Southwire 10/3 Solid Copper UF-B Underground Feeder Cable with Ground 250-Foot Roll – Model 13059155

The Southwire 10/3 UF-B is the residential underground feeder cable specifically engineered for direct burial 30-amp 240V circuits and outdoor branch applications that require more capacity than the standard 14/2 UF-B can deliver. As a 10/3 direct burial cable, this product features three insulated 10 AWG conductors plus a bare copper ground, with the three-wire configuration enabling 240V operation that two-wire cables cannot serve. As a 30 amp underground wire, the Southwire 10/3 UF-B handles the residential outdoor electrical applications that drive higher current consumption: hot tub circuits (typically 240V/30A or 240V/40A), detached garage subpanel feeders, well pump installations with significant starting surges, and pool equipment circuits. As Southwire 13059155, this specific SKU is a default specification for serious residential outdoor electrical work that goes beyond simple landscape lighting, particularly for the high-value installations homeowners increasingly add (hot tubs, outdoor entertainment areas, detached workshop subpanels, electrified outbuildings). As UF-B 240V outdoor cable, the Southwire 10/3 UF-B uses the same solid PVC fill construction and sunlight-resistant moisture-resistant outer jacket as the smaller 14/2 UF-B sibling, providing direct burial capability without the labor of conduit installation. Every Southwire 10/3 UF-B 250 ft roll ships nationwide from IB Lighting with free freight. Manufacturer specifications are available at the official Southwire website.

Southwire 10/3 UF-B Key Highlights

10/3 With Ground Configuration: Understanding the Conductor Setup

The Southwire 10/3 UF-B contains four conductors in the 10/3 with ground configuration: three insulated 10 AWG conductors (typically black, red, and white) plus a bare 10 AWG copper grounding conductor. Understanding what each conductor does helps you wire the cable correctly at both ends of the run.

The three insulated conductors serve specific roles in 240V circuit operation:

• Black conductor (Hot Leg 1): One of the two hot legs of the 240V circuit, connected to one phase of the residential split-phase service.
• Red conductor (Hot Leg 2): The second hot leg of the 240V circuit, connected to the opposite phase of the residential split-phase service. The 240V potential exists between the two hot legs.
• White conductor (Neutral): The neutral conductor that carries unbalanced current when 120V loads are operating. The 120V potential exists between either hot leg and the neutral.

The bare copper conductor is the equipment grounding conductor, which provides the fault path for safe ground-fault current return if any of the hot conductors should ever short to a metal enclosure or equipment housing. The grounding conductor is critical for both safety and code compliance, and it is wired separately from the neutral conductor at the destination panel or device.

For 240V-only loads (hot tubs, well pumps, electric water heaters at certain configurations), only the two hot legs and the ground are connected; the neutral is unused but still present in the cable. For 120V-only loads (lighting circuits, receptacle circuits), only one hot leg plus the neutral and ground are used; the second hot leg is unused. For 120/240V combination loads (most subpanel installations, where some subpanel circuits are 120V and some are 240V), all three insulated conductors plus the ground are connected.

240V Capability: Why 10/3 UF-B Serves Applications 14/2 UF-B Cannot

The headline differentiator between the Southwire 10/3 UF-B and the smaller Southwire 14/2 UF-B is the 240V capability. The 14/2 UF-B has only two insulated conductors (one hot, one neutral), which limits it to 120V circuit applications. The 10/3 UF-B has three insulated conductors (two hots, one neutral), which enables both 120V AND 240V applications.

This 240V capability matters because nearly all higher-current outdoor electrical equipment operates at 240V rather than 120V. The reason is technical but practical: at the same power consumption, 240V circuits draw half the current of equivalent 120V circuits, which means smaller wire gauges and lower energy losses over the cable run. Equipment manufacturers design hot tubs, larger pumps, electric ranges, and similar high-power equipment to operate at 240V for these efficiency reasons.

