Regency Wire 21204301 12SOLPUR 500'/ROL #12 Purple THHN Solid Wire. Type THHN conductors are primarily used in conduit as branch circuits in commercial or industrial applications, as specified by the National Electric Code. Type AWM or MTW conductors are primarily used as appliance or machine tool wiring, as specified by the National Electric Code. Type THHN are available stranded in sizes 14 awg - 750 kcmiL, and as solid in sizes 14-10 awg. Stranded sizes 14 awg - 750 kcmiL are also rated as AWM or MTW. The conductors are soft-annealed, stranded or solid copper and are insulated with a tough heat and moisture resistant polyvinyl chloride (PVC), over which a nylon (polymide) jacket is applied. Sizes #4 – 750MCM made with friction reducing nylon jacket to aid in the installation process.