What is a limit switch? A limit switch is a switch that is used to detect or sense motion of an object and if the limits of that object have been exceeded. These are typically used to detect objects on a conveyer, the stroke of a hydraulic lift, opening or closing of an enclosure door, or upper and lower limits of movement of an object. They have many mounting options, are easy to install and maintain, and are simple mechanical switches that have a variety of options for compromised environments. However, because they are mechanical, they will wear out over time and can generally only operate at low to medium speeds.