Conductors and Insulation
The term conductor is used in two ways. It is used to describe:

1. the current-carrying portion of a wire or cable

2. the wire or cable composed of a current-carrying portion and an outer covering insulation

In this module, the term will be used to describe the wire assembly, which includes the insulation and current-carrying portion of the wire.

Conductors are identified by size and insulation material.

Size refers to the cross-sectional area of the current-carrying portion of the wire. The ampacity is affected by the conductor material and size, insulation, and installation location.

More Information on Conductors and Insulation
• Wire Size: Wire sizes are expressed in gauge numbers.
• Ampacity: Ampacity is the current in amperes a conductor can carry continuously under the conditions of use, without exceeding its temperature rating.

• Conductor Material: The most common conductor material is copper. Copper is used because of its excellent conductivity (low resistance), ease of use, and value.

• Conductor Insulation: A conductor is surrounded by insulation to prevent current leakage or short circuits.

• Fixture Wires: Fixture wires are used for the interior wiring of fixtures and for wiring fixtures to a power source.

• Cables: Cables are two or more insulated wires and may contain a grounding wire covered by an outer jacket or sheath. Cables are usually classified by the type of covering -- non-metallic (plastic) or metallic.