A lightning protection system begins with an assessment, not with product selection. Decisions such as “let’s install a lightning rod on this building” or “let’s install a surge protection device on the main panel” should not be made before determining the required level of protection. The result is often either unnecessary investment or a system that exists on paper but provides inadequate protection in practice.
TS EN 62305-2 does not leave this decision to intuition. The structure’s location, geometry, purpose of use, the density of people and equipment inside, regional lightning activity, and relevant risk calculations are assessed. The required level of protection is determined by the outcome of this assessment.
At YILKOMER, we also provide lightning risk assessment and system design as an independent engineering service, separate from system installation and implementation.
What Do We Assess in a Lightning Risk Analysis?
The assessment considers four different sources of lightning strikes separately: strikes directly to the structure, strikes near the structure, strikes directly to incoming lines, and strikes near those lines. Each creates a different damage mechanism, which is why protection must be designed using multiple layers.
Three main types of damage are assessed: injury to living beings caused by step and touch voltages; physical damage such as fire and explosion; and failure of electrical and electronic systems. For a data center or critical facility, the third category is particularly significant.
Damage becomes meaningful in terms of risk when it results in loss: loss of human life, interruption of public services, damage to cultural heritage, or economic loss. A hospital and a warehouse are therefore assessed under different risk conditions.
If the calculated risk is below the tolerable risk value defined by the standard, no additional protection measures are required. If it exceeds this value, the protection measures are determined by calculating how much each measure reduces the relevant risk and selecting the appropriate Lightning Protection Level (LPL).
Key Inputs Used in the Risk Assessment
- Regional Lightning Density — Annual lightning ground-flash density data for the location of the structure.
- Structure Geometry — Length, width, height, and roof shape, used to calculate the structure’s collection area.
- Location Factor — The structure’s exposure in relation to surrounding buildings and the local terrain.
- Structure Characteristics — Structural system, roof and façade materials, and fire load.
- Purpose of Use and Occupancy — Number of occupants, duration of occupancy, and evacuation conditions.
- Incoming Lines — Type, routing, and length of power, communication, and data lines entering the facility.
- Existing Protection Measures — Existing LPS, surge protection, shielding, and equipotential bonding arrangements.
After the Assessment: System Design
Risk analysis answers the question of “how much protection is required”; system design answers “how should it be achieved?”. Based on the required level of protection, the following components are designed as an integrated system:
- Air-Termination System — Rooftop arrangement verified using the rolling sphere and mesh methods.
- Down-Conductor System — The number, routing, and symmetrical distribution of down conductors.
- Separation Distance (s) Calculation — Preventing dangerous sparking and determining whether insulated conductors are required.
- Earthing System — Electrode type, quantity, and earthing network geometry determined according to soil resistivity.
- Equipotential Bonding — Locations of the main and supplementary bonding bars and the metallic infrastructure to be connected.
- Surge Protective Device (SPD) Coordination — Coordinated protection stages designed in accordance with equipment withstand capability.
Who Needs It?
- New Construction Projects — Performing the assessment during the design stage is significantly more cost-effective than making modifications after construction.
- Compliance Assessment for Existing Facilities — Documenting whether the existing lightning protection system provides an adequate level of protection.
- Tender and Specification Preparation — Clearly defining the technical requirements and selection criteria for the system to be procured.
- Insurance and Audit Processes — Assessing and documenting the risk through a formal, calculation-based analysis.
- Facilities Experiencing Recurring Failures — Identifying the underlying cause of repeated equipment failures.
