1.What is XHHW Wire?
XHHW stands for Cross-Linked Polyethylene High Heat-Resistant Water-Resistant. This thermoset-insulated cable is engineered to withstand high temperatures (up to 90°C in dry conditions and 75°C in wet environments) while resisting moisture, chemicals, and physical abrasion. Its cross-linked polyethylene (XLPE) insulation ensures long-term reliability, making it a preferred choice for commercial, industrial, and residential projects.
2.Key Features of XHHW Wire
2.1 Temperature Resistance:
XHHW's XLPE insulation allows it to operate safely in high-heat environments, reducing risks of insulation breakdown or fire hazards.
2.2 Moisture and Chemical Resistance:
The water-resistant jacket protects against corrosion in damp or underground installations. It also resists oils, acids, and alkalis.
2.3 Flexibility and Durability:
Despite its robust insulation, XHHW remains flexible, simplifying installation in conduit systems or tight spaces.
2.4Voltage Rating:
Most XHHW wires, including 3/0 XHHW Copper 600V, are rated for 600V applications, ideal for power distribution and feeder circuits.
3.Is XHHW Wire Suitable for Direct Burial?
The short answer: Yes, but with conditions.
Standard XHHW is approved for direct burial only if specified by the manufacturer and compliant with the National Electrical Code (NEC). However, the XHHW-2 variant is explicitly rated for direct burial due to enhanced insulation properties. Let's break this down:
3.1 XHHW vs. XHHW-2: What's the Difference?
XHHW: Rated for dry and damp locations. Requires conduit for underground use unless labeled for direct burial.
XHHW-2: Features thicker, sunlight-resistant insulation and meets stricter UL standards (UL 44). Approved for direct burial without conduit in wet or dry conditions.
For projects like underground feeders or outdoor lighting, XHHW-2 direct burial cables are the go-to solution.
4.Popular XHHW Wire Sizes and Applications
4.1 1AWG and 2AWG XHHW
Current Capacity: 1AWG (130A) and 2AWG (115A) at 75°C.
Use Cases: Ideal for residential service entrances, subpanels, and medium-load circuits.
Advantages: Compact design, easy to route through conduits, and cost-effective for mid-sized projects.
4.2 3/0 XHHW Copper 600V
Current Capacity: 225A at 75°C.
Use Cases: Heavy-duty applications like industrial machinery, large commercial buildings, and feeder lines.
Advantages: Combines copper's superior conductivity with XHHW's durability, ensuring minimal voltage drop over long runs.
4.3 4/0 XHHW Wire
Current Capacity: 260A at 75°C.
Use Cases: Main service panels, high-demand circuits, and underground utility lines.
Advantages: Robust construction for extreme environments; pairs well with XHHW-2 direct burial in outdoor settings.
4.4 500MCM XHHW Aluminum
Current Capacity: 310A at 75°C.
Use Cases: Large-scale industrial projects, renewable energy systems (e.g., solar farms), and substations.
Advantages: Lightweight and cost-efficient compared to copper, while maintaining high ampacity.
5.Why Choose XHHW-2 for Direct Burial?
5.1 Compliance with NEC Standards:
XHHW-2 meets NEC Article 310 for underground installations, eliminating the need for conduit in most cases.
5.2 Enhanced Insulation:
The dual-layer XLPE insulation resists moisture ingress, soil acidity, and physical damage from rocks or roots.
5.3 Longevity:
XHHW-2's UV and sunlight resistance ensure decades of reliable performance in exposed or buried environments.
5.4 Cost Savings:
By skipping conduit, contractors reduce material and labor costs-a major advantage for large-scale projects.
6.Comparing XHHW to Other Cable Types
THHN/THWN-2: Requires conduit for direct burial; less resistant to moisture and chemicals.
UF-B: Designed for direct burial but lacks the high-temperature tolerance of XHHW-2.
USE-2: Rated for underground service but limited to 90°C in dry conditions.
XHHW-2 outperforms these alternatives with its balanced combination of heat resistance, flexibility, and direct burial approval.
7.Installation Best Practices for XHHW Direct Burial
7.1 Depth Requirements:
Bury cables at least 24 inches deep (18 inches if protected by a concrete slab).
7.2 Trench Preparation:
Remove sharp debris and use sand bedding to prevent insulation damage.
7.3 Grounding:
Ensure proper grounding for aluminum conductors like 500MCM XHHW Aluminum to mitigate corrosion risks.
7.4 Labeling:
Use warning tape above the trench to alert future excavators.
Dongguan Greater Wire & Cable Co., Ltd.'s scale and certification advantages are very attractive in the US market. Our production scale is large and the production process is standardized. Our products have passed UL83, UL44, UL719, UL493 UL1277 and other certifications, and the safety performance is guaranteed. The R&D team continues to optimize the products. In terms of price, we provide competitive quotations to US customers with scale effects and cost control, and we are a good choice for your project.