What type of wiring system is typically used for residential electrical installations?

The correct choice is non-metallic sheathed wiring, commonly known as NM cable or Romex. This type of wiring is widely used in residential electrical installations due to its flexibility, ease of installation, and affordability. NM cable consists of two or more insulated conductors and a bare ground wire, all encased in a non-metallic outer sheath, which protects the conductors and reduces exposure to moisture and environmental damage.

Non-metallic sheathed wiring is well-suited for typical indoor residential applications, where it can be easily run through walls, ceilings, and floors of a home. It is also typically rated for use in dry locations, making it ideal for living spaces.

Other wiring systems, such as conduit systems, are more common in commercial or industrial settings because they provide additional protection and organization for the wires but can be more complicated to install. The knob and tube wiring method, while historically used, is considered outdated and has been largely replaced by modern wiring methods due to safety concerns. Service entrance cable is specifically designed for connecting electrical service to a building and is not used for typical in-home wiring.