Mutual coupling between finite lengths of parallel or angled horizontal earth return conductors

Mutual coupling between earth return current and potential test conductors used during stage tests of a grounding system is discussed. The coupling is a source of significant error in measuring grounding potential and grounding system impedance. Mutual impedance formulae are presented for correcting mutual coupling errors resulting from any length of paralleled or angled horizontal ground return current and potential conductors. The formulae are an extension of the complex image plane approximation of J.R. Carson's (1926) formula for infinitely long parallel conductors.>