Thunderstorms can be dangerous even when you are indoors. While many people know to avoid trees and stay away from windows, fewer realize that lightning can travel through plumbing and electrical systems, making certain everyday activities risky during a storm.
One important precaution is to avoid showering, bathing, washing dishes, or doing laundry while lightning is nearby. If lightning strikes a building or nearby power lines, electrical currents can travel through plumbing and connected metal components. Although metal pipes pose a particular concern, plastic plumbing does not eliminate the risk entirely.
Showers are especially concerning because they involve running water and plumbing systems. The safest approach is to postpone activities involving water until the thunderstorm has passed.
Electrical appliances also require caution. Avoid using devices connected to electrical outlets, as lightning can send dangerous surges through wiring. Corded telephones should likewise be avoided. Cell phones and other wireless devices are generally safe to use during a storm, provided they are not connected to a charger.
Lightning is extraordinarily powerful. According to the National Weather Service, a lightning strike can heat the surrounding air to approximately 50,000°F (27,760°C), causing it to expand rapidly and produce the sound of thunder.
Lightning injuries can occur in several ways, including direct strikes, contact with struck objects, electrical currents traveling through the ground, and side flashes from nearby trees or structures. Even people who are not struck directly can suffer serious injuries.
You can estimate how far away lightning is by counting the seconds between a flash and the accompanying thunder, then dividing the number by five to estimate the distance in miles. For example, a five-second interval suggests lightning is approximately one mile away. However, this calculation should never be used to decide whether it is safe to remain outdoors.
During thunderstorms, stay inside a substantial, enclosed building, keep away from windows and doors, and avoid contact with plumbing and plugged-in electrical equipment. Concrete floors and walls should also be avoided when possible because they may contain conductive metal reinforcement.
Remember that no outdoor location is completely safe during a thunderstorm. Wait at least 30 minutes after the last thunder before resuming outdoor activities. Simple precautions can significantly reduce the risk of lightning-related injuries and help keep you and your family safe.