THHN wires have a thin flame-resistant PVC insulation that is covered by an abrasion-resistant nylon jacket. THHN wires are suitable for applications up to 90ºC in dry locations and 75ºC in wet conditions. Although THHN wire can perform in high temperature environments, you must correct the wire's ampacity at high ambient temperatures and when bundling cables together in a raceway or conduit.
The maximum voltage rating of the THHN cable is 600 volts. All THHN cables meet the UL 83 standard for safety thermoplastic-insulated wires and cables as well as the UL 106 Standard for safety machine-tool wires and cables. You can request Canadian Standards Association (CSA) approval if desired, and certain THHN cables also have European Restriction of Hazardous Substances (RoHS) Directive approval. Contact us today to learn more.
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Additional Information
What does THHN mean?
Thermoplastic high heat nylon (THHN) wire is a single conductor general-purpose building and hook-up wire. The first letter T shows the insulation is a thermoplastic material made from polyvinyl chloride (PVC). The middle letters (HH) indicate it's high heat resistance and suitable for high-temperature use up to 90 degrees Celsius. The last letter, N, refers to the wire's abrasion- and heat-resistant nylon jacket. You'll find the letters THHN printed on the wire jacket.
What type of conductors does THHN have?
THHN wires with a smaller diameter between 10 and 14 American Wire Gauge (AWG) have solid, soft-drawn, copper conductors. Larger THHN wires have stranded copper conductors. Allied Wire & Cable stocks THHN cable made with pure copper conductors.
Where is THHN wire used?
You use THHN cable for general-purpose residential and commercial building wiring. The cable's nylon jacket provides moderate protection against abrasion, and you must install THHN wire in a conduit or raceway. You may use THHN wire indoors and outdoors in dry and damp applications. Other applications for this wire include machine tools, appliances, and control circuits. Most types of THHN cable sold by AWC carry a dual thermoplastic high-temperature water-resistant nylon-jacket (THWN) rating, allowing their use in wet conditions.
The maximum voltage rating of the THHN cable is 600 volts. All THHN cables meet the UL 83 standard for safety thermoplastic-insulated wires and cables and the UL 106 Standard for safety machine-tool wires and cables. You can request Canadian Standards Association (CSA) approval, and certain THHN cables also have European Restriction of Hazardous Substances (RoHS) Directive approval.
What are the alternatives to THHN wire?
Similar wires and cables to THHN include THWN, thermoplastic, heat- and water-resistant wire (THHW), and thermoplastic flexible fixture nylon (TFFN):
THWN Wire:
THWN jacket that's suitable for use in dry (90ºC) and wet applications up to a maximum temperature of 75ºC. This wire has PVC insulation and a nylon jacket. Most THHN wires have a dual THHN/THWN rating.
THWN-2 Wire:
Similar to THWN wire but rated for a maximum operating temperature of 90ºC in wet conditions.
THHW Wire:
THHW without a nylon jacket. It's suitable for dry use to a maximum temperature of 90ºC and wet applications to a maximum of 75ºC.
TFFN Wire:
TFFN wire for use in buildings. The wire is very flexible, has a nylon jacket, and is available in smaller gauges including 16 and 18 AWG.
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