The Southwire 10/3 UF-B serves the residential outdoor 240V applications that homeowners increasingly add as backyard improvements:

• Hot tubs and spas: Typically 240V/30A or 240V/40A depending on heater size and pump configuration.
• Detached garage subpanels: 240V feeders allow the subpanel to serve both 120V circuits (lighting, receptacles) and 240V circuits (welder, table saw, air compressor) at the detached building.
• Well pumps: Most residential submersible well pumps operate at 240V for efficiency, particularly larger pumps for deep wells or higher water demand.
• Pool equipment: Pool pumps, pool heaters, and similar pool equipment typically operate at 240V.
• Outdoor compressors and large equipment: Air compressors, generator paralleling equipment, and other higher-power outdoor electrical equipment.

For 120V-only outdoor applications (landscape lighting, outdoor receptacles for general use, small detached shed lighting), the smaller and more affordable Southwire 14/2 UF-B is the right specification. Choose the 10/3 specifically when 240V capability is required or when the higher current capacity is needed.

Hot Tub and Spa Installations

Hot tub installations are one of the most common applications for the Southwire 10/3 UF-B in residential settings. The popularity of backyard hot tubs has grown significantly in recent years, and the cable specification for hot tub circuits is well-standardized in residential electrical code.

Most residential hot tubs require 240V/30A or 240V/40A electrical service, depending on the specific model and the heater wattage. For the 240V/30A hot tubs (which represent the majority of residential installations), the Southwire 10/3 UF-B is the correct cable specification. For 240V/40A or larger hot tubs, step up to 8/3 UF-B. The hot tub manufacturer’s installation manual specifies the exact circuit requirements for the specific model.

NEC Article 680 governs hot tub electrical installations with specific safety requirements beyond general residential wiring. Key requirements include: GFCI protection for the entire hot tub circuit (not just downstream receptacles), a dedicated circuit serving the hot tub only (no other loads on the same circuit), proper bonding of the hot tub equipment to the home’s electrical grounding system, a disconnect switch located within sight of the hot tub but at least 5 feet from the water, and specific clearance requirements for any overhead conductors.

The GFCI requirement for hot tubs specifically requires a 240V GFCI breaker at the home’s electrical panel. This is a different device from the 120V GFCI receptacles common in bathrooms and kitchens. The 240V GFCI breaker is installed in place of a standard breaker in the panel, providing GFCI protection for the entire hot tub circuit fed by the Southwire 10/3 UF-B.

The typical hot tub installation: install a 30A or 40A 240V GFCI breaker at the home’s electrical panel, run the Southwire 10/3 UF-B from the panel via a trench (24-inch depth, code-compliant) to the hot tub location, transition the cable into a disconnect switch in a weatherproof enclosure within sight of the hot tub but at least 5 feet from the water, then continue from the disconnect to the hot tub equipment compartment. Total cable consumption for typical installations is 50 to 150 feet, which fits comfortably within the 250-foot Southwire 10/3 UF-B roll.

Detached Garage and Workshop Subpanel Feeders

Detached garage subpanels are the second major application for the Southwire 10/3 UF-B. Many homeowners with detached garages, workshops, or larger outbuildings want a complete subpanel at the structure rather than just a single 15-amp branch circuit. The subpanel provides flexibility to install multiple branch circuits within the detached structure for lighting, receptacles, and higher-power equipment.

For a 30-amp subpanel feed to a detached garage or workshop, the Southwire 10/3 UF-B is the correct cable specification. The 30-amp feeder supports approximately 7,200 watts of total load at 240V (or 3,600 watts at 120V), which is sufficient for small to medium workshop loads: lighting throughout the structure, several general-purpose receptacles, a small table saw or other moderate-power workshop equipment, and basic ventilation or heating.

For larger detached structures requiring more current capacity, step up to larger UF-B gauges: 8/3 UF-B for 40-amp subpanels, 6/3 UF-B for 50-amp subpanels, and larger for higher capacities. The decision between 30-amp and larger subpanels depends on the actual load requirements of the detached structure, which homeowners often underestimate during initial planning.

