Type NM-B cable meets or exceeds UL Standard 83, UL Standard 719, Federal Specification A-A-59544 and requirements of the National Electrical Code® (NFPA 70).
Type NM-B cable is manufactured as 2- or 3- conductor (Type THHN/THWN-2) cable, with a ground wire. Copper conductors are soft-annealed. Stranded conductors are compressed stranded. Phase conductors are insulated with tough, heat- and moisture-resistant, lead-free Polyvinyl Chloride (PVC) over which a nylon (polyamide) or UL-recognized equivalent jacket is applied. They are jacketed with moisture- and fungus-resistant lead-free PVC. Jackets are color-coded for ease of conductor size identification: 14 AWG - White; 12 AWG - Yellow; 10 AWG - Orange; 8 & 6 AWG - Black.
Type NM-B may be used for both exposed and concealed work in normally dry locations at temperatures not to exceed 90°C (with ampacity limited to that for 60°C conductors) as specified in the National Electrical Code®. NM-B cable is primarily used in residential wiring as branch circuits for outlets, switches, and other loads. NM-B cable may be run in air voids of masonry block or tile walls where such walls are not subject to excessive moisture or dampness. Voltage rating for all applications is not to exceed 600 volts.