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XHHW insulation specifications

XHHW cable is identified by its cross-linked polyethylene (XLPE) insulation that provides a maximum operating temperature of 90 °C in dry and wet conditions. The XHHW-2 designation extends the temperature rating to 90 °C in both dry and wet environments, meeting National Electrical Code requirements for indoor, outdoor, and direct burial installations. The internal conductor dimensions are governed by the American Wire Gauge (AWG) standard, where a larger gauge number corresponds to a smaller diameter.

Material Composition and Properties

Section titled “Material Composition and Properties”

The insulation is composed of cross-linked polyethylene (XLPE), a thermoset material that offers resistance to moisture, heat, abrasion, and most chemical compounds. The ability to withstand temperatures up to 90 °C in wet environments distinguishes XHHW from other insulation types, as the “W” rating signifies suitability for use in wet locations. The outer jacket, when present, is generally made of sunlight-resistant and oil-resistant polyvinyl chloride (PVC).

Technical Specifications

Section titled “Technical Specifications”

The maximum operating temperature of XHHW cable is 90 °C / 194 °F in dry conditions and 90 °C / 194 °F in wet conditions. The conductor is available in copper or aluminum, with the copper variant being the most common for small and medium gauges.

AWG Size Conductor Diameter (mm) Conductor Diameter (in) Cross-sectional Area (mm²)
14 1,63 mm 0.0641 in 2,08 mm²
12 2,05 mm 0.0808 in 3,31 mm²
10 2,59 mm 0.102 in 5,26 mm²
8 3,26 mm 0.129 in 8,36 mm²
6 4,11 mm 0.162 in 13,3 mm²
4 5,19 mm 0.204 in 21,1 mm²
2 6,54 mm 0.258 in 33,6 mm²
1/0 8,25 mm 0.325 in 53,5 mm²
2/0 9,27 mm 0.365 in 67,4 mm²
3/0 10,4 mm 0.410 in 85,0 mm²
4/0 11,7 mm 0.460 in 107 mm²

Insulation thickness varies according to gauge and rated voltage. For 600 V cables, typical XLPE insulation thickness values range from 0,76 mm / 0.030 in for gauges 14 to 10 AWG and 1,14 mm / 0.045 in for gauges 8 to 2 AWG.

Comparison with Other Insulations

Section titled “Comparison with Other Insulations”

XHHW insulation offers advantages over thermoplastic THHN/THWN in applications requiring greater moisture resistance and higher temperatures in wet environments. While THHN is limited to 75 °C in wet locations, XHHW maintains its dielectric integrity at 90 °C under the same conditions. The thermoset nature of XLPE also provides superior resistance to cold flow and deformation under load.

Typical Applications

Section titled “Typical Applications”

XHHW cable is used in service entrances, feeder circuits, and branch circuits in commercial and industrial buildings. It is suitable for installation in cable trays, conduits, ducts, and direct burial when approved for such use. It is employed in systems requiring high dielectric reliability against moisture, such as installations in basements, exteriors, and process areas, as well as in motor circuits and distribution panel power supply.

Frequently Asked Questions (FAQ)

Section titled “Frequently Asked Questions (FAQ)”

What is the maximum operating temperature of XHHW cable? The maximum operating temperature of XHHW cable is 90 °C / 194 °F in dry conditions and 90 °C / 194 °F in wet conditions for the XHHW-2 version.

What conductor gauges are available for XHHW cable? The conductor gauges available for XHHW range from 14 AWG (1,63 mm / 0.0641 in) up to 1000 kcmil (25,4 mm / 1.00 in or larger), depending on the manufacturer and application.

What is the diameter of a 2/0 AWG conductor in XHHW cable? The diameter of the 2/0 AWG conductor in XHHW cable is 9,27 mm / 0.365 in, with a cross-sectional area of 67,4 mm².

What cross-sectional area does a 4 AWG conductor have? The 4 AWG conductor has a cross-sectional area of 21,1 mm², with a diameter of 5,19 mm / 0.204 in.

What is the diameter of a 14 AWG conductor? The diameter of the 14 AWG conductor is 1,63 mm / 0.0641 in, with a cross-sectional area of 2,08 mm².

What cross-sectional area corresponds to a 1/0 AWG conductor? The 1/0 AWG conductor has a cross-sectional area of 53,5 mm², with a diameter of 8,25 mm / 0.325 in.

References

Section titled “References”