THHN vs XHHW Wire: What’s the Difference and Which One Should You Use?

When choosing electrical wire for residential, commercial, or industrial applications, you may come across two common types: THHN and XHHW. Both are copper or aluminum conductors used in building wiring, but they differ in insulation material, temperature rating, and environmental performance. In this article, we’ll compare THHN vs XHHW wire to help you understand which is better for your specific needs.

thhn vs xhhw

What Is THHN Wire?

THHN stands for Thermoplastic High Heat-resistant Nylon-coated. It is one of the most widely used wires in building wiring and control systems.

Key Features:

• Insulation: Thermoplastic (PVC) with a nylon outer jacket

• Temperature Rating: 90°C (dry), 75°C (wet)

• Voltage Rating: 600 volts

• Jacket: Nylon coating improves abrasion resistance

• UL and NEC Compliance: Yes

• Typical Use: Conduit, control panels, commercial wiring

What Is XHHW Wire?

XHHW stands for Cross-Linked High Heat-resistant Water-resistant. It is insulated with a cross-linked polyethylene (XLPE) material.

Key Features:

• Insulation: XLPE (Cross-linked Polyethylene)

• Temperature Rating: 90°C (dry & wet)

• Voltage Rating: 600 volts (XHHW) or 1000 volts (XHHW-2)

• Water Resistance: Higher than THHN

• Typical Use: Wet or damp locations, outdoor conduits, industrial power systems

THHN vs XHHW: Side-by-Side Comparison

When to Use THHN Wire

Choose THHN wire when:

• The installation is indoors and dry

• You need lower-cost wire

• You’re pulling wires through conduit

• Water or chemical exposure is not a concern

When to Use XHHW Wire

Choose XHHW or XHHW-2 wire when:

• You need higher moisture and chemical resistance

• The wiring will be outdoors or underground

• You want higher durability and UV resistance

• Local code requires wet-location rating

THHN vs XHHW for Underground or Wet Locations

THHN is not rated for direct burial or continuous wet environments unless it’s dual-rated as THWN-2. In contrast, XHHW-2 is approved for both wet and dry locations, making it a better choice for outdoor conduits, underground runs, and high-moisture areas.

Which Is Better: THHN or XHHW?

There’s no one-size-fits-all answer. If cost is your primary concern and you’re working in a dry, indoor setting, THHN is sufficient. If you need better environmental protection and long-term durability, XHHW-2 is the better option—especially in outdoor, industrial, or damp settings.

Need Help Choosing THHN or XHHW Wire?

At TOT Wire & Cable, we stock a wide range of copper and aluminum THHN and XHHW wires in all standard gauges. Whether you’re working on a new building, industrial upgrade, or underground wiring job, we’ve got the right product at competitive prices.

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