Product Corner – THHN

Building wire is generally used to carry electrical current to all circuits of power in a building or dwelling. This product is utilized in the construction of almost every industrial, residential, and commercial building. The most popular type of building wire is THHN.


THHN – thermoplastic high-heat-resistant nylon

THHN  stands for Thermoplastic High Heat-resistant Nylon coated. THHN is available in stranded or solid conductors depending on the size. It is either manufactured in copper or aluminum and covered in PVC (polyvinyl chloride) insulation with a nylon jacket. THHN is UL listed with a rated 90 degrees Celsius in dry locations or 75 degrees Celsius in wet applications with a THWN rating. The vast majority of THHN building wire carries a dual rating on the cable marked THHN / THWN for both the wet and dry temperature rating. THHN building wire may also be used for wiring of machine tools, control circuits, or on certain household appliances.

THHN wire has several main distinctions compared to other building wire products. THHN uses a thinner PVC insulation which is a key factor in terms of its electrical properties and uses. THHN lacks the flexibility of some other products due to its nylon coating. This can often be a factor for many contractors or end-users since there is usually a preference to use a product that saves energy and time during installation. However, THHN building wire has grown in popularity due to it being a cost-effective alternative compared to other types of building wire. Despite some of its drawbacks, many users of THHN building wire have found these products to be a great fit for being budget-friendly and meeting project specifications.

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