What type of wire is typically used for residential branch circuits?

The use of non-metallic sheathed cable, commonly known as Romex, is the standard for residential branch circuits due to its versatility and ease of installation. This type of cable consists of two or more insulated conductors plus a bare ground wire, all encased in a flexible plastic sheath.

Romex is particularly suitable for residential wiring because it is lightweight, allows for quick and easy installation in walls and ceilings, and does not require additional conduit for protection under most conditions. Its design minimizes the risk of electrical shorts while ensuring that wires remain insulated from each other and from moisture where applicable.

In contrast, Rigid metal conduit is used primarily in commercial and industrial settings where robust protection for the wiring is necessary under severe conditions. THHN wire, while commonly used, is typically run inside conduit rather than being directly used for branch circuits in homes. MC cable, or Metal-clad cable, is also used in certain applications but is more common in commercial environments where added mechanical protection is needed. Thus, for standard residential wiring, non-metallic sheathed cable is the most practical and widely accepted choice.