One of the most versatile wires used in construction is the 10 XHHW-2 copper building wire. The uses for this wire are specified in the National Electrical Code 1 listing. This durable, highly conductive wire differs from some other building wires because of its insulation. It uses Cross-Linked High Heat Water Resistant insulation (abbreviated to XHHW), making it very resilient and keeping the copper wires safe from water, heat, and sunlight. The jacket also protects the wire from rough use and from abrasions and cuts.

Most 10 XHHW-2 copper building wire is designed to actually exceed many of the standards the National Electrical Code states that it must meet. These standards include UL Standard 44, Federal Specification A-A-59544, c(UL) Type RW90, NEC, ICEA 2-95-658 / NEMA WC70, and all OSHA guidelines.


The 10 XHHW-2 wire is made from annealed (soft) copper, which is a better material for use in building wire than aluminum since it doesn’t need as much insulation. Aluminum also does not transmit current as well when it’s covered in aluminum oxide, which occurs if the wire comes into contact with air. While copper can also develop copper oxide, it still conducts current very well.

The “Cross-Linked” part of the XHHW abbreviation indicates that this wire uses a special type of cross-linked polyethylene (XLPE) insulation. This insulation is very heat and water resistant. If an electrical fire occurs, this insulation will keep the flames contained within the wiring, preventing the spread of the fire. Because it’s also waterproof, this insulation makes the wire perfect for use in damp areas.

10 XHHW-2 wire has a standard size of 10 AWG. It uses 7 strands and has a nominal O.D. of 171. The insulation has a thickness of 30 mils. The wire’s allowable ampacity at 60, 75, and 90 degrees Celsius is 30 across the board. A spool of 1,000 feet of wire weighs around 40 pounds.


This type of wire is most often used in the wiring of residential, industrial, and commercial buildings. The National Electrical Code lists the uses for this type of wiring, which is mainly used in raceways or conduits for services, branch circuit wiring, and feeders. The code does state that 10 XHHW-2 wires may be used in either dry or wet/damp locations thanks to the cross-linked insulation used in it. However, even though this insulation does protect the wire from heat, that doesn’t mean the wire can be used in areas where it will regularly be subject to very high heat. The maximum recommended temperature is 90 degrees Celsius. Any regular exposure to higher temperatures may result in abnormal operation.

Because this type of wiring was designed to exceed standards rather than simply meet them, it is used in cases where contractors require a finished project that is of the highest quality. The special insulation also means that the cable can be used in projects that may place the wiring in contact with water.

10 XHHW-2 wiring is rated for use at 600 volts maximum.

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