Jul 11, 2025
How XHHW-2 Wire Outperforms THHN in High Heat Environments
Getting to Know XHHW-2 and THHN Wires
What Makes XHHW-2 Special?
XHHW-2 stands for “XLPE (cross-linked polyethylene) High Heat-Resistant Weather-Resistant” wire. It can handle 90°C in wet or dry places, and it’s often used in conduit systems for power distribution.XHHW-2 uses thermoset cross-linked polyethylene (XLPE) insulation. It has excellent weather resistance and chemical corrosion resistance. It’s perfect for indoor and outdoor setups where conditions are rough.
What About THHN Wire?
THHN means “Thermoplastic Nylon-Coated” wire. It has polyvinyl chloride (PVC) insulation with a nylon outer layer. THHN is rated for 90°C in dry spots but only 75°C in wet ones.THHN is common in building wiring and conduit systems where conditions are steady. But its nylon layer can get damaged during installation or from harsh elements over time.
Main Differences in Build and Insulation
The biggest difference of XHHW-2 and THHN lies in their insulation. XHHW-2 uses thermoset XLPE insulation. It stays solid after curing. THHN uses the nylon-coated thermoplastic PVC insulation.The long-term operating temperature of XLPE insulation material in XHHW-2 is higher than that of PVC in THHN.
How They Perform in High Heat
Heat Resistance and Temperature Limits
XHHW-2 has a clear advantage in hot conditions.XHHW-2 is rated 90°C for both wet and dry places. THHN is rated 90°C only in dry settings. It drops to 75°C in wet ones. XHHW-2 has a wider range of applications.
How Heat Affects Conductivity and Insulation
Conductivity is related to conductor resistance and the long-term allowable operating temperature of the material. The thermoset XLPE insulation of XHHW-2 has a higher long-term operating temperature and better conductivity than the PVC insulation of THHN.Behavior in Constant High Heat
At 90℃ operating temperature, XHHW-2 thermoset material is more stable than THHN thermoplastic material. THHN is more prone to breakdown or failure under overload operation.Insulation Strength and Durability
Thermoset vs. Thermoplastic Insulation
Cross-linked Polyethylene (XLPE) in XHHW-2
Cross-linked XLPE insulation has a more stable molecular structure, enhanced heat resistance and a higher long-term operating temperature.Resistance to Deformation, Cracking, and Melting
Thermoset materials like XLPE resist deformation better than thermoplastics like PVC.XHHW-2’s insulation stays stable under mechanical stress and high heat. It doesn’t soften or melt. THHN may deform in similar conditions due to its lower melting point.
Moisture and Chemical Resistance in Harsh Settings
Performance in Wet or Damp Conditions
XHHW-2 beats THHN in moisture resistance.XHHW-2 holds its 90°C rating in wet locations. THHN drops to 75°C in wet spots, which limits its use in places like basements or outdoor conduits.
Chemical Stability Against Oils, Solvents, and Gases
XLPE in XHHW-2 can have the properties of gasoline resistance, acid and alkali resistance, low smoke and halogen-free environmental performance, but THHN PVC insulation does not have these properties. Under the same special environmental conditions, XHHW-2 has a longer service life.Certifications for XHHW-2 and THHN
Both wires usually have UL listings. And they usually have flame retardant properties, increasing the safety of use.Long-Term Reliability and Maintenance
Lifespan Under Heat Stress
Because XHHW-2 has a higher long-term operating temperature than THHN, it has a longer service life at high temperatures..jpg)
