Product Information

Specification

300 MCM THHN THWN-2 Stranded Copper Building Wire

Allowable Ampacity:

• 240 Amps for General Applications (60°C)

• 285 Amps in Wet Locations (75°C)

• 320 Amps in Dry Locations (90°C)

Description

300 MCM THHN/THWN-2 stranded copper wire is a high-capacity conductor designed for heavy-duty residential, commercial, and industrial applications. Rated for THHN (thermoplastic high heat-resistant nylon, dry) and THWN-2 (wet) environments, it operates at up to 600 volts and temperatures of 90°C. Its flame-retardant PVC jacket resists sunlight, moisture, and chemicals, making it ideal for demanding installations.

Applications for 300 MCM THHN Wire

300 MCM THHN wire, with a capacity of up to 320 amps, is suitable for:

• Major Feeders: Distributing power from service entrances to subpanels in large commercial buildings.

• Industrial Complexes: Powering heavy machinery and equipment with high current demands.

• Large Residential Projects: Ideal for central electrical services in multi-unit buildings or complexes.

• Service Entrances: Supporting power distribution in large structures like theaters, shopping malls, and convention centers.

• Motor Connections: Connecting motors in large industrial and commercial setups.

• Conduit Systems: Designed for easy installation through conduits in structured wiring systems.

Also Known As

300 MCM THHN wire, 300 stranded THHN wire, 300 gauge stranded wire, 300 copper wire, 300 MCM stranded copper wire, 300 MCM conduit wire, 300 MCM nylon wire, 300 MCM thermoplastic-insulated copper wire, 300 MCM THHN/THWN-2 wire, 300 MCM stranded copper building wire.

Construction of 300 MCM THHN Stranded Wire

• Conductor:
  Flexible annealed soft copper per ASTM B3 and ASTM B8.

• Insulation:
  Flame-retardant PVC jacket that resists sunlight, moisture, and chemicals.

• Outer Jacket:
  Abrasion-resistant nylon coating for smooth installation in conduits.

Standards for 300 MCM THHN/THWN-2 Wire

• ICEA S-73-532

• UL 1277 (Resistant to flame, moisture, and sunlight)

• UL 1581, UL 83, UL 1063, UL 758

• ASTM B3 and B8 conductor standards

• ANSI/NFPA 70 for Safe Electrical Design and Installation

• RoHS compliant

• Approved for NEC Class I and II systems and Division 2 hazardous locations

• Allowed for Exposed Run (ER) and complies with NEC regulations

• Complies with A-A59544 specifications for durability and safety

Specifications of 300 MCM THHN Wire

• Size (AWG): 300 MCM

• Weight per 1,000 ft: 1,030 lbs

• Outside Diameter: 0.780 inches

• Conductors: Annealed Soft Copper per ASTM B3 and ASTM B8

• Number of Strands: 37

• Insulation: PVC

• Insulation Thickness (mils): 60

• Nylon Thickness (mils): 8

• Jacket: PVC

*Data provided on this page is subject to change based on different manufacturers' variances

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