The most common type of home electrical wiring is the NM cable, also known as the Romex cable, after the most popular electrical wiring brand name. The NM cables contain three or more individual conductors, wrapped together in a sheathing, which is a flexible plastic jacket. This type of cable is generally used for dry, interior home wiring and this includes appliances, fixtures, switches, and outlets. Today, the NM cables are color-coded, meaning that the outer jacket of the cable comes in different colors to indicate the wire gauge. Here are the most common NM cables you most likely find in modern homes:
When it comes to house electrical wiring, local ordinances are more strict than national codes. That is why you might find that in some areas NM cables are not permitted for use and in these locations, armored or AC cables are used instead. AC wiring, also known as BX, goes back to the early 1900s and is designed with flexible metallic sheathing, which offers extra protection for the conductors inside. In commercial buildings or residential constructions with more than three stories, AC cannot be used.