From $0.20/ft
128 Products
-
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 : NMB8-2
SKU : NMB8-2-250
Bridging the gap between standard household outlets and heavy-duty power requirements, this 8 AWG NM-B Copper Building Wire is the go-to solution for high-wattage residential branch circuits. Engineered with two high-purity copper conductors and a dedicated bare ground, this cable offers the ruggedness needed for sustained loads while maintaining the flexibility required for fast-paced residential construction.
This 2-conductor (with ground) assembly is designed to streamline the installation of dedicated 40-amp circuits. The Type NM-B construction allows you to route the cable directly through wooden studs and floor joists in dry, interior locations, eliminating the labor and material costs associated with conduit systems.
Optimized Copper Conductivity: Soft-annealed copper provides superior electrical throughput and minimal heat buildup, ensuring long-term efficiency for high-draw appliances.
Tough, Low-Friction Outer Shell: The black PVC jacket is specifically formulated to resist tearing and snagging, allowing it to glide through bored holes during the rough-in stage.
Integrated Grounding Safety: Features a full-sized bare copper grounding conductor, providing an essential low-impedance path to ensure maximum circuit safety.
THHN-Grade Primary Insulation: Individual conductors are protected by a dual layer of heat-resistant PVC and a slick nylon topcoat, providing an extra barrier against installation abrasion.
Conductor Size: 8 AWG
Number of Conductors: 2 (plus Ground)
Color Code: Black, White, Bare Ground
Ampacity: 40 Amps at 60°C (NEC Table 310.16)
Voltage: 600V
Insulation: Polyvinyl Chloride (PVC) with Nylon Covering (Type THHN)
Max Temp: 90°C (Dry locations only)
Conductor Material: Annealed (Soft) Copper
Standards: UL Standard 83, UL Standard 719, ASTM B-3, B-8, Federal Spec A-A-59544
Residential HVAC Units: Ideally suited for powering central air conditioning condensers and smaller heat pump systems requiring a 40A feed.
Electric Cooktops: The primary choice for dedicated 240V circuits supplying modern high-induction or standard electric cooktops.
Large Space Heaters: Frequently utilized for permanent garage heaters and large electric baseboard units in cold-weather climates.
Pool and Spa Equipment: Used for the interior portion of the run feeding pool heaters or small spa disconnects where a neutral is not required.
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. NM-B is for dry, indoor use only.
Â
*All values are nominal and subject to correction. Ampacity is based on the National Electrical Code (NEC) 60°C column for NM-B cable, regardless of the conductor temperature rating.
| Wire Size (AWG/MCM) | 8 AWG |
| Conductor Material | Copper |
| Conductor Type | Stranded |
| Strand Count | 7 |
| Outer Diameter (OD) (in/mm) | .320 x .680 in. |
| Jacket Type | PVC |
| Conductor Count | 2 |
| Shield | Unshielded |
| Insulation Type | (PVC) Polyvinyl Chloride |
| UL Listing Numbers | UL 83 |
| Voltage Rating | 600V |
| Ampacity Rating | 40 |
| Submersible | No |
| Temperature Rating | 90ºC |
| Standards | US 719 UL 83 ASTM B3 and B8 |
| Miscellaneous Information | All values are nominal and subject to correction. |
| RoHS Compliance | Yes |
| Primary Applications | Wiring outlets, switches, and lighting circuits in residential buildings. |
| Weight per Foot | 0.2 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.
Get notified when this product is back in stock
Physical Specifications
Technical Specifications
Usage & Installation:
Packaging & Dimensions:
|
||||||||||||||||||||||||||||||||||||||
This 8 AWG, 2-conductor cable is the industry standard for dedicated 240V residential loads that pull up to 40 amps. Unlike smaller 10 AWG wire (limited to 30A) or larger 6 AWG wire (used for 55A), 8/2 NM-B provides the exact thermal capacity required for high-draw equipment like large electric water heaters and central AC condensing units. It offers a more cost-effective and easier-to-handle solution than 6 AWG when a 40-amp circuit is all that is required by the equipment manufacturer.
The "2-conductor" designation means this cable contains two insulated "hot" legs and a bare ground, but no white neutral wire. This specific configuration is designed for 240V-only appliances that do not have 120V onboard electronics (like a clock or a light). By choosing 8/2 over 8/3, installers benefit from a slimmer cable profile that is significantly easier to pull through bored holes in wood studs and takes up less volume inside the electrical junction box.
Even though the internal copper conductors are often rated for higher temperatures, NEC Article 334.80 mandates that NM-B cable be sized according to the 60°C temperature column. For 8 AWG copper, this results in a maximum allowable ampacity of 40 Amps. It is vital to use a 40-amp circuit breaker with this wire; using a 50-amp breaker (which would be allowed for 8 AWG in a conduit/THHN setup) is a code violation for NM-B and can lead to excessive heat buildup within residential wall insulation.
Because 8/2 NM-B is a "2-wire" cable, it typically contains a Black wire, a White wire, and a Bare ground. In a 240V application, the White wire must be re-identified. Per the NEC, you must wrap black or red electrical tape around the white insulation at both the breaker panel and the appliance junction box. This signals to future electricians that the wire is a "hot" leg carrying 120V, rather than a neutral, preventing dangerous wiring errors during future maintenance.
8 AWG copper is significantly stiffer than the 10 or 12 AWG wire used in standard wall outlets, requiring more careful physical handling. To prevent "stress whitening" or cracking of the PVC jacket, you must maintain a minimum bending radius of 5 times the cable diameter. Additionally, because the cable is heavier, it must be securely supported with extra-wide staples or cable straps within 12 inches of every box and every 4.5 feet along the run to prevent the weight of the copper from straining the connections.
(833) 268-8644
Get this thing filled up so you can help Wire America!