The initials, or acronym, for XHHW stand for Cross-Linked High Heat Water Resistant Insulated Wire. This XHHW is the designation for a specific insulating material for electrical building wire and cable. The term XHHW also designates the temperature rating as well as the conditions that the cable can be used under. XHHW wire is generally used in residential, commercial and industrial buildings and installations for the purpose of power distribution. .