Innovations in station ground testing

A sample box and ac resistance meter find contamination in surface stone. Commercial dc resistance meters verify grid integrity but have short leads and experience ac interference. A custom built micro ohmmeter addresses these deficiencies. Wenner, Schlumberger and Palmer resistivity tests differ in their ability to resolve a highly resistive deep soil layer. The classic Fall of Potential impedance test will not work at sites with external connections, leading to a new Proximity Correction method. A rational polynomial models mutual resistance in multilayer soil, which is much more efficient than image methods in grounding analysis.