4 kV), Uk = 6%: Primary distribution: The incoming feeder switchgear is equipped with a 2000 A ACB, with LSIG protection; L setting is 1600 A, and S setting is 0. According to GB 50054 and IEC 60364 standards, low-voltage distribution systems are typically divided into three levels. Let's make a hypothesis: a newly built residential area introduces a 10kV incoming line and builds a distribution room. Choose the right box based on environment (indoor/outdoor), load capacity, and durability. Check for proper IP/NEMA ratings and material quality. This eliminates direct connections from each device back to the main source, reducing cable runs and minimizing blown fuse risk.