Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. XHHW Is an alphabetism or initialism which stands for "XLPE (cross-linked polyethylene) High Heat-resistant Water-resistant." XHHW is a designation for a specific insulation material, temperature rating, and condition of use (suitable for wet locations) for electrical wire and cable. WIres with XHHW insulation are commonly used in the alternating current (AC) electrical distribution systems of commercial, institutional, and industrial buildings and installations, 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 which are either solid or stranded, depending on size.