Lightning rod down-conductors and grounding alone cannot completely prevent lightning damage; a comprehensive lightning protection system is necessary. A complete system requires the installation of external and internal protective elements, equipotential bonding, and surge protection devices (SPDs).

 

Limitations of down-conductors and grounding

Simply grounding a lightning rod through a down-conductor after receiving a lightning strike does not prevent damage to electrical and electronic equipment inside a building, induced lightning strikes, or even indirect lightning strikes. If lightning current does not flow smoothly to the ground or is improperly routed, it can pose a risk to buildings, equipment, and even people.

 

Components of a complete lightning protection system

• External lightning protection system: Lightning rods (air-termination units), down conductors (vertical and horizontal conductors), grounding electrodes, etc. safely guide lightning to the outside of the building.

• Internal lightning protection system: Minimizes induced lightning and indirect damage through equipotential bonding, surge protection devices (SPDs), and metal structure bonding.

• Build a lightning protection device, or surge monitoring system.

• Design criteria: Detailed items such as risk analysis, protection range setting, mesh conductor combination, horizontal/vertical conductor design, and securing appropriate grounding resistance must be reviewed in accordance with international standards (IEC 62305, KS C IEC 62305, etc.).

 

Practical Application and Design Guidelines

Based on an on-site risk analysis, an appropriate lightning protection rating should be derived, and detailed design, including mesh conductors, horizontal and vertical conductors, and securing grounding resistance, should be implemented depending on the structure type. Equipotential bonding should be used to connect all grounded objects inside and outside the structure, ensuring the same potential across all metal parts in the event of a lightning strike. For internal facilities, surge protection devices (SPDs) and surge monitoring should be added to prevent and manage damage from induced lightning and surges.

 

Representative IEC and KS standards related to lightning protection systems are as follows.

List of IEC and KS standards

• IEC 62305 / KS C: International Standard and Korean Industrial Standard for Lightning Protection. It stipulates the overall design, construction, inspection, and maintenance principles for lightning protection systems.

• IEC/KS C IEC 62305-1: Protection against lightning - Part 1: General principles

• IEC/KS C IEC 62305-2: Risk management, risk assessment

• IEC/KS C IEC 62305-3: Physical damage to structures and life hazard

• IEC/KS C IEC 62305-4: Electrical and electronic systems within structures

• IEC 61643 / KS C IEC 61643: International and Korean industrial standard for the performance and test methods of surge protective devices (SPDs).

• IEC 62561 / KS C IEC 62561: Requirements for major components of lightning protection systems (conductors, grounding electrodes, etc.).

• IEC 60364 / KS C IEC 60364: Standard for building electrical installations. Includes design guidelines for lightning protection wiring, grounding, etc.

• IEC 61400-24 / KS C IEC 61400-24 International and industry standards for lightning protection of wind turbines and wind power systems.

• IEC 62561-6:2011 specifies requirements and test methods for lightning strike counters.

 

Note

IEC 62305 and KS C IEC 62305 are essential for the design and operation of lightning protection systems, including lightning risk analysis, external and internal lightning protection, and surge protection for buildings and facilities worldwide. IEC 61643 and KS C IEC 61643 define the installation and performance of surge protection devices. IEC 62561 presents quality and testing methods for lightning protection system components, and IEC 60364 covers safety, grounding, and wiring technology standards for electrical installations in buildings .

 

conclusion

Lightning rod down-conductors and grounding alone provide only limited protection. A comprehensive lightning protection system, encompassing both an external lightning protection system (including lightning rods) and an internal lightning protection system (equipotential bonding, SPD surge monitoring), provides complete protection. True lightning damage prevention is only possible through systematic implementation of risk assessment, design, construction, and maintenance in accordance with international standards.