The critical NEC requirement for detached structure subpanels is grounding configuration. Per current NEC, the bare grounding conductor in the Southwire 10/3 UF-B must be connected as the equipment ground at the detached subpanel, with a separate grounding electrode system (typically two ground rods driven at the detached structure) bonded to the subpanel grounding bar. The neutral and ground bars at the detached subpanel must be SEPARATE (not bonded together as they are at the main service panel). This separation prevents objectionable current from flowing on the equipment grounding conductor under normal operation.

This grounding requirement is one of the most commonly misunderstood aspects of detached subpanel installations. Pre-2008 NEC formerly allowed the bare conductor to serve double duty as both neutral and ground at detached subpanels, but current code requires separation. Verify your installation with the current NEC adopted in your jurisdiction before completing the wiring.

Well Pump Installations

Residential well pump installations frequently use the Southwire 10/3 UF-B for the underground feeder from the home’s electrical panel to the well pump pressure switch and motor controller. Well pump electrical requirements vary based on pump size, depth, and water demand, but most residential submersible well pumps require 240V circuits with starting surge capacity for the pump motor.

The typical residential well pump installation: a dedicated 240V/30A circuit from the home’s electrical panel runs via the Southwire 10/3 UF-B underground to the wellhead location. At the wellhead, the cable connects to a pressure switch (which controls pump operation based on water pressure) and the pump motor control circuit. The actual submersible pump motor wires are different from the UF-B and are typically supplied with the pump.

For deep wells (300+ feet of well depth) or wells with significant water demand, larger pumps may require 240V/40A or 240V/50A circuits. In these cases, step up to 8/3 or 6/3 UF-B respectively. The well pump installation manual specifies the exact circuit requirements for the specific pump model.

One important consideration for well pump circuits is voltage drop on long underground runs. The Southwire 10/3 UF-B at 10 AWG handles 30-amp circuits with acceptable voltage drop for runs up to approximately 100 feet. For longer runs (which are common when the well is located far from the house), voltage drop calculations become important and may require larger gauge cable than would otherwise be needed based purely on current capacity. Consult a voltage drop calculator or licensed electrician for runs over 100 feet.

Pool Equipment Circuits

Residential pool installations include several electrical loads that frequently use the Southwire 10/3 UF-B for the underground feeders from the home to the pool equipment area. Pool pumps, pool heaters, automatic chlorinators, and pool lighting all require specific electrical circuits with NEC Article 680 compliance requirements.

The pool equipment pad (the area where pool pumps, filters, heaters, and similar equipment are installed) typically receives its electrical service via underground UF-B from the home’s electrical panel. For typical residential pool installations, the equipment pad needs a 240V/30A or 240V/40A subpanel that distributes power to the various pool equipment loads. The Southwire 10/3 UF-B serves the 30-amp configuration; step up to 8/3 UF-B for 40-amp pool equipment subpanels.

NEC Article 680 has specific requirements for pool electrical installations that go beyond general residential wiring code: GFCI protection for all pool-related circuits, proper equipotential bonding of the pool structure and surrounding deck to the electrical grounding system, specific clearance requirements for any overhead conductors, dedicated circuits for pool lighting (low-voltage transformer-fed systems are common), and a disconnect switch located within sight of the pool equipment but at least 5 feet from the water.

The Southwire 10/3 UF-B is the right cable specification for the underground feeder portion of pool installations. The equipment-specific wiring (pump motor leads, heater control wiring, low-voltage lighting transformer feeds) uses different cable types specific to those applications. Contract with a licensed pool electrical contractor for complete pool installation work because the NEC requirements are specific and inspection failures are expensive to remediate.

EV Charging at Detached Structures

An increasingly common application for the Southwire 10/3 UF-B is electrical service to detached structures that include EV charging equipment. Many homeowners with detached garages or carports want EV charging at the detached structure rather than at the main house, which requires running adequate electrical service underground from the main service panel.

