Thunderstorms are dangerous even when you are indoors, because lightning that strikes a building or nearby power lines can send electrical current travelling through plumbing and wiring. That is why experts advise postponing showers, baths, dishwashing and laundry until the storm has passed.
The risk comes from water and pipes. Metal and even plastic plumbing can conduct current, so standing under a shower or putting your hands in running water during a storm can put you in the path of a surge.
The same caution applies to anything plugged in. Electrical outlets, wired appliances and corded phones should be avoided during a storm, while unplugged mobile and wireless devices are generally considered safe to use.
The safest course is to shelter inside a solid, enclosed building, stay away from windows, doors, plumbing and wiring, and wait at least 30 minutes after the last thunder before heading back outside. A simple rule — if you can hear thunder, you are close enough to be at risk.