NM Cable Color

Nonmetallic Sheathed Cable’s Outer Jacket Labeling

As with all nonmetallic sheathed cable, the outer jacket is labeled with letters that show how many insulated wires are concealed within the sheath.  This wire count does not, however, include the uninsulated wire that is used as a ground wire.  For instance, if the cable lists 12-2 WG, it means there are two insulated 12-gauge wires (a black and a white wire), plus a ground wire.  If the label says 12-3, this is a three-conductor, 12-gauge cable with a bare copper ground wire included.