1. Cable Definitions and Standards
1.1 What is RHW Cable?
RHW stands for Rubber-insulated Heat and Water-resistant. This type of cable uses rubber insulation and is built to perform in moist and hot conditions. It's flexible and durable, often used in underground raceways, industrial sites, and even residential renovations.
Put simply, cable RHW is known for its flexibility and moisture resistance. It's rated for 600V or 1kV and performs well in both dry and wet locations.
You'll also see RHH cables, which are closely related. While RHW is moisture-resistant, RHH is intended primarily for dry environments. Both fall under typical RHH RHW use, but RHH is better suited for indoor, dry-space installations.
1.2 What is XHHW/XHHW-2 Cable?
XHHW stands for Cross-linked High Heat-Resistant Water-Resistant. It features RHH wire insulation made from cross-linked polyethylene (XLPE), not rubber like RHW. This gives it superior heat and chemical resistance.
XHHW-2 is the next-generation version with enhanced heat resistance - rated up to 90°C in both dry and wet conditions. It's widely used in commercial buildings, solar installations, and outdoor or buried environments.
2. Construction and Material Comparison
2.1 Insulation Materials
RHW cable uses rubber insulation - softer and more flexible, making it easier to install in tight spaces.
XHHW/XHHW-2 uses XLPE insulation, which is more rigid but offers excellent heat and chemical resistance.
This is why people often say RHW is easier to install, but XHHW is better for tough conditions.
2.2 Conductor Material
RHW typically comes with copper conductors.
XHHW and XHHW-2 are available in both copper and aluminum options, allowing for budget flexibility.
For larger projects where cost matters, XHHW aluminum conductors can be a smart, economical choice.
2.3 Temperature Ratings
RHW: 75°C in dry or wet environments.
XHHW: 90°C (dry), 75°C (wet).
XHHW-2: 90°C in both dry and wet conditions - making it more suitable for high-temperature or enclosed spaces.
3. Application Scenarios
3.1 When to Use RHW
RHW cables are perfect for tight, curved pathways because of their flexibility. You'll commonly find them in:
Underground conduit systems,
Medical or institutional wiring,
Older building renovations.
These are typical RHH RHW use environments where flexibility and moisture resistance are essential.
3.2 When to Use XHHW/XHHW-2
Thanks to their high-heat tolerance and rigid insulation, XHHW and especially XHHW-2 are ideal for:
Industrial power systems,
Commercial high-rise buildings,
Solar power plants,
Outdoor or direct burial installations.
4. Compliance and Safety Performance
Moisture and Fire Resistance
RHW cables have solid moisture protection, but their heat resistance is limited to 75°C.
XHHW-2 cables offer better temperature handling while maintaining water resistance, making them better for hot and damp locations.
Certification Differences
Both RHW and XHHW series cables meet UL and NEC standards, but their usage differs slightly:
RHW is more commonly used in older residential setups.
XHHW-2 is more in line with modern commercial and solar standards.
5. How to Choose: Practical Tips
Here's how you can decide between RHW and XHHW/XHHW-2:
Budget: XHHW-2 aluminum versions offer a more affordable solution.
Environment: For hot, wet, or underground conditions, go with XHHW-2.
Installation Needs: For tricky, tight spaces, RHW's flexibility makes it a winner.
Code Compliance: Always confirm NEC/UL compliance before selecting a cable.
6. Case Studies
Case 1: RHW Cable for Home Renovation
In a residential retrofit project, contractors chose RHW cables due to the tight routing in the existing structure. Its flexibility made installation easier, and its moisture resistance suited the building's aging, damp basement.
Case 2: XHHW-2 in a Solar Power Farm
A solar energy project required reliable, outdoor-grade wiring. XHHW-2 aluminum cables were used due to their cost-effectiveness and ability to handle extreme temperatures. The cables delivered long-term reliability and passed all NEC inspections.
7. Frequently Asked Questions
1. What's the difference between RHW and RHW-2?
RHW-2 can handle up to 90°C in both dry and wet conditions. RHW is limited to 75°C.
2. Is XHHW better than THHN for outdoor use?
Yes. XHHW is more resistant to moisture and better for buried or exposed applications.
3. Can XHHW-2 be used underground?
Absolutely. It meets NEC requirements for direct burial and wet locations.
4. Can I replace RHW with XHHW-2?
In many cases, yes - especially if you need better heat or chemical resistance.
5. Are XHHW-2 aluminum conductors NEC compliant?
Yes, as long as they're UL listed and installed per NEC guidelines.
Dongguan Greater Wire & Cable Co., Ltd. provides excellent cable products for customers in various industries, including silicone cables for high temperature environments, rubber cables that are resistant to mechanical damage, compact cross-linked cables, and widely used PVC cables. Our products widely serve key fields such as construction, power, medical, and aviation, helping to achieve efficient and safe power transmission solutions. We have a professional pre-sales team that can quickly respond to your consultation and technical needs. Call us now or send an email to start cooperation with us.