XHHW-2 is a single insulated copper conductor with thermoset, cross-linked polyethylene (XLP) insulation. It can be solid or stranded, bare or tinned annealed copper, designed to operate up to 90°C and up to 600 V in dry and wet environments. XHHW-2 is the ‘upgraded’ version of XHHW, which can operate up to 90°C in dry environments, but only 75°C in wet ones.