处理设备的选择和安装。它提供了符合安全防护措施、装置预期用途的正常运行要求以及适用于预期外部影响的要求的通用规则。 与上一版相比，主要变化如下: -根据旧第3部分中的表321更正表51中的印刷错误； -引入新的第516条，处理减少保护导体电流的措施； -介绍本标准附录E中摘自IEC 61140的信息性附录B。IEC 61140的附录B涉及保护导体电流。

Deals with the selection of equipment and its erection. It provides common rules for compliance with measures of protection for safety, requirements for proper functioning for intended use of the installation, and requirements appropriate to the external influences foreseen. The main changes with respect to the previous edition are listed below: - corrections of misprints in Table 51 based on Table 321 derived from the old Part 3; - introduction of a new Clause 516 dealing with measures for mitigation of protective conductor currents; - introduction of an informative Annex B extracted from IEC 61140 in Annex E of this standard. Annex B of IEC 61140 deals with protective conductor currents.