Grab wire switches, or rope pull switches, are a type of emergency stop switch that is hung by a cable around a piece of machinery. They are operated by pulling on the cable, which isolates the circuit connecting the machinery, stopping whatever hazardous action is occurring. They are usually equipped with a reset knob, so that the equipment can only be restarted deliberately.
Grab wire switches are especially helpful when an emergency stop function is needed for an awkwardly-shaped piece of equipment, such as a conveyor. Because they are attached via a cable, they can also be used over a long distance, so any worker along the line may stop the equipment. They switch itself can also equipped with an emergency stop button, which provides another method of stopping the machinery.
Though all grab wire switches operate in broadly the same way, they differ in the length of cable they can accommodate, their maximum current and voltage, and the material they are made from. Some stainless steel switches, for example, may be used in areas where there are hygiene requirements.