12/2 15 FEET NM-B (nonmetallic-sheathed) cable is suitable for use in both visible and hidden applications in standard dry environments, as long as the temperatures do not exceed 90°C (although its ampacity is restricted to that of 60°C conductors), as indicated in the National Electrical Code. The primary usage of NM-B cable is in residential wiring, serving as branch circuits for sockets, switches, and various other loads. The cable can be installed in the air gaps of masonry block or tile walls, provided these walls are neither wet nor damp. The voltage capacity for NM-B cable is established at 600 volts.