For Level 2 EV charging at a detached structure using the Southwire 10/3 UF-B, the installation typically involves: running the 10/3 UF-B underground from the main service panel to a subpanel at the detached structure (10/3 supports a 30-amp feeder), then installing a Level 2 EV charger configured for 24-amp output (a sub-50-amp setting that fits within the 30-amp feeder capacity).

For full-speed 48-amp Level 2 EV charging at a detached structure, the 10/3 UF-B feeder is not large enough. A 48-amp continuous load requires a 60-amp circuit per NEC, which requires larger UF-B (6/3 UF-B typically, or 4/3 UF-B for longer runs). For most detached-garage EV charging installations where 24-amp or 32-amp charging is acceptable (delivering 18 to 25 miles of range per hour, still much faster than Level 1 charging), the 30-amp 10/3 UF-B feeder is appropriate.

For the EV charger itself, the Tesla Universal Wall Connector includes adjustable amperage settings that allow the installer to configure the unit for the available circuit capacity. A Tesla Wall Connector configured for 24-amp output charges from a 30-amp feeder served by 10/3 UF-B comfortably, though at slower charging speed than a 48-amp configuration would deliver on a larger feeder. For homeowners wanting full-speed charging at a detached structure, plan the underground feeder accordingly (larger gauge UF-B or conduit-protected installation).

Direct Burial Code Requirements

The Southwire 10/3 UF-B is approved for direct burial underground without conduit protection in residential applications, the same as the smaller 14/2 UF-B. The same NEC depth requirements apply, with one practical difference: the larger 10/3 cable creates more visible disruption when the trench is open, which often makes homeowners more careful about depth compliance than they would be with smaller wire.

NEC Article 300.5 depth requirements (same for all UF-B gauges):

• Direct burial without conduit: Minimum 24 inches of cover.
• Direct burial under residential driveways: Minimum 18 inches plus 4 inches of concrete or equivalent above the cable.
• Direct burial under concrete slabs: Minimum 18 inches.
• Underground installation in PVC conduit: Minimum 18 inches of cover.
• Underground installation in rigid metal conduit: Minimum 6 inches of cover.

For hot tub and pool installations specifically, NEC Article 680 may require deeper burial in some configurations or specific routing requirements that prevent the cable from running directly under the pool or hot tub. Verify specific requirements with your local building department before excavation.

Frost line considerations apply to all UF-B installations in cold climates. The cable should be buried below the local frost line to prevent ground heaving damage from winter freeze-thaw cycles. Northern US frost lines often exceed the NEC 24-inch minimum, so frost line typically governs depth in cold climates rather than the NEC minimum.

GFCI Protection: Required for Most 10/3 UF-B Applications

The Southwire 10/3 UF-B applications almost universally require GFCI protection per NEC. Hot tubs, pool equipment, outdoor receptacles, and most outdoor equipment circuits all carry GFCI protection requirements that the installer must address as part of the complete installation.

GFCI protection for 240V circuits served by the Southwire 10/3 UF-B is provided by a 240V GFCI breaker installed at the home’s electrical panel. This is different from the 120V GFCI receptacles common in bathrooms and kitchens. The 240V GFCI breaker replaces a standard 30-amp or 40-amp 240V breaker in the panel and provides GFCI protection for the entire downstream circuit fed by the Southwire 10/3 UF-B.

240V GFCI breakers come in standard sizes matching common circuit ratings: 30-amp 240V GFCI for hot tubs and 30-amp subpanels, 40-amp 240V GFCI for larger hot tubs and 40-amp subpanels, 50-amp 240V GFCI for larger equipment, and others. The breaker must match the circuit ampacity and be the correct brand for the home’s electrical panel (Eaton, Square D, Siemens, GE, and others all have their own GFCI breaker product lines).

