18 August 2026, 04:24 PM
![[Image: f2672e9b-7d94-4145-a59c-f4cdaebde04e.png]](https://i.ibb.co/8gJQFY9q/f2672e9b-7d94-4145-a59c-f4cdaebde04e.png)
Manufactured with thermoset insulation, this type of wire is commonly used in conduit, raceways, and other recognized wiring systems. Depending on the construction and application, UL 44 thermoset-insulated wires are available in designations such as XHHW-2, RHH, and RHW-2. These wire types are widely used for power distribution and building wiring applications where dependable long-term performance is required.
What Is UL 44 Thermoset Insulated Wire?
UL 44 Thermoset Insulated Wire refers to wires and cables manufactured in accordance with UL 44, the standard covering thermoset-insulated wires and cables. The insulation system is based on cross-linked materials that provide enhanced thermal and mechanical properties compared with conventional thermoplastic insulation systems.
Dynamic Cables' UL 44 Thermoset-Insulated Wire is available for 600V and 1000V applications and uses XLPE insulation in XHHW-2, RHH, and RHW-2 constructions. The product is designed primarily for installation in conduit and recognized raceways and can also be used in suitable open-air, raceway, and cable-tray applications in accordance with applicable installation requirements.
The wire is suitable for both wet and dry locations, with a maximum operating temperature of 90°C under the specified conditions. Its insulation also provides resistance to sunlight and various environmental stresses, making it suitable for demanding electrical installations.
Key Features of UL 44 Thermoset Insulated Wire
The performance of a thermoset-insulated wire depends on its conductor, insulation system, construction, and compliance with applicable standards. Key features include:
1. 600V / 1000V Voltage Rating
UL 44 thermoset-insulated wire can be manufactured for electrical systems requiring 600V or 1000V voltage ratings. This makes it suitable for a broad range of building, industrial, commercial, and power distribution applications.
2. 90°C Wet and Dry Temperature Rating
One of the important advantages of XHHW-2 insulation is its 90°C temperature rating in wet and dry locations. Proper temperature performance helps the conductor operate reliably under demanding electrical loads while complying with applicable installation requirements.
3. XLPE Thermoset Insulation
The insulation is manufactured using cross-linked polyethylene (XLPE). Cross-linking improves the thermal and mechanical characteristics of the insulation, helping the wire withstand heat, moisture, and demanding installation environments.
4. Copper or Aluminum Conductors
Depending on project requirements, UL 44 thermoset-insulated wire can be manufactured with copper or aluminum conductors. Copper provides excellent electrical conductivity, while AA-8000 series aluminum alloy conductors can offer a lighter-weight alternative for suitable applications.
5. Wet and Dry Location Suitability
The wire is designed for applications in both wet and dry locations when installed according to the applicable requirements. This flexibility makes it suitable for a wide range of indoor and outdoor electrical distribution systems.
6. Sunlight Resistance
For installations exposed to sunlight, sunlight-resistant constructions can provide additional protection against environmental exposure. This is particularly useful for suitable outdoor raceway, cable-tray, and related applications.
XHHW-2, RHH and RHW-2: What Do These Designations Mean?
UL 44 thermoset-insulated wires may carry different designations depending on their intended performance and application characteristics.
XHHW-2 generally identifies a cross-linked synthetic polymer-insulated wire with a 90°C wet or dry temperature rating and 600V or 1000V voltage rating, depending on the construction.
RHH identifies a thermoset-insulated wire with a high-temperature rating and is used for specific electrical applications defined by the applicable standards.
RHW-2 identifies a thermoset-insulated wire intended for applications requiring a 90°C wet or dry temperature rating.
Selecting between these designations should be based on the electrical system, installation environment, applicable codes, conductor size, and project specifications.
