Ground rods act as large electrodes that are attached by a ground wire to an electricity ground source. Your home is required by law to be properly grounded to protect you from accidental electrocution while you are inside using the house's electrical system or during lightening storms.
Electric fences are also grounded for the safety of the people and livestock who live and work around them. The ground rod collects electrical current and expels it safely underground.
There are certain certifications that a ground rod must meet in order to pass inspection and be lawful.
A ground rod must be at least 8 feet long and driven to a minimum depth of 8 feet. It is illegal to shorten the rods, and the industry standard is that all rods be marked in such a way that an inspector is able to tell if the rod has been tampered with or altered in any way.
A ground rod must be 5/8 inch in diameter, minus the coating if coated, in order to be certified. Small deviations in this measurement are difficult to detect without a micrometer, but a certified ground rod that is already marked for length will be the proper diameter.
Materials and Plating
Ground rods may be constructed of copper or stainless steel, or be galvanized. Copper is the preferred material due to its high conductivity and low corrosion rate.
Stainless steel is conductive but tends to break down over time. Galvanized rods have gained popularity due to low corrosion above-ground, but the zinc coating breaks down more quickly when buried.
Coated rods, which are usually steel with either a 0010- to 0013-inch thick coating of copper, or 00039 inch of zinc, are also acceptable.
In addition to the length and thickness of an Underwriters Laboratories (UL)-approved ground rod, it may either be threaded or not, and must have a slightly angled end that is tapered at 60 degrees, with the chamfer end being 1/16 inch in diameter. The point end should have the same angle, with the end diameter being 1/32 inch.