Thermoplastic high-heat-resistant nylon (THHN) and thermoplastic high-heat and water-resistant nylon (THWN) building wire is a coated wire typically run through conduit or cable trays. This general purpose wire supplies an electrical current in a range of indoor wiring projects, including control circuits and appliances. It has a durable nylon jacket that resists abrasion, protects against shock, and shields the thermoplastic insulation and metal conductor from damage. THWN building wire is moisture-resistant and withstands higher temperatures than THHN building wire.