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.

April 12, 1991

Mr. James Kirton
Chief Engineer
LSB Products Inc.
43 Falls Avenue
Waterbury, Connecticut 06708

Dear Mr. Kirton:

Thank you for your inquiry of February 1, concerning the acceptability of the use of a presence sensing device (light curtain) on a mill as the safety controls required by 29 CFR 1910.216(b).

The Occupational Safety and Health Administration (OSHA) will accept protection of employees from hazards when the employer's action provides equal or greater employee protection than an OSHA standard requires. This policy is described in the enclosed section of OSHA Instruction CPL 2.45B, Revised Field Operations Manual.

The ISB light barrier tested and listed by Underwriters Laboratories Inc. (UL) under test outline 491 for fail safe operation may replace or support the safety trip controls on mills or other machinery with machine guarding hazards. The installation and use shall be in accordance with any instruction included in the listing or labelling as required by 29 CFR 1910.303(b)(2). The equipment must also be properly maintained. OSHA cannot give approval in advance of the application of a product, because through improper installation or misuse a hazard may develop.

We appreciate your interest in employee safety and health. If we can be of further assistance, please do not hesitate to contact us.



Patricia K. Clark, Director
Directorate of Compliance Programs