wire size codes

A number of wire sizes and types are needed to wire homes. Non-metallic sheath cable, often referred to as NM cable, is a type of electrical wiring commonly used in residential and light commercial construction. It consists of individual insulated wires bundled together and covered by a non-metallic outer sheath, typically made of PVC. This sheathing is designed to be flame-resistant and moisture-resistant. NM cable is available in various configurations, with the number of insulated wires and their gauges indicated on the sheath. For example, "12-2" indicates a cable with two insulated 12-gauge wires plus a bare ground wire. The color of the sheath can indicate the gauge of the wires or special properties of the sheathing itself. NM cable is easier to handle and install compared to metal-sheathed cables like BX cable. It is lightweight, easy to cut, rip, and strip, and can be pulled effortlessly through holes in studs. However, NM cable must always be installed in enclosed locations such as within walls, ceilings, or under floors, and it requires a separate grounding wire. In contrast, metal-sheathed cables like BX offer stronger protection but are heavier and more difficult to work with. They can achieve grounding through the outer metal casing, which needs to be attached to metal boxes.