Install the Level 3 surge protection device inside the equipment or at the equipment's power supply input, especially for critical or sensitive electronic devices. Technical Requirements Maximum discharge capacity: 20kA per phase or lower. Voltage protection level: ≤ 1800V. In a newly constructed residential area, a 10kV power line is introduced into the substation. After stepping down the voltage through the transformer's low-voltage side (0. 4kV), power distribution is achieved through three levels of distribution boxes: the main distribution board, secondary. A distribution box is installed under the main distribution box, and a switch box is installed under the distribution box. According to the principle of graded lightning protection, and based on the likelihood of a building being struck by lightning, it is necessary to deploy surge protector against lightning in stages to. Primary distribution systems consist of feeders that deliver power from distribution substations to distribution transformers.