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What is THHN Wire?

THHN stands for Thermoplastic High Heat-Resistant Nylon. It is a building wire that is abrasion, oil, and gasoline-resistant. Building wires carry electrical currents to external power sources in many buildings. This building wire is extremely popular due to its affordability and diverse uses.

THHN Wire Construction

THHN is a single-conductor building wire. The conductor is often bare copper or aluminum, stranded or solid. It features thermoplastic insulation, typically Polyvinyl Chloride (PVC). The Nylon Jacket in this wire makes it durable and resistant to many environmental factors. It is abrasion, gasoline, and oil-resistant. We offer THHN Wire in gauge sizes 14 AWG to 1000 MCM. Wires 10 AWG and larger are only available with a stranded copper conductor, but wires 10 AWg to 14 AWG are available with either a stranded or solid conductor.

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THHN Wire Specifications

This wire is often dual rated as THWN Wire. THWN stands for "Thermoplastic Heat and Water-Resistant Nylon." This dual rating gives a THHN/THWN wire a maximum temperature of 90°C in dry locations and 75°C in wet locations. Regardless of dual ratings, this wire has a voltage rating of 600V. It also often meets UL Styles 83 and 1063. Stranded constructions also meet UL MTW (machine tool wire) standards. We also offer THHN Wire with RoHS Compliance.

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THHN Wire Applications

This type of wire is often used to carry electrical currents to external power sources. It is also suitable for use as general-purpose wiring in machine tools, appliances, and control circuit wiring. It may be used for installation in conduit, cable tray, and other recognized raceways. However, the jacket on this wire may release toxic gases if it comes into contact with flame, so it is not suitable for use in outdoor or direct burial applications.

Other Types of Building Wire

TFFN Wire is another popular type of building wire. TFFN stands for Thermoplastic Flexible Fixture Nylon. Much like THHN wire, it features PVC insulation and a nylon jacket. However, it is not suitable for use in wet locations. In addition to being suitable for the same applications as THHN wire, TFFN is also classified as a fixture wire. We offer TFFN wire in 16 AWG and 18 AWG sizes. You can learn more about their differences here.

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