THHN/THWN-2: 12 AWG solid or stranded copper. Dual-rated for dry (THHN: 90°C) and wet (THWN-2: 90°C) locations. Ampacity: 20 amps in raceway (NEC Table 310.16 at 30°C ambient). Insulation: PVC with nylon jacket, 600V rated. Colors: black, red, blue (hot), white (neutral), green (ground), orange (hi-leg delta), yellow, purple. Uses: 20-amp branch circuits per NEC 210.3 — general purpose receptacles, lighting, small appliance. Required for 20-amp kitchen, bathroom, laundry, and garage circuits per NEC 210.11(C). Conductor OD: 0.128 in (solid). Cost: $0.15-$0.40/ft. Wire fill calculations per NEC Chapter 9 Table 5. Must be in raceway or cable assembly — bare THHN not permitted. CSI 26 05 19.