12/3 UF-B Underground Feeder Cable w/ Ground | Direct Burial

12/3 UF-B (Underground Feeder) Cable with Ground is a specialized, flat-profile branch circuit wire engineered specifically for direct-burial underground applications. Unlike standard interior building wire (like NM-B Romex), which requires a protective conduit when buried, UF-B features a solid, injection-molded polyvinyl chloride (PVC) jacket that completely fills all voids between the conductors. This unique construction encapsulates each individual wire in a protective shield, protecting the copper elements from direct exposure to underground moisture, continuous dampness, soil acids, and rot.

Rated for operations up to 600 Volts, 12/3 UF-B consists of three insulated phase/neutral conductors and one bare copper ground wire. It serves as an all-in-one distribution line for safely running standard 120V or 240V residential branch circuits from a primary service panel out to unattached exterior structures or outdoor installations without needing a continuous run of rigid PVC or metal conduit through the trench.

ELECTRICAL AMPACITY & PERFORMANCE DATA

Due to its heavy, solid plastic encapsulation, heat dissipates more slowly from UF-B cable than it does from traditional open-air wires. Per electrical safety standards, its current capacity must always be adjusted downwards:

• Maximum Current Capacity (Normal Conditions): 20 AMPS Ampacity limits are calculated using the 60C temperature column in accordance with National Electrical Code (NEC) Article 340. Even though the interior copper conductors are insulated with 90C thermoplastic (THHN/THWN equivalents), the overall cable installation is structurally restricted to the 60C limit for safety margin overhead.

Key Features

• Direct-Burial Self-Containment: Specifically listed for direct placement into earthen trenches without requiring a continuous conduit pipe run, dramatically reducing trenching material and labor costs.

• Solid PVC Core Encapsulation: Unlike standard house wire, which contains open air pockets inside its sheath, the gray PVC jacket on UF-B is pressure-extruded into every void, freezing the internal elements in place and stopping corrosive water tracking.

• Annealed Copper Conductors: Constructed with three high-grade 12 AWG solid copper conductors providing excellent conductivity, high thermal performance, and pull-strength resilience.

• Corrosion & Sunlight Resistance: The outer gray PVC compound is heavily treated with UV inhibitors (SUN-RES) and specialized chemical stabilizers, allowing sections of the cable to run in open sunlight along the side of buildings without degradation.

Common Applications

• Outbuilding Branch Circuits: Safely routing 120/240V power lines out to small detached garden sheds, gazebos, remote workshops, and greenhouse lighting setups.

• Outdoor Equipment & Amenities: Supplying dedicated power to outdoor installations such as fountain pumps, landscape lighting control hubs, automated gate openers, and detached patio ceiling fans.

• Multi-Wire Branch Circuits: Perfect for running two separate 120V circuits on a shared neutral (using the extra insulated hot leg) out to detached backyard structures or outdoor post receptacles.

Cable Layer Architecture (From Core to Jacket)

1. Phase/Neutral Conductors: 3 independent 12 AWG bare copper cores (typically solid copper).

2. Conductor Insulation: Color-coded (Black, Red, and White) high-dielectric Polyvinyl Chloride (PVC) jacketed with a smooth Nylon skin layer.

3. Ground Conductor: One (1) uninsulated, bare copper ground conductor (sized symmetrically at 12 AWG).

4. Encapsulated Web Sheath: Heavy, unified injection-molded Gray PVC jacket that locks the parallel conductors into a rigid flat-ribbon assembly.

Technical Specifications

• Conductor Size: 12 AWG

• Number of Insulated Conductors: 3

• Conductor Material: Annealed soft-drawn copper

• Conductor Stranding: Solid configurations

• Grounding Configuration: 1 bare copper grounding wire (12 AWG)

• Insulation Type: PVC with Nylon Covering (THHN/THWN-2 internals)

• Outer Jacket Material: Sunlight-resistant, moisture-impervious Gray PVC

• Cable Geometry: Flat profile (approx. 0.28 inches x 0.73 inches)

• Approximate Net Weight: Approx. 132 lbs per 1000 feet

• Voltage Rating: 600 Volts Maximum

• Temperature Limits: Dry locations up to 90C / Restricted to 60C for operational ampacity calculations

• Compliance Standards: UL Standard 493 (Underground Feeder Cables), ASTM Spec Requirements, National Electrical Code (NEC) Article 340, Federal Specification JC-30B, RoHS Compliant

Technical Note Regarding Installation: When burying 12/3 UF-B directly into the ground, NEC Article 300.5 mandates a minimum burial depth of 24 inches under standard soil configurations to safeguard the line against lawn aerators, shovels, or surface activity. Where the cable emerges from the deep trench to climb up a post or foundation wall to enter an electrical box, it is highly vulnerable to lawn mowers and string trimmers. In these exposed areas, the cable must be protected inside a schedule 80 PVC or rigid metal conduit sleeve starting from 18 inches below the ground line up to its final termination point.

CABLE TYPE: 12/3 AWG UF-B Underground Feeder and Direct Burial Cable (Copper with Bare Ground / Flat Gray PVC Outer Jacket)

DISCLAIMER: The technical information provided is for general reference only. All underground electrical distribution systems must be installed in strict compliance with the National Electrical Code (NEC), local municipal ordinances, and under the oversight of a licensed electrician. Always confirm trench depths, structural crossing protections, and final panel breaker pairings with local code enforcement bureaus before initiating an excavation.