Belt Conveyor Emergency Stop Switches

To ensure the safety of personnel in the event of an emergency, all conveyor belts should be equipped with “pull-rope” emergency switches.

These safety switches should be conveniently mounted along conveyor catwalks and right-of-ways and should run the full length of the accessible portion of the conveyor belt. Depending on the design of the conveyor this could be limited to the length of a walkway or the entirety of the belt.

In either case, emergency switches should be included on either side of the belt and should tie directly into the power system so that in an emergency, a pull of the rope interrupts the power to the conveyor, stopping the belt.

Emergency stop switches must be installed correctly and should be inspected regularly.

In 1995, the U.S. Mine Safety and Health Administrations completed a study of 1100 conveyor systems and discovered a 2 percent failure rate for emergency stop switches. When MSHA issued its subsequent warning to mine operators, the agency pointed to five key factors:

1. Spillage around the switch that prevents deactivation of the conveyor
2. Broken pull cords or excessive slack in cords
3. Frozen pivot bearings where the switch shaft enters the enclosure
4. Failure of electrical switches inside the enclosure
5. Incorrect wiring of switch or control circuits

These problems can be addressed through regular monthly servicing and testing drills, similar to school fire drills when maintenance can be performed.