For detached subpanel feeders that are not specifically pool/spa applications, the GFCI requirement depends on what is downstream from the subpanel. If the subpanel itself serves only the detached structure’s general-purpose circuits, GFCI protection may be provided at individual outlets and equipment within the structure rather than at the upstream feeder. If the subpanel serves any pool/spa/outdoor equipment requiring GFCI, the feeder is typically GFCI-protected at the main panel.

One technical note: long UF-B runs (200+ feet) sometimes produce nuisance GFCI trips because of capacitive ground leakage that accumulates along the cable length. For installations with long runs, discuss the GFCI configuration with your licensed electrician to plan for reliable operation.

Critical Grounding Rules at Detached Structures

One of the most commonly misunderstood aspects of installations using the Southwire 10/3 UF-B is the grounding configuration at detached structure subpanels. Current NEC has specific requirements that differ from older code, and incorrect grounding is a common inspection failure on detached subpanel projects.

Current NEC requirements for detached structure subpanels fed by underground UF-B:

• Separate neutral and ground bars at the subpanel: The neutral conductor (white) lands on the neutral bar, the bare equipment ground lands on the separate ground bar, and these two bars are NOT bonded to each other at the subpanel.
• Grounding electrode system at the detached structure: The detached structure typically requires its own grounding electrode system, typically two ground rods driven into the earth and bonded to the equipment grounding system at the subpanel.
• Equipment grounding conductor (the bare wire in 10/3 UF-B): Connects to the equipment ground bar at the subpanel and provides the fault path back to the main service.

What does NOT apply to current NEC installations: the older practice of using the bare conductor as both ground and neutral at the subpanel, with the neutral and ground bars bonded together at the subpanel. This older practice was permitted in earlier NEC editions but is no longer code-compliant for new installations or any installation where the existing wiring is being modified.

For specific grounding requirements based on the type of detached structure, the local AHJ (Authority Having Jurisdiction), and the specific subpanel configuration, consult a licensed electrician or the current NEC. The grounding configuration is one of the most common reasons for inspection failure on detached subpanel projects, and getting it right the first time avoids expensive rework.

Southwire 10/3 UF-B Specifications

Southwire 10/3 UF-B FAQs

Who the Southwire 10/3 UF-B Is Built For

The Southwire 10/3 UF-B serves four clear buyer types. The first is homeowners adding backyard improvements that require 240V outdoor electrical service, particularly hot tub installations which represent the dominant single application for this cable. For these buyers, the Southwire 10/3 UF-B is the right specification for the typical 240V/30A hot tub circuit, and the 250-foot roll matches typical installation consumption with comfortable margin.

The second buyer is electrical contractors handling detached garage, workshop, or outbuilding subpanel installations. For these contractors, the Southwire 10/3 UF-B delivers the 30-amp subpanel feeder capacity that handles small to medium detached structure electrical needs, supporting both 120V general-purpose circuits and 240V equipment circuits within the detached building. Multi-day projects benefit from the 250-foot roll matching typical job consumption.

The third buyer is the pool installer or pool electrical contractor running underground feeders to pool equipment pads. For these contractors, the Southwire 10/3 UF-B serves the 30-amp 240V pool equipment subpanel circuits, with NEC Article 680 compliance requirements specific to pool installations. The cable specification is correct; the supporting requirements (GFCI protection, equipotential bonding, disconnect placement) are additional work scope beyond the cable purchase.

The fourth buyer is the well pump installer or rural property electrical contractor handling underground feeders to wellheads, irrigation systems, and remote outdoor equipment. For these projects, the Southwire 10/3 UF-B serves the 30-amp 240V circuits that most residential well pumps require, with voltage drop considerations for longer underground runs. Browse the broader IB Lighting electrical wire collection for related supplies including larger UF-B gauges for higher-current applications.

Southwire 10/3 UF-B vs 14/2 UF-B: Which Size to Buy

The choice between the Southwire 10/3 UF-B and the smaller Southwire 14/2 UF-B is driven by circuit ampacity and voltage requirements. The two products serve fundamentally different outdoor electrical applications, and choosing the right one matters for code compliance and safe operation.

