Electrical grounding rods hot-dip galvanized by Galvan Industries have a minimum zinc thickness 3.9 mils (99.06 microns) per ASTM A-123. There are more than 200 different types of soil in the United States, varying in levels of corrosiveness. The estimated service life for galvanized steel with 3.9 to 5 mils of zinc coating in the harshest soil conditions is 35 to 50 years and in less corrosive soil 75 years or more. Zinc is also an excellent conductor of electricity. These characteristics make galvanizing an excellent protective coating for ground rods.