Steel grounding design guide and application notes

Based on the National Bureau of Standards (presently called The National Institute of Standards and Technology or "NIST") statistical data on corrosion of steel, an equation is introduced to estimate the corrosion rate of underground steel. The variables include the major soil characteristics (parameters), namely resistivity, pH value, moisture content and aeration. This formula, together with the IEEE Standard No. 80-2000, is used in the design of steel grounding. Also discussed in detail are the design procedures for a cathodic protection scheme to minimize corrosion of steel grounding. Numerical examples are included in the paper to enhance the understanding of steel grounding design for high voltage AC substations.