Lightning Protection Study: Understanding, Risks & System Design
Lightning Understanding
A lightning strike is an electrical discharge between the cloud and the earth. It is a natural, unpredictable phenomenon having an independent current source. This natural phenomenon is unpredictable and consists of components like:
✅ Lightning current
✅ High peak current
✅ Electric charge & energy
✅ Wave shape of 10/350 μs
Lightning is a naturally occurring phenomenon that often causes severe damage to life and property. Direct hits may cause structural failure, whereas indirect hits, through inductive or capacitive coupling, may affect the reliability and integrity of electrical and electronic equipment within the structure.
In general, it is assumed that downward flashes (cloud-to-earth flashes) place greater stress on objects hit by lightning than upward flashes (earth-to-cloud flashes), particularly about short strokes. In the majority of cases, downward flashes are to be expected in flat terrain and near low structures. However, structures are situated in an exposed location and/or are very high, and upward flashes typically occur.
Why is a Lightning Protection System (LPS) Necessary?
A Lightning Protection System (LPS) safeguards buildings and structures from:
✔ Direct lightning strikes and fire hazards.
✔ Electrical surges damaging sensitive equipment.
✔ Structural damage due to high-energy discharges.
✔ Loss of life, economic value, and service disruptions.
A properly designed and maintained LPS significantly reduces lightning-related risks.
Methodology
Lightning protection systems (LPS) are designed to safeguard structures, equipment, and the public from the potentially destructive effects of lightning strikes. A comprehensive methodology for Evaluating Lightning Protection systems on existing structures, buildings, designing, installing, and maintaining lightning protection systems
Evaluation Lightning Protection System on Existing Structure, Building
Risk Assessment & Site Evaluation
- Identify Exposure Level:
- Determine the likelihood of a lightning strike based on geographic location, height of the structure, and surrounding environment.
- To evaluate whether lightning protection of a structure and/or its connected service lines is needed, a risk assessment is required to be carried out.
- The following risks have been identified, corresponding to their equivalent type of loss
- R1-Risk of loss of human life (including permanent injury)
- R2- Risk of loss of service to the public
- R3- Risk of loss of cultural heritage
- R4- risk of loss of economic value.
Evaluate Structural Vulnerability:
- Analyze the potential consequences of a lightning strike, such as fire hazards, electrical surges, or physical damage.
Define Protection Goals:
- Set goals for the system’s performance (e.g., preventing fire, minimizing equipment damage, and reducing risks to human safety).
Vertical Loop Impedance Evaluation
- Vertical Loop Impedance Evaluation has to be carried out to check the continuity, Corrosion, and its resistibility to avoid damage caused during the lightning current discharge to the earth termination system.
Lightning Earth Termination System Evaluation
- Type of earth termination system (e.g., ring earth electrode, earth rod, foundation earth electrode), material, and cross-section of the connecting lines between the single earth electrodes
- Connection of the lightning equipotential bonding system to metal installations, electrical installations, and existing equipotential bonding bars
Zonal Protection Evaluation
- The Lightning Protection Zone (LPZ) concept was introduced in IEC 62305, particularly to assist in determining the Surge Protection Measures (SPM) required within a structure.
The LPZ concept, as applied to the structure, is illustrated in Figure and expanded upon in IEC 62305–3
- Rolling sphere method
- Mesh method
- Protective angle method
concept involves visualizing an imaginary rolling sphere over the surface of the structures. The streamers are launched at points of greatest electric field intensity and can move in any direction towards the approaching downward leader. It is for this reason that lightning can strike the side of tall structures rather than at their highest point.
The position of the greatest field intensity on the ground and structures will be at those points nearest to the end of the downward leader before the last step. The distance of the last step is termed the striking distance and is determined by the amplitude of the lightning current. For example, points on a structure equidistant from the last step of the downward leader are equally likely to receive a lightning strike, whereas points further away are less likely to be struck. This striking distance can be represented by a sphere with a radius equal to the striking distance.
This hypothesis can be expanded to explain why corners of structures are vulnerable to lightning strikes.
A sphere rolling over the surface of the building. The dotted line represents the path of the center of the sphere as it is rolled over the building. The radius of the sphere is the striking distance or last step of the lightning discharge. Thus, it can be seen that the corners are exposed to a quarter of the circular path of the sphere. This means that if the last step falls within this part of the circular path, it will terminate on the corner of the building.
Since the downward leader can approach from any direction, all possible approach angles can be simulated by rolling an imaginary sphere all around and over the structure to be protected, right down to the ground. The Rolling Sphere method is a simple means of identifying areas that need protection, taking into account the possibility of side strikes to the structures.
Design of Lightning Protection System
The design is critical to ensure the system works effectively and safely. The system components should adhere to national or international standards, such as NFPA 780, IEC 62305, or local regulations.
- Air Terminals (Lightning Rods): Install air terminals on the highest points of the structure. These should be made of conductive materials (such as copper or aluminum) and should be adequately spaced.
- Conductors: Use copper or aluminum conductors to form the network that will carry the lightning energy from the air terminals to the ground. The conductor size and layout are determined by the level of protection needed (e.g., single conductor, mesh, or ring).
- Grounding System: Design a grounding system that includes ground rods, plates, or a network of conductors buried in the earth to safely dissipate the lightning energy. Ensure the grounding system has low resistance and is well-maintained.
- Down Conductors: Install down conductors to connect air terminals to the ground system. Ensure these conductors are securely fixed and protected against corrosion.
- Surge Protection: Include surge protectors (e.g., lightning arresters, voltage suppression devices) on electrical and communication systems to prevent electrical damage from lightning strikes.
A coordinated set of SPDs should effectively operate together as a cascaded system to protect equipment in their environment. For example, the lightning current SPD at the service entrance should sufficiently handle the majority of surge energy, thus leaving the downstream overvoltage SPDs to control the overvoltage. Coordination of SPDs is vital since overvoltage is not sufficiently attenuated downstream in the electrical installation. Poor coordination could mean that an overvoltage SPD is subjected to an excess of surge energy, placing both itself and connected equipment at risk from damage
6. System Layout
- Clearance: Ensure adequate clearance around air terminals and conductors to minimize risk to nearby structures or sensitive areas.
- Documentation: Maintain detailed records of the system design, installation, testing, and maintenance activities for reference and regulatory compliance.
Compliance with Standards
Adhere to local and international standards (e.g., NFPA 780, IEC 62305 for international standards) when doing an Adequacy check, designing and installing the system.
Why Choose Our Lightning Protection Solutions?
✅ ISO-Compliant LPS Design & Installation
✅ Advanced Risk Assessment & Site Evaluation
✅ Cutting-Edge Lightning Simulation & Protection Methods
✅ Customized Solutions for Industrial, Commercial, & Residential Applications