General purpose electrical wire
THHN building/hookup wire is 19-strand 600V uncoated copper wire available in 4-14 gauge sizes and intended for general purpose, new construction or rewiring 600 V applications. MTW-type wire is available in 19- and 26-strand 600 V bare, annealed copper in 10-16 gauge sizes. MTW-type wire is primarily used in control cabinets, machine tool- and appliance-wiring applications. Both types are UL, cUL, CSA and NEMA rated, and are available in 500-foot spools. THHN can be used in wet or dry locations. TFFN-type wire is UL-approved, and available as 16 gauge, 26-strand, 600 V, uncoated copper. It’s primarily used as fixture wire in dry locations. All wire types are color-coded with tough, polyamide, Nylon outer covers per UL 1063 and UL 83 standards.