Lockout/tagout (also called lockout/blockout) means that any energy source, be it electrical, hydraulic, mechanical or any other source that may cause unexpected movement, must be disengaged or blocked, and electrical sources must be de-energized and locked in the off position.
 

In a U.S. Bureau of Labor Statistics survey on injuries related to servicing equipment, 80 percent of workers surveyed failed to turn off the equipment before performing the service work.
 

There is a difference between turning off a machine and actually disengaging a piece of equipment. When turning off a control switch, you are opening a circuit; however, there is still electrical energy at the switch, and a short in the switch or someone turning on the machine may start it running again.
 

Failure to lock out and block out machinery before working on it is a major cause of injury and death in the United States.
 

Workers can be electrocuted or lose fingers, hands, arms, or suffer severe crushing injuries because machinery is inadvertently turned on while being serviced or maintained. These injuries can be prevented by establishing an effective lockout program.

An effective lockout/tagout program should include the following:
 

1. An inspection of equipment by a trained individual who is thoroughly familiar with the equipment operation and associated hazards

2. Identification and labeling of lockout devices
 



3. Purchase of locks, tags, and blocks
 

4. A standard written operating procedure that is followed by all employees
 

NMSU Lockout Program (pdf)