XHHW-2/XLPE Wire vs THHN/THWN Wire
In our This vs. That series, we take a look at similar wire and cable products and define what makes them different. We hope that 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 both 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 The XHHW-2 specification has superseded the Type XHHW specification.
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.
| 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 are the types of insulation that is used. XHHW-2 wire uses Cross-Linked Polyethylene while THHN/THWN uses PVC insulation with nylon jacketing. The PVC insulation with nylon jacketing used in THHN/THWN wire is commonly cheaper than XLPE wire, which makes THHN/THWN wire an enticing choice for users seeking a general-purpose wire that meets their performance demands. Although the XLPE insulation that is found in XHHW-2 type wire is more expensive than the PVC insulation found in THHN/THWN, XLPE insulation does not emit toxic smoke if burned. XLPE insulation is also both more flexible and thicker than PVC insulation, making wire with XLPE insulation easier to install and more durable than wire with PVC insulation. XHHW-2 wire also performs better than THHN/THWN wire in low-temperature applications.
Even though XHHW-2/XLPE wire and THHN/THWN wire share similar voltage ratings and are used in similar applications, it is clear that they have their differences. 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.