When In Doubt, Lock It Out!


In October 1989, the Lockout/Tag-out Standard, 29 CFR 1910.147 went into effect. It was created to help reduce the death and injury rate caused by the unexpected energizing or start-up of machines, or the release of stored energy.

The standard covers the servicing and maintenance of machines and equipment in which the unexpected energizing, start-up or release of stored energy could cause injury [29 CFR 1910.147 (a)(l)(i), 1910.147 (a)(2)(i)]. Normal production operations, cords and plugs under exclusive control, and hot tap operations are not covered [29 CFR 1910.147 (a)(2)(ii)]. This is intended to apply to energy sources such as electrical, mechanical, hydraulic, chemical, nuclear, and thermal.


Lockout is the placement of a lockout device on an energy isolation device (circuit breaker, slide gate, line valve, disconnect switch, etc.) to ensure that the energy isolating device and equipment being controlled cannot be operated until the lockout device is removed. A lockout device utilizes a positive means such as a lock (key or combination type) to hold an energy isolating device in a safe position and prevent energizing a machine or equipment. The lockout device must be substantial enough to prevent removal without use of excessive force or unusual techniques.

Tagout is the placement of a tag-out device (a tag or other prominent warning device and a means of attachment) on an energy isolation device to indicate that the energy isolating device and the equipment being controlled may not be operated until the tag-out device is removed.

The lockout device shall be used unless the employer can demonstrate that the utilization of a tag-out system will provide full employee protection. The tag-out device shall be non-reusable, attached by hand, self-locking, and non-releasing with a minimum unlocking strength of no less than 50 pounds and must be at least equivalent to an all-environment tolerant nylon cable tie.

Written Program

OSHA 29 CFR 1910.147 (c)(4) covers the minimal acceptable written program procedures. It must include the following:

A specific written statement of the intended use of the procedure.

Specific procedural steps are taken for shutting down, isolating, blocking and securing machines or equipment to control hazardous energy. This must be done for each piece of equipment, unless it is a duplicate.

Specific procedural steps for the placement, removal and transfer of lockout devices and the responsibility for them.

Specific requirements for testing the effectiveness of the lockout devices, tagout devices and other energy control measures.

 Training Requirements

Training of employees will be done by an authorized employee [29 CFR 1910.147 (c)(7)(I)]. The affected employees shall be instructed in the purpose and use of the energy control procedure and all other employees whose work operations are or may be in an area where energy control procedures may be utilized. When tag-outs are used, employees must be instructed in the limitations of these devices.

Employee retraining shall be provided for all authorized and affected employees whenever there is a change in their job assignments, a change in machines, equipment or processes that present a new hazard, or when there is a change in the energy control procedures. After January 2, 1990, whenever replacement or major modification of a machine or equipment is performed, and whenever new machines or equipment are installed, energy isolating devices for such machines or equipment shall be designed to accept a lockout device. [29 CFR 1910.147 (c)(2)(iii)]

Removal of Lockout/Tag-out Devices

Before lockout or tag-out devices are removed, the authorized employee shall ensure that non-essential items are removed and machine components are operationally intact. The area should be checked to ensure all employees are safely positioned or removed and all affected employees notified that lockout/tag-out devices have been removed. The lockout/tag-out device must be removed by the person who applied the device. If the person who applied the device is not available, the device may be removed by another employee if the employer has established a specific procedure and training for this. When group lockout/tag-out devices are used, a procedure equivalent to the personal lockout/tag-out system should be followed. (29 CFR 1910.147 (f)(3)]

Since electrical hazards and other forms of stored energy can be found in almost every workplace, there is a good chance that workers can be seriously injured or killed from the accidental start up of machines or equipment. OSHA stated that many workers were killed every year before the passage of this regulation in 1990. Violation of this standard (29 CFR 1910.147) is one of the most commonly cited OSHA violations.

Workers should become familiar with the requirements in a lock-out/tag-out program to protect themselves, as well as co-workers from injuries due to an unexpected start-up or energization of equipment or machinery.

For more information and to obtain copies of the lockout/tag-out standard visit

www.osha.gov. 1910.147

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