All electricity can be dangerous.
Even a battery can cause a fire if you don't use it properly. Mains electricity can give you a bad electric shock because it produces more electricity than a small battery. We measure electricity as something called voltage . High voltages are more dangerous than low ones because they can pass right through your body and upset the way your heart is beating. The heartbeat is controlled electrically and stray electricity messes up the very delicate balance needed to keep your heart beating steadily.