Intended for general purpose applications, THHN building wire is
19-strand 600V uncoated copper wire available in 4-14 gauge sizes,
making it suitable for new construction or rewiring 600V applications.
MTW-type wire is also available in 19- and 26-strand 600V bare, annealed copper in 10-16 gauge sizes. MTW-type wire is primarily used in control cabinets, machine tool applications and appliance wiring applications. Both THHN and MTW-type wire are UL, cUL, CSA, and NEMA rated. Available in 500-foot spools, prices start at $32 for MTW-type wire. TFFN-type wire is available as 16 gauge, 26-strand, 600V, uncoated copper and is primarily used as fixture wire in dry locations. TFFN-type wire is UL approved and is $38 for a 500-foot spool.
