Wire sizes are expressed in terms of their diameters in inches. The diameter of a wire dictates the amount of electricity that can flow through it and is expressed using gauge numbers.
Wires are used for a wide range of applications and in different environments and need to be protected from water and corrosion. Exposed wires are dangerous when carrying heavy current, making insulation necessary for safety. Some of the insulation types are THW-2, THHN, TFFN and TFN -- all made from PVC. They are thermoplastic insulations with THW-2 and THHN designed for wet environments, and TFFN and TFN made for dry areas only.
The amount of current flowing through a conductor is dictated by the size of the wire. This is known as the load carrying capacity of the wire, which is the limit of electricity that can flow through a conductor without any damage or loss of power. The load carrying capacity is expressed as the ohm per unit length in feet or kilometers.
Plugs connect a circuit to power supplies through receptacles. They are also known as the male receptacle in a connection. There are different types of plugs depending on the country of application and manufacturer. There are flat blade plugs and round pinned plugs, with two or three pins. Some plugs have both round and flat pins.