Precautions for lightning protection and grounding in network equipment rooms
1. Considering the interference of lightning or other telecommunication equipment, the computer room should not be located on the top floor of the building or on the side of the outer wall. If limited by special circumstances, a shielding layer should be set up to prevent lightning interference. For particularly important computer systems, consideration should be given to setting up a separate shielded computer room. The grounding installation of equipment and pipelines in buildings (including computer rooms) should be carried out in accordance with relevant specifications, and equipotential bonding should be done well;
2. To prevent lightning hazards, it should also prevent electromagnetic pulses caused by lightning strikes. The power distribution box of the computer room should be equipped with SPD (anti-electromagnetic surge) protection devices to prevent the power supply of the computer room from being cut off due to electromagnetic pulses caused by lightning strikes. In addition, for important system hosts, the communication cables should also be equipped with SPD protection devices. Since the number of communication cables is generally large, the protection settings of communication lines should be reasonably set according to the actual situation;
3. The electrical grounding system should adopt the TN-S grounding system, the PE line and the phase line should be separated, and the power connection point of the equipment room should be grounded repeatedly;
4. The grounding of the computer room is generally divided into AC working grounding, DC working grounding, safety working grounding, and lightning protection grounding. According to the requirements of "Code for Lightning Protection Design of Buildings", when a common grounding system is adopted in the lightning protection design, each grounding system should share a set of grounding devices. All exposed conductive objects of the information system (metal components such as various boxes, shells, racks, etc.) should establish a first equipotential bonding network.
Therefore, in the design of electrical lightning protection, a dedicated equipotential bonding bar should be set up in the computer room, which should be connected to the general equipotential bonding bar of the building through down conductors. According to the layer-by-layer equipotential principle of the shared grounding system, the main structural steel bar is used as the downconductor, which is more suitable for the shared grounding system. In addition, it is emphasized that the grounding resistance of the building grounding system should not be greater than 1Ω.