If lightning strikes your house, a common concern is whether you will die. While a direct fatality inside a home is rare, a lightning strike is a serious event that can pose risks to occupants. Understanding how lightning interacts with a structure and its potential dangers helps in appreciating the importance of safety measures during a thunderstorm.
The Path of a Lightning Strike Through a Home
Lightning seeks the path of least resistance to the ground, and a house provides numerous conductive pathways. Common entry points include the roof, chimney, antennas, and utility lines such as power cables, telephone lines, and plumbing pipes that extend outside. Once lightning enters a home, it can travel through internal systems like electrical wiring, metal plumbing, and structural elements containing rebar.
The electrical current and heat from a lightning strike, which can reach up to 50,000°F, can cause physical effects on the house. This includes structural damage such as fractured concrete, brick, cinder blocks, and stone, often seen in chimneys. Fires are a risk, commonly igniting in attics or within walls where the lightning contacts flammable building materials. Lightning also generates electrical surges that overload the home’s wiring, potentially destroying plugged-in electronics and appliances.
Direct and Indirect Dangers to Occupants
While being inside a house offers protection, lightning can still pose a threat to occupants. A direct strike on a person indoors is extremely rare but could occur if someone is in direct contact with the lightning’s primary path. Injuries can range from muscle pains and broken bones to cardiac arrest and severe burns.
More commonly, indirect effects cause harm. A “side flash” occurs when lightning jumps from a primary conductive path, like a wire or pipe, through the air to a nearby person. Ground current is another danger, as lightning energy spreads through the ground, potentially making a person part of the electrical circuit if they are standing on points with different electrical potentials. Contact voltage happens when someone touches an object, such as a corded phone, appliance, or faucet, that has become energized by the lightning strike.
The rapid expansion of air heated by lightning creates a shockwave, which can lead to blast injuries, causing blunt force trauma or hearing damage. The intense heat can also cause direct thermal burns, characterized by unique fern-like patterns on the skin. Fires ignited by lightning within the house can result in smoke inhalation or burn injuries, posing a risk to occupants.
Factors Affecting Personal Risk Inside a Struck Home
Certain actions and locations within a house can increase personal risk during a thunderstorm. Avoid contact with corded electrical appliances, landline telephones, and remote controls connected to wired systems, as lightning can travel through these pathways. Using cordless or cellular phones is safer because they are not directly connected to the house’s wiring.
Stay away from windows, doors, and open garages or porches, as these areas can provide a path for lightning or flying debris. Avoid contact with plumbing, including taking showers, baths, or washing dishes, since lightning can travel through metal pipes and water. Also, steer clear of large metal objects like radiators or appliances, and concrete floors or walls which may contain conductive metal rebar. Interior rooms, away from utility entry points and external walls, offer a safer location within the home.