Control systems incorporate many kinds of switches and accessories. Control switches serve various control purposes, such as bypass, transfer, multi-step and changeover. These switches come in various types, such as push-button, joystick, toggle switch, twin push-button and more. Load control switches, which include a relay switch and a communication module, can be used to remotely regulate appliances such as air conditioners and water heaters. Load switches also find use in smart grids, to implement demand response systems. Control switches and signaling systems are often installed with accessories such as LED modules and switching contacts. Power switches, such as motor protection switches, ensure rapid shut down of a device or machinery in the event of a short circuit or phase failure. Installation of power circuit breakers may require accessories such as assembly housings and insular casings. Cam switches find common use in industry and building control panels, especially for automation. They monitor and control the work of a wide range of machines, such as air conditioners and construction machinery, and also control various processes. The common accessories for cam switches include neutral leads, interlock extensions and shaft extensions. A limit switch prevents an object from moving beyond a predetermined point. These switches are often installed with accessories such as roller levers and roller cranks.