长期以来,我国民用建筑中普遍采用三相四线制配电方式,其实这种方式是一种中性点直接接地的380/220伏的低压电力网,引入用户室内为单相两线制。近年来,随着人民生活水平的提高,家用电器不断普及,为了安全可靠地使用好家用电器,对金属外壳的家用电器必须进行接零或接地保护,然 For a long time, the three-phase four-wire power distribution method is widely used in China’s civil buildings. In fact, this method is a low-voltage power grid with a neutral point directly grounded at 380/220 volts, and is introduced into the user’s room as a single-phase two-wire system. In recent years, with the improvement of the people’s living standards, household appliances have become increasingly popular. In order to use household appliances safely and reliably, household appliances with a metal shell must be grounded or grounded.