In electrical work, the term “conductor” refers to the wiring used to carry current from the power source to the end-user device. Different types of conductors are used in electrical installations, each with its own purpose and characteristics. One common type is nonmetallic-sheathed cable, consisting of insulated conductors and a ground wire wrapped in a plastic sheath. This type of cable is often used in residential applications. Another type is armored cable, which has insulated wires enclosed in a flexible metal housing. These cables provide extra protection and are commonly used in residential and commercial settings.
The outer sheath color of a nonmetallic-sheathed cable indicates the wire gauge and amperage rating. For example, white is used for 14-gauge wire, yellow for 12-gauge, orange for 10-gauge, and black for 6- or 8-gauge. Gray is typically used for underground installations. Additionally, the outer jacket of the nonmetallic-sheathed cable is labeled with letters indicating the number of insulated wires, excluding the ground wire. For instance, 12-2 WG refers to a cable with two insulated wires and a ground wire, while 12-3 indicates three insulated wires and a ground wire.
Romex wiring is another commonly used type of conductor in residential applications. It is categorized as an underground feeder (UF) or a non-metallic sheathed cable (NM and NMC). To ensure safe and reliable electrical connections, Romex cables must be adequately protected, secured, and clamped to devise boxes, junction boxes, and fixtures. Armored cables (AC) are similar to Romex cables but have flexible metallic sheathing that provides additional protection.
It’s important to note that certain conductors have restrictions on their use. For example, service entry (SE) conductors are generally not permitted inside homes, except for “style R” SE cable designed explicitly for ovens and dryers. On the other hand, knob-and-tube (KT) wiring is an obsolete system that poses fire hazards and should be evaluated by a qualified electrician.
In conclusion, conductors play a crucial role in electrical installations, carrying current from the power source to the end-user device. Different types of conductors, such as nonmetallic-sheathed cable and armored cable, are used based on specific requirements and applications. Electricians and inspectors need to thoroughly understand these conductors to ensure safe and reliable electrical systems.