1. Understanding XHHW Wire: Composition and Key Features
XHHW stands for "Cross-Linked Polyethylene High Heat-Resistant Water-Resistant." This type of wire is widely recognized for its robust insulation system, which combines cross-linked polyethylene (XLPE) with other materials to deliver exceptional thermal, chemical, and mechanical resistance. Here's a breakdown of its key components:
Conductor: Typically made of copper (XHHW copper wire) or aluminum. Copper is preferred for its superior conductivity, corrosion resistance, and durability.
Insulation: XLPE provides high-temperature resistance (up to 90°C in wet/dry conditions) and excellent dielectric strength.
Jacket: A protective outer layer, often PVC or sunlight-resistant polyolefin, shields against abrasion, moisture, and environmental stressors.
These features make XHHW wire suitable for both indoor and outdoor applications, including conduit, tray installations, and direct burial scenarios.
2. XHHW-2 Direct Burial: What Sets It Apart?
The XHHW-2 direct burial variant is an upgraded version of standard XHHW wire. The "2" designation signifies compliance with stricter industry standards (UL 44 and UL 1277), allowing it to operate at higher temperatures (up to 90°C in wet conditions and 150°C in dry conditions). This makes it ideal for harsh environments, including underground installations.
Why Choose XHHW-2 for Direct Burial?
Enhanced Insulation: The thicker XLPE layer and robust jacket provide superior resistance to moisture, soil acidity, and physical damage from rocks or shifting earth.
Temperature Resilience: Its ability to withstand higher temperatures reduces the risk of insulation breakdown in buried applications.
Long-Term Durability: XHHW-2 resists UV degradation, oil, and chemicals, ensuring a longer lifespan compared to non-rated cables.
3. 1 AWG XHHW 1000V: Powering Heavy-Duty Applications
For projects requiring high current capacity and voltage ratings, 1 AWG XHHW 1000V cables are a go-to solution. The 1 AWG (American Wire Gauge) size offers low resistance and high ampacity, making it suitable for industrial, commercial, and utility applications.
Key Benefits in Direct Burial:
Voltage Rating: The 1000V rating ensures safe operation in high-voltage circuits, even in damp underground environments.
Current Capacity: 1 AWG copper conductors efficiently handle heavy loads, reducing voltage drop over long distances.
Compliance: Meets NEC (National Electrical Code) requirements for direct burial when installed at appropriate depths (typically 24–36 inches).
4. XHHW Tray Cable: Versatility Above and Below Ground
While XHHW tray cable is primarily designed for use in cable trays, its rugged construction also allows for direct burial in certain scenarios. These multi-conductor cables bundle multiple XHHW-insulated wires under a single jacket, simplifying installation in industrial settings.
Direct Burial Considerations:
Mechanical Protection: Ensure the tray cable's outer jacket is rated for burial (look for markings like "Direct Burial" or "Sunlight Resistant").
Shielding: Some tray cables include aluminum interlocking armor (AIA) for added protection against rodents and crushing forces.
Code Compliance: Verify local regulations, as tray cables may require additional conduit for burial depending on the environment.
5. Installation Best Practices for XHHW Direct Burial
To maximize the performance of XHHW wire in direct burial applications, follow these guidelines:
Depth Requirements: Bury cables at least 24–36 inches deep to avoid damage from surface activities or frost lines.
Bedding Material: Use sand or fine-grained soil to cushion the cable and prevent abrasion from rocks.
Warning Tape: Install detectable tape 12 inches above the cable to alert excavators.
Conduit Use: While XHHW-2 is rated for direct burial, conduit adds an extra layer of protection in high-risk areas (e.g., rocky soil).
6. Advantages of XHHW Copper Wire in Buried Environments
Corrosion Resistance: Copper's natural resistance to oxidation ensures stable conductivity over decades.
Flexibility: Even at larger sizes like 1 AWG, XHHW copper wire remains easier to handle than aluminum alternatives.
Eco-Friendly: Copper is 100% recyclable, aligning with sustainable construction practices.
7. Limitations and Mitigation Strategies
While XHHW excels in most scenarios, consider these challenges:
Cost: Copper XHHW is pricier than aluminum, but its longevity offsets initial expenses.
Soil Conditions: Highly acidic or alkaline soils may degrade non-XHHW-2 cables over time. Use XHHW-2 for such environments.
Voltage Drop: For very long runs, calculate voltage drop and adjust wire size accordingly.
8. Case Study: XHHW-2 in a Solar Farm Installation
A recent solar farm project in Arizona utilized 1 AWG XHHW 1000V cables for underground connections between inverters and transformers. The XHHW-2's heat resistance (critical in desert temperatures) and direct burial rating minimized conduit costs and ensured reliable performance despite sandy, abrasive soil.
9. FAQs About XHHW Direct Burial
Q: Can standard XHHW be buried without conduit?
A: Only if labeled for direct burial (e.g., XHHW-2). Check manufacturer specifications.
Q: How does XHHW compare to THHN in underground use?
A: THHN lacks the moisture resistance needed for burial. Always use XHHW or XHHW-2.
Q: Is aluminum XHHW suitable for direct burial?
A: Yes, but copper offers better corrosion resistance in wet soils.
Dongguan Greater Wire & Cable Co., Ltd. is well aware of the dual pursuit of cable quality and price in the US market. We have a modern production plant, and the production process strictly follows international standards to ensure stable product quality. The R&D team continues to overcome technical difficulties and launch cables that are more suitable for the complex climate and construction needs of the United States. Our products are all UL certified. For example, XHHW WIRE meets the UL44 standard and has excellent insulation performance. Moreover, our price is 25% lower than similar products in the United States, providing you with cost-effective cable solutions.