300 MCM THHN/THWN-2 Copper Building Wire | Stranded 600V

“The heavy-duty choice for high-amperage industrial powerengineered with dual-rated THHN/THWN-2 insulation and a friction-reducing nylon jacket for maximum reliability in 600V applications.”

Why Electricians Choose 300 MCM THHN/THWN-2 Copper The 300 MCM copper building wire is a high-capacity conductor designed for major power distribution. It is the primary choice for 300-amp commercial services, large-scale HVAC systems, and industrial switchgear. The stranded construction is essential at this massive size, providing the flexibility required to “train” the wire into large enclosures and land it securely in high-torque mechanical lugs.

• Dual Rated (THHN/THWN-2): Engineered for dry locations up to 90C (THHN) and wet locations (THWN-2), providing maximum versatility for indoor and outdoor conduits.

• Tough PVC/Nylon Jacket: The high-heat and moisture-resistant PVC insulation is protected by a tough, friction-reducing Nylon outer sheath, making for easier pulls through tight bends.

• High-Conductivity Copper: Manufactured with soft-annealed stranded copper to provide maximum flexibility and superior electrical conductivity for branch circuits and feeders.

• Oil & Gasoline Resistant: The specialized jacket is designed to resist chemical degradation, making it ideal for industrial environments and service station wiring.

Common 300 MCM THHN/THWN-2 Applications

• Commercial & Industrial Feeders: Supplying power from main service panels to subpanels, distribution boards, and large machinery.

• Industrial Motor Supplies: Ideal for powering mid-to-large sized 3-phase industrial motors and heavy manufacturing equipment.

• Commercial Building Mains: Used to distribute power from the main service entrance to large distribution panels in retail and office spaces.

• UPS & Battery Systems: Providing the high-conductivity backbone for large uninterruptible power supplies in data centers.

• Parallel Power Sets: Frequently run in sets of two or three per phase to handle 600A to 800A commercial services.

Technical Specifications

ENGINEERING OVERVIEW: 300 MCM STR THHN 600V

• APPLICATION: Feeder wire for sub-panels, large appliances, and industrial power distribution.

• VOLTAGE: Rated for 600 Volts.

• CONDUCTORS: Stranded soft-annealed copper.

• INSULATION: Heat and moisture-resistant PVC (Polyvinyl Chloride).

• JACKET: Tough, abrasion-resistant Nylon.

• TEMPERATURE: 90C Dry (THHN), 90C Wet (THWN-2).

• Ampacity: 285 amps at 75C | 320 amps at 90C

Technical Note: All values are nominal and subject to industry tolerances and manufacturer corrections. Specifications are subject to change without notice. It is the buyers responsibility to verify that all materials meet the specific requirements of the project and comply with local electrical codes.