Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at

October 30, 1996



SUBJECT:          Enforcement of 29 C.F.R. 1910.147,
                  the Control of Hazardous Energy (LOTO)

This memorandum provides guidance to Regional Administrators and field staff regarding the enforcement of the LOTO standard following the recent decision in Secretary v. General Motors Corporation, Delco Chassis Division, 89 F.3d 313 (6th Cir. 1996). The Sixth Circuit concluded that the precautions GM used would effectively protect servicing workers from machine hazards even when the machine was restarted without the servicing worker's knowledge. GM addressed the relatively uncommon situation of an employer's use of a multi-step start-up procedure, time delays, and audible warnings to (arguably) enable employees to avoid injury even when the machine was started during the middle of a servicing procedure.

In most workplaces where the LOTO standard applies, enforcement will not be affected by the GM decision because the facts will be dissimilar. Because the Review Commission had reached a similar interpretation to that of the 6th Circuit, however, OSHA can expect that citations will be contested and vacated under facts similar to GM. Therefore, citations should not be issued under circumstances comparable to GM.

If an employer claims that it falls under the GM decision or the Compliance Safety and Health Officer (CSHO) is aware that the employer is relying on precautions in lieu of lockout and tagout procedures, the CSHO must evaluate and document the adequacy and reliability of the particular safety features. Areas of inquiry shall include both 1) characteristics of the equipment, such as, how it is supposed to operate or whether safety devices could be overcome by equipment failure; and, 2) the potential for human error, such as, inadequate employee training or peculiar characteristics of an individual employee that would reduce the effectiveness of safety devices. Also, if the inspection is conducted as a result of an accident, the CSHO should document the type of failure that led to the accident. The following factors should be used as a guide to assess compliance under the LOTO standard:

* The particular configuration and operation of the equipment.

* The nature of the servicing operations which put employees at risk, i.e., the particular procedures that the employees are using, the time during which servicing operations are performed, and the place where the servicing operations performed -- in, on, or around the machine or equipment.

* The ability of the servicing employees to move quickly out of the way of hazardous machine movement if other employees prematurely started the equipment. Put another way, consider the amount of time between the warning signal and the machine's start-up and the amount of time needed by employees to move to safety.

* The ease of operating the machine's safety devices and whether the safety features could easily by circumvented by employees.

* The reliability of the safety features including whether mechanical failure can defeat their function.

* The adequacy of the instructions that are provided to employees regarding the safety features. Employees should also be questioned as to their knowledge and understanding of these instructions.

* Facts peculiar to individuals which might have an effect on the adequacy or reliability of the safety features. For example, an employee's ability to hear and recognize an audible warning signal will depend on factors such as the background noise levels, the strength and pitch of the warning signal, the worker's position relative to the source of the warning signal and other noise sources in the area, and the particular worker's hearing acuity. If the employer relies on visual signals, attention will have to be paid to the direction the worker is facing, any obstructions between the worker and the persons or moving parts that the worker must be able to see, the lighting conditions in the area, and possible deficiencies in the worker's eyesight. For example, a nearsighted employee may be able to service nearby parts without being able to clearly see movements that may be some distance away. Visual signals that are sufficient for a worker with 20-20 vision may, in some instances, be inadequate.

In short, the signaling systems must be effective in warning employees who are exposed to the unexpected release of energy during maintenance and servicing operations. Thus, the above factors must be carefully evaluated and documented. If the CSHO finds no reason to doubt the adequacy and reliability of the employer's precautions, no citation should issue. In situations where precautions similar to those in GM are in use but there is evidence casting doubt on their effectiveness, proposed citations should be approved through the OSHA Regional Office and the Solicitor's Office.