Choose the Southwire 10/3 UF-B (this product) when your application requires: 30-amp circuit capacity for higher-current equipment, 240V operation for hot tubs/subpanels/well pumps, three-conductor configuration (two hots plus neutral) for serving both 120V and 240V loads at a subpanel, or any outdoor equipment specifically rated for 240V/30A circuits.

Choose the Southwire 14/2 UF-B when your application is: 120V only (most outdoor lighting, garden receptacles, small landscape circuits), 15-amp circuit capacity (sufficient for landscape lighting transformers, outdoor receptacles, and small detached shed circuits), two-conductor configuration (one hot, one neutral) for simple 120V branch circuits, or budget-conscious projects where premium 10/3 UF-B would be overspecification.

The price difference is meaningful: the 14/2 UF-B at $120 for 250 feet ($0.48/ft) versus the 10/3 UF-B at $370 for 250 feet ($1.48/ft) reflects the substantially thicker conductors and three-wire vs two-wire configuration. The right specification matches your actual circuit requirements rather than over-specifying for the application.

Installation Best Practices for the Southwire 10/3 UF-B

Installing the Southwire 10/3 UF-B for 30-amp 240V outdoor circuits follows the same general practices as smaller UF-B installations, with several considerations specific to the higher-current nature of the applications it serves.

Plan the GFCI configuration: Most Southwire 10/3 UF-B applications require GFCI protection at the main electrical panel via a 240V GFCI breaker. Identify the correct GFCI breaker brand and sizing for your specific panel before starting work. The 240V GFCI breaker is a specific device that costs significantly more than standard breakers.

Plan trench depth carefully: The 24-inch minimum depth applies as for all UF-B installations. The larger 10/3 cable creates a more visible disruption to the yard during trenching, which often makes the project more disruptive than smaller UF-B installations. Plan the trench route to minimize landscape impact and verify depth compliance before backfill.

Use larger junction boxes at terminations: The thicker 10 AWG conductors require larger wire-fill capacity at electrical boxes. Standard residential boxes that handle 14/2 NM-B Romex may not have adequate volume for 10/3 UF-B terminations. Use appropriately-sized boxes throughout the installation.

Pay attention to grounding at detached subpanels: If the 10/3 UF-B feeds a subpanel at a detached structure, the grounding configuration is critical to code compliance. Separate neutral and ground bars at the detached subpanel (not bonded together), with the detached structure having its own grounding electrode system (typically two ground rods bonded to the equipment ground bar). Verify this configuration before requesting inspection.

Voltage drop calculations for long runs: For underground runs over 100 feet, the voltage drop on the Southwire 10/3 UF-B may become significant enough to affect equipment operation. Standard rule-of-thumb: keep voltage drop under 3 percent for branch circuits and under 5 percent for combined feeder plus branch circuit applications. For long runs, voltage drop calculators or licensed electrician consultation are advisable.

Transition properly at above-grade terminations: Where the Southwire 10/3 UF-B emerges from the ground at the equipment pad, detached building, or service location, transition the cable into rigid metal conduit or equivalent physical protection. The transition typically extends from below grade to at least 8 feet above grade or into the protective enclosure. The transition protects the cable from physical damage at this vulnerable location.

Inspect before backfill: Permitted installations are typically inspected before backfill to verify trench depth, cable placement, and termination quality. Schedule the inspection in advance to avoid project delays. Document the installation with photographs in case of future questions about the buried installation.

Browse the complete IB Lighting electrical wire and cable collection, compare with the smaller Southwire 14/2 UF-B for 15-amp outdoor lighting circuits, compare with the indoor equivalent Southwire 10/3 NM-B Romex SIMpull for indoor 30-amp circuits, explore other Southwire products, pair with a Tesla Universal Wall Connector for detached-structure EV charging, consider a Generac standby generator for backup power that keeps hot tubs and outdoor equipment running during outages, or visit our customer FAQ hub. Manufacturer technical sheets are available at the official Southwire website.