USE / USE-2 (UL 854) Underground Service Entrance Cable

1. Definition, Model Difference & Standards

Full Name & Code Explanation

USE stands for Underground Service Entrance Cable, designated exclusively for direct underground burial service feeders in North America, governed by UL 854 Standard for Service-Entrance Cables and regulated under NEC Article 338UL Standar....

• USE: Original type, 90°C continuous rating for dry locations, only 75°C for wet underground environments

• USE-2: Upgraded mainstream version, fixed 90°C operating temperature for both dry and wet conditions, the dominant specification in the market

Compliance Certifications

Primary standard: UL 854; complies with US National Electrical Code (NEC), NEC 690 for solar PV systems; insulation performance aligned with UL 44 thermoset cable criteria; flame performance meets UL1581 VW-1 vertical flame test; available in copper and aluminum conductor constructions.

2. Internal Construction (Single-Core Most Common, Inner to Outer)

1. Conductor Two mainstream options: Class B compact stranded bare annealed copper; AA8000 series aluminum alloy (preferred for residential service due to lighter weight, lower cost and superior soil corrosion resistance). AWG sizes range from 6AWG up to 1000kcmil, maximum 2000kcmil for oversized versions. Multi-conductor round/flat cables come with insulated grounding conductors, whose gauge can be smaller than phase conductors.

2. Insulation Layer Integral extruded XLPE thermoset insulation, serving dual purposes of electrical insulation and outer weatherproof jacket without an extra independent sheath. Thickened insulation is engineered to withstand soil compression, water immersion and underground moisture ingress for direct burial service.

3. Multi-Conductor Integrated Cable 2 phase + neutral + ground conductors stranded into round or flat assemblies, color coded: black for phases, white for neutral, green for equipment ground. No overall outer jacket; the XLPE insulation itself provides full underground environmental protection.

3. Key Technical Specifications

Rated voltage: 600V AC universally Continuous operating temperature: USE (90°C dry /75°C wet); USE-2 constant 90°C for all dry & wet locations Short-circuit withstand temperature: maximum 250°C Cold resistance: no cracking under -40°C cold bend & cold impact test Flame rating: UL VW-1 Installation restriction: approved solely for underground direct burial or underground conduit routing; permanent overhead outdoor exposure is prohibited by NEC codesMinimum bending radius: 7.5 times cable outer diameter for fixed installation Resistance: soil acid & alkali, salt spray, groundwater immersion, UV aging and mechanical crushing.

4. Core Advantages

1. Optimized for direct underground burial, easy installation The integrated XLPE structure delivers sufficient waterproof and compressive strength, permitting direct soil burial without extra protective conduits, the standard residential service feeder from utility transformers to meter bases across North America.

2. Interchangeable with RHW-2 under NEC codes, different application boundaries Identical thermal rating allows mutual substitution per electrical codes; USE is strictly limited to underground service entrance wiring by regulation; RHW-2 features a separate CPE outer jacket for universal use including open-air outdoor exposure, cable trays and conduits.

3. Cost-effective aluminum alloy option AA8000 aluminum conductors weigh nearly 40% less than copper, resist galvanic corrosion in soil, widely adopted for suburban residential district distribution projects.

4. Listed for solar photovoltaic applications USE-2 is approved by NEC 690 for underground DC wiring of PV arrays, extensively used for underground collector circuits of ground-mounted solar farms.

5. Slim compact design without overall jacket No outer sheath reduces cable overall diameter, enabling tighter layout inside underground ducts and boosting construction efficiency.

5. Difference Between USE-2 and RHW-2

USE-2 complies with UL 854, single-layer integral XLPE insulation without separate outer jacket, legally restricted to underground service burial only, not suitable for long-term outdoor sunlight exposure; slimmer and more economical for residential municipal underground feeders and solar underground wiring. RHW-2 follows UL 44, dual-layer construction with insulation plus dedicated CPE outer sheath, certified for all scenarios: open-air outdoors, cable trays, conduits and direct burial. It boasts superior oil resistance, abrasion and impact resistance, applied to damp industrial plants, outdoor main power feeders and energy storage systems.

6. Application Scenarios

1. North American residential municipal power distribution: underground service cables connecting street transformers to household meter boxes, overhead-to-underground renovation for suburban communities

2. Solar & renewable energy: underground DC feeders for PV arrays, collector cables inside solar power stations

3. Agricultural irrigation: underground power wiring for farm water pumps and submersible well pumps

4. Small commercial buildings: underground service entrance feeders for convenience stores and retail shops in suburban areas

5. Coastal & high-humidity power grids: salt-spray resistant underground wiring for waterfront regions