Standard Interpretations - Table of Contents

• Standard Number:

1910.304(d)(1) ; 1910.399

April 5, 2004 Mr. Lee Roop 73 Dasher Avenue Bear, DE 19701 Dear Mr. Roop: Thank you for your November 18, 2003 inquiry to the Occupational Safety and Health Administration (OSHA) regarding the requirements pertaining to locking out disconnect switches for equipment/transformers. This letter constitutes OSHA's interpretation only of the requirements discussed and may not be applicable to any questions not delineated within your original correspondence. We apologize for the delay in our response. Your paraphrased scenario, question, and our response are provided below. Scenario: I have a question about locking out disconnect switches for equipment/transformers which are attached to the main bus duct system in a high-rise building. All of the disconnect switches are protected on all phases with fuses, and they have the ability to be locked open (off) or locked closed (on). The disconnect switches are all located in designated electrical closets, and all maintenance personnel have keys to the locks. Question: Can the disconnect switches be locked in the closed (on) position? Response: There is no provision in the OSHA regulations that prohibits locking the disconnecting means in the closed (on) position. The OSHA rule at 29 CFR 1910.304(d)(1) requires that "the disconnecting means shall plainly indicate whether it is in the open or closed position and shall be installed at a readily accessible location nearest the point-of-entrance of service-entrance conductors." In accordance with 29 CFR 1910.399, readily accessible is defined as "capable of being reached quickly for operation, renewal, or inspections, without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders, chairs, etc." The definition of readily accessible does not preclude the use of a locked door for service equipment or the use of a lock on the disconnecting means, provided those for whom ready access may be necessary have a key (or lock combination) available. Please note, however, that the use of multiple locks or keys on disconnecting switches may preclude the installation from being readily accessible. Thank you for your interest in occupational safety and health. We hope you find this information helpful. 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 http://www.osha.gov. If you need further assistance, please contact the Office of General Industry Enforcement at (202) 693-1850. Sincerely, Richard E. Fairfax, Director Directorate of Enforcement Programs

Standard Interpretations - Table of Contents