THHW to oznaczenie kabla wg NEC / UL (USA): T = Thermoplastic (PVC) insulation; HH = High heat resistant, 90 C range (two H); W = Approved for wet locations; THHW = Thermoplastic high heat-resistant, moisture-resistant building wire. 600 V, 90 C dry, 75 C wet. UL 83; NEC Article 310.