本指南主要涉及户外交流变电站，无论是常规变电站还是气体绝缘变电站。 包括配电、输电和发电厂变电站。适当注意，本文描述的方法也适用于此类变电站的室内部分，或完全在室内的变电站。 未试图涵盖直流变电站特有的接地问题。雷电冲击影响的定量分析也超出了本指南的范围。

This guide is primarily concerned with outdoor ac substations, either conventional or gas-insulated. Distribution, transmission, and generating plant substations are included. With proper caution, the methods described herein are also applicable to indoor portions of such substations, or to substations that are wholly indoors. No attempt is made to cover the grounding problems peculiar to dc substations. A quantitative analysis of the effects of lightning surges is also beyond the scope of this guide.