, allowing a reduced production time.
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.
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