The quality of the cable is extremely important for the efficiency of cathodic protection system, especially the anode cables. Commonly use cathodic protection cables are PVDF/ HMWPE, XLPE/PVC, THHN, HMWPE etc. Cables used for cathodic protection systems must be highly corrosion resistant and capable of withstanding adverse environments to which they are exposed. 

THHN Wire stands for Thermoplastic High Heat-resistant Nylon coated. THHN can come in stranded or solid conductors depending on the size. It is either manufactured in copper or aluminum, and covered in a PVC (polyvinyl chloride) insulation with a nylon jacket. THHN is UL listed with a rated 90 degrees Celsius in dry locations or 75 degrees Celsius in wet applications with a THWN rating. The vast majority of THHN building wire carries a dual rating on the cable marked THHN /THWN for both the wet and dry temperature rating. THHN building wire may also be used for wiring of machine tools, control circuits or on certain appliances.