**Basic Requirements for Lightning Protection of Safety and Security Systems:**
Lightning protection is a critical aspect when designing and implementing safety and security systems, especially in areas prone to lightning strikes. To ensure the reliability and effectiveness of these systems, several key requirements must be followed.
First, the division of lightning protection zones and the classification of protection levels should be based on the guidelines provided in Chapters 3 and 4 of GB50343-2004. This ensures that the system is properly categorized according to its exposure risk.
For security systems installed in mountainous or remote areas, comprehensive measures must be taken to protect against both direct lightning strikes and electromagnetic induction. These measures are outlined in Chapters 1–5 of GB50057-1994 (2000 Edition) and Section 3.9 of GB50348-2004. It's important to implement a multi-layered approach to safeguard equipment from various lightning-related threats.
In buildings, the safety and security system must follow the recommendations in Section 1.0.5 of GB50343-2004. This includes both external and internal lightning protection. External measures should comply with GB50057-1994 (2000 version), while internal protection should focus on shielding, equipotential bonding, proper wiring, and strategic placement of equipment. Surge protectors and a common grounding system should also be integrated to minimize damage from lightning discharges.
Outdoor front-end devices such as cameras, detectors, and antenna feeders must be placed within LPZB (Lightning Protection Zone B). If their height exceeds surrounding objects by more than 10 meters, surge protectors should be installed at the input and output ports of power, signal, and control lines. For devices that must be located in LPZOA (direct lightning strike zone), additional protection against direct strikes is required, following the guidelines in Chapter 5.
Power lines, video/audio signal lines, and control lines for outdoor equipment should have metal shielding layers and be routed through buried steel conduits. The conduits must be grounded at both ends to enhance protection.
The power circuits of the security system should include surge protection devices (SPDs) to prevent voltage surges from damaging sensitive equipment. Similarly, signal and control lines entering or exiting the building should be equipped with SPDs at the interface to provide an extra layer of defense.
The monitoring center of the security system should ideally be located away from areas exposed to direct lightning strikes. If this is not possible, appropriate shielding measures should be implemented to reduce the risk of damage.
Grounding is essential for the monitoring center equipment. Local equipotential bonding should be used, and a ground ring or pool should be installed using bare copper wire with a cross-sectional area of at least 35 mm². Grounding connections between the system and the building’s grounding body should use stranded copper conductors with a minimum cross-section of 35 mm².
Finally, the grounding resistance of the entire system should not exceed 4Ω. In field installations, it should not be greater than 10Ω. In high-resistivity areas like alpine rock regions, where soil resistivity exceeds 2000Ω·m, the grounding resistance can be up to 20Ω.
By following these guidelines, safety and security systems can be effectively protected from the damaging effects of lightning, ensuring long-term performance and reliability.
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