According to NFPA and related international publications, fires caused by lightning and switching surges are primarily caused by overvoltage and insulation breakdown in electrical equipment, and are identified as one of the causes of fires that occur repeatedly in structures, houses, and industrial facilities.

 

Fire caused by lightning

• Lightning strikes are hotter than the sun's surface, and discharge energy of tens to hundreds of thousands of volts can be instantly transferred to structures, which can directly ignite flammable materials (wood, surface coatings, etc.).

• According to actual U.S. NFPA data, tens of thousands of lightning fires occur annually, resulting in structural damage and ignition of combustible materials. When lightning strikes a building or nearby structures, it can trigger a surge in the electrical system, potentially causing insulation failure and overheating of wiring, potentially leading to fire.

• The main damage paths are along continuous conductive paths within structures such as electrical wiring, metal structures, water pipes, and communication lines. If the insulation strength is insufficient, this can lead to heat generation, arc discharge, and sparks, increasing the risk of fire.

• A direct lightning strike can cause high temperatures and high currents to combustible materials such as structures or trees, which can ignite them instantly and lead to a fire.

• Lightning can cause induced voltage, corona discharge, or insulation breakdown on metal surfaces, distribution panels, etc., which can generate an electric arc, and at this time, the insulating coating or surrounding combustible materials can be ignited.

• The ground potential at the lightning strike point rises significantly, and if it exceeds the insulation strength between the ground and the ground wire, a fire is caused by insulation breakdown.

• In actual cases investigated, fires occur when lightning (induced lightning) causes arc discharge at the distribution panel terminals.

 

Fire caused by opening and closing surge

• NFPA analyzes that surges caused by switching surges (such as switching of power supplies, capacitors, and internal equipment) can stress the insulation of electrical equipment and, when combined with internal equipment defects or aging wiring, can cause fires through arcs and sparks.

• Surges occur instantaneously with a range of 1,000 V to 40,000 V or more, and cause heat generation, sparks, or arc discharges in areas with weak insulation in wiring in industrial sites, home wiring, and distribution panels, increasing the risk of actual ignition.

• NFPA's industrial equipment standards (e.g., NFPA 79) require the application of surge protection devices (SPDs) to all major equipment and recommend them to reduce the risk of frequent equipment damage and fire caused by switching surges.

• The switching surge (high voltage, high frequency surge) that occurs at the moment of switching, etc. , puts stress on the electrical insulation of control panels, communication and control devices, sensors, etc., and when insulation breakdown occurs, arcs and sparks are generated, which can ignite nearby combustible parts.

• Surge damage can occur when sparks or overheating occur in electrical equipment or distribution panels when there is no or insufficient SPD protection device, which can cause fire.

• Accidents caused by surges in opening and closing occur frequently in underground utility tunnels (GIS), etc., and can cause damage or malfunction to equipment such as firefighting equipment, communications equipment, and PCBs, which can lead to the spread of fire in critical conditions.

 

Statistical and practical analysis

• Approximately 16% of structural fires are caused by electrical causes (wiring, equipment defects, overvoltage, etc.), with poor installation, aging, and physical damage being the main underlying factors.

• A significant number of structural fires are caused by a combination of factors, including electrical distribution and lighting equipment, poor grounding, and overvoltage surges, with tens of thousands of lightning and surge-induced fires reported annually in the United States.

• The majority of fires caused by natural disasters in Korea are caused by lightning, with insulation breakdown and electrical sparks being the main causes.

• In fact, fire damage caused by lightning and surges is continuously reported, causing serious damage to sandwich panel structures, waste treatment facilities, and power distribution equipment.

• The number of fires, damage cases, and prevention management measures caused by these causes are continuously managed in the National Fire Statistics System and National Fire Agency statistics.

 

Conclusion and Precautions

• Fires caused by lightning and switching surges are mainly caused by overvoltage (surge) , insulation breakdown , and arc discharge due to strong energy , and the risk of fire increases when there are physical and electrical vulnerabilities in wiring and structures.

• International regulations such as NFPA suggest the application of SPDs, increasing insulation strength, regular inspections, surge monitoring, and proper grounding and wiring management as basic preventive principles.

• A fire protection system with integrated surge protection devices (AC SPD, DC SPD, SLC SPD, Comm. SPD, potential difference reduction SPD, bonding SPD) and surge monitoring is required.

• Fires caused by lightning and switching surges are a recurring hazard in residential and industrial facilities. Electrical effects in electrical equipment, distribution panels, and structures can lead to insulation breakdown and arc discharge, leading to actual ignition and spread. To prevent fires, appropriate protective systems, such as surge protection devices (SPDs), insulation strength reinforcement, insulation monitoring, surge monitoring, and regular inspections are essential.