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.

January 7, 1998

Mr. Richard Kramer
Trans-Lux Corporation
P.O. Box 5090
Norwalk, CT 06856-5090

Dear Mr. Kramer:

This is in response to your letter of May 12, 1997, requesting clarification of the Occupational Safety and Health Administration's (OSHA) standard 29 CFR 1910.146 [Permit-Required Confined Spaces (PRCS)] and how it relates to outdoor electric display signs. Please accept our apology for the delay in this response.

In your letter you stated that the outdoor display sign in question meets the definition of a confined space as OSHA defines one, but these signs do not contain any of the hazard characteristics that would require them to be classified as permit-required confined space. Thus, you believe that the signs do not fall under the PRCS standard.

Based on the information provided in your letter, it appears that your determination that these signs are not permit-required spaces is accurate. However, your general statement that the signs do not fall under the requirements of the 1910.146 standard is not accurate. By definition, the sign becomes a non-permit confined space. Paragraph (c)(6) requires employers to reevaluate any non-permit space when there are changes in the use or configuration that might increase the hazard to entrants. Thus, not only does the non-permit space continue to fall under the PRCS standard, but the standard requires employers to look at any procedures taking place in the non-permit space.

Your letter did not address the sign's manufacture or an employee's exposure to hazards during any maintenance activity carried on inside the sign. The following is provided for your information and appropriate action.

During the manufacturing process, when a sign becomes a space meeting the definition of a confined space, the PRCS standard is applicable. As the sign's assembly progresses, the PRCS determination/evaluation must be applied to those processes that would involve hazard characteristics found in the definition of a permit-required confined space. Where the phases and processes of manufacturing are the same for each sign manufactured, a one-time determination for each separate phase should be able to be applied for each subsequent sign manufactured. To illustrate, if the interior surface of the sign is required to be painted, the hazard assessment associated with the painting process would have to be measured against the hazard characteristics of the "permit-space" definition to determine if a permit space exists. Given that the process, materials used, and the spaces are somewhat the same, a single permit-space determination would be appropriate for future signs undergoing the same painting process.

Based on your premise that the manufactured signs is a confined space, any maintenance activity within the sign should undergo a review of the activity and any hazard created by that activity to determine if a permit space condition exists. Employees who would be exposed to mechanical/electrical non-atmospheric hazards can be protected by applying paragraph 1910.146(c)(7). For example, the elimination of electrical power to the sign or breaking linkages of mechanical movements in the signs.

To illustrate a potential atmospheric hazard, the following is provided. In erected signs, where welding is necessary to do the task, and the 1910.252 required ventilation cannot be provided, the metal fume, gases, and smoke hazards associated with the welding process would have to be evaluated to determine if a permit space condition exists.

If you have further questions on this correspondence, please contact Mr. Don Kallstrom of my staff (202) 219-8031 xl09.


John B. Miles, Jr., Director
Directorate of Compliance Programs