By Alma Krause on February 11 2018 12:12:30
A wiring diagram usually gives information about the relative position and arrangement of devices and terminals on the devices, to help in building or servicing the device. This is unlike a schematic diagram, where the arrangement of the components, interconnections on the diagram usually does not correspond to the components, physical locations in the finished device. A pictorial diagram would show more detail of the physical appearance, whereas a wiring diagram uses a more symbolic notation to emphasize interconnections over physical appearance.
Modern non-metallic sheathed cables, such as (US and Canadian) Types NMB and NMC, consist of two to four wires covered with thermoplastic insulation, plus a bare wire for grounding (bonding), surrounded by a flexible plastic jacket. Some versions wrap the individual conductors in paper before the plastic jacket is applied.
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.
The best way to understand wiring diagrams is to look at some examples of wiring diagrams. Click on any of these wiring diagrams.