What is Romex? What is 12/2 or 14/3 Electrical Cable?
The electrical system in most homes and businesses is wired using Romex wire. Romex is a brand name that has become a generic name for flexible, sheathed, insulated wire. Romex cable, (pronounced rome-ecks), contains two or more insulated wires in a flexible plastic sheath that can be run through walls, under floors, through attics and so on. There are other brands of flexible, sheathed cable which can be used interchangeably, though many electricians prefer to use the brand name product. The labeling for all electrical cable is standardized and so is the same regardless of who manufactures it.
Flexible sheathed cable is easier to run through holes in studs than metallic sheathed cable, it is also cheaper. Romex wire is labeled as NMC, which means the sheathing is non-metallic cable. NM refers to the sheathing to differentiate it from metallic (BX or AC) sheathed cable. Another designation, UF, indicates the cable is rated for direct burial in the ground (although local codes may not permit that use).
A rating of 14/3 refers to the gauge of the wire and how many wires are in the cable. In this case, the wire gauge is fourteen (lower numbers mean larger wires) and the three indicates that there are three wires in addition to a non insulated ground wire. So, in the image above of 12/2 Romex, there are two twelve gauge insulated wires plus a bare twelve gauge ground wire.