From $0.20/ft
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Solid THHN/THWN-2 WireFrom $0.20/ft -
Solid THHN/THWN-2 WireFrom $0.20/ft - Solid THHN/THWN-2 WireFrom $0.20/ft
- Solid THHN/THWN-2 WireFrom $0.20/ft
Parent SKU : THN4/0CST
SKU : THN4/0CST-250-BK
"The definitive standard for 250-amp industrial feeders and commercial service entrances—engineered with dual-rated THHN/THWN-2 insulation and a friction-reducing nylon jacket for maximum reliability in 600V applications."
The 4/0 copper building wire is a massive conductor designed for the most demanding electrical loads. It is the primary choice for 225-amp to 250-amp commercial services, large industrial motors, and main distribution panels. At this size, our stranded construction is a necessity, providing the flexibility required to "train" the wire into large gear and land it securely in high-torque mechanical lugs.
Dual Rated (THHN/THWN-2): Engineered for dry locations up to 90°C (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 large-diameter conduits.
High-Conductivity Copper: Manufactured with soft-annealed stranded copper to provide maximum flexibility and superior electrical conductivity for heavy feeders.
Oil & Gasoline Resistant: The specialized jacket is designed to resist chemical degradation, making it ideal for industrial environments, refineries, and service stations.
225-Amp to 250-Amp Feeders: Used for high-capacity power distribution in large commercial and industrial facilities.
Large Residential Services: Often used for massive estates requiring more than a standard 200-amp service.
Data Center Backbones: Providing the primary power feed for server rooms and massive UPS systems.
Generator Hookups: The standard for connecting large industrial or multi-family standby generators.
ENGINEERING OVERVIEW: 4/0 AWG STR 600V
APPLICATION: Industrial service entrance conductors, heavy feeders, and large-scale 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: 90°C Dry (THHN), 90°C Wet (THWN-2).
Ampacity: 230 amps at 75°C | 260 amps at 90°CÂ
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Technical Note: All values are nominal and subject to industry tolerances and manufacturer corrections. Specifications are subject to change without notice. It is the buyer’s responsibility to verify that all materials meet the specific requirements of the project and comply with local electrical codes.
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| Wire Size (AWG/MCM) | 4/0 |
| Conductor Material | Copper |
| Conductor Type | Stranded |
| Strand Count | 19 |
| Outer Diameter (OD) (in/mm) | 0.660 in. / 16.764 mm |
| Conductor Count | 1 |
| Shield | Unshielded |
| Insulation Type | (THHN) Thermoplastic High Heat-Resistant Nylon-coated |
| UL Listing Numbers | UL 83, UL 1063, UL 758 |
| Voltage Rating | 600V |
| Ampacity Rating | 260 |
| Submersible | No |
| Standards | UL 83 UL VW-1 Size 1/0 & larger suitable for cable tray use MTW per UL 1063 ASTM B1, B3, B8 Federal Spec A-A-59558 |
| Miscellaneous Information | All values are nominal and subject to correction. *90°C Wet/Dry Per NEC Table 310.15 (B)(16) for not more than three conductors in raceway based on 30°C ambient temperature. |
| Primary Applications | General-purpose electrical wiring in commercial, industrial, and residential structures. It's widely used to supply power to outlets, switches, lighting fixtures, and other electrical loads throughout a building |
| Weight per Foot | 0.71 lb |
In-stock orders placed before 3pm EST typically ship within 1-2 business days. Our business days are Monday through Friday; we do not process orders on Saturday, Sunday, or major US Holidays.
You will receive an e-mail with a tracking number within 1-2 business days from the time its shipped. You will also be able to view your order status and tracking numbers in your account order history.
Expedited shipments are delivered Monday-Friday except on US Holidays. The order must be placed before 12pm CST to ship same day ( Mon-Fri Only).
You have 30 days from the day you receive the item to contact us for a return. Returns are subject to a 30% Restocking Fee.
Please contact us at help@wireamerica.com to request a return authorization. Have your order number or name the order was placed with ready and we will email you an RMA (return) number and instructions for return. Currently, we do not offer exchanges. A new order must be placed if you need a different item. If you provide the new order number at the time of your return request, the restocking fee may be lowered.
Orders on any items with a material value of $50 or less are non-returnable.
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Physical Specifications
Technical Specifications
Usage & Installation:
Packaging & Dimensions:
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4/0 THHN copper wire is rated for 260 Amps at 90°C. When following the NEC 75°C column (the standard for most heavy-duty industrial breakers and terminals), the allowable ampacity is 230 Amps. Always consult with a local electrician or engineer to confirm sizing before purchasing.
A 2-inch conduit is the minimum standard for up to three 4/0 AWG conductors. If you are pulling a 4-wire system (three phases plus a neutral), a 2.5-inch or 3-inch conduit is highly recommended. Because 4/0 copper is heavy and thick, using a 3-inch pipe will significantly reduce the risk of "jamming" and lower the pulling tension.
Note on Conduit Sizing: These recommendations are based on standard NEC 40% fill guidelines for general informational purposes. Always consult with a licensed electrician or project engineer to verify final conduit specifications and gauge size.
Yes, but it is often considered "over-engineered" for a standard 200A service. While 3/0 copper is the typical requirement for 200A commercial feeders, some engineers specify 4/0 to account for long voltage drops or to provide extra overhead for continuous heavy industrial loads.
Yes, as long as it is installed in a protective conduit. The THWN-2 rating ensures the insulation is engineered for wet locations, making it suitable for underground PVC or rigid metal conduit systems where water may be present. It is not rated for direct burial; for that, you would need Type USE-2 or Aluminum URD.
The primary advantages are conduit savings and "terminal space." While 4/0 Copper is rated for 230 Amps, the equivalent Aluminum size—350 MCM—is nearly 40% larger in diameter. Choosing 4/0 Copper allows you to:
4/0 THHN is very heavy (nearly 7100 lbs per 1,000 feet). We recommend having proper lifting equipment ready for your installation.
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