Overview

This chapter focuses on the standard wire, cable, and electrical devices used in homes and offices, with emphasis on branch circuits. Many different kinds of standard wire and cable are available for use in 120/240-V AC branch-circuit wiring. Wire is defined as a single solid or twisted copper or aluminum conductor with or without insulation, and cables for power and lighting typically consist of two or more insulated wires and a bare ground wire with a protective jacket. There are also untwisted and twisted wire pairs for telephone service and coaxial cables for TV and Internet reception.

Conduit is tubing or pipe that encloses and protects wires and cables. It can be metal or nonmetallic, and rigid or flexible. In outdoor locations, conduit protects the enclosed wires or cable above ground from rain, snow, condensed moisture, and abrasion as well as accidental severence during excavation or trench digging. It is also used to protect buried cable. Short lengths of conduit are used under concrete sidewalks to make it easier to pull wires or cable under those obstructions. In addition, short lengths are used to protect wire or cable as it emerges from the ground to a meter base or other enclosure.

Conduit bodies are fittings that permit electrical metallic tubing (EMT) conduit to be joined in straight lengths or in 90 turns. Many different kinds of conduit connectors and couplings are available for coupling or connecting similar or dissimilar conduit. These products are made from materials such as zinc-plated...