What is IEC 62305?
IEC 62305 is a set of international standards developed by the International Electrotechnical Commission (IEC) to address all aspects of lightning protection. It’s structured into four parts, each focusing on a different aspect of risk and mitigation:
1. General Principles
This part of IEC 62305 provides general principles to be followed for protection of structures against lightning, including their installations and contents, as well as persons. It lays the foundation for the entire standard – outlining the need for lightning protection and introduces the key concepts, including:
- Types of lightning flashes
- Direct and indirect effects
- Protection levels
- The importance of a risk-based approach
2. Risk Management
IEC 62305-2 outlines a comprehensive methodology to evaluate the risks posed by lightning to structures and their contents. The Lightning Risk Assessment (LRA) determines whether protection is necessary and to what extent.
The standard focuses on different types of loss that can occur due to lightning, which then contribute to calculating a
single, overall risk. These critical types of loss are:
- Loss of human life (including permanent injury)
- Loss of public service (e.g., disruptions to essential services like power or communication)
- Loss of cultural heritage (damage to historical buildings, artifacts, etc.)
- Economic loss (damage to structures, contents, and loss of business or operational activity)
Instead of the previous system where R1, R2, R3, and R4 were separate “risk values,” the 2024 revision of the standard integrates these consequences into a more holistic risk assessment. The goal is to ensure the combined risk is below a tolerable limit.
To perform this assessment, the standard prefers the use of Lightning Ground Strike-Point Density (Nsg). This metric replaces the older “lightning flash density (Ng)” to provide a more accurate count of where lightning actually impacts the ground or a structure. Unlike Ng, which assumed one strike point per flash, Nsg accounts for the fact that a single lightning flash can have multiple points where it connects with the ground, providing a more precise basis for calculations.
Lytech uses proprietary software tools to execute these calculations with high precision and generate custom reports that help stakeholders make informed decisions about mitigation investments.
3. Physical Damage to Structures and Life Hazards
The IEC 62305-3 section addresses the design and implementation of a Lightning Protection System (LPS). This system is comprised of external components such as the Air Termination System to capture the lightning strike, Down Conductors to safely channel the current to the ground, and the Earth Termination System which disperses the current into the ground, as well as internal components. Some design considerations include:
- Lightning Protection Levels (LPL): Ranges from I to IV depending on the structure’s risk level
- Separation Distances: Ensures safe distances between conductive paths to prevent dangerous sparking
- Equipotential Bonding: Minimizes potential differences within the structure
Lytech engineers use CAD and simulation tools to create precise LPS layouts and verify compliance with LPL requirements.
4. Electrical and Electronic Systems Within Structures (IEC 62305-4)
Modern facilities are filled with sensitive electronics, making protection of internal systems crucial. Part 4 focuses on limiting surge voltages and ensuring continued operation of internal systems using:
- Surge Protective Devices (SPDs): These are installed at service entries, distribution boards, and sensitive equipment. Emphasis should be applied on the correct selection (Class/Type) and precise placement of SPDs. The level of protection required from SPDs (e.g., Type 1, Type 2, Type 3) is directly determined by the calculated Lightning Protection Level (LPL) and the risk assessment results, ensuring coordinated protection from the point of entry to sensitive equipment. Proper connection, including minimal lead lengths, is critical for their effectiveness.
- Shielding and Cable Routing: These measures reduce induced voltages by creating protective barriers and ensuring cables are routed away from potential interference paths.
- Functional Earthing Systems: Ensures correct operation of surge protection measures and sensitive electronic equipment.
Lytech designs custom SPD schemes based on equipment vulnerability and energy coordination principles to ensure maximum protection. Our protection methods ensure your data and control systems are defended against surges, even from indirect lightning strikes.
Why Compliance With IEC 62305 Matters
Non-compliance with IEC 62305 can have significant consequences. Including life safety risks (fire, structural collapse, or electrocution), business continuity risks (due to equipment damage, data loss, and operational downtime) and insurance liability (possible claim rejections due to non compliance).
Investing in proper lightning protection is not just regulatory compliance—it’s strategic risk management. By following IEC 62305, businesses gain:
- Increased safety
- Regulatory and insurance compliance
- Protection of investment
- Peace of mind
How LYTECH Can Help
At Lytech, we don’t just interpret standards – we operationalise them. Our team of experienced engineers and technicians bring clarity and confidence to lightning and surge protection.
Whether you’re seeking a new system design, a compliance audit, or rectification of existing installations, we offer turnkey solutions rooted in the IEC 62305 framework.
Protect your people. Preserve your assets. Power your operations.
📧 Contact Lytech today to schedule your lightning and surge protection audit.