THHN/THWN wire stands for Thermoplastic High Heat-resistant Nylon-coated / Thermoplastic Heat and Water-resistant Nylon-coated conductor. It is one of the most commonly used building wires for electrical installations.

General Description
• A single-conductor electrical wire made of annealed copper (solid or stranded)
• Insulated with PVC (thermoplastic) and covered with a nylon jacket for added protection
• Rated for 600 volts (600V) maximum operating voltage
• Designed for:
o 90°C in dry locations (THHN)
o 75°C in wet locations (THWN)

Stranded Wires (Small Sizes)
• Stranded conductors consist of multiple small copper strands twisted together
• Typical small sizes range from 2.0 mm² and above
• Features:
o Flexible (easier to bend and install than solid wire)
o Suitable for tight conduit runs and panel wiring
o Reduced risk of breakage due to vibration or movement

Construction
• Conductor: Soft annealed copper, stranded (Class B)
• Insulation: Flame-retardant PVC
• Outer Jacket: Nylon (polyamide) for:
o Abrasion resistance
o Oil and chemical resistance
o Smooth surface for easy pulling in conduits

Key Characteristics
• Heat-resistant up to 90°C (dry)
• Moisture-resistant (THWN rating)
• Flame retardant and oil-resistant
• Durable against mechanical damage and chemicals
• Color-coded insulation for identification

Typical Applications
Used mainly in:
• Residential, commercial, and industrial wiring
• Conduits, cable trays, and raceways
• Branch circuits, feeders, and service wiring

Summary:

THHN/THWN 600V 90°C stranded wire (small size) is a flexible copper conductor with PVC insulation and nylon jacket, designed for safe and durable electrical wiring in buildings, especially where bending and easy installation are needed.