Lightning is one of nature’s most formidable electrical phenomena. While seeking shelter indoors offers a high degree of protection, it does not guarantee complete safety. The immense electrical discharge can still pose a threat inside a structure, even if it is not struck directly. About one-third of lightning-strike injuries occur indoors, demonstrating that the risk is real and requires specific precautions. Understanding how this energy enters and moves through a home is the first step toward staying safe.
Pathways Lightning Uses Inside
Lightning’s electrical current seeks the path of least resistance to the ground, and a home’s infrastructure provides multiple conductive routes.
Electrical Wiring
The current often enters through the electrical wiring system, extending from the utility pole into the house. A nearby strike can induce a massive power surge that travels along these wires. This surge can damage plugged-in appliances and create a hazardous electrical arc.
Plumbing
Plumbing is another significant pathway, especially in homes with metal water pipes or fixtures. Lightning can travel through the ground and be conducted by buried metal pipes leading to the house. Even if a home uses plastic piping, metal fixtures like faucets and showerheads remain excellent conductors.
Communication Lines and Ground Current
Communication lines, such as corded landline phones, cable television, and internet connections, also serve as effective conductors. These metal lines run from the outside into the home. A strike near the house can energize the ground, causing a ground current that travels through conductive materials in the foundation. This current, often using metal rebar, can then jump to nearby objects in a phenomenon called side flash.
Activities to Avoid During a Storm
Understanding lightning pathways informs the specific activities that should be avoided during a thunderstorm.
Avoid Contact with Conductors
Contact with water should be avoided, meaning refraining from showering, bathing, washing dishes, or doing laundry. The water and metal plumbing fixtures can act as a direct conduit for an electrical charge.
Staying off corded electronic devices is important, as current can travel through the connected wiring. This includes landline phones, desktop computers, or any appliance plugged into a wall outlet. Cellular and cordless phones are safe because they lack a physical connection to the external wiring system.
It is important to keep a distance from large metal appliances, such as refrigerators or stoves, as they are hardwired into the electrical system. Standing near doors and windows, especially those with metal frames, can also be dangerous. Finally, avoid lying down on concrete floors or leaning against concrete walls, as they often contain metal rebar that can conduct a ground current.
Common Indoor Lightning Misconceptions
Several common beliefs about indoor lightning safety can create a false sense of security.
Windows and Glass
One prevalent misconception is that windows are the single greatest danger because lightning targets the glass itself. The greater risk associated with windows comes from wind-driven debris shattering the glass or from the metal components of the frame conducting a charge.
Rubber-Soled Shoes
Another inaccurate belief is that rubber-soled shoes provide a protective layer against indoor strikes. The massive voltage in a lightning strike renders the thin layer of rubber completely ineffective as an insulator. Wearing rubber-soled footwear offers no meaningful protection from a strike that has entered the home’s infrastructure.
Surge Protectors
A third misunderstanding relates to surge protectors, with many people believing these devices guarantee safety from a direct lightning strike. While surge protectors are effective at guarding electronics against typical power surges, they are not designed to handle the enormous electrical energy of a direct hit. A direct strike will likely overwhelm a standard surge protector, which only offers protection against transient surges.