While being indoors offers protection from lightning, certain activities within a home can still pose a risk. This apprehension stems from how lightning behaves and interacts with a building’s infrastructure. Understanding how lightning can enter and travel through a home helps explain these safety recommendations.
How Lightning Enters Your Home
Lightning, a powerful discharge of electricity, seeks the path of least resistance to the ground. It can enter a structure in several ways, including a direct strike, through wires or pipes extending outside, or by traveling through the ground near the structure. Once inside, lightning can spread through various conductive systems within the house.
Plumbing systems, especially those with metal pipes, can conduct lightning current if a strike occurs nearby. While modern plumbing increasingly uses plastic, many homes still have metal components that conduct electricity.
Water itself is not a perfect conductor, but tap water contains dissolved minerals and salts, which make it conductive. Water flowing through metal pipes can carry an electrical charge from a lightning strike. Contact with water during a thunderstorm, such as when showering, can expose an individual to this electrical current. Beyond plumbing, electrical wiring and telephone lines also serve as common pathways for lightning to enter a home.
Beyond the Shower: Other Indoor Risks
The principles of electrical conductivity that make showering risky apply to other indoor activities involving water or direct connections to outside utility grids. Washing dishes or doing laundry can also expose individuals to lightning traveling through plumbing systems, as water within these appliances can become energized.
Corded electronic devices, such as computers, televisions, and other appliances, are also potential pathways for lightning. Lightning can send a massive surge through a home’s electrical wiring, potentially damaging electronics and posing a shock risk to anyone using them. Even devices plugged into surge protectors are not fully immune, as the immense voltage of a lightning strike can overwhelm typical surge protection. Corded landline phones can also carry a lightning charge through their outdoor connections directly to the handset. Concrete floors and walls that contain metal wires or bars can also conduct electricity if struck by lightning, making contact with them unsafe.
Staying Safe During a Thunderstorm
To minimize risks, avoid all contact with water during a thunderstorm. This includes showering, bathing, washing dishes, or doing laundry until the storm passes. Disconnecting corded electronic devices and appliances from outlets before a storm protects them from power surges and reduces shock risk.
Avoid using corded phones, as lightning can travel through phone lines. Cordless or cellular phones are safe if not plugged into a charger, as they lack a direct connection to outdoor wiring. Stay away from windows and doors, as lightning can strike nearby and cause injury from flying debris or conducted electricity. Also, avoid lying on concrete floors or leaning against concrete walls that may contain metal.
A common safety guideline is the “30-30 rule”: if you hear thunder less than 30 seconds after seeing lightning, the storm is close enough to be dangerous, and you should seek shelter immediately. Remain indoors for at least 30 minutes after the last clap of thunder to ensure the storm has moved a safe distance away.