What is the use of ‘No Trespassing’ signs? To understand them, it is probably worth looking at things from another angle. Every year, hundreds of people die from attempts to enter high voltage electrical substations. Tragic accidents can occur when people throw themselves into perilous adventures such as crossing a crumbling bridge, climbing on a steep hill, swimming in very deep or polluted waters, going to the edge of a cliff, falling on a construction site during dangerous work, etc. Some people are also killed after entering a territory where they were not supposed to be. This list is far from being exhaustive. When we talk about ‘No Trespassing’ signs, people only think of the trespass bans. The main purpose of these signs is to prevent people from putting their lives, or the lives of loved ones, unnecessarily at risk.