Voltage reduction: For safety reasons, the box needs to convert high-voltage electrical energy into low-voltage electrical energy. This process is accomplished through a transformer. Transformers work on the principle of electromagnetic induction. During this process of transfer, if the AC. Electrical transformer boxes, often seen in residential neighborhoods, play a crucial role in powering homes and businesses. Although they may appear as mere green metal boxes, these essential components of the electrical grid are responsible for converting high-voltage electricity from power lines. Distribution substations connect to the transmission system and lower the transmission voltage to medium voltage ranging between 2 kV and 33 kV with the use of transformers.