Seeking shelter in a garage during an electrical storm is a common concern. While a garage offers significantly more protection than being outdoors, its safety level depends heavily on its structural connection to the main dwelling and the presence of conductive materials inside. Determining the risk involves assessing the building’s ability to handle a direct strike and the internal pathways electricity can follow.
Structural Safety and Lightning Protection
The construction of a garage dictates its protective capability during a thunderstorm regarding lightning current dispersal. An attached garage generally benefits from the comprehensive grounding system of the main house, which channels a lightning strike safely into the earth. This system often incorporates the home’s plumbing and electrical infrastructure, providing multiple paths of low resistance for the electrical charge to follow.
A detached garage, in contrast, frequently lacks a dedicated, robust grounding system and may be constructed with less substantial materials or an isolated foundation. If a detached structure takes a direct strike, the lightning current may not have a safe, intended pathway to the ground, potentially causing a side flash or traveling through the building materials themselves. Structures with metal framing can help conduct current to the ground, but without proper grounding, they present a risk of energizing the entire frame.
Specific Internal Hazards to Avoid
Even within a structurally sound garage, numerous interior elements can become dangerous pathways for electrical current if the building is struck directly or if ground current spreads nearby. Lightning energy can easily travel through metal objects, which are abundant in a typical garage environment. This includes tools, metal shelving units, bicycles, and the metallic components of stored vehicles.
Electrical appliances and wiring pose a hazard because lightning current readily follows the electrical system, causing dangerous surges. The motor and tracks of an automatic garage door opener are vulnerable, and contact with the mechanism should be avoided during a storm. Ground current, which spreads outward from a strike site, can travel through a concrete floor, especially if the slab contains metal reinforcing mesh or rebar, or if the concrete is damp. Therefore, avoid lying or sitting directly on the concrete floor and remain insulated from any conductive surfaces.
Safety Verdict and Comparison to Other Shelters
The safety verdict is that a garage is a better option than being outside, but it is not the safest place within a property during a thunderstorm. The safest location remains a fully enclosed, central room within a house, away from windows and plumbing, as the main structure offers greater protection and a more robust grounding system. The garage, due to its large, less structurally reinforced door and proximity to the exterior, is inherently a greater risk than the interior of a home.
A vehicle, if its occupants are fully inside with windows closed, can provide a high level of protection due to the “Faraday cage” effect. This effect directs the electrical current around the metal exterior and into the ground. Therefore, if caught outside, a car is often a safer immediate option than a shed or a poorly grounded detached garage.