Abstract: According to the regulations and specifications, there is usually a residual current action protector installed in the meter box, which can quickly cut off the power supply when the leakage fault occurs in the line to ensure the safety of the person and equipment. It is necessary to check and test the residual current action protector every month. Once the damage is found, it should be replaced immediately. However, there are many models of residual current action protectors and different installation methods, which cannot be directly replaced, and it is necessary to transform the installation site, which has many steps and takes a long time, causing huge pressure on the front-line work. Therefore, a conversion base suitable for the residual current action protector of the watch box is developed, and the installation site does not need to be reformed. By using the conversion base, the residual current action protector can be directly replaced by each other, which greatly reduces the installation time, alleviates the working pressure of the first line, improves the work efficiency and improves the service quality of the power supply.