**Basic Requirements for Lightning Protection of Safety and Security Systems:**
The lightning protection requirements for safety and security systems must be carefully designed and implemented to ensure the system remains functional and safe during lightning events. These requirements are based on national standards and should be followed strictly.
First, the division of lightning protection zones and the classification of lightning protection levels should be carried out according to the guidelines provided in Chapters 3 and 4 of GB50343-2004. This ensures that different areas within a building or site are properly categorized based on their exposure to lightning risks.
For security systems installed in mountainous or remote areas, comprehensive protection measures against both direct lightning strikes and electromagnetic induction from lightning must be applied. These measures should align with the requirements outlined in Chapters 1 through 5 of GB50057-1994 (2000 edition) and Section 3.9 of GB50348-2004. This is essential due to the increased vulnerability of such locations to lightning activity.
In buildings, the safety and security system must follow the guidelines in Section 1.0.5 of GB50343-2004. This involves implementing both external and internal lightning protection strategies. While external measures should comply with the relevant provisions of GB50057-1994 (2000 version), internal protection should be prioritized. This includes shielding, isolation, equipotential bonding, proper wiring practices, and strategic placement of equipment. Additionally, surge protectors and a shared grounding system should be used to minimize damage caused by lightning discharges.
Outdoor front-end devices such as cameras, detectors, and antenna feeders should be located within LPZB (Lightning Protection Zone B). If these devices are mounted higher than surrounding objects within a 10-meter radius, their power, signal, and control lines must be equipped with surge protectors at the input and output ports. For devices that must be placed in LPZOA (the most vulnerable zone), additional protection against direct lightning strikes is required, following the specifications in Chapter 5 of the relevant standard.
Power lines, video/audio signal lines, and control lines for outdoor equipment must have metallic shielding and be installed through buried steel conduits. The steel pipes should be grounded at both ends to provide an effective path for lightning currents.
Lightning protection should also be applied to the power circuits of the entire security system. A suitable power line surge protector must be installed to prevent voltage spikes from damaging sensitive equipment.
Signal and control lines of the security system should be protected with surge protectors at the interface between the system and the building. This helps prevent surges from entering the system through external connections.
The monitoring center of the security system should be located as far away as possible from the building’s main lightning protection system. If this is not feasible, appropriate shielding measures should be taken to reduce the risk of interference or damage.
The grounding of the monitoring center equipment should use local equipotential bonding. A ground ring or pool should be installed, using bare copper wire with a cross-sectional area of at least 35 mm². This ensures a low-resistance connection to the earth.
All grounding conductors connecting the monitoring center to the building's grounding body or main grounding conductor should be made of stranded copper wire with a minimum cross-sectional area of 35 mm². This enhances the reliability and effectiveness of the grounding system.
Finally, the grounding resistance of the entire system should not exceed 4 ohms. In field installations, where the soil resistivity may be higher, the grounding resistance should not exceed 10 ohms. In high-altitude rocky areas where the soil resistivity exceeds 2000 Ω·m, the grounding resistance should not be greater than 20 ohms. Proper grounding is crucial for the overall performance and safety of the system.
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