GB50303-2002, the Construction Quality Acceptance Code for Building Electrical Engineering, has requirements: Metal conduits and trunking must be reliably grounded (PE) or zeroed (PEN), and meet the following requirements: 1. Galvanized Steel conduits, flexible conduits and metal trunking shall not be welded to the ground wire. The edge line between the two cards of the special ground jumper shall be a copper-core soft conductor with a cross-sectional area of ??not less than 4mm2; 2. When non-galvanized steel conduits are used When threaded connection is used, jumper ground wires are welded at both ends of the connection; when galvanized steel conduits are threaded, special grounding clips are used at both ends of the connection to fix the jumper ground wire; 3. Metal trunking is not used as the grounding conductor of the equipment. , when there is no requirement in the design, the total length of the metal trunking shall be connected to the ground (PE) or zero (PEN) trunk line at no less than 2 places. 4. The two ends of the connecting plate between non-galvanized metal wire ducts should be connected with copper core ground wires. The two ends of the connecting plate between galvanized wire troughs should not be connected with ground wires, but no less than two ends of the connecting plate should be anti-loosening. Nuts or lock washers attach to the fastening bolts.