By Stacy Calhoun on January 31 2018 20:21:43
The best way to understand wiring diagrams is to look at some examples of wiring diagrams. Click on any of these wiring diagrams.
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.
Most of wiring diagram software has a unique feature for electrical cabling: the wiring diagram or single line diagram, allowing a simplified representation of an electrical cabling installation in pre-study phase.
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.