THWN/THWN-2 for Construction

THWN and THWN-2 are common electrical conductor types used in building wiring systems, conforming to the National Electrical Code (NEC) and UL certification standards. Both use copper or aluminum as the conductor, with an outer thermoplastic PVC insulation layer and a nylon sheath for enhanced abrasion resistance, water resistance, and oil resistance. THWN-2 is an upgraded version of THWN, offering higher temperature resistance up to 90°C, suitable for both dry and humid environments. THWN, on the other hand, withstands 90°C in dry environments and 75°C in humid environments. Applications of THWN wire/THWN-2 wire in buildings are as follows:

• Power distribution systems and main feeders

Due to its high-temperature and moisture-proof properties, THWN-2 is commonly used for main power supply feeders, distribution cables, and vertical shaft wiring in buildings. Its outer nylon sheath effectively resists friction and chemical corrosion, making it suitable for use in both metal conduits (such as EMT, RMC, IMC) and non-metallic conduits (such as PVC pipes).

• Lighting and Socket Circuits

In commercial and residential buildings, THWN/THWN-2 is commonly used for branch circuits of lighting, power sockets, air conditioning, and water heaters. When used in damp or outdoor conduit wiring, no additional waterproofing is required, complying with NEC requirements for "wet zone" wiring.

• Equipment Grounding and Control Circuit

THWN-2 can also be used as an equipment grounding conductor (EGC) and Control Circuit, especially in machine rooms, pump rooms, and building automation control systems (BAS), providing safe and durable electrical connections.

•  Outdoor and Underground Installation

Due to the moisture-proof and abrasion-resistant properties of its nylon sheath, THWN-2 cable can be used for outdoor and underground wiring (such as parking lot lighting and landscape electrical systems) under conduit protection. With waterproof junction boxes and qualified seals, it can operate stably for a long time.

THWN/THWN-2 wires, with their excellent heat resistance, water resistance, and mechanical strength, have become a universal standard conductor in modern construction engineering. THWN-2, in particular, is widely used in residential, commercial buildings, industrial plants, and public infrastructure due to its ability to operate continuously at 90°C in both dry and humid environments.