Applications of UL 44 Thermoset Insulated Wire
UL 44 Thermoset Insulated Wire is suitable for numerous electrical installations. Typical applications include:
- Building electrical distribution systems
- Commercial electrical installations
- Industrial power distribution
- Manufacturing facilities
- Electrical panels and equipment connections
- Conduit and raceway installations
- Cable tray installations where permitted
- Indoor and outdoor electrical systems
- Wet and dry location wiring
- Utility and infrastructure projects
- Power distribution within commercial and industrial facilities
Its combination of temperature resistance, moisture resistance, and mechanical durability makes it particularly useful where electrical wiring may encounter challenging environmental conditions.
Standards and Compliance
Compliance with recognized standards is an important consideration when selecting electrical wire for North American applications. Dynamic Cables' UL 44 thermoset-insulated wire is manufactured with reference to applicable standards and requirements, including:
- UL 44 – Thermoset-Insulated Wires and Cables
- ASTM B3 – Soft or Annealed Copper Wire
- ASTM B8 – Concentric-Lay-Stranded Copper Conductors
- ASTM B800 / B801 / B836 – Aluminum Alloy Conductors
- UL 2556 – Wire and Cable Test Methods
- NEC (NFPA 70) – National Electrical Code
These standards address areas such as conductor construction, insulation performance, testing, and installation requirements.
Why Choose Thermoset-Insulated Wire for Electrical Projects?
Thermoset-insulated wire offers several advantages for applications that demand dependable electrical performance. Its cross-linked insulation system provides good resistance to elevated operating temperatures and environmental conditions. The availability of copper and aluminum conductor options also allows engineers and contractors to select a suitable construction based on system requirements.
Another advantage is installation flexibility. Depending on the applicable code and product designation, these wires can be used in recognized conduits, raceways, and suitable cable-tray systems. Their suitability for wet and dry locations further expands their potential application range.
For large commercial and industrial projects, selecting a wire that meets the required electrical ratings and applicable standards can also help simplify project specifications and support consistent installation practices.
How to Select the Right UL 44 Thermoset Insulated Wire
Before specifying UL 44 Thermoset Insulated Wire, consider the following factors:
Voltage requirement: Confirm whether the electrical system requires a 600V or 1000V-rated product.
Conductor material: Select copper or AA-8000 series aluminum based on electrical, mechanical, installation, and project requirements.
Conductor size: Determine the appropriate AWG or kcmil size according to ampacity, voltage drop, installation conditions, and applicable electrical codes.
Installation environment: Confirm whether the wire will be installed in a wet, dry, indoor, outdoor, conduit, raceway, or suitable cable-tray application.
Temperature requirements: Verify the required operating temperature rating and ensure it is appropriate for the installation.
Applicable standards: Confirm that the selected product complies with the standards and specifications required for the project.
Working with the cable manufacturer and electrical design team can help ensure that the selected construction meets the project's technical requirements.
UL 44 Thermoset Insulated Wire from Dynamic Cables
Dynamic Cables manufactures UL 44 Thermoset Insulated Wire in XHHW-2, RHH, and RHW-2 constructions for applications requiring reliable thermoset insulation and compliance with applicable standards. The product range includes copper and aluminum conductor options, with sizes ranging from 8 AWG to 1000 kcmil, subject to the specific construction and product requirements.
With 600V/1000V ratings, 90°C wet and dry temperature capability, XLPE insulation, and suitability for various recognized wiring methods, these wires are designed to support demanding electrical distribution applications.
For project-specific requirements, customers should review the applicable datasheet and confirm conductor material, size, insulation type, voltage rating, installation method, and regulatory requirements before placing an order.
Conclusion
UL 44 Thermoset Insulated Wire is a versatile solution for electrical distribution and building wiring applications where thermal performance, insulation durability, and suitability for wet and dry locations are important. Available in constructions such as XHHW-2, RHH, and RHW-2, these wires can support a wide range of commercial, industrial, infrastructure, and electrical distribution projects.
Choosing the right product requires careful consideration of voltage rating, conductor material, conductor size, temperature requirements, installation environment, and applicable electrical standards. With appropriate product selection and installation, UL 44 thermoset-insulated wire can provide reliable performance for demanding electrical systems.
Looking for UL 44 Thermoset Insulated Wire for your electrical project? Contact Dynamic Cables to discuss your technical requirements and request a product quotation or datasheet.