THHN

THHN stands for "Thermoplastic High Heat-resistant Nylon-coated."[20] THHN is a designation for a specific insulation material, temperature rating, and condition of use (suitable for dry and damp locations) for electrical wire and cable.[21]
Wire with THHN insulation is commonly used in the alternating current (AC) electrical distribution systems of all types and sizes throughout North America, usually at voltage levels (potential difference or electromotive force) ranging from 110-600 volts. This type of insulation is used for both copper and aluminum conductors [22] which are either solid or stranded, depending on size.