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 https://www.osha.gov.

September 25, 1985

Mr. Robert P. Shurkey
Production Services Department
3001 Miller Road, Room 3221
Dearborn, Michigan 48455

Dear Mr. Shurkey:

This is in response to your letter of July 23, 1986, in which you inquired if the Occupational Safety and Health Administration (OSHA) has any prohibition on the use of Presense Sensing Device Initiation (PSDI) light curtains in regard to:

1. Mechanical Power Presses
2. Hydraulic Power Presses
3. Hydraulic Welding Presses

The OSHA standard, concerning the use of presense sensing devices on mechanical power presses at 29 CFR 1910.217(c)(iii)(b), states: "The device may not be used as a tripping means to initiate slide motion." This standard prohibits the use of PSDI on mechanical power presses only.

Hydraulic power presses and hydraulic welding presses are regulated under the standard at 29 CFR 1910.212, General requirements for all machines. 29 CFR 1910.212(a)(1) and (a)(3)(ii) require that effective safeguarding be provided at all hazardous portions of any machine. PSDI is not prohibited. However, the safeguarding aspects of PSDI must be fully effective to prevent employee exposure to the point of operation during the operating cycle.

Employers are cautioned to observe the applicable ANSI standards for safeguarding and to comply with the machine manufacturers' safety requirements.

If we may be of further assistance, please contact us.


John B. Miles, Jr., Director
Directorate of Field Operations