A dummy for testing whether sizes of receiving spaces for receiving electrical elements in an enclosure are suitable or not. The dummy includes a frame and a handle attached to the frame. The frame includes a bottom wall. A number of wheels are rotatably attached to opposite ends of the bottom wall. Thereby, the frame is slidably received in the enclosure. A width and a height of the frame are respectively equal to minimum values of a width and height of one of the receiving spaces.