Electric surge protector of low-voltage distribution system, which is the form of a box, is designed according to IEC standard. It has invalidation detection indication, lightning stroke numbering display, overflowing and overheating protection, and powerful discharge capacity of lightning current. It’s applicable to the protection of buildings’ general supply system against lightning. This lightning arrester is very convenient to be maintained. It connects with the circuit in parallel and has no limit to the power of equipment, fixed later