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In our This vs. That series, we examine similar wire and cable products and define what makes them different. We hope these product comparisons can help you decide which wire or cable will work best for your next application.

In this article, we take a closer look at the differences between XHHW-2/XLPE General Purpose Wires and THHN/THWN building wires. Both types of wires share very similar ratings and features. They both have a voltage rating of 600V and are resistant to abrasion, heat, and moisture. So what are the differences between XHHW-2/XLPE wire and THHN/THWN wire?

What is Type XHHW-2/XLPE Wire?

XHHW-2 Wire, also known as XLPE wire is a general-purpose wire that is suitable for applications in conduits, raceways, feeders, and branch circuits. It is also often found in power distribution systems in industrial, commercial, and residential buildings. "XHHW" is an acronym that stands for "High Heat-Resistant, Water Resistant". "XLPE" stands for "Cross-linked Polyethylene" which represents the Cross-linked Polyethylene that is used as insulation for XHHW-2 wire.

The thermoset material used in XHHW-2 wire provides excellent heat and water resistance. XHHW-2 building wire has a maximum temperature of 90°C in dry and wet locations, whereas Type XHHW wire can only be used in temperatures as high as 75°C in wet locations. The XHHW-2 specification has superseded the Type XHHW specification.

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What are Common Applications of XHHW/XLPE Wire?

XHHW-2/XLPE wire is highly versatile and used in various applications across industrial, commercial, and residential settings. It is commonly found in power distribution systems, service entrance cables, and feeder circuits. Additionally, XHHW-2 wire is suitable for installations in conduits and raceways, making it ideal for use in wiring buildings, including high-rise structures. Its excellent resistance to heat and moisture also makes it suitable for environments where these factors are a concern, such as in underground or damp locations.

What are Alternatives for XHHW-2/XLPE Wire?

While XHHW-2/XLPE wire is a robust option for many applications, alternatives include other types of high-temperature resistant wires such as RHW-2 and USE-2 wires. RHW-2 wire, with its rubber insulation, offers similar heat and moisture resistance, making it another viable option for high-stress environments. USE-2 wire, designed for underground service entrance applications, also provides excellent durability and moisture resistance. For applications that do not require the high-performance characteristics of XHHW-2 wire, THHN/THWN wires can be considered as a more cost-effective option.

What are THHN and THWN wires?

THHN and THWN wires are single conductor, general-purpose building wires that are also suitable for installation in conduits and raceways. THHN and THWN wire are also suitable for use as machine tool, control circuit, or appliance wiring. Both THNN and THWN have PVC insulation with nylon jackets. The thermoplastic PVC insulation makes THHN and THWN wire have flame-retardant properties, while the nylon jacketing also adds resistance to chemicals such as gasoline and oil.

The "THHN" part of THHN wire stands for "Thermoplastic High Heat-Resistant, Nylon-Coated". "THWN" wire has the same properties, but the "W" part of THWN adds "Water resistance". The main difference between THHN and THWN wires are their maximum recommended operating temperatures in wet locations. While THHN wire is rated to be used in wet locations with ambient temperatures up to 75°C, THWN wire has a higher maximum recommended operating temperature of 90°C in both wet and dry environments. Although THHN and THWN wires can often be used interchangeably, it is important to ensure that THHN or THWN wire will perform it's best for your specific application. Please reach out and contact us with any questions.

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What are Common Applications of THHN and THWN Wire?

THHN and THWN wires are widely used in building construction for electrical distribution systems. These wires are typically used for general-purpose wiring in residential, commercial, and industrial buildings. They are suitable for installation in conduit or other recognized raceways for services, feeders, and branch circuits. THHN/THWN wires are also frequently used for wiring machine tools, control circuits, and appliances due to their flexibility and flame-retardant properties.

What are Alternatives for THHN and THWN Wire?

ternatives to THHN and THWN wires include TFFN and TFN wires, which are also thermoplastic insulated wires but are more flexible and used for lighter applications. For environments that require higher temperature ratings or additional durability, XHHW-2 wires provide a suitable alternative. MTW (Machine Tool Wire) is another alternative that offers superior flexibility and durability, making it ideal for industrial applications where frequent movement and bending are required. Lastly, NM-B (Non-Metallic Sheathed Cable) can be considered for residential wiring applications where conduit is not used.

Max. Temperature Voltage Rating Insulation Jacket
XHHW 90°C dry locations, 75°C wet locations 600V Cross-Linked Polyethylene (XLPE) None
XHHW-2 90°C, dry and wet locations 600V Cross-Linked Polyethylene (XLPE) None
THHN 90°C dry locations, 75°C wet locations 600V Polyvinyl Chloride (PVC) Nylon
THWN 90°C, dry and wet locations 600V Polyvinyl Chloride (PVC) Nylon

What are the Differences Between XHHW-2/XLPE Wire and THHN/THWN Wire?

The major difference between XHHW-2/XLPE wire and THHN/THWN wire lies in their insulation materials. XHHW-2 wire uses Cross-Linked Polyethylene (XLPE), while THHN/THWN wires use Polyvinyl Chloride (PVC) with a nylon jacket. The XLPE insulation in XHHW-2 wire provides superior heat resistance and durability, making it more suitable for high-stress environments. In contrast, PVC insulation with a nylon jacket, used in THHN/THWN wires, is less expensive and still provides adequate performance for many general-purpose applications. Additionally, XLPE insulation does not emit toxic smoke when burned, making it a safer option in the event of a fire. XHHW-2 wire also maintains flexibility and durability in low-temperature applications, which can be advantageous over THHN/THWN wire.

Despite their differences, both types of wire are suitable for similar voltage ratings and applications, offering users various options depending on their specific needs. Allied Wire & Cable carries an extensive stock of both XHHW-2/XLPE and THHN/THWN type wires, including RoHS Compliant THHN Wire and Custom Wire configurations. If you have any more questions, please contact us today.

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