The purpose of this Guide is:1. To review grounding practices with especial reference to safety.2. To establish, as a basis for design, the safe limits for potential differences which can exist in a station, under fault conditions, between point which can be contacted by the human body.3. to provide a step by step guide for the design of practical grounding systems based on these limits.4. to recommend test methods for obtaining data for the design of ground systems, and for verifying the adequacy of ground systems as constructed.5. To develop mathematical methods as an aid in the understanding and solution of typical ground gradient problems.6. To make available in English translation, some of the more pertinent and valuable foreigh language articles.7. To provide a comprehensive bibliography, with abstracts, of existing literature related to the subject, for the benefit of those seeking additional information not included herein.This Guide, as a whole, is primarily concerned with alternating-current outdoor substation installations. A few sections are applicable to indoor portions of such stations or to stations which are wholly indoors.